HSEHealth & Safety

Executive

Whole-body vibration on agricultural vehicles:evaluation of emission and estimated

exposure levels

Prepared by Silsoe Research Institute and RMS Vibration Test Laboratory for the

Health and Safety Executive 2005

RESEARCH REPORT 321

HSEHealth & Safety

Executive

Whole-body vibration on agricultural vehicles:evaluation of emission and estimated

exposure levels

A J Scarlett, J S Price, D A SempleSilsoe Research Institute

Wrest Park, SilsoeBedford, MK45 4HS

R M StaynerRMS Vibration Test Laboratory

26 Coder RoadLudlow Business Park

Ludlow, ShropshireSY8 1XE

A study was conducted to quantify whole-body vibration (WBV) emission and estimated exposure levels found upon arange of modern, state-of-the-art agricultural vehicles (tractors, self-propelled sprayers and all-terrain vehicles(ATVs)), when operated in controlled conditions (traversing ISO ride vibration test tracks & performing a range ofagricultural operations) and whilst under normal ‘on-farm’ use. The potential consequences of WBV operatorexposure level limitations, prescribed by the European Physical Agents (Vibration) Directive:2002 (PA(V)D), uponagricultural vehicle usage patterns in the UK were also considered.

Agricultural tractor WBV emission levels were found to be very dependent upon the nature of field operationperformed, but less dependent upon vehicle suspension system capability (due to horizontal axis vibration levels).However, this trend was reversed during on-road transport. Virtually all ‘on-farm’ tractors (~95%) exceeded theExposure Action Value (EAV) during an 8-hour working day, requiring implementation of measures to reduce &manage worker vibration exposure. Few (~9%) ‘on-farm’ operations (cultivating & trailer transport) approached orexceeded the PA(V)D WBV Exposure Limit Value (ELV) during 8 hours operation, although this would have increased(to 27%) during longer, more typical working days.

The PA(V)D is unlikely to restrict the operation of large, modern tractors during an 8-hour day, but will become alimitation during certain operations if the working day lengthens significantly. Selfpropelled sprayers exhibited asimilar trend, with the EAV being exceeded in most cases; although working day length would have to reachunsustainable levels (~22 hours) for the ELV to be exceeded. Whilst ATVs exhibited high levels of both WBV andhand-arm vibration (HAV) on occasion, limited daily usage (generally less than 11/2 hours) prevented the (WBV orHAV) ELV being exceeded. Further ‘on-farm’ WBV data collection is required to enable creation of a robust, genericWBV emission database for agricultural vehicle operations. Standardised (ISO) methods of agricultural vehicle WBVmeasurement require further development to permit quantification of the likely effectiveness of tractor WBV-reducingdesign features during in-field operation(s).

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, includingany opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

HSE BOOKS

ii

© Crown copyright 2005

First published 2005

ISBN 0 7176 2970 8

All rights reserved. No part of this publication may bereproduced, stored in a retrieval system, or transmitted inany form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright owner.

Applications for reproduction should be made in writing to: Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk

ACKNOWLEDGEMENTS Silsoe Research Institute & the RMS Vibration Test Laboratory gratefully acknowledge the assistance provided by the Agricultural Engineers Association, CNH (UK) Ltd, JCB Landpower Ltd, John Deere (UK) Ltd, Renault Agriculture Ltd, Househam Sprayers Ltd, Fieldens plc, Honda UK Ltd, Kawasaki Motors UK Ltd, Suzuki GB plc and Yamaha Motor UK Ltd, for the provision of test vehicles. We are also indebted to the large number of farmers who willingly participated in the study: without their assistance and patience this investigation would not have been possible.

iii

iv

CONTENTS

Page No. Acknowledgements iii Contents v Executive Summary ix

1. INTRODUCTION 1 2. AGRICULTURAL VEHICLE REVIEW 3

2.1 Agricultural Vehicle Design Features 3 2.1.1 Operator seat suspension 3 2.1.2 Vehicle cab suspension 4 2.1.3 Vehicle axle suspension 5 2.1.4 3-point linkage dynamic ride control 9

2.2 Agricultural Vehicle Fleet Composition and Usage Patterns 9 2.3 Target Vehicle Identification 14

3. WHOLE-BODY VIBRATION (WBV) MEASUREMENT 15 3.1 European Union Physical Agents (Vibration) Directive 15

3.1.1 Introduction 15 3.1.2 Terminology and implementation 15 3.1.3 Practical implications 20

3.2 Instrumentation 24 3.2.1 Measured parameters 24 3.2.2 PC-based data acquisition 24 3.2.3 PC card recorder data acquisition 28

3.3 Data Analysis 28 3.3.1 ISO test track data 28 3.3.2 SRI ’in-field’ data 29 3.3.3 ‘On-farm’ data 29 3.3.4 Hand-arm vibration (HAV) data 29

4. SELF-PROPELLED SPRAYERS 31 4.1 Test Vehicles 31 4.2 ISO Test Track WBV Emission Measurement 34

4.2.1 Procedure 34 4.2.2 Results 35 4.2.3 Summary 37

v

4.3 SRI ‘In-Field’ WBV Emission Measurement 42 4.3.1 Procedure 42 4.3.2 Results 42 4.3.3 Summary 49

4.4 ‘On-Farm’ WBV Exposure Measurement 50 4.4.1 Introduction 50 4.4.2 Procedure 50 4.4.3 Results 51 4.4.4 Summary 57

5. AGRICULTURAL TRACTORS 59 5.1 Test Vehicles 59 5.2 ISO Test Track WBV Emission Measurement 60

5.2.1 Procedure 60 5.2.2 Results 62

5.3 SRI ‘In-Field’ WBV Emission Measurement 68 5.3.1 Introduction 68 5.3.2 Spraying 68 5.3.3 Ploughing 71 5.3.4 Plough transport 73 5.3.5 Cultivating 74 5.3.6 Trailer transport 77 5.3.7 Summary 81

5.4 ‘On-Farm’ WBV Exposure Measurement 83 5.4.1 Introduction 83 5.4.2 Procedure 83 5.4.3 Results 84 5.4.4 Summary 103

6. ALL-TERRAIN VEHICLES (ATVs) 105 6.1 Test Vehicles 105 6.2 ISO Test Track Vibration Emission Measurement 107

6.2.1 Procedure 107 6.2.2 Results 107 6.2.3 Summary 112

6.3 SRI ‘In-Field’ Vibration Emission Measurement 115 6.3.1 Procedure 115 6.3.2 Results 115 6.3.3 ‘In-field’ and ISO test track performance comparison 116

vi

6.3.4 Comments regarding standardised tests 119 6.3.5 Summary 119

6.4 ‘On-Farm’ Vibration Exposure Measurement 121 6.4.1 Farm description and ATV utilisation 121 6.4.2 Procedure 121 6.4.3 Results 122 6.4.4 Summary 130

7. DISCUSSION 133 7.1 Self-Propelled Sprayers 133 7.2 Agricultural Tractors 136 7.3 All-Terrain Vehicles (ATVs) 141 7.4 Overall 142

8. CONCLUSIONS & RECOMMENDATIONS 149 9. REFERENCES 153 APPENDICES 155

Appendix 1.1 Self-Propelled Sprayer Specifications:– ISO Test Track Programme 155 Appendix 1.2 Self-Propelled Sprayer WBV Emission Data:- ISO Test Track Programme 157

1.2.1 Unladen 157 1.2.2 Laden 161

Appendix 1.3 Self-Propelled Sprayer WBV Emission Data:- SRI ‘In-Field’ Programme 165

Appendix 1.4 Self-Propelled Sprayer ‘On-Farm’ WBV Exposure Data:- Synopsis of Results 167 Appendix 2.1 Agricultural Tractor Specifications:– ISO Test Track Programme 171 Appendix 2.2 Tractor Suspension Seat Specifications 173 Appendix 2.3 Agricultural Tractor WBV Emission Data:- ISO Test Track Programme 175 Appendix 2.4 Agricultural Test Tractor Set-up:- SRI ‘In-Field’ Programme 179 Appendix 2.5 Agricultural Tractor WBV Emission Data:- SRI ‘In-Field’

Programme 183 Appendix 2.6 Agricultural Tractor WBV Emission Data:- SRI ‘In-Field’ - Trailer Transport 184

vii

Appendix 2.7 ‘On-Farm’ Agricultural Tractor Cab Floor WBV Emission Data 185 Appendix 2.8 Agricultural Tractor ‘On-Farm’ WBV Exposure Data:- Synopsis of Results 186

2.8.1 Suspended Cab & Front Axle Tractor 186 2.8.2 Fully Suspended (Front & Rear Axle) Tractor 197

Appendix 3.1 ATV WBV & HAV Emission Data:- ISO Test Track Programme 209 Appendix 3.2 ATV WBV & HAV Emission Data:- SRI ‘In-Field’ Programme 213 Appendix 3.3 ATV ‘On-Farm’ WBV & HAV Exposure Data:- Synopsis of Results 215 Appendix 3.4 ATV ‘On-Farm’ WBV Programme:- Forward Speed & Operator Seat Presence Details 219 Appendix 4. Estimating WBV Exposure from Measured Data:- Particular Issues 225

viii

EXECUTIVE SUMMARY The overall objective of this investigation was to determine currently achievable Whole-Body Vibration (WBV) emission and exposure levels associated with representative ‘state-of-the-art’ agricultural vehicles. For each of the test vehicles WBV levels have been measured in three generic test situations; namely whilst:-

• traversing standard ISO 5008:2002 ride vibration test tracks; • performing typical agricultural field operations in representative, controlled

field conditions (‘in-field’); • performing the same range of field tasks during normal operation on working

farms (‘on-farm’). Additionally, the investigation has considered the consequences, for agricultural vehicle usage patterns in the UK, of prescribing limits for operator daily exposure to WBV, as specified by the European Union Physical Agents (Vibration) Directive (PA(V)D). The investigation has targeted three generic types of agricultural vehicle: self-propelled sprayers; all-terrain vehicles (ATVs); and agricultural tractors, the latter whilst performing typical agricultural tasks (‘in-field’ and ‘on-farm’) with a range of attached implements (spraying / fertiliser spreading, cultivating, ploughing, plough transport, and tractor-trailer transport). Two comparable 2500 litre-capacity, self-propelled sprayers have been investigated, one embodying an advanced design of (self-levelling, air spring) axle suspension system. The vehicles were compared in terms of WBV emission levels, measured both upon the cab floor and the operator’s (suspension) seat, whilst performing a range of ‘back-to-back’ tests, both upon the ISO track and in controlled ‘in-field’ conditions. WBV emission and operator exposure levels were then recorded upon three ‘on-farm’ examples of the advanced machine during typical usage over ½ day (~4-hour) periods. A similar procedure was followed during assessment of the agricultural tractors, with the exception that four state-of-the-art 4-wheel-drive vehicles in the 90-130 kW engine power range were considered, each embodying a different level of (cab and/or axle) suspension system complexity (each incorporated an operator’s suspension seat). The tractor suspension systems included:-

• unsuspended;

• suspended cab;

• suspended front axle & cab;

• fully suspended (front & rear axle). Cab floor and operator’s seat WBV emission levels were recorded upon each vehicle whilst traversing both (‘smoother’ and ‘rougher’) ISO 5008 ride vibration test tracks, at a range of forward speeds. WBV levels were subsequently measured upon each machine in turn, whilst performing the abovementioned range of operations in controlled ‘in-field’ operating conditions. Finally, cab floor and operator’s seat WBV emission levels, and operator ~4-hour WBV exposure levels were determined upon 11 ‘on-farm’ examples of the suspended front axle & cab tractor, and a corresponding number of the fully suspended (front & rear axle) tractor. These vehicle variants being selected as being representative of the current leading edge of popular agricultural tractor suspension system design, and having demonstrated marginally superior ride comfort to that of the other test tractors during the majority of ‘in-field’ test operations.

ix

ATVs (quad bikes) were evaluated in a similar manner, whilst traversing the ISO track (100 m ‘smoother’ track only), in controlled ‘in-field’ conditions, and ‘on-farm’. However a marked difference was that vibration levels were measured upon the operator’s seat (saddle), one of the footrests (having first established its representative nature), and upon both handlebars (to assess hand-arm vibration emission levels). Four vehicles in the popular 300-400 cc engine capacity range were selected, each embodying a different degree of axle suspension system complexity, each being subjected in turn to ISO track and ‘in-field’ test programmes. Three examples of one machine variant were subsequently targeted during subsequent ‘on-farm’ emission / exposure measurements. The PA(V)D stipulates daily vibration exposure criteria in the form of an employee daily Exposure Action Value (EAV), above which actions for reduction of vibration exposure must be taken, and an Exposure Limit Value (ELV) which must not be exceeded. Daily exposure in excess of the EAV requires the implementation of measures to reduce and manage worker vibration exposure, as proposed by the Directive (see Section 3.1.3). It should be stressed that the WBV Exposure Limit Value (ELV) should not be considered a ‘safe’ level of vibration exposure in the workplace, but rather as a high, undesirable level of vibration exposure (and a legal threshold) to be avoided at all costs. It is for this reason the Directive requires action to be taken, so far as is reasonably practicable, to minimise vibration exposure once levels exceed the Exposure Action Value (EAV); Virtually all the agricultural vehicle operations investigated, involving modern, state-of-the-art tractors, self-propelled sprayers or ATVs, will result in operator WBV daily exposure exceeding the PA(V)D Exposure Action Value (EAV) during a normal working day (see Table ES.2), thereby requiring the implementation of vibration reduction / management measures. Following the stipulations of the Directive, the daily WBV exposure levels encountered upon the agricultural vehicles targeted by the investigation, and the extent to which they may affect typical daily usage, sub-divide into three broad categories (see also Tables ES.1 & ES.2 attached):-

• Vehicle-operations that generate sufficiently low WBV levels, such that the ELV is unlikely to be exceeded even if the working day length exceeds 8 hours. This scenario applies to self-propelled sprayers, and tractors whilst spraying / fertiliser spreading, whilst transporting ploughs (on farm tracks & roads), and ploughing conducted in favourable operating conditions;

• Vehicle-operations, whose (moderate - high) WBV levels may cause operator daily exposure to approach or reach the ELV during 8 hours operation, but will cause the ELV to be reached and/or exceeded if the working day lengthens significantly (~12 – 14 hours). This scenario was found to apply to agricultural tractors whilst cultivating medium to rough stubble ground, whilst performing tractor-trailer transport operations, and possibly (on occasion) whilst ploughing;

• Vehicle-operations that generate high WBV levels, but the (apparently typical) short duration of daily use (less than 2 hours per day) ensures that operator daily exposure does not exceed the ELV. However, this would not be the case if daily operating duration were to increase. This scenario applied to the ATVs investigated, but in these particular instances hand-arm vibration exposure could on occasion become a limiting factor.

x

Table ES.1 Relative WBV magnitudes arising from agricultural tractor operations performed during the SRI ‘in-field’ investigation

WBV Emission Level (energy-equivalent continuous (overall average) r.m.s. acceleration)

Low Moderate High

Ploughing Cultivating (rough ground) Spraying / Fertiliser Spreading

Plough Transport Trailer Transport

Table ES.2 Summary of ‘on-farm’ agricultural vehicle operations investigated

Likelihood of Exceeding Value in a Normal

Working Day:- Vehicle / Activity

Seat overall average r.m.s.

(Aeq) WBV level (m/s2)

Time to EAV (A(8))

(hrs:mins)

Time to ELV (A(8))

(hrs:mins)

Average Working

Day (hrs) EAV ELV

S.P. Sprayer 0.53 – 0.69 4:12 – 7:7 22 - >24 10.1 Yes No

Tractor – Spraying 0.36 – 0.78

(0.5 – 0.74)

3:17 – 15:26 17:23 - >24 8.9 Probably No

Tractor - Ploughing 0.49 – 0.93

(0.73 – 0.89)

2:19 – 8:20 12:14 - >24 8.9 Yes Unlikely

Tractor – Trailer Transport

0.47 – 1.12

(1.05 – 1.32)

1:36 – 9:3 8:26 - >24 8.9 Yes Possibly

Tractor – Cultivating 0.53 – 1.39

(1.2 – 1.49)

1:2 – 7:7 5:29 - >24 8.9 Yes Possibly

ATV 0.85 – 1.39 1:2 – 2:46 5:29 – 14:39 1 - 2 Possibly V.unlikely

NB:- Tractor WBV data in parentheses originates from SRI ‘in-field’ measurements (performed in controlled field conditions) and encompasses all tractor suspension system designs investigated;

All other WBV data above relates to ‘on-farm’ measurements and, in the case of tractors, only includes suspended front axle & cab, and fully suspended (front & rear axle) tractor models.

The requirements of the Directive, as expressed via the ELV can potentially restrict agricultural vehicle daily operating durations in instances of potentially high daily vibration exposure. In the majority of instances it appears unlikely that it will have significant impact upon current usage patterns of modern, state-of-the-art agricultural vehicles in the UK. Over 50% of the ‘on-farm’ tractors / operations surveyed would have to work for approaching 24 hours per day to

xi

exceed the ELV. However, longer shifts, extending to 12 – 14 hours per day, which are common at peak times in agriculture, would result in over 25% of the large, modern ‘on-farm’ tractor-operations surveyed causing the ELV to be exceeded. Also, it is possible that WBV emission levels upon older and/or smaller vehicles may be greater than those reported here, requiring careful selection of appropriate machines for given tasks. However, perhaps such machines will not be subjected to daily operational periods of the magnitudes expected of newer vehicles. Differences between overall average (Aeq) WBV emission levels generated by individual tractor (axle and cab) suspension designs, operating in controlled ‘in-field’ conditions, were generally found to be less than those evident between the different agricultural operations performed (spraying / fertiliser spreading, ploughing, plough transport, cultivating, trailer transport), particularly when evaluated by the ‘largest single weighted axis’ (ISO 2631-1:1997 ‘Effect of Vibration on Health’) methodology favoured by the Directive. However, WBV exposure levels evident during ‘on-farm’ agricultural vehicle operations were found to vary by as much as ±50% or more for the same task (see Table ES.2) depending upon ground conditions, driving technique and operational requirements (‘the need for speed’). This is much greater than the likely differences in WBV levels generated by alternative types (capabilities) of tractor cab and/or axle suspension system, whilst operating in similar conditions. Developments in suspension system design were shown to reduce the WBV emission levels of self-propelled sprayers. Developments in tractor (cab and axle) suspension systems appear to yield improvements in subjective ride comfort: a fact confirmed by evaluation of cab floor and operator seat WBV levels by the vector sum (RSS) method. The latter suggested the ride comfort of the fully suspended (front & rear axle) tractor and the suspended front axle & cab tractor to be marginally superior to that of the other test vehicles in the majority of instances. Cab floor WBV levels derived by the largest single axis method displayed a similar trend between tractor designs, but this was not so apparent amongst operator seat WBV values derived by the technique: and the latter are, of course, the WBV emission levels from which operator daily exposure would be derived. The Directive requires WBV levels in each axial direction to be assessed separately, and the axis with greatest (overall average) magnitude be identified. However, action is required to reduce exposure to vibration in all axial directions in which the EAV is exceeded (see Section 7.4). A given vehicle / application may exhibit high overall average longitudinal (X) or transverse (Y) axis WBV levels, whilst significant peak acceleration events (shocks and jolts) are generated in one or more of the other axial directions, and are possibly not well represented by the r.m.s. (A(8)) evaluation method. During the majority of self-propelled sprayer and tractor-implement operations, largest (overall average, axis weighted) WBV magnitudes were generated in the transverse (Y) axis: during tractor-trailer transport the longitudinal (X) axis WBV took precedence. However, maximum peak acceleration levels frequently occurred in the vertical (Z) axis, and vertical (Z) axis WBV levels dominated ATV operation. Certain methodologies employed by the Directive give rise to debate. The apparent importance of horizontal (X & Y) axes WBV levels reported in this investigation is undoubtedly accentuated (and arguably distorted) by use of the ‘largest single weighted axis’ (ISO 2631-1:1997 ‘Effect of Vibration on Health’) methodology, arguably employed without adequate justification. Were 1.4x multiplying factors not applied to horizontal vibration components, vertical (Z) axis WBV levels would be the largest for a greater number of the vehicles / operations surveyed. For agricultural operating conditions, there is little equivalence between the 8-hour energy-equivalent, frequency-weighted r.m.s. acceleration (A(8)) and vibration dose value (VDV)

xii

methods of WBV exposure assessment, as specified by the Directive. This is because the equivalence is based upon the estimated vibration dose value (eVDV), and the requirements for using eVDV are not met by the WBV encountered in real agricultural conditions. In agricultural operating conditions the A(8) EAV and ELV appear to be less stringent (equate to longer operating durations) than their VDV-specified equivalents. If a comprehensive, generic database of agricultural vehicle WBV emission levels is deemed desirable, to provide farmers with adequately robust data to enable estimation / calculation of likely WBV daily exposure levels (as required by the Directive), and/or to identify the possible need for workplace measurement of WBV exposure levels, where these may approach the ELV (see Table 7.3), then a more comprehensive WBV exposure data gathering exercise will be required, embodying a greater number of measurement replications. This issue is particularly pertinent to tractor-implement operations, which typically generate WBV daily exposure levels between the EAV and ELV (see Table ES.2). Such a database would be of considerable value, enabling an employer to target specific operations of concern in greater detail (workplace exposure measurement), whilst permitting recommended WBV estimation / calculation techniques to be used for other (lower exposure level) operations, with confidence. Use of ISO 5008 ride vibration track tests provide a reasonable basis for comparison of self-propelled sprayer WBV emission levels, but for agricultural tractors the resulting data bears little resemblance to WBV levels measured under ‘in-field’ or ‘on-farm’ conditions. This is largely because of the lack of attached implements or trailers and consequent differences in vehicle mass, weight distribution, tyre inflation pressures and external force systems acting upon the vehicle. Consequently, current test track techniques require development / adaptation to improve their suitability for tractor-implement combination WBV emission assessment. Such developments would ideally deliver standardised testing methodologies, capable of quantifying the likely effectiveness of tractor WBV-reducing design features when operating in typical agricultural conditions (discussed further in Section 7.2). Finally, in the case of ATVs, hand-arm vibration exposure is more likely to restrict vehicle daily operating duration (due to exposure in excess of the ELV), rather than exposure to whole-body vibration. The slatted construction form of the ISO 5008 test track is inappropriate for ATVs, because of vibration generated by the inter-slat spacing. The suitability of the alternative moulded concrete type of track has not as yet been evaluated.

xiii

xiv

1. INTRODUCTION It has been widely recognised for a number of decades, that whole-body vibration (WBV) is a major source of discomfort for agricultural tractor operators during typical farm operations (Matthews, 1966; Stayner & Bean, 1975; Bovenzi & Betta, 1994; Lines et al., 1995). Engineering solutions to reduce WBV levels experienced by agricultural vehicle operators are commonplace, historically in the guise of spring suspension seats (see Section 2.1.1), but more recently in the form of cab and/or axle suspension systems (see Section 2.1.2 & 2.1.3). Whilst these measures have undoubtedly reduced vehicle WBV emission levels, increased annual utilisation of fewer, larger vehicles in UK agriculture has conspired to increase likely exposure durations for many operators. The situation is further complicated by the absence of a detailed and reliable quantitative dose-response relationship between WBV exposure and the development of lower-back disorders. Nonetheless, strong evidence exists linking both WBV exposure to ill health, and increasing levels of exposure to an increased risk to health. Minimising WBV exposure is therefore highly desirable, although until recently legislation has not existed to attempt to limit the daily exposure of workers to WBV in the workplace, thereby protecting against the possibility of vibration-induced spinal injury. The European Union Physical Agents (Vibration) Directive (EU PA(V)D, 2002) (see Section 3.1) attempts to address this shortfall by specifying both practical limits for daily personal vibration exposure, and (lower) levels above which employers should take steps to reduce exposure. However, there are widespread concerns within the UK that the Directive will limit WBV daily exposure levels for operators of agricultural and other off-road vehicles, thereby potentially requiring alterations in vehicle usage patterns at a time when the farming industry is under severe economic pressure. It was therefore in the interest of employers, vehicle manufacturers and the Health and Safety Executive (HSE) to ensure that the proposed legislation was both adequate (in terms of operator protection) and realistic (in terms of practical implementation) prior to its introduction in the Member States (proposed 2007 for new agricultural & forestry vehicles; 2005 for all other new vehicles). Consequently, the overall objective of this investigation was to determine currently-achievable Whole-Body Vibration (WBV) emission and exposure levels associated with representative ‘state-of-the-art’ agricultural vehicles, both whilst traversing standard ISO ride vibration test tracks and whilst performing typical agricultural operations, the latter in both representative controlled field conditions and during normal operation on working farms. Additionally, the investigation proposed to consider the consequences of prescribing limits for operator WBV daily exposure, upon agricultural vehicle usage patterns in the UK. The investigation targeted three generic types of agricultural vehicle (self-propelled sprayers, all-terrain vehicles (ATVs), and agricultural tractors), the latter whilst operating (‘in-field’ and ‘on-farm’) with a range of attached agricultural implements. Details regarding the design, selection and evaluation of these vehicles are given in the following Sections. It is to be expected that agricultural vehicle operators will be exposed to WBV levels above the (PA(V)D-specified) Exposure Action Value in almost all tasks during typical working days. The work presented here indicates the extent to which the Directive may impinge on modern farming operations, by possibly restricting the working day length of certain machines / tasks, unless daily vibration exposure levels can be reduced even more than at present. The latter possibly being achievable by further developments in machine design (for enhanced operator comfort) and/or by informed changes in vehicle driving or operating practice / techniques on farms.

1

2

2. AGRICULTURAL VEHICLE REVIEW 2.1 AGRICULTURAL VEHICLE DESIGN FEATURES As previously stated, it is widely recognised that agricultural tractor operators are exposed to high levels of whole-body vibration (WBV) during typical farm operations. Low-frequency tractor ride vibration, the resultant problem of driver discomfort and the possibility of spinal injury, first became recognised issues during the 1960’s. Since that time the majority of agricultural tractors have incorporated one or more design features that attempt to reduce the levels of WBV experienced by the operator. This vibration reduction ‘technology’ has subsequently been transferred to other self-propelled agricultural machines as the latter became commonplace during the 1970’s and 1980’s. The following sections review these features found on current, state-of-the-art tractors and other agricultural vehicles. 2.1.1 Operator seat suspension Suspension seats have been an almost universal feature of agricultural tractors throughout the last 30 years, being a mandatory requirement upon wheeled agricultural and forestry tractors in Europe since 1978 (EEC, 1978). Primarily introduced to improve driver comfort, thereby reducing fatigue and improving productivity (e.g. higher vehicle forward speeds on rough ground; preparedness of operators to work longer daily periods at peak times), suspension seats were rapidly recognised by employers and workers alike as being a worthwhile investment, especially coupled with the introduction of other driver comfort-enhancing features, such as low-noise level tractor cabs, during the mid-1970’s. The effectiveness of some early suspension seat designs may have left something to be desired, but their ability to attenuate the extreme peak accelerations so common in tractor ride, was indisputable. Early suspension seats of the late 1960’s and early 1970’s, which provided suspension solely in the vertical (Z) axis, mainly utilised adjustable rubber-in-torsion or tension coil spring suspension elements, together with telescopic hydraulic dampers, giving simple vertical movement. Later designs, some utilising adjustable mechanical torsion springs, incorporated low-friction ‘scissor’-type suspension linkages, giving true vertical (Z) axis movement and adjustable ride height. Many modern tractor seats still utilise this basic design, albeit higher specification models use air springs which are readily adjustable to the operator’s weight, in place of the earlier mechanical suspension elements. Current off-road vehicle seats are produced almost exclusively by specialist ‘Original Equipment Manufacturers’ (OEMs). The majority of modern seats commonly fitted to medium – high-powered tractors incorporate (adjustable) air spring & (adjustable) damper suspension systems in the vertical (Z) axis, and (fixed) mechanical spring & (fixed) damper systems in the longitudinal (X) axis (see Table 5.2), the latter in an attempt to attenuate vehicle pitch acceleration. Certain manufacturers also offer similar (fixed) mechanical spring & (fixed) damper suspension systems in the transverse (Y) axis, vehicle lateral ‘roll’ being a major source of WBV as tractors become larger and seat positions become higher relative to the vehicle roll centre. However, limited cab internal width and seat proximity to side-mounted controls, restrict available suspension system movement in this direction, thereby limiting the scope of this albeit desirable feature. One of the most recent developments in agricultural tractor seating was introduced by John Deere in 2002. The John Deere ‘Active Seat’ utilises combined (parallel) electro-hydraulic and air suspension systems, featuring electronic sensing and electro-hydraulic control of ride height, plus automatic sensing of seat top (vertical) acceleration (via an integral accelerometer), effecting dynamic adjustment of seat suspension system stiffness in response to the accelerometer output. In combination,

3

these features are designed to reduce driver WBV still further, reductions in Z-axis weighted r.m.s. acceleration (in comparison with a typical air suspension seat) of over 65% being claimed by the manufacturers (Dufner & Schick, 2002). Tractor suspension seat technology has been progressively transferred to other self-propelled agricultural machines (e.g. sprayers, forage harvesters, combines), although many of these machines do not experience the same rough operating conditions / ride vibration levels as agricultural tractors in the majority of applications. Smaller vehicles (e.g. garden tractors, ride-on lawn mowers, all-terrain vehicles (ATVs)) typically do not incorporate suspension seats, either due to seat (relative to vehicle) cost or incompatible vehicle design (lack of space for installation). 2.1.2 Vehicle cab suspension The logical method of reducing ride vibration levels upon any vehicle is to introduce one or more suspension systems between the vehicle vibration source and the operator. The majority of whole-body vibration present upon tractors is ground-induced. The basic requirements of a tractor, namely to pull draught (soil-engaging) implements, to provide a stable mounting platform for carried implements, and to provide high levels of traction in adverse, off-road conditions (i.e. incorporate large diameter tyres), together with the historic ‘unitary’ structural engine-transmission-rear axle construction method, makes the incorporation of an effective axle suspension system a significant (and costly) design challenge. Consequently, many tractor manufacturers, having embraced the ride vibration reduction benefits of suspension seats, regarded incorporation of vehicle cab suspension as the logical (and potentially most economic) next step. Experimental tractor cab suspension systems were developed by a number of research institutes / universities during the 1970’s, initially as proof-of-concept systems (Stayner et al., 1975). Having achieved worthwhile reductions in operator WBV levels, subsequent systems were developed to facilitate simple, economic incorporation into tractor designs of the period (Lines et al., 1989). Regrettably, at that time (late-1980’s), few tractor manufacturers considered provision of tractor cab suspension systems, however effective, to be justified by European market demand. Consequently no ‘global’ tractor manufacturers (e.g. Ford, John Deere, Massey Ferguson, International Harvester) offered this feature during the next 10 years, the only exception being Renault. Today (2003) every ‘mainstream’ tractor manufacturer either offers some form of cab suspension system, or is rapidly in the process of developing a system to meet perceived market demand! The Renault ‘Hydrostable’ cab suspension system (see Figure 2.1) was the first, mass-produced tractor cab suspension system and is the most numerous in use, having been available on many tractor models since 1987. A true ‘full’ suspension system, combined coil spring & telescopic damper units (4) support the cab upon each corner (3); cab lateral location is provided by transverse Panhard rods front and rear (5), and twin longitudinal struts (7) provide longitudinal location. A rear-mounted anti-roll bar (6) limits cab (Y-axis) roll. The majority of other European tractor manufacturers have opted for simpler cab suspension systems in which the rear of the cab is suspended from the tractor rear axle, but the front pivots on anti-vibration rubber mountings; lateral location at the rear being provided by a Panhard rod(s). This approach is typified by the New Holland ‘Comfort Ride’ cab suspension system, as fitted to the New Holland Series TM tractors (see Figures 2.2 & 2.3). Some manufacturers utilise air-over-oil suspension elements in these systems, thereby permitting control of cab ride height with operators of different mass. However, the majority of

4

manufacturers choose the simpler combined mechanical spring-hydraulic damper solution, as used by New Holland (see Figure 2.3).

Figure 2.1 Renault ‘Hydrostable RZ’ cab suspension system (courtesy Renault) 2.1.3 Vehicle axle suspension As previously discussed, during the 1980’s many tractor manufacturers viewed tractor axle suspension as a complex design challenge of dubious economic benefit. Experimental, proof-of-concept tractor front axle suspension systems were developed by a number of research institutes and universities during the 1970’s and 1980’s, frequently in conjunction with ‘global’ tractor manufacturers. These experimental systems, as typified by Peachey et al. (1989), met with considerable success, the Silsoe Research Institute (then NIAE) example undergoing extended practical evaluation on working farms. The majority of systems provided suspension of the tractor front axle only, this being a simpler and cheaper modification of the two-wheel-drive tractors which comprised the majority of 1970’s sales. Provision of rear axle suspension was a considerably more complex task, given variable weight transfer onto the rear axle from mounted implements and the characteristic unitary construction of tractors of that period. The Trantor vehicle, developed and marketed in the 1970’s, proved that a fully suspended (front & rear axle) tractor was feasible. However, the vehicle suffered from a number of design and component availability restrictions, and arguably preceded market demand: it consequently failed to become a commercial success. Other fully suspended vehicles, such as the Unimog, were marketed in agriculture, but failed to satisfy all requirements placed upon the typical agricultural tractor. (continued)

5

Figure 2.2 New Holland Series TM tractor ‘Comfort Ride’ cab suspension system

(courtesy CNH)

Figure 2.3 New Holland ‘Comfort Ride’ cab suspension system (detail) (courtesy CNH)

6

Figure 2.4 JCB Fastrac chassis and suspension system (courtesy JCB)

2.1.3 Vehicle axle suspension (continued) JCB took up the challenge in the late 1980’s, culminating in the launch of the ‘Fastrac’; a fully suspended, four-wheel-drive (4wd) vehicle capable of performing all tractor-type draught operations and travelling legally (and safely) at up to 65 km/h (40 mph) on the road. Unhindered by previous construction practices, JCB designed a fully suspended vehicle first (arguably drawing much upon commercial vehicle design principles), and subsequently made it perform adequately as an agricultural tractor. Departing from the unitary method of construction, driven axles were attached, via suspension components, to a ‘ladder’-type chassis (see Figure 2.4). Radius arms, coil springs, telescopic dampers and a Panhard rod (not shown) provide front axle location / suspension. A self-levelling hydro-pneumatic suspension system supports the rear axle, upper and lower radius arms providing axle location. Anti-roll bars (not shown) are fitted to both front and rear axles to provide lateral roll stability. The rear 3-point linkage system and trailer hitch attach directly to the rear axle. Over a decade on, with an unchanged basic design and a range comprising six models, JCB can justly claim the Fastrac to be the most successful fully suspended agricultural tractor produced to date. Whilst no other major tractor manufacturers have yet launched a fully suspended vehicle in Europe in direct competition with the Fastrac, during the last 4 years there has been a widespread introduction of ‘optional’ front axle suspension systems on 4wd tractors of otherwise ‘conventional’ design, especially above ~70 kW engine power. Indeed, market demand for this feature is such that front axle suspension and cab suspension systems may almost be regarded as standard product offering on frontline (high utilisation) arable farm tractors in Europe today. ‘Conventional’ 4wd tractor front axle suspension systems are typified by those offered by New Holland and John Deere (see Figures 2.5 & 2.6 respectively). Both utilise self-levelling air-over-oil (hydro-pneumatic) suspension elements, powered by the tractor hydraulic system and providing both springing and damping functions. Longitudinal axle location is provided

7

by a pivoting, tubular radius arm that encases the front axle driveshaft, its rear end being attached to the centre of the tractor chassis via a spherical bearing. A Panhard rod effects axle lateral location, but the axle is free to oscillate in a similar manner to an unsuspended design, no anti-roll functionality being provided. Certain manufacturers (Steyr, Massey Ferguson, McCormick, John Deere (8020 Series)) utilise independent ‘wishbone’-type front axle suspension systems, dispensing with the conventional ‘live’ front axle and embodying universal-jointed driveshafts to the front wheels. Whilst an interesting solution to the problem, it is not known whether this approach delivers any benefits over other ‘live’ front axle suspension designs. It is debatable whether the recent introduction of ride-comfort enhancing features, such as front axle and cab suspension systems, would have been quite so widespread had it not been for the commercial competition provided by the JCB Fastrac. In any case, the vehicle operator can only benefit from the greater availability of this technology

Figure 2.5 New Holland ‘Terraglide’ front axle suspension system (courtesy CNH)

Figure 2.6 John Deere ‘Triple Link Suspension’ (TLS) front axle suspension system

(courtesy John Deere)

8

2.1.4 3-point linkage dynamic ride control This feature is almost exclusive to agricultural tractors, as indeed is the 3-point (3pt.) implement attachment linkage system of which it is a feature. Harry Ferguson developed the 3pt. hydraulic linkage, as a means of attaching or ‘mounting’ soil-engaging implements onto tractors, in 1925. Since then it has become a universal feature of agricultural tractors throughout the World. During the late-1980’s the implement (draught force and position) sensing and hydraulic control components of many 3pt. linkage systems were upgraded by the incorporation of microprocessor-based electronics (e.g. Bosch EHR-D system). This revolution permitted the subsequent development of other 3pt. linkage features, amongst them dynamic ride control. The basic principle of dynamic ride control is that during road/track transport with mounted implements, particularly long, heavy equipment such as fully-mounted ploughs, a substantial proportion of tractor pitch (X-axis) acceleration results from the dynamic movement of the implement in the vertical (Z) axis. These forces are transferred from the implement to the tractor chassis via the 3pt. linkage, which (fortuitously) incorporates electronic force sensors as part of the draught control system. Dynamic ride control systems sense the magnitude of these dynamic forces and dynamically modulate the hydraulic pressure in the 3pt. linkage lift cylinder(s), thereby permitting the implement to lower/raise slightly relative to the tractor at critical moments in the combination’s (relatively slow) pitching cycle, effectively operating as an active suspension system between the tractor and mounted implement. An effective dynamic ride control system can substantially reduce the ride vibration of a tractor-implement combination during transport. Unfortunately, current systems are unable to determine the position of the implement’s centre of gravity: an important factor in the performance of the system. Consequently, the majority of systems are optimised for long, heavy mounted implements, for which they are indeed most needed, but they perform less effectively with shorter/wider implements. However in the latter instances, vehicle pitching during transport is a lesser problem. 3pt. linkage dynamic ride control is a standard feature on the majority of European tractors over 75 kW engine power and was present upon all the tractor models evaluated during this investigation. 2.2 AGRICULTURAL VEHICLE FLEET COMPOSITION AND USAGE

PATTERNS Agricultural vehicle usage patterns, in general, reflect changes in both the nature and prosperity of agriculture as a business. To that end the following comments are, admittedly, based purely upon an interpretation of available facts, to enable derivation of the desired information: they also relate solely to the UK. Reductions in the value of most arable commodities (e.g. wheat, oilseed rape) during the last 3 years have significantly reduced UK arable farm profitability, many enterprises reaching the verge of commercial viability. Figure 2.7 illustrates that during the 1987 – 2000 period, the number of UK agricultural holdings diminished significantly across both arable and livestock sectors: however, those remaining increased in both size (see Figure 2.8) and productivity. Farm enterprise structure has also changed, with moves towards operational amalgamation of enterprises, as typified by corporate / contract farming arrangements in the arable sector, in order to optimise utilisation of larger, more productive machinery and spread labour costs over larger cropped areas, thereby reducing Fixed Costs. However, during the period in question, farm labour force reductions have not been restricted to the arable sector; the number of workers employed in the industry having reduced by 35% (DEFRA, 2001).

9

Figure 2.7 Change in number of UK agricultural holdings: 1987-2000

-70

-60

-50

-40

-30

-20

-10

0

10

Crops &Grass

Cereals OilseedRape

Potatoes Sugar Beet Dairy Cows Beef BreedingSheep

BreedingPigs

Broilers

% C

hang

e: 1

987

- 200

0

0

10

20

30

40

50

60

70

80

90

100

110

120

130

Crops &Grass

Cereals OilseedRape

Potatoes Sugar Beet Dairy Cows Beef BreedingSheep

BreedingPigs

Broilers

% C

hang

e: 1

987

- 200

0

Figure 2.8 Change in UK holding average cropped area / herd size: 1987-2000

These changes have, to an extent, been offset by corresponding changes in agricultural machinery and associated working practices. Agricultural tractor sales are recognised by the industry as an accurate indicator of mechanisation trends, particularly in the arable sector. The 1987 – 2001 period witnessed a substantial reduction in tractor unit sales (see Figure 2.9), but this was largely offset by significant rise in the average size (engine power) of vehicles sold (see Figure 2.10). Although this trend may have stabilised in recent years (2000 – 2002), numbers of medium / large (100 – 160 hp) four-wheel-drive tractors sold has continued to increase (see Figure 2.11), indicating that today’s agricultural industry uses fewer, larger, more productive machines, frequently selected to enable labour force reductions. Whilst such equipment generally embodies higher technological content and improved levels of operator comfort (see Section 2.1), its higher purchase price necessitates greater annual usage in order to offset cost of ownership.

10

0

5

10

15

20

25

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year of manufacture

Trac

tors

sal

es>

40 h

p (th

ousa

nds)

Figure 2.9 UK sales of agricultural tractors (above 40 hp)

60

70

80

90

100

110

120

130

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year of manufacture

Aver

age

hors

epow

er o

f tra

ctor

s >

40 h

p

Figure 2.10 Average engine power of tractors (above 40 hp) sold in the UK

Although independent data is not available to support the view, it is widely recognised within the agricultural engineering industry that annual, and particularly daily, usage levels of higher capacity / higher cost machines has increased significantly, especially given that many customers are large farming enterprises and/or agricultural contractors. Today many front line agricultural tractors complete 2000 hours work per year, whereas two decades ago usage

11

exceeding 1,000 hours per year was considered intense. For example a typical contractor would now wish to operate a self-propelled sugar beet harvester (and associated tractors / trailers) for at least 70 hours per week during the October – February period. Consequently, more acres (hectares) are being farmed by fewer enterprises, using fewer men. Whilst the proportion of farm work performed by contractors has undoubtedly increased, the fact remains that tractor drivers, be they farmers, farm workers or contractor’s employees, spend more hours each year in the driving seat: tractor annual utilisation is increasing. Farm restructuring and greater use of contractors has led to increased use of self-propelled sprayers, although this is not immediately evident from recent vehicle sales statistics (see Figure 2.12). Nonetheless, the fact that machine sales levels have been maintained, despite reductions in arable farm profitability, indicates the importance of this machine type in modern UK agriculture. Need to reduce both the initial purchase and operating costs of machines has also led to a significant increase in (non-recreational) sales of All-Terrain Vehicles (ATVs) (‘Quad Bikes’) (see Figure 2.13), these machines frequently supplementing or replacing expensive four-wheel-drive utility vehicles on livestock farms.

0

1000

2000

3000

4000

5000

6000

7000

1997 1998 1999 2000 2001 2002

Year of manufacture

Agr

icul

tura

l tra

ctor

s cu

rren

tlly

licen

ced

(est

imat

ed)

(with

resp

ect t

o hp

cla

ss)

41 - 60 61 - 80 81 - 100 101 - 130 131 - 160 161 - 200 201+ (hp)

Figure 2.11 Engine power distribution of UK agricultural tractor sales (above 40 hp)

12

0

50

100

150

200

250

1998 1999 2000 2001 2002

Year of manufacture

UK

sal

es o

f lar

ge S

elf-P

rope

lled

Spra

yers

Figure 2.12 UK sales of self-propelled sprayers

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1998 1999 2000 2001 2002

Year of manufacture

ATV

's s

old

for n

on-r

ecre

atio

nal u

se

Figure 2.13 UK sales of ATVs (for non-recreational use)

13

2.3 TARGET VEHICLE IDENTIFICATION Given the trends in UK agricultural vehicle fleet composition and usage discussed above, it appeared appropriate for this investigation to target vehicles which were likely to be subject to high annual usage, the operators of which therefore receiving longer exposure to whole-body vibration (WBV). Additionally, it also seemed correct to target vehicles which potentially subject their operators to high WBV levels and/or are increasing in popularity within UK agriculture. To this end the following vehicles were selected as targets for this investigation:- Agricultural tractors The primary agricultural power unit and therefore a must for inclusion in the investigation, four state-of-the-art 4wd tractors were selected from the very popular 120 – 170 hp (90 – 125 kW) engine power range, these representing front-line tractors from medium-large UK farms and farm contractors. The vehicles were selected to encompass the entire range of WBV reduction features currently available on the UK tractor market, these being:-

• Unsuspended • Suspended cab • Suspended front axle & cab • Fully suspended (front and rear axle).

Self-propelled sprayers These machines were selected due to their increasing market popularity and high utilisation by agricultural contractors. Self-propelled sprayers have historically embodied some form of axle suspension, but system complexity / capability is increasing due to market demand for greater operator comfort / productivity. To this end two typical (largely identical) machines were selected, albeit differing in design of suspension system used, one being the ‘new, improved’ replacement of the other. All terrain vehicles (ATVs or ‘Quad Bikes’) Selected due to increasing popularity within UK agriculture and typical use at medium-high speeds across rough terrain, which could potentially lead to high WBV emission levels. However, daily usage periods are likely to be relatively short and so operator WBV exposure may be acceptable. Very little data is currently available to confirm this. Four competitive machines in the popular (within UK agriculture) 300 – 400cc engine size range were selected for investigation.

14

3. WHOLE-BODY VIBRATION (WBV) MEASUREMENT 3.1 EUROPEAN UNION PHYSICAL AGENTS (VIBRATION) DIRECTIVE 3.1.1 Introduction The European Physical Agents (Vibration) Directive (EU PA(V)D – EEC:2002) was issued by the European Parliament and the Council for the European Union in July 2002, after undergoing lengthy debate over a period of years. The overall purpose of the Directive is to encourage improvements, particularly in the working environment, to effect an improved level of worker health and safety protection. The PA(V)D attempts to achieve this by protecting workers from the risks resulting from exposure to vibration, whole-body vibration (WBV) and/or hand-arm vibration (HAV), whereas other EU Directives consider noise and other so-called physical agents. The justification for the PA(V)D is “to introduce measures to protect workers from the risks arising from vibrations, owing to their effects on the health and safety of workers, in particular muscular / bone structure, neurological and vascular disorders.” The Directive defines whole-body vibration as “the mechanical vibration that, when transmitted to the whole body, entails risks to the health and safety of workers, in particular lower-back morbidity and trauma of the spine.” Strong evidence exists linking regular, long-term WBV exposure to the development of lower back pain and related disorders although, given the absence of a detailed and reliable quantitative dose-response relationship, the precise risks are not well-defined. Nonetheless, higher levels of exposure have been shown to increase the risk to health. Also, other workplace factors, such as manual materials handling and poor or constrained driving posture, are recognised as contributory factors, and should therefore be considered and addressed wherever possible. However, returning to WBV, the main sources are considered to be the seats of industrial and/or agricultural vehicles, and the platforms of heavy machinery. Hand-arm vibration is defined as “the mechanical vibration that, when transmitted to the human hand-arm system, entails risks to the health and safety of workers, in particular bone or joint, neurological or muscular disorders.” HAV is deemed to result from use of powered, hand-held tools; powered, hand-guided machinery, and from holding work pieces being processed by machine. This investigation concerns itself primarily with emission of whole-body-vibration (WBV) from agricultural vehicles, and the subsequent exposure of the vehicle operators to this vibration. Hand-arm vibration is measured and commented upon within the All-Terrain Vehicle (ATV or Quad Bike) investigation programme (see Section 6), but WBV remains the main target of the study. 3.1.2 Terminology and implementation The PA(V)D stipulates vibration exposure criteria for WBV and HAV, in the form of employee daily vibration exposure levels which must not be exceeded (limit values), and (lower) exposure levels (action values), above which actions for reduction of employee vibration exposure must be taken. These specific Exposure Action Values (EAV) and Exposure Limit Values (ELV) are stated in Table 3.1. With particular regard to WBV, it should be stressed that the Exposure Limit Value (ELV) stated by the PA(V)D should not be considered a ‘safe’ level of vibration exposure in the workplace, but rather as a high, undesirable level of vibration exposure (and a legal threshold) to be avoided at all costs. It is for this reason the Directive requires action to be taken, so far

15

as is reasonably practicable, to minimise vibration exposure once levels exceed the Exposure Action Value (EAV). As mentioned above, although risks are not well-defined, there is a lack of strong evidence of health risk from daily exposure to WBV levels at or below the EAV. However, if daily exposure levels exceed the EAV and approach the ELV, it is likely the level of risk to health will increase. Hence justification for requiring actions, on the part of the employer, to reduce risks / vibration exposure wherever practicable (see later). Whilst the Directive refers to vibration in terms of daily exposure, it will be noted that the majority of vibration measurements made upon vehicles within this investigation relate to vibration emissions or emission levels. The situation may be further confused by the fact that the units of measurement of both parameters can be the same, namely metres-per-second-squared (m/s2). To clarify the situation (in admittedly simplistic terms), vibration emissions are a quality of a product or machine, i.e. the vibration levels which come out of a machine, in the form of an acceleration level with varies (very rapidly) with time (an acceleration time history). As a first stage of analysis, WBV acceleration time histories are frequency-weighted to reflect the sensitivity of the human body to vibrations in certain frequency ranges (see ISO 2631:1997). Vibration exposure, on the other hand, is the level of vibration received by a person (from a machine / source) over a period of time. It is therefore a function of the magnitude of vibration emissions received during that period and the length of the (exposure) period. WBV emission levels are evaluated in terms of frequency-weighted root-mean-square (r.m.s.) acceleration (aw) (units: m/s2). This technique generates a single value to represent a period of vibration measurement:-

aw = ( )2

121

⎥⎦⎤

⎢⎣⎡

∫T

ow dtta

T (1)

where:- aw(t) = frequency-weighted acceleration time history (m/s2) T = duration of measurement (seconds) Where vibration exposure consists of two or more periods of exposure to different magnitudes and durations, the (frequency-weighted) energy-equivalent acceleration (Aeq) corresponding to the total duration of exposure may be derived. This is effectively an overall average r.m.s. acceleration value for the total period in question (∑Ti):-

Aeq = 2

12 .⎥⎦

⎤⎢⎣

⎡∑

∑T

Taki

iwi (2)

where:- Aeq = axis-weighted energy-equivalent continuous acceleration (r.m.s.

acceleration (m/s2)) awi = vibration magnitude (r.m.s. acceleration (m/s2)) for exposure period Ti

∑Ti = total duration of exposure / measurement k = orthogonal (measurement) axis multiplying factor specified by ISO 2631-

1:1997 (see Table 3.2)

16

For whole-body vibration (WBV), as opposed to hand-arm vibration (HAV), the PA(V)D has proposed two alternative methods of vibration exposure assessment and European Member States have the option to implement the Directive using either technique. The Exposure Action Value (EAV) and/or the Exposure Limit Value (ELV) may be defined either as a daily vibration exposure, expressed as frequency weighted, energy-equivalent continuous r.m.s. acceleration over an eight-hour period (A(8)), or as a vibration dose value (VDV) of the frequency-weighted acceleration (see Table 3.1). In either case, the vibration exposure levels are evaluated individually from the acceleration time histories recorded in each of three orthogonal axes (X-longitudinal, Y-transverse & Z-vertical), following application of the frequency-weightings (Wd or Wk) and axis weighting factors (k), as stated in ISO 2631-1:1997 regarding “Effect of Vibration on Health” (see Table 3.2 and Paddan et al., 1999). The resulting A(8) or VDV values for each (X, Y & Z) axis are then compared individually with the EAV and ELV. The axis-weighting (or multiplying) factor (k) effectively increases the magnitudes of the horizontal (X & Y) axes WBV values (see Equation 2). The daily vibration exposure level (A(8)) (units: m/s2), expressed as eight-hour energy-equivalent continuous, frequency-weighted r.m.s. acceleration (A(8)) may be derived from the equivalent continuous r.m.s. acceleration (Aeq) via Equation 3, below:-

A(8) = Aeq 8t

(3)

where:- t = daily exposure period (hours)

Aeq = the energy-equivalent continuous r.m.s. acceleration which is representative of the exposure period (m/s2)

Alternatively, if the equivalent continuous r.m.s. acceleration (Aeq) value (effectively the overall average r.m.s. value) for a period of vibration exposure has not previously been derived (thereby permitting the use of Equation 3 above), the daily vibration exposure A(8) value may be derived directly from the frequency-weighted acceleration time history using the formula:-

A(8) = k ⎥⎦⎤

⎢⎣⎡

∫T

0

2 d)(1 21

ttaT wo

(4)

where:-

aw(t) = frequency-weighted acceleration time history at the supporting surface (m/s2)

T = total duration of exposure within any period of 24 hours To = reference duration of 8 hours (28,800 seconds)

k = orthogonal (measurement) axis multiplying factor specified by ISO 2631-1:1997 (see Table 3.2)

17

Table 3.1 Vibration exposure values specified by the EU PA(V)D

8-hour energy-equivalent

r.m.s. acceleration – A(8)

(m/s2)

Vibration Dose Value

(m/s1.75)

Exposure Action Value (EAV) 0.5 9.1

Whole-Body Vibration Exposure Limit

Value (ELV) 1.15 21

Exposure Action Value (EAV) 2.5 -

Hand-Arm Vibration Exposure Limit

Value (ELV) 5.0 -

Table 3.2 Frequency weightings and multiplying factors for health aspects of whole-body vibration (WBV) as specified by ISO 2631-1:1997 for seated persons

Measurement axis Frequency weighting Multiplying factor (k)

Longitudinal (X) axis Wd 1.4

Transverse (Y) axis Wd 1.4

Vertical (Z) axis Wk 1

For comfort evaluation ISO 2631-1:1997 recommends multiplying factors of 1 in all axes.

The daily vibration dose value (VDV) (units: m/s1.75) of a person may be derived from the formula:-

VDV = k ( )4

14 d ⎥

⎦

⎤⎢⎣

⎡∫T

ottaw (5)

where:-

aw(t) = frequency-weighted acceleration time history at the supporting surface (m/s2)

T = total duration of exposure (seconds) within any period of 24 hours

k = orthogonal (measurement) axis multiplying factor specified by ISO 2631-1:1997 (see Table 3.2)

18

The relative advantages and disadvantages of the alternative A(8) and VDV approaches are discussed by Coles (2002). However, one point to highlight relates to the equivalence of the A(8) and VDV techniques. The A(8) and VDV EAV and ELV values specified by the Directive (see Table 3.1) are intended to be equivalent for exposure to vibration over an 8 hour period (see Figure 3.1). However, this equivalence is based upon the calculation of an estimated VDV (eVDV) from the r.m.s. acceleration value (as proposed by ISO 2631-1:1997 and Equation 6). Regrettably the eVDV only provides an accurate estimate of the actual VDV if the prevailing vibration is more or less continuous and devoid of transient high acceleration events and/or shocks: otherwise an underestimate is likely to result (Coles, 2002). Most conditions in which WBV exposure is of concern do not conform to these limitations. Thus a vibration exposure that yields an r.m.s. (A(8)) of 1.15 m/s2 is likely to result in a true VDV very different from the (supposedly equivalent) 21 m/s1.75. At the time of writing the HSE is undertaking a public consultation exercise regarding implementation of the PA(V)D in the UK. Whilst it is highly likely that the ELV will be specified by the A(8) technique, debate is currently ongoing as to whether the EAV will be implemented in VDV or A(8) terms. Irrespective of this, all VDV values reported in this study are based upon actual measurement of the parameter, as opposed to its estimation from r.m.s. acceleration values. Estimated vibration dose value (eVDV) = taw

414.1 (6)

where:-

aw = frequency-weighted r.m.s. acceleration (m/s2) t = exposure duration (seconds) Issues concerning the use of the eVDV with regard to agricultural vehicles, and derivation of the A(8) and VDV from WBV field data, are discussed further in Section 7.4 and Appendix 4 respectively. The Directive provides a derogation permitting weekly averaging of daily personal vibration exposures, but this is intended for use in circumstances where occasional high vibration exposure levels (greater than the ELV) are likely to be encountered during the working week, but otherwise levels are usually low (below the EAV). In such circumstances, which may well be rare in agriculture, the weekly average personal vibration exposure (A(8)week) (units: m/s2), i.e. the total exposure occurring within a period of seven consecutive days, normalised to a reference duration of 40 hours, may be derived from Equation 7:

A(8)week = ∑=

7

1

2j(8)A

51

j (7)

where:-

A(8)j = the daily vibration exposure for day j (m/s2) Unlike WBV, exposure to hand-arm vibration (HAV) is quantified by calculation of the eight-hour energy-equivalent, root-sum-of-squares (RSS) frequency-weighted total r.m.s. acceleration value (A(8)), derived from three orthogonal measurement axes (X-longitudinal, Y-transverse & Z-vertical) (see ISO 5349-1:2001 and Equations 8 & 9). The vector-sum vibration value (ahv), which represents vibration magnitudes in all three axial directions, is

19

used to calculate a single A(8) value for the exposure duration in question: this A(8) value may then be compared with the HAV EAV and ELVs specified in Table 3.1.

A(8) = TT

ahv0

(8)

where:-

ahv = the vector-sum vibration magnitude (m/s2) T = duration of exposure to the vibration magnitude ahv

To = reference duration of 8 hours (28,800 seconds) The vector-sum (root-sum-of-squares) vibration magnitude (ahv) is derived by use of the formula:- ahv = aaa hwzhwyhwx

222 ++ (9) where, ahwx ahwy and ahwz are the r.m.s. acceleration values (m/s2) measured in three orthogonal directions (X, Y & Z), at the vibrating surface in contact with the hand and frequency-weighted using the function Wh (see ISO 5349-1:2001). 3.1.3 Practical implications As previously stated, at the time of writing the HSE is undertaking a public consultation exercise regarding implementation of the PA(V)D in the UK, so it is not currently possible to give a definitive review of all the practical implications of the Directive. Indeed, one of the main justifications for this investigation was to identify and explore the extent of these implications regarding the use of agricultural vehicles. Nonetheless, it is possible to highlight the main practical requirements of the Directive and consider how these may translate into practical actions required in the workplace. The current form of the PA(V)D (EEC, 2002) requires employers, where there is likely to be a risk from exposure to vibration, to:-

Reduce vibration exposure to a minimum (an overall requirement) Assess the particular risks Implement a programme of measures to reduce those risks Keep worker daily exposure below the Exposure Limit Value (ELV) Provide information & training to workers, on the risks of vibration exposure &

means of their control Provide appropriate health surveillance when daily exposure levels reach / exceed

the Exposure Action Value (EAV)

20

Given that agricultural vehicles are a known source of WBV, a vibration risk must be assumed to be present during their operation, requiring an employer to perform a “suitable and sufficient assessment of risk”. A key purpose of the assessment is to determine whether the daily vibration exposure level of an employee performing a given operation, is likely to exceed the EAV or the ELV. In certain instances, it may be possible to perform a vibration exposure assessment by combining vibration emission data published for the machine / operation and knowledge of the likely period of operation (see Equation 3). However, in the absence of suitable published data, or in situations where exposure levels may approach the ELV, an employer may consider it necessary to actually measure the levels of vibration to which workers are exposed. If a worker’s daily vibration exposure level should exceed the (WBV or HAV) Exposure Action Value, the Directive requires an employer to implement a programme of technical and/or organisational measures intended to reduce vibration exposure in the workplace to a minimum. Whilst admittedly revisiting many of the points already highlighted, it is interesting to note that the Directive actually states that such measures would include:-

• Limitation of the duration and intensity of exposure Choice of appropriate work equipment of appropriate ergonomic design,

producing the least possible vibration Selection / implementation of alternative working methods which incur less

worker exposure to mechanical vibration Implementation of appropriate work schedules with adequate rest periods Provision of auxiliary equipment that reduces the risk of vibration-related

injuries, e.g. seats which effectively reduce WBV or vibration-isolated handles which reduce the transmission of HAV

Provision of clothing to protect exposed workers from cold and damp

• Consideration of the design and layout of workplaces and work stations

• Provision of adequate information / training / instruction to workers to ensure work equipment is used correctly and safely, to reduce vibration exposure to a minimum

• Implementation of appropriate maintenance programmes for work equipment, the workplace and workplace systems

As previously stated, on no account should workers be exposed to vibration above the Exposure Limit Value (ELV). If the ELV is exceeded, immediate action must be taken to reduce vibration exposure below the ELV and measures be implemented to prevent it being exceeded again. As discussed earlier, the Directive does provide a derogation permitting weekly averaging of daily personal vibration exposure levels, but this is intended for use in circumstances where occasional high vibration exposure levels (greater than the ELV) are likely to be encountered during the working week, but otherwise levels are usually low (below the EAV). Current evidence strongly suggests that the majority of agricultural vehicle operators will exceed the EAV during most normal (full) days, thereby preventing the use of this derogation. It is likely that workers who are subject to high levels of mechanical vibration in the workplace (daily exposure exceeding the EAV) will be entitled to appropriate health monitoring. However the method(s) of implementation of this requirement in the UK are currently the subject of a consultation exercise between the HSE and relevant industries. A

21

major difficulty is the non-specific nature of the ill effects of WBV (primarily lower back pain), unlike the well-documented ill effects of HAV. As previously discussed, these (back pain) symptoms may also result from a range of causations, such as manual handling and poor posture, acting in addition or in place of WBV exposure, any of which may be encountered both within or outside the workplace. One important practical issue to note is that (as stated previously) the EAV and ELV values stated by the Directive refer to either exposure to equivalent continuous r.m.s. vibration over an eight-hour (daily) reference period (A(8)) or, alternatively, a daily vibration dose value (VDV). The issue is the time dependency of vibration exposure. The period of time over which an individual must be exposed to WBV in order to reach the PA(V)D-specified EAV or ELV depends upon the magnitude of the prevailing WBV emissions level (see Equations 3 & 5 and Figure 3.1). In simple terms, exposure to higher vibration (acceleration) levels will cause the EAV and ELV to be reached in less time, and vice versa. This directly affects the maximum operating durations for particular machines and/or operating conditions.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 2 4 6 8 10 12 14 16 18 20

Time (hours)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Exposure Action Value (A(8)) Exposure Action Value (eVDV) Exposure Limit Value (A(8))

Figure 3.1 Effect of WBV emission magnitude upon exposure duration required to

reach the PA(V)D EAV and ELV

As indicated by Figure 3.1, if a worker’s period of exposure is likely exceed 8 hours/day, the maximum average r.m.s. WBV magnitude is in fact lower than the stated (A(8)) ELV of (1.15 m/s2). For example, an operator receiving an overall average r.m.s. acceleration (Aeq) level of, say, 1 m/s2, in the vertical (Z) axis, would receive a daily vibration exposure (A(8)) of 1 m/s2 after 8 hours operation (see Equation 3). However, if the operating period extended to 12 hours, the daily vibration exposure (A(8)) value would increase to 1.22 m/s2, exceeding the ELV. The operating duration would in fact be restricted to approx. 10½ hours by the Directive (see Figure 3.1). This is a potentially important fact for industries such as agriculture, where working day lengths frequently exceed 8 hours. Conversely, it may be legally acceptable (but arguably not best practice) for an individual to be exposed to WBV

22

emission levels (overall average frequency-weighted r.m.s. acceleration (Aeq) magnitudes) above the nominal, numerical A(8) EAV and ELV levels IF the period of exposure is less than 8 hours. Figure 3.1 indicates the extent to which this is the case. ISO 2631-1:1997 suggests approximate indications of public perception to a range of overall total (RSS – r.m.s.) vibration emission values (see Table 3.3). These are admittedly approximations, but nonetheless they provide some indication to the layman of levels of perceived discomfort that may be associated with broad r.m.s. WBV levels, in an otherwise complex world of vibration evaluation. This information also serves to reinforce an important message concerning WBV: specifically that the Exposure Limit Value (ELV) stated by the PA(V)D should not be considered a ‘safe’ level of vibration exposure in the workplace, but rather as a high, undesirable (and uncomfortable) level of vibration exposure (and a legal threshold) to be avoided at all costs. It is for this reason the Directive requires action to be taken, so far as is reasonably practicable, to minimise vibration exposure once levels exceed the Exposure Action Value (EAV) (0.5 m/s2 A(8)). Also, it is important to highlight that whilst the Directive requires WBV exposure levels to be assessed separately in each axial direction, and the measurement axis with the greatest (overall average) magnitude is identified, action is required to reduce WBV exposure in all axial directions where the EAV is exceeded. In practical terms whilst, for a given vehicle / application, the longitudinal (X) or transverse (Y) measurement axes may exhibit the highest axis-weighted overall-average acceleration levels, marginally lower Aeq levels in the remaining axial directions may still require vibration-reducing actions on the part of the employer if above the EAV, especially if significant peak acceleration events (shocks and jolts) are present (see Section 5.4).

Table 3.3 Likely perception of discomfort resulting from WBV (as suggested by ISO 2631-1:1997)

Vibration total value (m/s2) Perceived comfort level

Less than 0.315 Not uncomfortable

0.315 – 0.63 A little uncomfortable

0.5 – 1.0 Fairly uncomfortable

0.8 – 1.6 Uncomfortable

1.25 – 2.5 Very uncomfortable

Greater than 2.0 Extremely uncomfortable

Finally, whilst the precise methods of implementation of the Directive in the UK are, as yet, subject to the outcome of a consultation exercise, it is likely that practical guidance will be provided to employers where necessary. This may include guidance to assist employers to make simple vibration exposure assessments, to plan control measures, to source appropriate training and, to identify instances where additional (expert) help may be needed.

23

3.2 INSTRUMENTATION 3.2.1 Measured parameters Throughout the self-propelled sprayer and agricultural tractor programmes, acceleration levels were measured simultaneously in three mutually - perpendicular directions (X - longitudinal, Y - transverse, Z - vertical), at two locations on each machine. Tri-axial vibration present on the cab floor, close to the seat mounting point (see Figure 3.2) was measured using an array of three mutually-perpendicular piezo-resistive accelerometers with integral signal conditioning (IC Sensors type 3140-005, Serial Nos. 0673 005, 0673-007 and 0673-042). Vibration on the driver’s seat was measured by placing a semi-rigid mounting disc, incorporating a tri-axial 100mV/g ICP accelerometer (PCB model 356B40, serial no 18201), on the seat cushion, approximately between the driver's ischial tuberosities (vertically below the Seat Index Point) (see Figure 3.3). In addition to these six vibration signals, a seventh channel was used to record either marker pulses, for the beginning and end of the ISO 5008 test track sections, or forward speed from a Doppler radar speed meter during the ‘in-field’ and ‘on-farm’ measurement programmes. For tests involving all-terrain vehicles (ATVs) (see Section 6), an eighth channel was used to record the signal from an operator presence switch attached to the seat pad, so that later data processing could eliminate periods when the driver was not in contact with the seat. The ATV tests were also repeated when acquiring data from tri-axial accelerometers attached to the handlebars (see Figure 3.4), in place of the usual signals from the seat (see Figure 3.5) and footrest (see Figure 3.6). These were, for the right hand a PCB tri-axial unit type 356A24 (s/n 14583), and for the left hand a composite unit comprising two PCB model 352C22 (s/n 23863, 23865) and one PCB model 353B16 (s/n 64999). Two data acquisition arrangements were used to record the above signals. The first was a PC-based system, which was used upon the tractors during the ISO test track and SRI ‘in-field’ programmes. For the ‘on-farm’ tractor investigation this was replaced by a PC-card recorder, which was more suitable for longer recording durations and was easier to package within the cabs of everyday working vehicles. This system was subsequently used for all measurements on both self-propelled sprayers and ATVs, whether ISO track, ‘in-field’ or ‘on-farm’. 3.2.2 PC-based data acquisition During the agricultural tractor ISO test track and SRI ‘in-field’ test programmes, accelerometer outputs were acquired by a ruggedised laptop-Personal Computer-based signal conditioning, data acquisition and analysis system (HVLab version 3.81) (see Figure 3.7). This system was developed by the Institute of Sound and Vibration Research, University of Southampton, for acquisition and analysis of time-varying signals. Silsoe Research Institute’s HVLab system incorporates signal-conditioning circuitry to enable direct interface with piezo-resistive or strain gauge-based transducers. A Larson Davis Human Vibration Meter type HVM100 (serial No 272) was used to condition the seat accelerometers’ output, prior to data acquisition. The acceleration waveforms were low-pass filtered at 100 Hz, via integral anti-aliasing filters in the HVLab system, and then digitised at 300 samples/second. An additional data acquisition channel was used to record either marker pulses, for the beginning and end of the ISO 5008 test track sections, or vehicle forward speed during the ‘in-field’ and ‘on-farm’ measurement programmes. The forward speed signal was derived from either the test tractor’s own Doppler radar speed meter, or from a separately attached unit (Vansco Model 33800 s/n M0115AP-0067), depending on the availability.

24

Figure 3.2 Cab floor accelerometer system

Figure 3.3 Tractor WBV measurement instrumentation showing seat pad accelerometer unit

25

Figure 3.4 ATV handlebar accelerometers (for HAV measurement)

Figure 3.5 ATV seat pad accelerometer unit

26

Figure 3.6 ATV footrest accelerometer installation

Figure 3.7 PC-based signal conditioning, data acquisition and analysis system

27

3.2.3 PC card recorder data acquisition During the investigation a miniature, 8-channel digital data recorder, using PCMCIA-sized flash data storage cards (TEAC model DR-C2 PC-card recorder serial no 751160 with 128Mb data card), replaced the PC-based data acquisition system. This produced a more compact data acquisition system, which could be housed in a standard tractor toolbox, thereby greatly assisting rapid ‘on-farm’ installation. The process of importing the data into the HvLab system (for subsequent analysis) was transferred to the laboratory, where analysis could be performed more rapidly upon a desktop PC. Digitising rates used upon the PC card recorder were either 200 Hz for whole-body vibration or 2 kHz for hand-arm vibration. In a further adaptation, the signals from the floor accelerometers were passed through a second Human Vibration Meter (Larson Davis type HVM100 serial No 215) before acquisition. The Human Vibration Meters (HVMs) provided the equivalent of anti-aliasing filters for the PC card recorder and also an alternative acquisition system for acceleration time histories, but not for the seventh and eighth data channels. For data acquisition purposes, the memories of the HVMs were set to hold r.m.s. averages of the weighted acceleration signals, together with the peak acceleration, for each minute of work, and Vibration Dose Values (VDV) for each 15-minute period. For the ‘on-farm’ measurements, the HVM memories were downloaded to a desktop PC for post-processing, as described below, while the digitised recording provided vehicle forward speed histories and a backup record of the vibration data. For the self-propelled sprayer and ATV ISO test track and SRI ‘in-field’ programmes, this digitised data provided the main source of vibration information, as provided previously by the laptop PC-based acquisition system (see Figure 3.7). 3.3 DATA ANALYSIS The analysis procedures for the three types of data (ISO test track, SRI ‘in-field’ and ‘on-farm’) differed slightly because of differences in the acquisition methods or in the parameter values. However, all sets of acceleration histories were examined visually for abnormalities before processing. 3.3.1 ISO test track data ISO test track data was derived from the digitised acceleration histories recorded either by the PC-based (HVLab) acquisition system (tractors) or the PC card recorder (self-propelled sprayers and ATVs). During the process of data analysis, it was initially necessary to extract the sections of the acceleration time-histories which corresponded solely to travel upon the ISO tracks; i.e. to eliminate the run-up and run-off periods. These sections were extracted from the acceleration-time data by use of the driver-instigated start and stop marker pulses acquired during each test. The acceleration records were then normalized (to remove any remaining zero offsets) and frequency-weighted, using the weighting factors wd and wk specified in ISO 2631-1:1997 for the horizontal and vertical axes respectively, before calculation of root-mean-square (r.m.s.) acceleration values. The horizontal (X and Y-axis) components were multiplied by a factor of 1.4, as also specified in ISO 2631-1:1997. Combined (vector-sum) three-axis acceleration values were obtained for both the cab floor and driver’s seat, by calculating the root-sum-of-squares (RSS) of the combined orthogonal axes components (see ISO 2631-1:1997).

28

The frequency-weighted r.m.s. acceleration values were entered into spreadsheets for plotting against vehicle forward speed and for comparison with r.m.s. acceleration values obtained from the SRI ‘in-field’ measurement programme. 3.3.2 SRI ‘in-field’ data SRI ‘in-field’ ride vibration data was derived from the digitised acceleration time histories recorded either by the PC-based (HVLab) acquisition system (tractors) or the PC card recorder (self-propelled sprayers and ATVs). In these applications there was generally only one section of data to “extract” and analyse, namely that corresponding to the duration of the ‘in-field’ activity (usually 25 – 30 minutes). There were some exceptions where it was of interest to obtain values for separate parts of the road / field transport records, or to distinguish between values in work and those travelling to / from the field. The boundaries of the complete records, or of the specific sections, were identified from vehicle speed vs time data. Otherwise, the same data analysis procedure as that described for the ISO test track data was used. 3.3.3 ‘On-farm’ data ‘On-farm’ vibration data were mainly calculated from the acceleration - time histories acquired by the HVMs. These histories were stored as frequency-weighted values, whether r.m.s. or VDV. However, although the 1.4 multiplying factor had been used in generating the stored RSS values, it was not applied to the individual horizontal axes values as stored. Consequently, after downloading to a desktop PC as text files, the HVM-stored data was imported into spreadsheets for calculation of cumulative r.m.s. values (Aeq) and Vibration Dose Values (with 1.4 multiplier where necessary) for the measurement period in question. These spreadsheets were also used to calculate, for each ‘on-farm’ ‘seat’ acceleration record, estimates of VDV’s for an 8-hour exposure period and the operating time to reach the Exposure Action and Limit Values, as defined in the Physical Agents (Vibration) Directive. They were also used for presentation of acceleration history curves. As in all cases, it was necessary to derive vehicle forward speed histories from the digitised PC card recorder data. In the case of the ATVs, the ‘on-farm’ data were calculated from the digitised histories, by use of HVLab software, as well as by the method described above. This was done in order to set to zero the seat acceleration values during those periods when the driver was not in contact (standing or dismounted). 3.3.4 Hand-arm vibration (HAV) data (ATVs) The hand-arm (handlebar) data from the ATVs was processed in a similar way to the whole-body data, with the differences that the frequency weighting for all three axes was the same (wh); no 1.4 multiplying factors were applied and Vibration Dose Value was not relevant. There was no method for identifying any periods when the driver may have taken his hand off either grip.

29

30

4. SELF- PROPELLED SPRAYERS 4.1 TEST VEHICLES As previously discussed in Section 2.4, self-propelled sprayers were included within this investigation because they are vehicles which typically have high annual usage and which perform considerable amounts of road and farm track travel; activities which previous studies Lines et al. (1995) have associated with moderate to high WBV levels. Two very similar self-propelled sprayers were kindly loaned by their manufacturer for the purposes of the investigation. Both were state-of-the-art, fully (front and rear axle) suspended, hydrostatic transmission, four-wheel drive and steer machines, incorporating forward control cabs, 24 m booms and 2500 litre capacity spray tanks. The major constructional difference between the vehicles concerned their respective suspension systems; one utilising a mechanical coil spring and hydraulic damper system (see Figure 4.1), the other being fitted with a self-levelling air spring and hydraulic damper system (see Figure 4.2): the air spring machine representing the latest evolutionary development of the base vehicle. Each machine was operated in turn fitted with standard (12.4 R32) and flotation (600/55 R26.5) tyres. Test vehicle specifications are provided in Table 4.1. Both machines were fitted vertical (Z) axis ‘scissor’ linkage suspension seats, one of which also incorporated limited longitudinal (X) axis suspension capability (see Table 4.2). The vehicles were subjected to identical test programmes, including both a modified ISO 5008:2002 test track methodology and SRI ‘in-field’ operation (see Figure 4.3).

Table 4.1 Self-propelled sprayers used in the investigation

Operating mass (kg) Vehicle

Tank capacity (litres) Unladen Laden

(80%)

Wheelbase (m)

Tyre fitment (front & rear)

Suspension features

(in addition to seat)

Househam Super Sprint 2500 5340 7340 3.10

‘Standard’:- 12.4 R32

‘Flotation’:- 600/55 R26.5

Coil springs & hydraulic dampers

(front & rear axles)

Househam Super Sprint 2500 5825 7848 3.10

‘Standard’:- 12.4 R32

‘Flotation’:- 600/55 R26.5

Air springs & hydraulic dampers

(front & rear axles)

Complete sprayer test specifications may be found in Appendix 1.1

Table 4.2 Sprayer suspension seat details

Suspension type Sprayer (suspension

type)

Seat manufacturer

/ model Z-axis (vertical) X-axis (longitudinal)

Coil spring Isringhausen Mech. spring (adj.) + damper (fixed) None

Air spring KAB 856 Air spring (adj.) + damper (fixed)

Mech. spring (fixed) + damper (fixed)

“adj.” = adjustable rate or pre-load: “fixed” = fixed rate: “Mech.” = mechanical

31

Figure 4.1 Househam coil spring suspension, 2500 litre, 24 m boom, self-propelled sprayer fitted with ‘standard’ (12.4 R32) tyres: details of suspension system (inset)

Figure 4.2 Househam air spring suspension, 2500 litre, 24 m boom, self-propelled sprayer fitted with ‘flotation’ tyres: details of suspension system (inset)

32

Figure 4.3 Self-propelled sprayer experimental test programmes

33

4.2 ISO TEST TRACK WBV EMISSION MEASUREMENT 4.2.1 Procedure Whole-body vibration (WBV) emission levels were recorded upon each sprayer in accordance with a modified version of the test methodology described in ISO 5008:2002. Each vehicle was driven over the SRI ISO 100 m (smoother) ride vibration test track (see Figure 5.2) at a range of appropriate forward speeds (see Table 4.3), fitted with either standard or flotation tyres, with booms stowed (for travel) or extended (working position), in both unladen and laden (2000 litre (80%) tank fill) condition. The latter was chosen to represent the sprayer with a partial tank load during typical field operation and between field travel. Additionally, this condition encouraged any dynamic surging of the spray tank contents during travel. Full details of the ISO track test permutations are given in Figure 4.3. Wherever possible, tyre inflation pressures were adjusted to manufacturer’s recommended levels for the resulting (laden and unladen) axle loads (see Appendix 1.1). Tyre pressures were re-checked / adjusted following initial vehicle ‘warm-up’ travel, immediately prior to WBV emission measurement. Vehicle suspension seats were adjusted in accordance with operator instruction book recommendations: where seat designs embodied selectable longitudinal (X) suspension facilities (see Table 4.2), these features were enabled / utilised. During each pass across the tracks, acceleration time histories were recorded in three mutually-perpendicular directions (X-longitudinal, Y-transverse, Z-vertical), both upon the surface of the operator’s seat and the cab floor, close to the seat mounting (see Figures 3.3 & 3.2 respectively). Acceleration data was acquired and analysed by the methods previously described in Section 3.2 & 3.3, in accordance with the recommendations of ISO 2631-1:1997. The resultant frequency-weighted r.m.s. acceleration values are depicted in the line graph sections of Figures 4.4 to 4.11 inclusive. The ISO 5008:2002 test methodology was extended for the purposes of this investigation, in terms of the range and increments of vehicle forward speed used upon the ISO 100 m test track with the spray booms either extended or stowed (see Table 4.3). Whilst the ISO 35 m (rougher) track was considered to be unrepresentative of typical sprayer operational conditions (excessively severe), the speeds currently recommended by ISO 5008 for use upon the ISO 100 m (smoother) track were considered likely to be too low to adequately stress modern, state-of-the-art self-propelled sprayers embodying suspension features, particularly in relation to farm track travel with the booms stowed. Additionally, it was deemed prudent to incorporate sufficiently small speed increments to enable identification of points at which the test vehicles’ ride vibration behaviour may exhibit non-linear characteristics. To address these issues, the modified forward speeds ranges depicted in Table 4.3 were used for the investigation, solely upon the 100 m (smoother) track. Three test replicates were performed at each (original) ISO 5008 forward speed and one replicate at all others, in order to maintain the test programme within reasonable limits.

34

Table 4.3 Sprayer forward speeds used upon the ISO 100 m (smoother) ride vibration test track

Boom position Sprayer forward speed (km/h)

Extended (open) 10, 12, 14

Stowed (closed) 10, 12, 13, 14, 15, 16, 18, 20

4.2.2 Results The results of WBV emission measurement upon the ISO 100 m (smoother) test track are presented graphically within the line graph sections of Figures 4.4 – 4.11 inclusive, and numerically within Appendix 1.2. The data falls into four basic categories: the nature of the test vehicle’s suspension system (coil or air spring) and the tyre equipment fitted (‘standard’ or ‘flotation’). Within each of these categories the influence of the vibration measurement location upon the vehicle (‘floor’ or ‘seat’) and its loading condition (laden or unladen) may be considered. Primarily the semi- (80%) laden condition is considered in the following discussion of results, because it is deemed to represent a larger proportion of typical vehicle operation. Also, cab floor vibration levels provide a more reliable basis for comparison between given vehicle suspension system / tyre fitment configurations, given that they are independent of operator suspension seat performance. This is important given that the seats fitted to the vehicles were not of similar design or condition. Coil spring suspension – standard tyres Considering initially WBV measurement upon the cab floor of a semi- (80%) laden sprayer, with the spray booms in stowed position (see line graph section of Figure 4.4), the highest acceleration levels were recorded in the vertical (Z) axis, making this the ‘major’ axis in relation to the other (Y and X) axes. Transverse (Y) and longitudinal (X) axis levels were, respectively, of lower magnitudes. Z-axis WBV emission levels were found to increase significantly (~1.1 - 2.2 m/s2) with vehicle forward speed: X-axis levels exhibited a lesser trend (~0.4 - 0.6 m/s2), whereas Y-axis emissions were independent of vehicle speed. Operator seat WBV levels differed to those recorded on the cab floor in that the transverse (Y) and vertical (Z) axis emissions were of similar magnitude and significantly higher than those of the longitudinal (X) axis (see Figure 4.5). Whilst the seat Z-axis acceleration levels were similar to those recorded upon the cab floor, the seat X-axis levels were slightly higher than their cab floor equivalents and the Y-axis seat levels were significantly greater those of the cab floor (see Figures 4.4 & 4.5). The unladen vehicle exhibited similar WBV emission trends, with respect to the laden machine, upon both the cab floor and operator’s seat, with the exception that all recorded levels were of slightly reduced magnitude (see Appendix 1.2).

35

Air spring suspension – standard tyres This vehicle exhibited similar cab floor WBV trends to the coil spring suspension machine, in that acceleration levels were highest in the Z-axis followed, in reducing magnitude, by the Y and X-axes (see Figure 4.6). However, Z-axis emission levels were significantly lower than those of the coil spring suspension machine, being in the range ~0.8 - 1.28 m/s2. Both Z and X-axis emission levels increased with vehicle speed but, once more, transverse (Y) axis acceleration was independent of this parameter. Vertical (Z) axis acceleration levels measured upon the operator’s seat were also largest, followed, in reducing magnitude, by Y and X-axis emissions respectively (see Figure 4.7). X and Y-axis seat acceleration levels were marginally higher than their respective cab floor values, but Z-axis seat levels were lower than the floor values, probably indicating the effectiveness of the operator’s seat suspension system. Both Y and Z-axis seat acceleration levels were significantly lower than those recorded upon the coil spring suspension machine: longitudinal (X) axis levels were also lower, but to a lesser extent (see Figure 4.5). The unladen vehicle exhibited similar WBV emission trends, in comparison with the laden machine, upon both the cab floor and operator’s seat but, in this instance, acceleration magnitudes were of similar levels (see Appendix 1.2). Coil spring suspension – flotation tyres Cab floor WBV recorded upon this sprayer variant in laden condition, exhibited similar trends to those of the coil spring suspension machine fitted with ‘standard’ tyres. Z-axis acceleration levels were largest followed, in reducing magnitude, by those of the Y and X-axes (see Figure 4.8). However, whilst longitudinal (X) and vertical (Z) axis acceleration levels were similar to those experienced with ‘standard’ tyres fitted, transverse (Y) axis levels were significantly higher (~1.15 compared with ~0.75 m/s2)(see Figures 4.4 & 4.8). Whilst Z-axis floor vibration was found to increase significantly with vehicle speed, X-axis emission levels exhibited a similar but less substantial trend: transverse (Y) axis acceleration was independent of this parameter (see Figure 4.8). A similar trend of Z-axis dominance was recorded upon the operator’s seat: however, in this instance, both X and Z-axis emission levels increased significantly with vehicle speed. Once more Y-axis values were independent of speed (see Figure 4.9). Z and Y-axis acceleration levels were similar to those recorded upon the cab floor (see Figure 4.8), but X-axis levels were higher. Once more the unladen vehicle exhibited similar WBV emission trends, both upon the cab floor and seat but, as in the case of the coil spring suspension vehicle when fitted with ‘standard’ tyres, vibration levels were slightly lower in all measurement axes. Air spring suspension – flotation tyres As in all other self-propelled sprayer tests upon the ISO 100 m track, cab floor Z-axis acceleration levels were typically the largest, equalled, at lower test speeds, by Y-axis magnitudes; X-axis levels being the lowest recorded at all test speeds (see Figure 4.10). Once again X and Z-axis vibration increased with respect to forward speed, but Y-axis acceleration remained relatively constant. X and Z-axis WBV emission levels were similar to those recorded upon the air spring suspension machine fitted with ‘standard’ tyres, but transverse (Y) axis levels were significantly higher (~1.0 compared with ~0.75 m/s2)(see Figures 4.6 & 4.10). However, whilst cab floor X and Y-axis WBV levels were similar to

36

those recorded upon the coil spring suspension machine fitted with ‘flotation’ tyres, Z-axis acceleration levels were significantly lower. Operator seat measurements demonstrated similar Y and Z-axis WBV levels at given forward speeds, these both being higher than the X-axis emission levels. Once more, whilst Y-axis seat WBV emissions were independent of forward speed, both X-and Z-axis vibration levels increased with vehicle speed (see Figure 4.11). As in the case of the coil spring suspension sprayer fitted with ‘flotation’ tyres, Y and Z-axis seat acceleration levels were similar to those recorded upon the cab floor (see Figure 4.10), but X-axis levels were marginally higher. However, Z-axis seat acceleration levels were significantly lower than those recorded upon the coil spring suspension machine. When compared with the air spring suspension sprayer fitted with ‘standard’ tyres (see Figure 4.7), seat X and Y-axis WBV levels were higher but Z-axis levels were of similar magnitude. Additionally, in comparison with the laden machine, the unladen vehicle exhibited similar WBV emission trends and magnitudes, upon both the cab floor and operator’s seat (see Appendix 1.2). 4.2.3 ISO Test track WBV Emission Measurement - Summary An overall summary of the self-propelled sprayer ISO test track programme is as follows:-

• Vertical (Z) axis WBV emission levels were consistently higher than longitudinal (X) and transverse (Y) axis levels, irrespective of vehicle forward speed. However, in many instances, Y-axis WBV levels approached those recorded upon the Z-axis;

• Cab floor transverse (Y) axis WBV levels are independent of vehicle forward speed; • Cab floor vertical (Z) axis WBV levels recorded on the air spring suspension vehicle

are significantly lower than those of the coil spring suspension machine. However, longitudinal (X) and transverse (Y) axis acceleration levels are comparable between the vehicles;

• Cab floor transverse (Y) axis WBV levels are significantly higher when the vehicles are fitted with ‘flotation’ rather than ‘standard’ tyres. This is to be expected because the lower inflation pressures of the flotation tyres gives lower stiffness and hence greater low-frequency roll motion;

• The air spring suspension seat fitted to the air spring suspension vehicle was more effective in reducing vertical (Z) axis vibration than the (rather ‘tired’) mechanical suspension seat fitted to the coil spring suspension machine;

• WBV emission levels upon the coil spring suspension vehicle were found to be lower in the ‘unladen’ rather than the ‘laden’ condition;

• Extending (unfolding) the sprayer booms (24 m), rather than operating with them in ‘stowed’ position, consistently caused an increase in longitudinal (X) axis WBV levels and, less frequently, increased vertical (Z) axis acceleration levels. Transverse (Y) axis levels decreased slightly or remained the same. Coil spring suspension machines demonstrated these trends more consistently than air spring suspension vehicles. Vehicle loading condition (laden or unladen) had no effect upon these trends, which are probably a result of the sprayer weight distribution and pitch centre moving rearwards when the booms are unfolded, their stowed position being forwards alongside the operator’s cab (see Figure 4.1).

37

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.28 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

Spe d (km/h)e

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.4 Coil spring suspension sprayer: Floor acceleration (1.4 multiplier): Standard tyres; Laden (full tank)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.28 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

Sp ed (km/h)e

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track Spraying

Figure 4.5 Coil spring suspension sprayer: Seat acceleration (1.4 multiplier): Standard tyres; Laden (full tank)

38

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.

m.s

. Acc

eler

atio

n (m

/s2 )

30

Sp d (km/h)ee

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.6 Air spring suspension sprayer: Floor acceleration (1.4 multiplier): Standard tyres; Laden (full tank)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

Sp ed (km/h)e

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.7 Air spring suspension sprayer: Seat acceleration (1.4 multiplier): Standard tyres; Laden (full tank)

39

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

S ed (km/h)pe

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.8 Coil spring suspension sprayer: Floor acceleration (1.4 multiplier): Flotation tyres; Laden (full tank)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

eed (km/h)Sp

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.9 Coil spring suspension sprayer: Seat acceleration (1.4 multiplier): Flotation tyres; Laden (full tank)

40

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

S ed (km/h)pe

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.10 Air spring suspension sprayer: Floor acceleration (1.4 multiplier): Flotation tyres; Laden (full tank)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.08 10 12 14 16 18 20 22 24 26 28

Road Track OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

30

eed (km/h)Sp

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test TrackSpraying

Figure 4.11 Air spring suspension sprayer: Seat acceleration (1.4 multiplier): Flotation tyres; Laden (full tank)

41

4.3 SRI ‘IN-FIELD’ WBV EMISSION MEASUREMENT 4.3.1 Procedure Following the self-propelled sprayers ISO test track investigation (Section 4.2), a detailed programme of sprayer ‘in-field’ WBV emission measurement was performed upon the Silsoe Research Institute (SRI) estate, using the same test vehicles. The objectives of this work were:-

• To quantify each sprayer’s ‘in-field’ WBV emission levels whilst performing a range of typical operations, in known / controlled conditions;

• To investigate the similarity (if any) between WBV emission levels encountered during these operations and those generated during ISO 5008 ride vibration track testing (Section 4.2).

Each self-propelled sprayer (coil spring suspension and air spring suspension – see Figures 4.1 & 4.2) was operated in (semi) laden condition (~80% spray tank load), whilst fitted with either ‘standard’ or ‘flotation’ tyres, along a composite test circuit comprising smooth road travel, farm track travel and field (spraying) (see Figures 4.3, 4.12 & 4.13). The test circuit composition was selected to represent typical operations which a self-propelled sprayer would be subjected to during ‘on-farm’ use. Accordingly, the sprayer booms were stowed (closed) for ‘road’ and ‘track’ travel and extended (open) for field ‘spraying’. During performance of the test circuit, which occupied approx. 25 minutes, acceleration time histories were recorded simultaneously upon the operator’s seat and the sprayer cab floor, by use of the vehicle-mounted instrumentation described in Section 3.2. Additionally, vehicle forward speed was derived from a Doppler radar sensor mounted upon each test vehicle (see Figure 4.13). The test circuit duration was chosen to encompass and minimise variations relating to operating conditions. Each machine permutation (suspension type / tyre fitment) performed two replicates of the test circuit. To minimise variations attributable to personal operating technique, the same individual operated each test vehicle in turn. 4.3.2 Results Detailed results of the self-propelled sprayer SRI ‘in-field’ test programme are depicted graphically in the bar graph sections of Figures 4.4 to 4.11 inclusive, and in tabular form within Appendix 1.3. Figures 4.4 - 4.11 indicate weighted acceleration magnitudes recorded in the X (longitudinal), Y (transverse) and Z (vertical) axes, upon the seat and floor of each sprayer ‘permutation’, during the ‘road’, farm ‘track’ and field ‘spraying’ sections of the composite test circuit, plus an overall average of the three test conditions. Typical sprayer forward speeds used in each test circuit section are indicated in Figure 4.13. Sprayer axle loadings and tyre inflation pressures used the SRI ‘in-field’ test programme are detailed in Appendix 1.1 Standard tyres Considering primarily the floor acceleration levels, thereby removing the influence of the operator’s seat suspension system, it is evident that when fitted with ‘standard’ tyres, vertical (Z) axis acceleration was consistently the largeset during both road travel and field spraying operations, both for the coil and air spring suspension machines (see Figures 4.4 & 4.6). Z-axis WBV emission levels were followed (in reducing magnitude) by those upon the transverse (Y) and longitudinal (X) axes, respectively.

42

: Figure 4.12 Househam 2500 litre, 24 m boom, self-propelled sprayer fitted with

‘standard’ (12.4 R32) tyres, performing ‘field’ section of composite test circuit

43

Figure 4.13 Typical sprayer forward speed history during SRI ‘in-field’ test circuit

Indicates:- Initial and final calibration checks Short farmyard travel before - High-speed ‘road’ travel (~35 km/h) Slower travel on rough farm ‘track’ (~12-14 km/h) Pause for extending booms (~420 – 450 seconds)

Sequence of simulated ‘field’ spraying bouts (~14 km/h spraying speed but lower speeds during headland turns)

0

5

10

15

25

35

40

45

50

0 200 400 600 800 1000 1200 1400 1600 1800

Time (seconds)

Spee

d (k

m/h

) 30

20

‘In-field’ spraying generated higher WBV acceleration levels than high-speed road travel. However, floor acceleration magnitudes upon the air spring suspension machine were typically ~30% lower than those of the coil spring suspension vehicle in these particular test conditions. Travel upon a rough farm ‘track’ generated the highest WBV levels of the test conditions, but in this case acceleration levels in the transverse (Y) axis were the largest, followed, in reducing magnitude, by those in the Z and X axes respectively. The air spring suspension sprayer produced similar X-axis floor acceleration levels to those of the coil spring suspension machine, but its Y and Z-axis emission levels were lower (see Figure 4.6 & 4.4). Overall (average of all ‘in-field’ test conditions), in the case of the coil spring suspension sprayer, vertical (Z) axis floor acceleration was the largest by a substantial margin, followed, in reducing magnitude, by levels in the Y and X axes (see Figure 4.4). The air spring suspension machine demonstrated a different pattern in which Z and Y-axis acceleration levels were of similar magnitude, but those of the X-axis were approx 35% lower (see Figure 4.6). Comparing the performance of the two machines, they produced identical transverse (Y-axis) WBV emission levels, but the air spring suspension sprayer generated marginally lower levels in the longitudinal (X) axis and substantially (~30%) lower levels in the vertical (Z) axis. In terms of seat acceleration levels, upon the coil spring suspension sprayer, overall these were approx. 20-25% higher than the floor levels in each respective measurement axis; those in the vertical (Z) axis being the largest (see Figure 4.5). Seat acceleration levels upon the air spring suspension machine were similar to the floor levels in the X-axis, but seat Z-axis levels were approx. 9% higher than the corresponding floor levels and Y-axis seat values were approx. 15% higher than those recorded upon the floor. Y-axis WBV emission levels were larger than those in the Z-axis by a small margin upon this vehicle (see Figure 4.7). Flotation tyres Once more considering cab floor acceleration levels, both coil and air suspension sprayers exhibited similar behaviour during ‘road’ and farm ‘track’ travel. For both vehicles Y-axis WBV emission levels were the largest (by a substantial margin) during ‘track’ travel, followed in reducing magnitude by Z and X-axis levels respectively. During farm ‘track’ travel the X and Y-axis floor acceleration levels of the air spring suspension sprayer were similar to those generated by the coil spring suspension machine. However the air suspension machine returned lower Z-axis levels than the coil spring suspension vehicle in this test condition, and also lower levels in the Y and Z axes during ‘road’ travel (see Figures 4.8 & 4.10). ‘In-field’ spraying with the coil spring suspension machine generated largest average WBV emission levels in the Z-axis, the Y and X axes following in reducing magnitude (see Figure 4.8). The air spring suspension machine exhibited slightly different behaviour: Y-axis emission levels being the largest, followed by the Z-axis and then the X-axis (see Figure 4.10). Comparing the performance of the two vehicles during field ‘spraying’, the air spring suspension machine generated Y-axis WBV levels similar to those of the coil spring suspension vehicle, but lower comparative levels in the X and Z axes. Overall, averaging the results of each ‘in-field’ test condition and considering WBV emission levels in individual measurement axes, the coil spring suspension sprayer produced its highest (average) acceleration levels in the Y-axis, closely followed by those in the Z-axis and thereafter by X-axis levels. The air spring suspension machine also generated its highest (average) acceleration levels in the Y-axis, but the Z-axis acceleration magnitude was approx. 30% lower than that of the Y-axis: levels in the X-axis were lower still. Comparing the air and

44

coil spring suspension machines, similar WBV levels were recorded in the X and Y axes, but the former vehicle returned 25% lower levels in the vertical (Z) axis (see Figures 4.8 & 4.10). Comparing operator seat and cab floor acceleration levels when the sprayers were fitted with flotation tyres, upon the coil spring suspension machine, seat acceleration levels were higher than floor levels by approx. 19%, 27% and 14% in the X, Y and Z axes respectively: Y-axis WBV levels being largest (see Figures 4.8 & 4.9). The air spring suspension machine demonstrated a similar trend of Y-axis dominance and higher seat acceleration levels, but in this instance seat WBV levels were larger than cab floor levels by approx. 15% and 9% in the Y and Z axes respectively, whereas those in the X-axis were similar (see Figures 4.10 & 4.11). Y-axis seat acceleration levels would be expected to be higher than those recorded upon the cab floor, due to the greater relative distance of the seat surface from the vehicle roll centre. ‘In-field’ overall performance A summary of self-propelled sprayer ‘in-field’ WBV emission performance is presented in Figures 4.14 and 4.15 for ‘standard’ and ‘flotation’ tyre fitment respectively. These Figures depict both cab floor and operator seat weighted acceleration levels of the air and coil spring suspension machines, for each ‘in-field’ test condition, in ‘largest-single-axis’ terms, as required by the Physical Agents (Vibration) Directive (see Section 3.1). The identity of the measurement axis in which largest average r.m.s. acceleration level was encountered during each test condition, is also indicated. It is advisable to base comparisons between vehicle ride performance primarily upon cab floor acceleration values, thereby removing the effects of different suspension seats (design and condition) fitted to the machines. However suspension seat performance will mainly affect seat vertical (Z) axis acceleration levels and, to a lesser extent, those in the longitudinal (X) axis, given that the seat upon the air spring suspension sprayer embodied a degree of X-axis suspension (see Table 4.2). In cases where transverse (Y) axis acceleration levels were the largest (e.g. ‘standard’ tyres – ‘track’ and virtually all ‘flotation’ tyre instances), a direct comparison may be drawn between vehicle seat WBV levels. Considering initially sprayer performance when fitted with standard tyres (see Figure 4.14) the dominance of operator seat acceleration levels over those recorded upon the cab floor is immediately evident, as are the lower WBV levels achieved by the air spring suspension machine in comparison with the coil spring suspension vehicle, in virtually all test conditions. The largest WBV levels were encountered in the transverse (Y) axis during farm ‘track’ travel. However, in virtually all other test conditions (with standard tyres), highest WBV emission levels were found in the vertical (Z) axis. Nonetheless, although the WBV emission levels of the coil spring suspension machine exceeded the r.m.s.-specified Exposure Action Value (EAV) (A(8) - 0.5 m/s2), even these did not reach the PA(V)D-prescribed Exposure Action Value (ELV) (A(8) - 1.15 m/s2). As noted before during the ISO test track programme, sprayer performance when fitted with flotation tyres appears to be worse in terms of ride vibration (see Figure 4.15). Once more, seat acceleration levels were higher than those recorded upon the cab floor, in all operational conditions, and once again the air spring suspension machine achieved lower WBV emission levels than the coil spring suspension vehicle in virtually all test conditions. Transverse (Y) axis average r.m.s. acceleration levels were larger than those of the X or Z axes in virtually all test conditions, the highest levels being encountered during farm ‘track’ travel. However, whilst the WBV levels generated by the flotation-tyred sprayers during field ‘spraying’ were marginally lower than the machines when equipped with standard tyres, farm ‘track WBV emission levels were substantially higher: the air spring suspension sprayer ‘seat’ values approached the ELV, whilst those of the coil spring suspension machine exceeded it.

45

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Road (Z-axis)

Track (Y-axis)

Spraying(Z-axis)

Road (Z-axis)

Track (Y-axis)

Spraying(Z-axis)

Road (Y-axis)

Track (Y-axis)

Spraying(Z-axis)

Road (Z-axis)

Track (Y-axis)

Spraying(Z-axis)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Coil (seat) Coil (floor) Air (seat) Air (floor)

Fig 4.14 Sprayer ‘in-field’ average weighted floor & seat acceleration levels:- coil

spring & air spring suspension vehicles:- ‘standard’ tyres (largest axis indicated)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Road (Y-axis)

Track (Y-axis)

Spraying(Y-axis)

Road (Y-axis)

Track (Y-axis)

Spraying(Z-axis)

Road (Y-axis)

Track (Y-axis)

Spraying(Y-axis)

Road (Y-axis)

Track (Y-axis)

Spraying(Y-axis)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Coil (seat) Coil (floor) Air (seat) Air (floor)

Fig 4.15 Sprayer ‘in-field’ average weighted floor & seat acceleration levels:- coil

spring & air spring suspension vehicles:- ‘flotation’ tyres (largest axis indicated)

46

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SRI Field (flotation tyres) SRI Field (standard tyres) ISO 100m Track (flotation tyres)

ISO 100m Track (standard tyres)

Ave

rage

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Longitudinal (X) Transverse (Y) Vertical (Z)

Figure 4.16 Coil spring suspension sprayer average weighted floor acceleration

levels (incl. 1.4 multiplier):- SRI ‘in-field’ (‘track’) and ISO test track (12 km/h)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SRI Field (flotation tyres) SRI Field (standard tyres) ISO 100m Track (flotation tyres)

ISO 100m Track (standard tyres)

Ave

rage

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Longitudinal (X) Transverse (Y) Vertical (Z)

Figure 4.17 Air spring suspension sprayer average weighted floor acceleration levels

(incl. 1.4 multiplier):- SRI ‘in-field’ (‘track’) and ISO test track (12 km/h)

47

Self-propelled sprayer ‘in-field’ and ISO test track performance The comparison of ‘in-field’ and ISO test track data is frequently an unrewarding activity, primarily because the vehicle state (axle loadings / weight distribution, tyre pressures and forward speeds) is often different between the test conditions under consideration. Also it is only possible to draw valid comparisons between similar operating surfaces and measurement locations upon the vehicles. Fortunately, in the case of the self-propelled sprayers, it was possible to select particular test conditions between which ride vibration performance comparisons could be drawn. The ISO 100 m ‘smoother’ test track was originally devised to represent a farm track surface. ‘In-field’ farm ‘track’ travel was performed in (80%) ‘laden’ condition with the spray booms stowed, at ~12 km/h forward speed (see Figure 4.13). Consequently it was possible to compare these results to those derived from the vehicles when operated upon the ISO test track in a similar loading condition at 12 km/h. The respective cab floor weighted acceleration levels are depicted in Figures 4.16 and 4.17 for the coil spring suspension and air spring suspension vehicles respectively. Considering the coil spring suspension vehicle (see Figure 4.16), longitudinal (X) axis acceleration levels recorded upon the ISO test track were similar, regardless of the tyre equipment fitted. However, the ‘in-field’ WBV levels were approx. 30% lower than ISO test track values. Much greater similarity existed between transverse (Y) axis ‘in-field’ and ISO track acceleration levels, those for ‘standard’ tyres being almost identical. However, in the case of ‘flotation’ tyres, ISO track Y-axis levels were marginally higher than the ‘in-field’ values. The greatest disparity existed between vertical (Z) axis acceleration levels, those recorded upon the farm ‘track’ being more than 50% lower than the ISO track values. Therefore, in summary, good comparability existed between Y-axis values, but this deteriorated in the X-axis and became very poor in the Z-axis. Tyre equipment, whilst affecting the particular WBV levels recorded, had no effect upon the nature or degree of agreement. A similar pattern was evident in the case of the air spring suspension sprayer. X-axis ‘in-field’ ‘track’ levels were approx. 23% lower than comparative ISO test track values (see Figure 4.17), regardless of tyre equipment. Y-axis acceleration levels were identical when the vehicle was fitted with ‘flotation’ tyres, but a slight difference was apparent between ‘standard’ tyre ISO test and ‘in-field’ values. Z-axis ‘in-field’ ‘track’ levels were once more approx 50% lower than comparative values recorded upon the ISO test track. Consequently, once more very good agreement was found between transverse (Y) axis acceleration levels; this relationship deteriorated in the longitudinal (X) axis and became very poor in the vertical (Z) axis. Once again, tyre equipment had little effect upon the quality of relationships demonstrated. It was regrettably beyond the financial and logistical constraints of this investigation to explore the relationships between ISO test track and ‘in-field’ vehicle ride vibration behaviour in greater detail. However, this approach is considered to be beneficial if an improved understanding of the factors contributing to these differences is to be gained. This is surely a requirement if vehicle test track WBV emission assessment procedures are to be improved in the future.

48

4.3.3 ‘In-Field’ WBV Emission Measurement – Summary The objectives of the ‘in-field’ self-propelled sprayer WBV investigation were:-

• To quantify each sprayer’s “in-field” WBV emission levels whilst performing a range of typical operations, in known / controlled conditions;

• To investigate the similarity (if any) between WBV emission levels encountered during these operations and those generated during ISO 5008 ride vibration track testing.

The results of the SRI ‘in-field’ self-propelled sprayer WBV measurement programme may be summarised as follows:-

• Air spring suspension sprayer cab floor WBV emission levels were generally lower than those generated by the coil spring suspension machine in the longitudinal (X) and vertical (Z) axes, but the transverse (Y) axis levels of both machine were similar;

• Tyre equipment (and associated inflation pressures and carcass stiffness) has a substantial effect upon vehicle WBV emission levels, especially in the transverse (Y) axis, ‘standard’ tyres being deemed to be dynamically stiffer than ‘flotation’ tyres;

• Farm ‘track’ travel generated the highest WBV emission levels of all ‘in-field’ test operations; these levels always occurring in the Y (transverse) axis;

• Operator seat WBV emission levels were always higher than those measured upon the cab floor, but this trend was less pronounced upon the air suspension machine. The latter is almost certainly due to the disparate suspension seats (of both different design and age) fitted to the test machines;

• When fitted with ‘standard’ tyres, vertical (Z) axis WBV emission levels were found to be the largest during ‘road’ travel and field ‘spraying’, whereas transverse (Y) axis emissions were the largest during farm ‘track’ travel, once again irrespective of the vehicle suspension system or the measurement location (see Figure 4.14);

• Transverse (Y) axis WBV emission levels were almost always the largest of any axis during the ‘in-field’ test programme, when machines were fitted with ‘flotation’ tyres (see Figure 4.15);

• ‘In-field’ and ISO test track transverse (Y) axis WBV emission levels exhibited very good agreement, but the degree of agreement was less good in the longitudinal (X) axis and very poor in the vertical (Z) axis. Vehicle tyre equipment was found to have no effect upon the degree of agreement observed;

• When attempting to compare WBV emission levels recorded ‘in-field’ and upon the ISO test tracks, it is important to select appropriate track and field test conditions for comparison;

• Differences between ISO test track and ‘in-field’ data require closer investigation if improved test track WBV assessment methodologies are to be developed (see Section 7.4).

49

4.4 ‘ON-FARM’ WBV EXPOSURE MEASUREMENT 4.4.1 Introduction A programme of ‘on-farm’ WBV exposure level measurement was performed upon a number of self-propelled sprayers across East Anglia. The objectives of this part of the investigation were:-

• To verify the practical applicability of the detailed self-propelled sprayer WBV emission data derived from the SRI ‘in-field’ and (possibly) ISO Test Track measurement programmes;

• To explore the variation in (and magnitudes of) WBV emission and resultant exposure levels encountered upon ‘on-farm’ self-propelled sprayers during typical half-day (4 hour) work periods;

• To enable limited investigation of typical usage patterns of ‘on-farm’ examples of one self-propelled sprayer design included in the overall investigation.

4.4.2 Procedure The principle objective of the overall investigation was “to determine WBV emission and exposure levels associated with representative ‘state-of-the-art’ agricultural vehicles performing agricultural operations….”. Consequently the ‘on-farm’ WBV study was intentionally restricted to one of the self-propelled sprayers previously tested, i.e. the vehicle design considered to embody the greatest proportion of WBV-reducing features. Therefore ‘on-farm’ examples of the Househam Super Sprint sprayer fitted with ‘Air Ride’ self-levelling suspension system and ‘standard’ tyres were targeted. As the previously completed SRI ‘in-field’ WBV emission measurement programme had embodied all aspects of typical sprayer operation (road & farm track travel, in-field spraying plus optional tyre equipment), it was not difficult to locate ‘on-farm’ machines performing similar tasks during day-to-day operation. During May-June 2002, WBV acceleration time histories were recorded upon 3 separate examples of the chosen sprayer model, thereby providing 3 test replications and permitting derivation of WBV emission and exposure levels. Suitable ‘on-farm’ test vehicles (i.e. correct physical specification and less than 2 years old) were identified with the assistance of the sprayer manufacturer. Indeed, one ‘on-farm’ machine was actually the air suspension machine evaluated at SRI, having subsequently been delivered to customer. Given each owner’s preparedness to participate in the study, ‘on-farm’ WBV measurements were made during a nominal ‘half-day’ (4-hour) period (in one instance comprising 2 x 2-hour periods due to prevailing weather conditions), during typical sprayer operation. This was considerably simpler than the comparable tractor ‘on-farm’ WBV measurement programme (see Section 5.4), given that the additional factor of attached implement / operation selection was not present. Acceleration time histories were recorded simultaneously upon the operator’s seat and the cab floor of each sprayer, by use of the vehicle-mounted instrumentation described in Section 3.2, but in this application individual Larson Davis Human Vibration meters (type HVM100) were also used to reduce the acceleration data in real-time, to record peak values and to derive vibration dose values (VDV) for each 15-minute section of the total operating period. As before, vehicle forward speed was recorded (derived from a Doppler radar sensor mounted upon each vehicle), to enable quantification of this important operational parameter and identification of any stationary / inactive periods during the measurement periods.

50

4.4.3 Results As discussed previously (Section 3.1), the European Union Physical Agents (Vibration) Directive (PA(V)D) defines the WBV Exposure Action Value (EAV) and Exposure Limit Value (ELV) in two alternative ways. Either as an 8-hour energy-equivalent frequency weighted r.m.s. acceleration value (A(8)), or as a vibration dose value (VDV). Member States are given the option of implementing the Directive using either method, using the values stated below (see Table 4.4). Specific details are discussed in Section 3.1, but an important difference between the methods is as follows. The root-mean-square (r.m.s.) or A(8) method produces a value which is an average vibration level adjusted to represent an 8-hour working day, whereas the vibration dose value represents cumulative exposure to vibration over the working day. The practical significance of this is clearly depicted by Figure 4.20. If, over a given working period, frequency-weighted r.m.s. acceleration levels recorded upon the operator’s seat are relatively consistent, the resultant equivalent continuous acceleration (Aeq) value (only A(8) if exposure period = 8 hours) changes little, having once reached an average ‘plateau’ value. However, in the same circumstances, the VDV increases throughout the work period in a cumulative manner. Additionally, the A(8) method represents steady levels of vibration with reasonable accuracy but gives poor representation of shocks and jolts, whereas the VDV method performs well in both instances (Griffin, 1998; Coles, 2002). These issues, together with those of sampling duration, are discussed in greater detail in Appendix 4. Throughout this investigation we have primarily utilised the A(8) method but, during ‘on-farm’ exposure measurement, vibration dose values have also been derived (see Figure 4.20 and Appendix 1.4). At the time of writing the HSE is undertaking a public consultation exercise regarding implementation of the PA(V)D in the UK. Whilst it is highly likely that the ELV will be specified by the A(8) technique, debate is currently ongoing as to whether the EAV will be implemented in VDV or A(8) terms: the implications of this stance are discussed in Sections 3.1 & 7.4. An important aspect of interpretation of results concerns how estimates for a whole day’s vibration exposure can be made from values measured over a shorter period (see also Appendix 4). Nominal half-day (approx. 4-hour) measurement periods were used ‘on-farm’ to ensure the data acquired were characteristic of the operation. If using the r.m.s. A(8) approach, the resultant overall average frequency-weighted r.m.s. acceleration (Aeq) value measured for the shorter (~4-hour) period can be considered to extend throughout the entire day’s use of the machine. The Aeq value becomes equivalent to the daily occupational vibration exposure (A(8)) value for that operation, if the vehicle in question were to be operated for 8 hours. Consequently the Aeq values generated by this investigation may be compared directly with the A(8) EAV and ELV values stipulated by the PA(V)D whenever the working day length approximates to 8 hours. For shorter or longer working days the respective A(8) value for the daily exposure period in question may be calculated from the Aeq value, prior to comparison with the EAV or ELV (see Section 3.1, Equation 3). A similar approach is necessary for the VDV: its cumulative nature requires a value for a shorter period be re-calculated to estimate the VDV after the full day’s exposure. This is performed by assuming subsequent WBV emission levels are similar to those recorded during the (~4 hour) measurement period (see Appendix 4). Examples of estimated 8-hour VDV’s appear in Table 4.5, Figure 4.20 and Appendix 1.4. Seat WBV data arising from the ‘on-farm’ self-propelled sprayer investigation are summarised in Table 4.5 and Figure 4.19. Corresponding cab floor data appear in Table 4.6 & Figure 4.18. Generally the individual ‘on-farm’ operations reflect similar WBV emission

51

levels to those obtained from SRI ‘in-field’ measurements, with one possible exception. (see Figures 4.18 & 4.19). Seat acceleration levels were in all instances higher than those recorded upon the cab floor. The major axis (the generating the largest overall average r.m.s. acceleration (Aeq) values) was primarily the transverse (Y) axis for seat WBV emissions, but for measurements made upon the cab floor, the vertical (Z) axis took precedence (see Tables 4.5 & 4.6). This would seem to suggest that Z-axis acceleration levels were the largest in the forward-mounted sprayer cab, but the operator’s suspension seat, if not particularly effective in attenuating vibration in this axis, at least caused little amplification of Z-axis acceleration. However, the suspension seat was unable to effect any attenuation whatsoever in the transverse (Y) axis, the greater relative distance of the seat surface from the vehicle roll centre resulting in significantly higher Y-axis seat acceleration levels when compared with those recorded upon the cab floor (see Tables 4.5 & 4.6).

Table 4.4 WBV exposure values specified by the EU PA(V)D

8-hour energy-equivalent

r.m.s. acceleration – A(8)

(m/s2)

Vibration Dose Value

(m/s1.75)

Exposure Action Value (EAV) 0.5 9.1

Exposure Limit Value (ELV) 1.15 21

Table 4.5 ‘On-farm’ WBV seat data: self-propelled sprayer with air spring suspension

X Y Z Major axis

1 3.50 0.28 0.52 0.53 Z / Y 0.79 0.53 13.8 1.52 7.12 >24

2 4.50 0.38 0.59 0.37 Y 0.80 0.59 15.8 0.88 5.73 >24

3(a) 1.75 0.94 1.27 0.88 Y 1.81 1.27 33.3 0.04 1.23 6.52

3(b) 2.00 0.69 0.68 0.68 X / Y / Z 1.18 0.69 18.6 0.46 4.23 22.39

3 (ave.) 3.15 0.82 1.00 0.78 Y 1.51 - - - -

Time to ELV (hr)

(A(8))

Average r.m.s. acceleration (m/s 2 ) RSS (m/s 2 )

Time to EAV (hr)

(A(8))

Est. 8 hr VDV

(m/s 1.75 )

Time to EAV (hr)

(VDV)

Duration (hr)

Aeq (m/s 2 )

Sprayer

Table 4.6 ‘On-farm’ WBV floor data: self-propelled sprayer with air spring suspension

X Y Z Major axis

1 3.50 0.26 0.39 0.39 Y / Z 0.61

2 4.50 0.31 0.36 0.37 Z / Y 0.61

3(a) 1.75 0.57 0.59 0.78 Z 1.13

3(b) 2.00 0.44 0.54 0.65 Z 0.95

3 (average) 3.75 0.50 0.56 0.71 Z 1.04

Sprayer Duration (hr)

Average r.m.s. acceleration (m/s 2 ) RSS (m/s 2 )

52

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Longitudinal (X) Transverse (Y) Vertical (Z)

Ave

rage

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field, standard tyres) Farm 1 Farm 2 Farm 3

Figure 4.18 Air spring suspension sprayer average weighted floor acceleration

levels (incl. 1.4 multiplier):- SRI ‘in-field’ (‘overall’) and ‘on-farm’ use

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Longitudinal (X) Transverse (Y) Vertical (Z)

Ave

rage

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field, standard tyres) Farm 1 Farm 2 Farm 3

Figure 4.19 Air spring suspension sprayer average weighted seat acceleration

levels (incl. 1.4 multiplier):- SRI ‘in-field’ (‘overall’) and ‘on-farm’ use (plus PA(V)D Exposure Limit Value)

53

0

0.5

1

1.5

2

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.

m.s

. Acc

eler

atio

n (m

/s2 )

0.00

3.00

6.00

9.00

12.00

15.00

VD

V (m

/s1.

75)

Transverse (Y) Aeq VDV

Larson Davis HVM100 SN:00215 Day Month Year

Location: Seat 29 May 2Machin Househam Air SuspendedReg No FY02GRU Start time: 08:50

SprayingBush & Sons (Farmers)

e::

Task:Place:

tal VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )ToTime X Y Z Sum X Y Z Sum

13.7 8.8 17.7 0.38 0.59 0.37 0.8015.8 10.2 20.5

ti

04:30 8.6t 9.98-hr est to

Es mated values VDV r.m.s./A(8) Maximum peak value (m/s 2 ) to EAV (hr): 0.88 5.73 X Y Z SumTime

Time to ELV (hr): >24 >24 5.12 9.44 17.20 17.10

g

eat WBV parameters

Co

ctivity

eatest peaks actually occur in the Z-axis;

• The overall average (Aeq) acceleration level is moderate: this calculation method smoothes the time history to a degree and does not respond to the peak events as significantly as the VDV method (see trace and also Appendix 4);

• The Aeq reduces during refilling periods, but remains relatively constant (0.5 – 0.6 m/s2) throughout the survey period, any significant increases being due to uncharacteristic peaks (~ 3 & 3¼ hrs);

• The VDV Exposure Action Value (EAV) is exceeded in less than 1-hour operation; • The A(8) Exposure Action Value (EAV) is exceeded in approx. 5¾ hours operation • The (A(8)) Exposure Limit Value (ELV) will not be exceeded in a 24-hour period;

ure 4.20 Typical time history oFi f weighted 1-minute r.m.s. accelerations (seat, Y-

axis, Air Spring Suspension Sprayer) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV) and table of s

mments

• An extremely variable vibration record (Y-axis largest) reflecting cyclical nature of a(refilling, travel to field, spraying, travel to base, refilling);

• Whilst overall average r.m.s acceleration (Aeq) value identifies Y-axis as largest, gr

54

Figure 4.20 depicts the parameters arising from the ‘on-farm’ sprayer WBV measurement programme in a generic presentation format. Tabular data specifies the measurement location (seat or floor), sprayer model, geographical location, date and measurement duration. The corresponding graph depicts a time history of frequency-weighted 1-minute average r.m.s. acceleration values, as recorded in the orthogonal axis which consistently generated the largest overall average values throughout the operating period. This is supplemented by traces depicting 15-minute vibration dose values (VDV) and development of equivalent continuous frequency-weighted r.m.s. acceleration (Aeq) which, as previously discussed, may be related to the A(8) value. Tabular WBV data are presented in terms of overall average frequency-weighted r.m.s. acceleration (Aeq) and peak values for each measurement axis, together with corresponding root-sum-of-squares (RSS) values. Individual axis and RSS VDV values for the measurement duration, and estimated (VDV) values for an 8-hour period, are also included. Finally, estimated operating periods until the EAV and ELV are reached, are shown, both in relation to the A(8) and VDV calculation methods. Comments relating specifically to the measurement example appear at the base of the Figure. A summary of cab floor and seat WBV data from the entire ‘on-farm’ measurement programme is presented in this tabular / graphical format in Appendix 1.4. As previously stated (see Section 3.1), the Directive specifies action and limit values for operator daily exposure to WBV and requires actions on the part of the employer, to reduce worker daily exposure should the EAV be exceeded. In simplistic terms, vibration exposure is a function of the intensity of vibration to which an operator is exposed and the period of exposure to it. A seated vehicle operator (as in this case) primarily receives WBV through the vehicle seat (can be via the feet for a standing operator): it is therefore the equivalent continuous (Aeq) WBV levels recorded upon the operator’s seat which are of importance. The range of seat WBV emission levels (0.53 – 1.27 m/s2) encountered during the ‘on-farm’ spraying operations are shown in greater detail by the equivalent continuous r.m.s. (Aeq) acceleration traces depicted in Figure 4.21. These traces indicate the degree of (Y-axis) WBV magnitude variation between the measurement replicates performed, the Aeq value at the end of each measurement period (end of trace) being the (overall average) Aeq value stated in Table 4.5. It would appear that considerable similarity exists between the Aeq levels of three replicates (0.53 – 0.69 m/s2), with only one test replicate exhibiting a significantly higher WBV magnitude (1.27 m/s2), apparently as a result of uncharacteristically rough local operating conditions. Despite the limited size of the ‘on-farm’ sprayer WBV survey, it would appear reasonable to propose ‘generic’ WBV emission levels for self-propelled sprayer operation. This being the case, the data given in Table 4.5 suggests that the operator of a state-of-the-art self-propelled sprayer would receive sufficient exposure to vibration to exceed the Exposure Action Value (EAV) in 2-3 hours operation – if specified in VDV terms (see Table 4.4). However, if specified in A(8) terms, the EAV would only be exceeded after approximately 4 – 7 hours operation. Irrespective of the specification method used, it is very likely that the EAV would be exceeded during typical sprayer operating days (see below), thereby requiring employers to implement a range of measures to reduce vibration exposure, as discussed in Section 3.1. However, the data also suggests it is extremely unlikely that the A(8) Exposure Limit Value (ELV) would be exceeded during the longest working day. Operating periods in excess of 22 hours being necessary in all but the most extreme operating conditions. As part of the ‘on-farm’ investigation, the sprayer operators recorded their driving hours during the (5-day) ‘week’ encompassing the target WBV measurement day. This effectively produced a survey of 15 ‘sprayer-days’ of which 14 days (93%) were operational. The results obtained are summarised in Table 4.7 and Figure 4.22. Whilst 57% of ‘sprayer-days’ exceeded 8 hours operation, a significant proportion reached 12 or 14 hours per day.

55

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Sprayer 1 Sprayer 2 Sprayer 3(a) Sprayer 3(b)

Figure 4.21 Equivalent continuous r.m.s. seat acceleration (Aeq, Y-axis) traces for

‘on-farm’ self-propelled sprayers

0

1

2

3

4

5

4 6 8 10 12 14 16

Period of daily operation (hrs)

Num

ber o

f wor

king

day

s

Figure 4.22 ‘On-farm’ daily usage of self-propelled sprayers surveyed

56

Table 4.7 ‘On-farm’ daily usage of self-propelled sprayers surveyed

Number of days surveyed

Number of operational days

Number of operational days

<= 8 hrs

Number of operational days

> 8 hrs

Average operational day length (hours)

15 14 6 8 10.1

However, despite the fact that self-propelled sprayers are (theoretically) expensive, highly utilised machines, especially during the seasonal period studied, average weekly usage for the three machines studied was a very consistent 45 hours over a 7-day week. Whilst the survey performed was admittedly of restricted scope and a survey encompassing a greater number of machines and other seasonal periods would be advisable, the consistency exhibited and data generated is somewhat of a revelation. Consequently, given the evidence provided by this investigation, it seems unlikely that the PA(V)D Exposure Limit Value (ELV) will be exceeded during typical machine operation, and therefore the requirements of the Directive will not restrict the daily or weekly usage of self-propelled agricultural sprayers of this generic design / construction, in the UK. However, the Exposure Action Value (EAV) will very probably be exceeded during typical working days, requiring employers to implement measures to reduce and manage operator exposure to WBV (see Section 3.1) and advise potential operators of the WBV risk. 4.4.4 ‘On-Farm WBV Exposure Measurement - Summary The findings of the ‘on-farm’ self-propelled sprayer WBV exposure measurement programme may be summarised as follows:-

• The majority of ‘on-farm’ self-propelled sprayers generated WBV emission levels similar to those experienced during the SRI ‘in-field’ measurement programme (see Figures 4.18 & 4.19);

• Only during one instance did an ‘on-farm’ sprayer generate WBV magnitudes which were significantly different to those encountered during the SRI ‘in-field’ operations. This was deemed a result of disparate (unusually rough) ‘on-farm’ operating conditions (see Figures 4.18, 4.19 & 4.21);

• In all instances, seat acceleration levels were higher than those recorded upon the sprayer cab floor (see Tables 4.5 & 4.6 and Figures 4.18 & 4.19);

• Whilst the largest overall average r.m.s acceleration (Aeq) levels recorded upon the vehicle seats, were primarily in the transverse (Y) axis, the greatest peak values actually occurred in the vertical (Z) axis (see Table 4.5, Figure 4.20 & Appendix 1.4);

• Vertical (Z) axis overall average r.m.s WBV emissions were consistently largest amongst measurements made upon the vehicle cab floor (see Table 4.6 & Figure 4.18);

• A majority (57%) of the sprayers surveyed were operated for more than 8-hours per day. A number of machines were operated for up to 14-hours per day (see Figure 4.22), but total weekly operation was a remarkably consistent average of 45 hours;

• All of the ‘on-farm’ sprayers surveyed exceeded the PA(V)D 8-hour Exposure Action Value (EAV), whether specified in vibration dose value (VDV) or equivalent continuous r.m.s. acceleration (A(8)) terms.

57

• Only one ‘on-farm’ sprayer exceeded the Exposure Limit Value (ELV) within 8 hours operation, in an uncommonly rough application (see above). Working day length would have to increase to unsustainable levels (> 22 hours) for the other sprayers surveyed to exceed the A(8) ELV;

• During a typical working day, it is very likely that the operator of an ‘on-farm’ self-propelled sprayer would receive WBV exposure in excess of the Exposure Action Value (EAV), but below the Exposure Limit Value (ELV). In these circumstances the PA(V)D would require employers to implement measures to reduce and manage the operator’s exposure, but daily operation of large, modern, ‘state-of-the-art’ self-propelled sprayers is unlikely to be restricted by the requirements of the Directive, even if the working day were to lengthen significantly beyond 8 hours(see Table 4.5);

• Daily working patterns, including rest breaks, machine maintenance and periods of general inactivity, can all contribute to a reduction in the Aeq WBV exposure value;

• Variation in WBV exposure levels was found to be present between certain example sprayers. This was not assisted by the relatively small number of individual machines investigated; the 3 replicates performed being adequate to indicate ‘on-farm’ WBV levels, but insufficient to determine the degree of WBV emission variability between supposedly identical vehicles / operations;

• Whilst the consistency between WBV emissions encountered during ‘on-farm’ sprayer operation is encouraging, a more detailed investigation of similar format, but comprising a larger number of measurement replications, is advisable in order to enable creation of a robust database of generic WBV emission data for modern self-propelled agricultural sprayers.

58

5. AGRICULTURAL TRACTORS 5.1 TEST VEHICLES As previously discussed (Section 2.4), a range of modern, state-of-the-art tractors deemed suitable for the investigation were identified and kindly loaned by their respective manufacturers (see Table 5.1 and Figure 5.1).

Table 5.1 Tractors used in the investigation

Tractor Engine power (kW)

Unballasted mass (kg)

Wheelbase (m) Tyre fitment

Suspension features

(in addition to seat) John Deere

7810 129 7036 2.800 Front:- 16.9 R28 Rear:- 20.8 R38 None

Renault Ares 630 RZ 88 5537 2.750 Front:- 14.9 R28

Rear:- 18.4 R38 Fully-suspended cab

New Holland TM165 120 6502 2.787

Front:- 540/65 R28

Rear:- 650/65 R38

Suspended front axle – Cab suspended at

rear only

JCB Fastrac 3185 127 7245 3.050

Front:- 540/65 R30

Rear:- 540/65 R30

Suspended front & rear axles

Complete test tractor specifications may be found in Appendix 2.1

Figure 5.1 Tractors used in the investigation at SRI

59

All test tractors were four-wheel drive models: all were fitted with ‘scissor’ linkage-type suspension seats embodying air spring / hydraulic damper vertical (Z) axis suspension systems, with the exception of the Renault Ares 630 RZ, whose seat incorporated an adjustable mechanical spring / hydraulic damper system. All seats embodied limited longitudinal (X) axis mechanical spring and hydraulic damper suspensions: the John Deere 7810 also incorporated this feature in the transverse (Y) axis. In certain cases the seat suspension damping was also adjustable. A summary of test tractor suspension seat specifications is given in Table 5.2: full details are provided in Appendix 2.2.

Table 5.2 Tractor suspension seat details

Suspension type Tractor

Seat manufacturer

/ model Z-axis (vertical) X-axis (longitudinal)

Y-axis (transverse)

John Deere 7810 Sears FS 92/01 Air spring (adj.)

+ damper (adj.) Mech. spring (fixed)

+ damper (fixed)

Mech. spring (fixed)

+ damper (fixed)

Renault Ares 630 RZ

Grammer MSG 85/731

Mech. spring (adj.) + damper (fixed)

Mech. spring (fixed) + damper (fixed) None

New Holland TM165

Sears SA15748

Air spring (adj.) + damper (adj.)

Mech. spring (fixed) + damper (adj.) None

JCB Fastrac 3185

Grammer MSG95A/721

Air spring (adj.) + damper (fixed)

Mech. spring (fixed) + damper (adj.) None

“adj.” = adjustable rate or pre-load: “fixed” = fixed rate: “Mech.” = mechanical 5.2 ISO TEST TRACK WBV EMISSION MEASUREMENT 5.2.1 Procedure Following a similar test procedure to that employed for the self-propelled sprayers (see Section 4.2), whole-body vibration emission levels were recorded upon each tractor in accordance with an extended version of the test methodology described in ISO 5008:2002. Each vehicle was driven over the SRI ISO 100 m (smoother) and ISO 35 m (rougher) ride vibration test tracks (see Figure 5.2), at a range of appropriate forward speeds (see Table 5.3). During each pass across the tracks, acceleration time histories were recorded in three mutually-perpendicular directions (X-longitudinal, Y-transverse, Z-vertical), both upon the surface of the operator’s seat and the cab floor, close to the seat mounting (see Figures 3.3 & 3.2 respectively). Acceleration data was acquired and analysed by the methods previously described in Section 3.2 & 3.3, in accordance with the recommendations of ISO 2631-1:1997: the resultant frequency-weighted r.m.s. acceleration values are depicted in the line graph sections of Figures 5.3 to 5.10 inclusive. The ISO 5008:2002 test methodology was extended for the purposes of this investigation, in terms of the range and increments of vehicle forward speed used upon each test track (see Table 5.3). Whilst the speeds currently recommended by ISO 5008 for use upon the ISO 35 m (rougher) track were considered adequate, those proposed for the ISO 100 m (smoother) track were considered likely to be too low to adequately stress modern, state-of-

60

the-art tractors embodying axle and/or cab suspension features. Additionally, it was deemed prudent to incorporate sufficiently small speed increments to enable identification of point(s) at which the test vehicles’ ride vibration behaviour may exhibit non-linear characteristics (usually 12-16 km/h for conventional tractors). To address these issues, the modified forward speed ranges depicted in Table 5.3 were used for the investigation. Three test replicates were performed at each (original) ISO 5008 forward speed and one replicate at all others, in order to maintain the test programme within reasonable limits. ISO 35 m (rougher) track ISO 100 m (smoother) track

Figure 5.2 ISO 35 m and 100 m ride vibration test tracks All additional ballast weights were removed from the tractors prior to testing (as required by ISO 5008). Wherever possible, tyre inflation pressures were adjusted to manufacturer’s recommended levels for the resulting unladen axle loads, but frequently a combination of generous tyre sizes and low axle loads made this impossible. In such instances inflation pressures were reduced to the lowest levels recommended for 30 km/h operation of the tyres in question. Tyre pressures were re-checked / adjusted following initial vehicle ‘warm-up’ travel, immediately prior to WBV emission measurement. Tractor suspension seats were adjusted in accordance with operator instruction book recommendations: any adjustable damper features were adjusted to mid-range settings and where seat designs embodied selectable longitudinal (X) and transverse (Y) axis suspension facilities (see Table 5.2), these features were enabled / utilised. Full details of test tractor specifications and set-ups are provided in Appendix 2.1.

61

Table 5.3 Tractor forward speeds used upon the ISO ride vibration test tracks

Tractor forward speed (km/h) Test track

Current ISO 5008 ‘Extended’ ISO 5008

ISO 35 m (rougher) 4, 5, 7 4, 5, 6, 7

ISO 100 m (smoother) 10, 12, 14 10, 12, 13, 14, 15, 16, 18, 20, 24, 30

5.2.2 Results The results of WBV emission measurement upon the ISO test tracks are presented graphically within the line graph sections of Figures 5.3 – 5.10 inclusive, and numerically within Appendix 2.3. The data falls into four basic categories: the test track used (35 m ‘rougher’ or 100 m ‘smoother’) and measurement location upon the vehicle (‘floor’ or ‘seat’). Within each of these categories the behaviour of the (four) test tractors may be considered. An immediate overall conclusion is that in all instances, measured WBV emission levels increased in proportion with forward speed, irrespective of the suspension systems present upon the test vehicles. Cab floor – ISO 35 m ‘rougher’ track Consideration of vibration levels measured upon the cab floor (see line graph sections of Figures 5.3, 5.5, 5.7 & 5.9) enables the (potentially variable) influence of the vehicle suspension seats to be minimised. The 35 m track generated the highest WBV levels recorded, equalled only (occasionally) by the conventional tractors (i.e. unsuspended, suspended cab, suspended front axle & cab) when operating at high speeds (24-30 km/h) on the 100 m ‘smoother’ track. All vehicles generated highest acceleration levels in the transverse (Y) axis: followed (in reducing magnitude) by the longitudinal (X) and vertical (Z) axes. A degree of Y-axis dominance is to be expected, given the nature of the test surface and its tendency to encourage lateral roll of the vehicle. All the test vehicles performed similarly, irrespective of their different suspension system designs / capabilities. Cab floor – ISO 100 m ‘smoother’ track Once more WBV levels were found to increase with forward speed, but at a lesser rate than had been encountered upon the 35 m track (see Figures 5.3, 5.5, 5.7 & 5.9). However, in this case, slight differences were found between the test vehicles. The conventional tractors (i.e. unsuspended, suspended cab, suspended front axle & cab) all exhibited very similar behaviour. Up to forward speeds of approx. 20 km/h, transverse (Y) axis weighted r.m.s. acceleration levels were generally highest, followed (in reducing magnitude) by those in the vertical (Z) and longitudinal (X) axes respectively. At speeds above 20 km/h, vertical (Z) axis acceleration levels exceeded those of the transverse (Y) axis and continued to increase at higher speeds. This behaviour was not, however, exhibited by the fully (front & rear axle) suspended tractor, whose overall WBV levels demonstrated a much smoother and more predictable increase with forward speed, and lower overall levels than the other test tractors (see Figure 5.9).

62

Operator’s seat – ISO 35 m ‘rougher’ and ISO 100 m ’smoother’ tracks What effect do the suspension seats have? Initial observation of the test results (see line-graph sections of Figures 5.4, 5.6, 5.8 & 5.10) would appear to question their effectiveness upon any of the test tractors in these conditions, given that longitudinal (X) and transverse (Y) axis ‘seat’ acceleration levels appear to increase relative to those recorded upon the cab floor at identical forward speeds (seat & floor WBV was measured simultaneously). This trend is particularly apparent within the 35 m ‘rougher’ track data where, additionally, vertical (Z) axis acceleration levels, if not amplified by the same degree as the X & Y-axes, were not attenuated. However, these characteristics are not as surprising or devastating, as one might first believe. The 35 m ‘rougher’ test track tends to generate high acceleration levels in the transverse (Y) and longitudinal (X) axes. The operator’s seat surface is further (higher) from the tractor’s lateral (roll) and longitudinal (pitch) centres than the cab floor: consequently, acceleration levels measured in those axes at that point will be greater than those recorded on the cab floor. Allied to this is the difficulty of incorporating effective horizontal (X or Y-axis) suspension systems into agricultural vehicle seats. Several of the tractors tested were fitted with seats incorporating X-axis suspension, and one included both X and Y-axis suspension (see Table 5.2). However, the low vibration frequencies involved, together with practical restrictions upon seat horizontal travel due to in-cab space, combine to greatly limit the effectiveness of horizontal axis seat suspension systems. Suspension seat development has, to date, concentrated upon vertical (Z) axis performance. Modern suspension seats undoubtedly do serve to improve operator ride comfort, but are most likely to attenuate Z-axis vibrations. Even then their effectiveness is limited to circumstances when the input acceleration (cab floor) frequency is greater than the natural frequency of the seat suspension system. This point is demonstrated by WBV data presented in Figures 5.7 & 5.8. Whilst the seat achieves little (if any) attenuation of Z-axis acceleration upon the 35 m track, significant reductions in Z-axis r.m.s. acceleration are achieved at higher forward speeds (above 20 km/h) upon the 100 m track. This is primarily due to the increasing importance of the vertical axis component of the seat input acceleration as forward speed on the 100 m track increases (see Figure 5.7).

63

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s2 )

0 5 10 15 20 25 30 35 40 45 50Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.3 Unsuspended tractor: Floor acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0 5 10 15 20 25 30 35 40 45 50

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.4 Unsuspended tractor: Seat acceleration (1.4 multiplier)

64

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s2 )

0 5 10 15 20 25 30 35 40 45 50Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.5 Suspended cab tractor: Floor acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0 5 10 15 20 25 30 35 40 45 50

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.6 Suspended cab tractor: Seat acceleration (1.4 multiplier)

65

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s2 )

0 5 10 15 20 25 30 35 40 45 50Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.7 Suspended front axle & cab tractor: Floor acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0 5 10 15 20 25 30 35 40 45 50

Sp d (km/h)ee

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.8 Suspended front axle & cab tractor: Seat acceleration (1.4 multiplier)

66

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s2 )

0 5 10 15 20 25 30 35 40 45 50Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.9 Fully suspended (front & rear axle) tractor: Floor acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

Field Task

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0 5 10 15 20 25 30 35 40 45 50

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal Track Transverse Track Vertical

ISO 100m Test TrackISO 35m Test Track Ploughing Plough Cultivating Spraying Trailer transport transport

Figure 5.10 Fully suspended (front & rear axle) tractor: Seat acceleration (1.4 multiplier)

67

5.3 SRI ‘IN-FIELD’ WBV EMISSION MEASUREMENT 5.3.1 Introduction Following a similar test methodology to that employed for the self-propelled sprayers (Section 4.3), a detailed programme of agricultural tractor ‘in-field’ WBV emission measurement was performed upon the Silsoe Research Institute (SRI) estate, using the same test tractors as used within the ISO test track experimental programme (Section 5.2). The objectives of this work were:-

• To quantify each tractor’s ‘in-field’ WBV emission levels whilst performing a selected range of identical agricultural operations, in known / controlled conditions;

• To investigate the similarity (if any) between WBV emission levels encountered during these operations and those generated during ISO 5008 ride vibration track testing (Section 5.2).

A range of target ‘field tasks’ was selected to reflect typical agricultural usage of modern four-wheel-drive tractors in the chosen (88-127 kW) engine power range; these being ploughing, plough transport, cultivating, spraying/top dressing and trailer transport. Acceleration time histories were recorded simultaneously upon the operator’s seat and the tractor cab floor, by use of the vehicle-mounted instrumentation described in Section 3.2. Additionally, vehicle forward speed was recorded (derived from a Doppler radar sensor mounted upon each vehicle), to enable quantification of this important operational parameter. Each vehicle performed each field operation for a sampling period of 25-30 minutes, to encompass and minimise task or operating condition-related variations. Two replicates of each task were performed. Additionally, to minimise variations attributable to personal operating technique, the same individual operated each test vehicle in turn. 5.3.2 Spraying A three-point (3pt.) linkage-mounted, 1000 litre capacity, air-assisted sprayer (Figure 5.11) was selected for this operation, this being a typical UK mounted sprayer and also, fortuitously, of similar mass and weight distribution to many linkage-mounted twin-disc granular fertiliser distributors. The target implement was therefore representative of both chemical application and fertiliser spreading equipment. (Test tractor axle loadings and tyre inflation pressures selected for this field task are detailed in Appendix 2.4). Each tractor performed a ‘mock’ spraying operation in turn, upon a damp, clay field, following existing post-harvest tramlines at a target forward speed of 10 km/h. The sprayer was operated with booms unfolded; headland turns were performed as per usual spraying practice: however, no water was actually discharged during the operation, so the tractor-implement combination’s mass and weight distribution remained unchanged throughout. The WBV emission levels recorded during this task were the lowest of any selected field operations (see Figure 5.13). This is not particularly surprising, given that tractor forward speed was not excessive and the only sources of ride vibration were due to crossing tramlines (at headlands) and occasional changes in direction (headland turns). As previously discussed (Section 3.1), the PA(V)D follows the ISO 2631-1:1997 WBV data analysis practice for ‘Operator Health’ as opposed to ‘Operator Comfort’, in that it considers only the frequency-weighted r.m.s. acceleration magnitude of the largest single orthogonal axis, rather than combining the magnitudes of all (X, Y & Z) axes into a vibration total value of weighted r.m.s. acceleration, via the vector sum or root-sum-of-squares (RSS) method. Also the largest single axis is chosen following application of an axis-specific multiplying factor.

68

Figure 5.11 Suspended cab tractor, spraying

Figure 5.12 Suspended front axle & cab tractor, ploughing

69

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

Spraying Plough in transport Ploughing Trailer transport Cultivating

Tasks

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

Y-axisY-axis

X-axis

Y-axis

Y-axis

Figure 5.13 Range of average WBV emission levels recorded upon tractor cab floors

during SRI ‘in-field’ investigation (largest axis denoted upon each bar)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

)

24

1.4

Unsuspended Cab suspension Front axle & cab suspension

Front & rear axle suspension

Tractor

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2

0

4

8

12

16

20

28

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.14 Cab floor WBV emission levels recorded during (tractor-based) spraying

operations at SRI

70

Consequently, following PA(V)D methodology, the highest axis-weighted overall average r.m.s. acceleration (Aeq) levels recorded on the cab floor during spraying were consistently in the transverse (Y) axis, irrespective of the tractor in question. Acceleration magnitudes were also very similar between vehicles (see Figure 5.14), cab floor average weighted r.m.s. acceleration levels being in the range 0.41 - 0.48 m/s2 (see Figure 5.13 and Appendix 2.5). Operator seat WBV levels displayed less marked differences between the measurement axes but, as previously discussed (Section 5.2.2), differences in suspension seat performance and vehicle / seat matching can introduce considerable uncertainties / variability. Comparing cab floor field spraying weighted r.m.s. acceleration levels with those recorded upon the ISO test tracks (see Figures 5.3, 5.5, 5.7 & 5.9) immediately indicates little similarity. Transverse (Y) axis acceleration magnitudes obtained upon the test tracks were much greater, particularly in the case of the conventional (unsuspended, suspended cab, suspended front axle & cab) tractors. The ISO 100 m track is probably the closest representation of the field surface conditions encountered during spraying, but even this is likely to be too severe, given that the 100 m track was designed to represent an un-metalled farm road. Also, it is appropriate to consider only the 10 km/h travel speed upon this surface, this being that used for the field task. Given this difference in operating surfaces and also the (unavoidably) different tractor weight distributions and tyre inflation pressures used for the field and ISO track tests (see Appendix 2.4 & 2.1 respectively), the lack of similarity between the ‘field’ and ‘track’ results is not surprising. However, greater similarity exists between the performance of the fully suspended (front & rear axle) tractor in these respective conditions (see Figure 5.9), but this may solely be a consequence of its relatively good ‘track’ performance and indifferent ‘field’ performance during the task in question. 5.3.3 Ploughing A fully-mounted 5-furrow reversible plough was chosen for both this and the subsequent ‘plough transport’ operation. The plough selected (see Figure 5.12) was typical of those likely to be used with the tractors under investigation, especially in the heavy, damp clay stubble field conditions encountered during the test period (mid-September). WBV data was acquired for a period of 30 minutes whilst ploughing at a 6.5 km/h target forward speed (typical for the field conditions), during which time the test vehicles managed to complete approx. 9 passes along the test field and 8 corresponding headland turns. Two replicates of this field test sequence were performed, the graphical results presented in this report being the means of parameter values acquired. Tractor average forward speed may appear to be somewhat lower than the intended target (see Figure 5.15 and Appendix 2.5), but this is a consequence of averaging data throughout the test period, including the deceleration and reversing cycles of headland turns. Cab floor weighted r.m.s. acceleration levels recorded during ploughing were of moderate magnitude in relation to other ‘field’ tasks, being in the range 0.60 – 0.70 m/s2 (see Figure 5.13 and Appendix 2.5). In all instances the greatest acceleration was recorded in the transverse (Y) axis, followed (in decreasing magnitude) by the longitudinal (X) and vertical (Z) axes respectively. Little significant difference was evident between the test tractors (see Figure 5.15), unless the vector sum (RSS) acceleration is considered, in which case the (fully) suspended front & rear axle tractor delivered a slightly lower vibration total values, when measured either upon the cab floor or the operator’s seat (see Appendix 2.5).

71

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Unsuspended Cab suspension Front axle & cab suspension

Front & rear axle suspension

Tractor

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0

2

4

6

8

10

12

14

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.15 Cab floor WBV emission levels recorded during ploughing at SRI

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Unsuspended Cab suspension Front axle & cab suspension

Front & rear axle suspension

Tractor

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0

4

8

12

16

20

24

28

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.16 Cab floor WBV emission levels recorded during plough transport at SRI

72

Once again there is little similarity between cab floor weighted r.m.s. acceleration levels recorded during ‘in-field’ ploughing and those obtained from the ISO test tracks (see Figures 5.3, 5.5, 5.7 & 5.9). However, as before, influential factors such as test surface, vehicle forward speed, tyre inflation pressures, tractor-implement weight distribution, moments of inertia and, importantly, external (plough draught) forces acting upon the vehicle should be taken into consideration. Given these factors, the 35 m test surface is excessively rough compared with the field conditions (mole-drained cereal stubble), the 100 m track surface being perhaps more appropriate. Vehicle weight distribution, moment(s) of inertia and external forces bear little or no relation between the test conditions. Consequently, upon initial consideration, it is hardly surprising that little similarity exists. 5.3.4 Plough transport This operational task was performed with the same tractor-implement combinations as used for ‘in-field’ ploughing activities (see Section 5.3.3), the intention being to represent typical travel to and from a field. A composite travel circuit was chosen, comprising sections of field headland, farm track, ‘country’ (rough) road and ‘smooth’ road travel in approximately 20:32:38:10% relative (time) proportions. Each tractor completed the test circuit twice, taking approximately 25 minutes per circuit; with the exception of the fully suspended (front & rear axle) machine, which benefited from a higher (legal) maximum road speed capability on the ‘smooth’ road sections. However, the resultant effect upon the tractor’s average speed over the entire test circuit was not substantial (see Figure 5.16). Each tractor was driven at similar (driver comfort-limited) forward speeds during the field and farm track sections of the test circuit. During the ‘on-road’ sections each vehicle was driven at the highest speed deemed suitable, as limited by driver comfort, vehicle safety and maximum speed capability. Each test tractor’s 3pt. hitch system embodied some form of active ride control, designed to minimise the transfer of vertical shock loading from the mounted implement to the tractor whilst in road transport (usually above 10 km/h). This feature (as described in Section 2.1.4) was used in all instances during this task. The WBV emission levels recorded upon the cab floor during plough transport were relatively low (see Figure 5.16), being only slightly greater than those encountered during spraying (see Figure 5.13). Once again the transverse (Y) axis exhibited the largest overall average r.m.s. acceleration levels, but only marginally so, vertical (Z) axis levels being a very close second, especially for the conventional tractors (unsuspended, suspended cab, suspended front axle & cab). In ‘largest-single-axis’ terms, there is little difference in cab floor acceleration magnitudes between the test vehicles (range 0.45 – 0.51 m/s2) as shown by Figures 5.13 & 5.16 and Appendix 2.5. However, the suspended cab and suspended front axle & cab tractors possibly deliver marginally better ride than the unsuspended tractor; whereas the fully suspended (front & rear axle) machine achieves WBV levels comparable with the best examples whilst travelling at a higher overall average forward speed (see Figure 5.16). In all instances the operator considered that the action of the 3pt. hitch active damping systems improved vehicle ride comfort and made the vehicles easier to control. This was particularly noticeable upon the ‘country’ road sections of the test circuit, but it should be emphasized that no objective WBV data was acquired to confirm or dispel this subjective impression. Comparing ‘plough transport’ cab floor weighted r.m.s. acceleration levels with those recorded upon the ISO test tracks, it is first appropriate to consider the respective test conditions. In terms of operating surface, the ISO 100 m track should bear closest similarity to the ‘farm track’ sections of the plough transport test circuit. However, as presented here, the plough

73

transport results are a composite of the entire test circuit, discouraging direct comparison. Additionally, it should be remembered that during this task each tractor was carrying a plough of mass ~1500 kg and ~500 – 1000 kg front ballast, not to mention operating at higher tyre inflation pressures (see Appendix 2.4). Add to this the effects of the 3pt. hitch active ride control system and the significantly different dynamic behaviour of a tractor and long, heavy mounted implement combination when compared with a solo, unladen tractor, and a disparity between the ISO test track and ‘in-field’ results is to be expected in this instance (see Figures 5.3, 5.5, 5.7 & 5.9). An appropriate course of action would be to revisit the WBV data acquired during ‘farm track’ travel and compare this with data obtained by subjecting the same tractor-implement combination to a limited 100 m ISO track test programme. However, whilst this was performed for the self-propelled sprayers in this study (see Sections 4.2 & 4.3), further such investigation in the case of tractors was unfortunately beyond the scope of this particular study. 5.3.5 Cultivating During this field task each test tractor was operated with a 4 metre wide heavy-duty ‘pigtail’ cultivator (see Figure 5.18); a popular implement for both post-harvest primary cultivation (e.g. on cereal stubbles) and initial secondary cultivation on previously ploughed land. The test conditions embodied both these characteristics, comprising the two distinct operating conditions of rough ploughed / rutted ground and rutted clay cereal stubble. The resulting operating conditions were both rough and uncomfortable for the vehicle operator, but nonetheless were representative of ‘challenging’ conditions that are often encountered in agriculture. To improve ride comfort marginally, whilst still achieving an adequate cultivation / levelling effect, the test vehicles were operated at an angle of 15-20° to the previous ploughing / tramlines / ruts. However, driver comfort limited forward speed to approx. 6 and 7.5 km/h on the ploughed ground and stubble respectively. WBV emission levels were recorded both upon the cab floor and driver’s seat of each vehicle throughout a 20 minute period of operation upon each surface. Cab floor weighted r.m.s. acceleration levels recorded during cultivating were the highest of all ‘field’ tasks investigated, being in the range 0.90–1.14 m/s2 (see Figure 5.13 and Appendix 2.5). Given the nature of the operating conditions, this is hardly surprising. Similarly, neither is the fact that all vehicles generated greatest WBV emission levels in the transverse (Y) axis; followed in most cases (in decreasing magnitude) by the longitudinal (X) and vertical (Z) axes respectively (see Figure 5.17). The higher transverse (Y) axis acceleration levels are probably a consequence of vehicle roll whilst traversing the rough, rutted ground. Little significant difference is evident between the cab floor WBV emission levels of test tractors (see Figure 5.17), although a certain similarity is apparent between the performance of the unsuspended, the suspended front axle & cab, and the fully suspended (front & rear axle) tractors: the suspended cab tractor returning a marginally poorer ride. However, this could possibly be due to a number of factors, including the slightly smaller overall size of the vehicle in question and possible variation in test conditions. A greater number of test replicates would be necessary to fully determine the significance of this apparent trend. Comparison of ‘cultivating’ cab floor weighted r.m.s. acceleration levels with those originating from the ISO test track programme (see Figures 5.3, 5.5, 5.7 & 5.9) indicates a certain, but not universal, similarity. ‘Field’-generated WBV magnitudes are for once similar to those resulting the ISO track at certain forward speeds, but the region of similarity (i.e. track type / forward speed range) appears to be somewhat vehicle-specific and not universal across all measurement axes. The ‘in-field’ WBV emission levels of the unsuspended and suspended front axle & cab tractors relate most closely to their performance upon the ISO 100 m test track in the 10 –

74

15 km/h speed range: those emission levels generated upon the 35 m track by these machines being considerably higher, especially in the transverse (Y) and longitudinal (X) axes. However, the suspended cab tractor exhibits the exact opposite trend, greatest similarity resulting from the 35 m track around 4 – 5 km/h. To further confuse the issue, the ‘in-field’ WBV performance of the fully suspended (front & rear axle) tractor relates most closely to its behaviour upon the 100 m ISO track around 15 – 20 km/h forward speed. What may be inferred from these results? Firstly, that the ‘in-field’ surface conditions were considerably rougher than the ISO 100 m (smoother) track: hence comparable WBV emission levels were only achieved upon the latter at twice or three times the ‘in-field’ vehicle forward speed. Secondly, that the ISO 35 m (rougher) track, which was originally intended to represent a ploughed field surface, is slightly rougher than the field conditions experienced during this operation, but only marginally so, because during field operation the implement draught forces (and their lines of action) would tend to stabilise the vehicles, both in pitch, yaw and possibly roll modes. The ride vibration behaviour of an unladen vehicle will not be the same as one operating a 3pt. linkage-mounted soil-engaging draught implement, even if the operating surfaces are identical, as indicated by Crolla (1976). Finally, it may appear that the fully suspended (front & rear axle) tractor failed to demonstrate its full potential for ride comfort enhancement during this operation in comparison with the other tractors, given its superior performance upon the ISO 100 m track (see Figures 5.9 & 5.17). However, this is probably a result of its suspension system design, namely the incorporation of anti-roll bars on the front and rear axles. These components generate greater roll stiffness, thereby providing better vehicle stability during cornering manoeuvres: however, they also serve to transfer a greater proportion of axle roll to the vehicle chassis than the freely-pivoting front axle designs utilised by the other tractors. Operating conditions in which transverse (Y) axis vehicle roll predominate, such as the ISO 35 m test track and driving at an angle across ruts / ploughing / tramlines, serve to highlight this particular suspension system characteristic.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Unsuspended Cab suspension Front axle & cab suspension

Front & rear axle suspension

Tractor

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0

2

4

6

8

10

12

14

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.17 Cab floor WBV emission levels recorded during cultivating at SRI

75

Figure 5.18 Unsuspended tractor, cultivating

Figure 5.19 Fully suspended (front & rear axle) tractor: trailer transport

76

5.3.6 Trailer transport This task was performed in a similar manner to ‘plough transport’ (see Section 5.3.4). Each tractor was connected, in turn, to an ‘unbalanced’ 12-tonne capacity Wootton tandem-axle trailer (see Figure 5.19) and driven along a composite test circuit, comprising sections of field headlands, farm tracks, ‘country’ (rough) roads and ‘smooth’ roads in approximately 38:25:27:10% relative (time) proportions. The trailer, which incorporated leaf-spring suspension systems upon both axles and the drawbar, was ballasted to achieve the legal maximum gross train weight (tractor + laden trailer) of approx. 24390 kg when operating with the heaviest test tractor (JCB Fastrac 3185): this trailer load was then retained for all further testing (see Appendix 2.4). Each tractor completed the test circuit twice, requiring approx. 25 - 30 minutes per circuit, with the exception of the fully suspended (front & rear axle) tractor, which benefited from a higher (legal) maximum road speed capability on the ‘smooth’ road sections. However, the resultant effect upon the tractor’s average speed over the entire test circuit was not substantial (see Figure 5.20 and Appendix 2.5). Each tractor was driven at similar forward speeds during the ‘field’ and ‘farm track’ sections of the test circuit: within the on-road sections each vehicle was driven to the highest speed deemed suitable, as constrained by driver comfort, road safety and maximum speed capability. Weighted r.m.s. acceleration levels measured on the cab floor and averaged over the entire (composite) test circuit for each vehicle, were of moderate to high magnitude relative to the other ‘in-field’ tasks performed, being in the range 0.74 – 0.89 m/s2 (see Figure 5.13 and Appendix 2.5). In virtually all cases the highest r.m.s. acceleration levels were generated in the longitudinal (X) axis, followed closely (in decreasing magnitude) by the transverse (Y) and vertical (Z) axes. However, given that vehicle WBV emission levels are strongly influenced by both operating surface and forward speed, it is appropriate to consider the different operating conditions present within the test circuit individually (see Figure 5.21 and Appendix 2.6). By this method the following observations may be made.

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Unsuspended Cab suspension Front axle & cabsuspension

Front & rear axlesuspension

Tractor

Weig

hted

r.m

.s. A

ccele

ratio

n (m

/s2 )

0

5

10

15

20

25

30

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.20 Overall cab floor WBV emission levels recorded during trailer transport at SRI (i.e. entire ‘composite’ test circuit)

77

Trailer transport, Field surface: Floor accelerations (1.4 multiplier) by tractor

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Unsuspended Cab suspension Front axle & cabsuspension

Front & rear axlesuspension

Tractor

Weig

hted

r.m

.s. A

ccele

ratio

n (m

/s2 )

0

10

20

30

40

50

60

Spee

d (k

m/h

)

Longitudinal (X) Transverse(Y) Vertical (Z) Speed

Trailer transport, Farm track: Floor accelerations (1.4 multiplier) by tractor

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Unsuspended Cab suspension Front axle & cabsuspension

Front & rear axlesuspension

Tractor

Weig

hted

r.m

.s. A

ccele

ratio

n (m

/s2 )

0

10

20

30

40

50

60

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Trailer transport, Country road: Floor accelerations (1.4 multiplier) by tractor

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Unsuspended Cab suspension Front axle & cabsuspension

Front & rear axlesuspension

Tractor

Weig

hted

r.m.

s. Ac

celer

ation

(m/s2 )

0

10

20

30

40

50

60

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Trailer transport, Smooth road: Floor accelerations (1.4 multiplier) by tractor

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Unsuspended Cab suspension Front axle & cabsuspension

Front & rear axlesuspension

Tractor

Weig

hted

r.m.

s. Ac

celer

ation

(m/s2 )

0

10

20

30

40

50

60

Spee

d (k

m/h

)

Longitudinal (X) Transverse (Y) Vertical (Z) Speed

Figure 5.21 Cab floor WBV emission levels recorded during trailer transport at SRI (by test circuit section)

78

79

Field headland This surface was a relatively soft, clay grassland field headland, but nonetheless firm enough to enable passage of the laden tractor-trailer combinations. Vehicle forward speed was maintained at approx. 11 km/h for all tractors, to enable comparison of results. Very similar cab floor weighted r.m.s. acceleration levels were recorded upon all the vehicles, irrespective of suspension system design / capability (see Figure 5.21 and Appendix 2.6), these typically being in the range 0.9 – 1.15 m/s2. Largest (overall average r.m.s.) acceleration levels were evident in the longitudinal (X) axis, followed (in decreasing magnitude) by the transverse (Y) axis. Vertical (Z) axis WBV emission levels were significantly smaller. Farm track An un-metalled farm road, complete with characteristic potholes. Forward speed of the conventional tractors (unsuspended, suspended cab, suspended front axle & cab) was limited to approx. 13 km/h by driver comfort, whereas the fully suspended (front & rear axle) tractor could comfortably maintain approx. 16 km/h (see Appendix 2.6). Despite its higher forward speed, the fully suspended (front & rear axle) tractor returned WBV emission levels comparable with, if not slightly lower than, the other test vehicles. In this test condition longitudinal (X) and transverse (Y) axis acceleration levels were more comparable with each other than in previous test conditions but, once again, vertical (Z) axis emission levels were of significantly lower magnitudes (see Figure 5.21). ‘Country’ (rough) road This section of the test circuit comprised undulating, minor roads between Silsoe and adjacent villages. Road width, surface condition, slope, forward visibility, driver comfort and oncoming traffic all served to limit vehicle forward speed to approx. 30 km/h for the conventional tractors (unsuspended, suspended cab, suspended front axle & cab), whereas the fully suspended (front & rear axle) tractor could comfortably achieve an average of 36 km/h (see Appendix 2.6). The largest overall average r.m.s. acceleration levels were found in the longitudinal (X) axis in all but one instance (see Figure 5.21), followed (in reducing magnitude) transverse (Y) and vertical (Z) axis levels, respectively. Upon this test surface the presence of either cab or front axle & cab suspension systems does appear to reduce the severity of longitudinal (X) axis vibration, but additional factors such as individual vehicle design and centre of gravity position, may have an unseen bearing upon this result. However full (front & rear axle) suspension does undoubtedly reduce vehicle ride vibration levels (as measured upon the cab floor) in this instance, especially given that this vehicle was indeed travelling at a higher forward speed than the others under test. ‘Smooth’ road A straight, level ‘A-road’ type surface upon which all vehicles could easily travel at their maximum design speeds, subject to adequate acceleration and deceleration capabilities. Upon this surface the conventional tractors (unsuspended, suspended cab, suspended front axle & cab) attained approx. 40 km/h, whereas the fully suspended (front & rear axle) tractor achieved an average of 57 km/h (see Appendix 2.6). Once more longitudinal (X) axis (overall average r.m.s.) acceleration levels were of greatest magnitude, followed closely by the transverse (Y) axis and, finally, by the vertical (Z) axis (see Figure 5.21). As would be expected, WBV levels were significantly lower (in certain cases 50% less) than the average weighted r.m.s. acceleration levels recorded upon the ‘Country’ roads. However, despite this smooth test surface, the suspended cab and suspended front axle & cab tractors returned lower

(single-largest-axis) WBV levels that the unsuspended vehicle. Once more the fully suspended (front & rear axle) tractor generated WBV emission levels comparable with the best performing ‘conventional’ tractors, but at a significantly higher forward speed. It is therefore reasonable to predict that at comparable operating speeds, its WBV emission levels would be the lowest of all the vehicles tested. Trailer transport - Summary Given the degree of control that could exercised upon the trailer transport test conditions and equipment, in terms of parameter control, repeatability, etc, it is possible to summarise what may appear a complex situation by comparing the relative performance of the test vehicles / suspension systems, as indicated by cab floor WBV emission levels. Figure 5.21 suggests that at similar speeds upon a ‘field’ surface, there is little to choose between the ride vibration performance of any of the test vehicles, especially in PA(V)D ‘largest-single-WBV-axis’ terms. As forward speeds increase (i.e. test conditions become more farm track / on-road orientated), the suspended cab and suspended front axle & cab tractors show an advantage over the unsuspended vehicle, in terms of lower WBV emission levels. However, this trend is also demonstrated, but to a much greater degree, by the fully suspended (front & rear axle) tractor, which proves itself a significantly more effective road transport vehicle. Superior performance (lower WBV emission levels) may also have been expected from the partially and fully suspended vehicles during ‘in-field’ operation (as opposed to ‘track’ or ‘road’). However, it is appropriate to recognise that the trailer represented over 70% of the tractor-trailer combination’s gross weight, of which approx. 3900 kg was transferred to the tractor pickup hitch, at a point behind the vehicle’s rear axle. Whilst the trailer drawbar incorporated a rudimentary leaf-spring suspension system, which undoubtedly served to reduce shock loadings, a variable vertical force approaching 50% of the unballasted tractor mass was applied via the trailer drawbar during operation. Substantial forces would also be applied to the tractor in the X and Y-axes during acceleration, braking, cornering and simply due to trailer draught (rolling resistance). To this end it is not surprising that, in many test conditions, the sheer ‘dynamic’ influence of the trailer (and the nature / position of its coupling to the tractor) would have a significant effect upon the ride vibration behaviour of the tractor, as demonstrated by Crolla and Dale (1979). Little comparability exists between trailer transport cab floor WBV emission levels and those obtained from the solo tractors upon the ISO test tracks (see Figures 5.3, 5.5, 5.7 & 5.9). Perhaps this is hardly surprising, giving the vast differences in vehicle weight distributions, tyre inflation pressures and external forces systems between the respective test conditions. The ISO 100 m (smoother) track would relate most closely to the ‘farm track’ and possibly ‘field’ test conditions, but little similarity can be expected between the dynamic behaviour of a 7-tonne solo tractor and a 24-tonne tractor-trailer combination. However, as discussed in Section 5.3.4, a possible course of action would be to revisit the WBV data acquired during ‘farm track’ section of the trailer transport test circuit and compare this with data obtained by subjecting the same tractor-trailer combination to a limited 100 m ISO track test programme. This would, in theory, generate comparable results and perhaps provide a starting point for the development of defined WBV test methodologies for vehicle WBV emission determination (see Section 7.4). However, whilst this was undertaken for the self-propelled sprayers in this study (see Section 4.3), this activity was unfortunately beyond the resources of this investigation.

80

5.3.7 ‘In-Field’ WBV Emission Measurement – Summary The objectives of this specific part of the investigation were:-

• To quantify each tractor’s ‘in-field’ WBV emission levels whilst performing a selected range of identical agricultural operations, in known / controlled conditions;

• To investigate the similarity (if any) between WBV emission levels encountered during these operations, and those generated during ISO 5008 ride vibration track testing (Section 5.2).

These activities generated reliable data which could be used:-

• To compare with WBV emission / exposure data subsequently recorded upon similar vehicles whilst working on farms (see Section 5.4);

• To enable broad assessment of the effectiveness of the generic suspension system designs encompassed by the investigation, in terms of WBV emission reduction.

Figure 5.13 depicts information supporting many of the important messages which may be derived:-

• Greater differences in WBV emission levels exist between the target operations than between the different tractors (suspension systems) performing each task;

• Spraying and plough transport generate low WBV emission levels Ploughing generates moderate WBV levels Trailer transport generates moderate to high WBV levels (Rough Ground) Cultivating generates high WBV levels;

• WBV emission levels generated during moderate / higher speed operations are highly dependent upon surface conditions;

• WBV emission levels recorded upon the operator’s seat during this section of the investigation (see Figure 5.22 and Appendices 2.5 & 2.6) suggest that operators of any of the vehicles performing any of the operations considered will exceed the proposed PA(V)D Exposure Action Value (EAV), if the WBV levels were to continue as measured (and the vehicles be operated) for an 8-hour working period;

• Similarly, operator seat WBV emission levels suggest that cultivating and trailer transport operations will cause drivers to exceed the proposed PA(V)D Exposure Limit Value (ELV), if WBV levels were to continue as measured (and the vehicles be operated) for an 8-hour working period. Ploughing may also cause the ELV to be exceeded, but only if the work period extends to approximately 12–14 hours;

• During all true field operations (spraying, ploughing & cultivating) and plough transport, the highest overall average r.m.s. acceleration (Aeq) levels (recorded on the cab floor & the seat) are found in the transverse (Y) axis, although in certain instances the differences between WBV levels in each axial direction is small;

• During trailer transport longitudinal (X) axis (floor & seat) Aeq levels are the largest; probably a result of vertical force input to the tractor pickup hitch (from the trailer drawbar) accentuating vehicle pitch;

• Use of the PA(V)D-recommended ISO 2631-1 ‘Effect of Vibration on Health’ evaluation methodology (i.e. application of a 1.4 multiplying factor to the horizontal axes and selection of the largest single weighted axis r.m.s. acceleration: see Section 3.1.2) undoubtedly accentuates and arguably distorts the magnitude of X and Y-axis WBV levels reported in this investigation;

• Except during cultivating and trailer transport operations, little difference was found between cab floor WBV emission levels of the test tractors (suspension system designs) (see Figure 5.13) when WBV levels were evaluated by the ISO 2631-1:1997 “Effect of Vibration on Health” method. Arguably the point vibration total value (vector sum or root-sum-of-squares: see Appendix 2.5), which represents the acceleration levels present in all axial directions as opposed to solely the axis of the largest magnitude, is a better indicator of the differences in vehicle ride comfort perceived by the operator during fieldwork;

81

• Cab floor vector sum acceleration levels return the same relative ranking and distribution of individual field operations, clarifying the relative differences between suspension system performance (WBV emission levels) as being small during spraying and plough transport; moderate during ploughing and trailer transport; and large during cultivating: apparently the more extreme the application, the greater the difference between the suspension systems;

• Whilst no vehicle / suspension system design appeared to be particularly superior for all the field operations investigated, and the differences between vehicles during certain operations were small, cab floor and operator seat vector sum (RSS) WBV levels suggested the fully suspended (front & rear axle) tractor and the suspended front axle & cab tractor offer marginally superior levels of ride comfort in the majority of instances. Evaluation of cab floor WBV levels by the largest single axis method displayed a similar trend between vehicle types, but this was not so apparent amongst operator seat WBV values derived by this technique: and the latter are, of course, the WBV emission levels from which operator daily exposure would be derived;

• Comparison of ISO test track WBV emission levels with those recorded during SRI ‘in-field’ operations is fraught with difficulty, mainly due to differences in vehicle mass, weight distributions, tyre inflation pressures and external force systems between the test conditions. The ISO ride vibration tracks were originally developed as a research tool and a method of assessing tractor suspension seat performance. The (current ISO 5008) measurement of WBV emission levels upon solo tractors traversing these tracks bears little relation to practical agricultural operational conditions, to the extent that any significant correlation between ISO track and ‘in-field’ results would be a cause for concern. Nonetheless, defined, repeatable WBV test conditions and methodologies are required for agricultural tractors and other ‘off-road’ vehicles. There is scope for further analysis of the results obtained from this investigation and development / refinement of test methodologies. This is discussed further in Section 7.2.

0.40

0.60

0.80

1.00

1.20

1.40

1.60

Spraying Plough in transport Ploughing Trailer transport CultivatingTasks

Wei

ghte

d r.

m.s

. acc

eler

atio

n (m

/s2 )

Y-axisY-axis

X-axis

Y-axis

Y-axis

Figure 5.22 Range of operator seat r.m.s. acceleration levels recorded during SRI agricultural tractor ‘in-field’ investigation (largest axis denoted upon each bar)

82

5.4 ‘ON-FARM’ WBV EXPOSURE MEASUREMENT 5.4.1 Introduction Following a similar methodology to that employed for the self-propelled sprayers (Section 4.4), a programme of ‘on-farm’ WBV exposure level measurement was performed upon a range of agricultural tractors across East Anglia. The objectives of this part of the investigation were to:-

• Verify the practical applicability of the detailed agricultural tractor WBV emission data derived from the SRI ‘in-field’ and (possibly) ISO Test Track measurement programmes;

• Explore the variation in (and magnitudes of) WBV emission and resultant exposure levels encountered upon ‘on-farm’ agricultural tractors during ‘typical’ half-day (4 hour) work periods;

• Enable limited investigation of typical usage patterns of ‘on-farm’ examples of selected test tractor designs included in the overall investigation.

5.4.2 Procedure Given that the original objective of the investigation was “to determine WBV emission and exposure levels associated with representative ‘state-of-the-art’ agricultural vehicles performing agricultural operations….”, the ‘on-farm’ WBV study was intentionally restricted to the two test tractor designs considered to embody the greatest proportion of WBV-reducing features. These were the:-

• Suspended front axle and cab tractor (New Holland TM 165); • Fully suspended (front & rear axle) tractor (JCB Fastrac 3185)

Whilst the JCB Fastrac can be regarded as somewhat unique in the marketplace, it is nonetheless well established, largely as a result of its suspension, handling and high-speed travel capabilities. A ride vibration study would therefore not be complete without its inclusion. Equally, suspended front axle and cab tractors now represent the ‘state-of-the-art’ in ‘conventional’ tractor development (see Section 2.1), examples being offered in the (100 – 130 kW) power range by all major manufacturers. Consequently, its inclusion in this part of the study was equally important. To ensure comparability with the SRI ‘in-field’ WBV emission measurement programme, an identical range of field tasks (field/road trailer transport, ploughing, cultivating, spraying/fertiliser application) was targeted, albeit in ‘on-farm’ situations. During the period December 2001 – March 2002 attempts were made to record WBV acceleration time histories (thereby permitting derivation of WBV emission and exposure levels) upon 3 separate examples of each tractor type performing each defined field task, thereby providing 3 replications of each tractor / field task combination. Theoretically this required identification of, and subsequent logistical coordination with, 24 different tractors / owners / operators across East Anglia: 22 tractor / task combinations were successfully completed within the seasonal constraints present (see Table 5.5 & Appendix 2.8). Suitable ‘on-farm’ test vehicles (i.e. correct physical specification and less than 2 years old) were identified with manufacturer / dealer assistance: vehicle owners were then approached to determine the typical operations performed by the vehicles. Given comparability with the target field tasks and preparedness to participate in the study, ‘on-farm’ WBV measurements were made during a nominal ‘half-day’ (4-hour) period, as the tractor performed the target task in conjunction with the ‘on-farm’ implement typically used for that purpose.

83

Acceleration time histories were recorded simultaneously upon the operator’s seat and the cab floor of each tractor, by use of the vehicle-mounted instrumentation described in Section 3.2, but in this application individual Larson Davis Human Vibration meters (type HVM100) were also used to reduce the acceleration data in real-time, record peak values and derive vibration dose values (VDV) for each 15-minute section of the total operating period. As before, vehicle forward speed was recorded (derived from a Doppler radar sensor mounted upon each vehicle), to enable quantification of this important operational parameter and identification of any stationary / inactive periods during the measurement period. 5.4.3 Results As discussed previously (Section 3.1), the European Union Physical Agents (Vibration) Directive (PA(V)D) defines the WBV Exposure Action Value (EAV) and Exposure Limit Value (ELV) in two alternative ways. Either as an 8-hour energy-equivalent frequency weighted r.m.s. acceleration value (A(8)), or as a vibration dose value (VDV). Member States are given the option of implementing the Directive using either method, using the values stated below (see Table 5.4). Specific details are discussed in Section 3.1, but an important difference between the methods is as follows. The root-mean-square (r.m.s.) or A(8) method produces a value which is an average vibration level adjusted to represent an 8 hour working day, whereas the vibration dose value represents cumulative exposure to vibration over the working day. The practical significance of this is clearly depicted by Figure 5.29. If, over a given working period, frequency-weighted r.m.s. acceleration levels recorded upon the operator’s seat are relatively consistent, the resultant equivalent continuous acceleration (Aeq) value (only A(8) if exposure period = 8 hours) changes little, having once reached an average ‘plateau’ value. However, in the same circumstances, the VDV increases throughout the work period in a cumulative manner. Additionally, the A(8) method represents steady levels of vibration with reasonable accuracy but gives poor representation of shocks and jolts, whereas the VDV method performs well in both instances (Griffin, 1998; Coles, 2002). These issues, and those of sampling duration, are discussed in Appendix 4. Throughout this investigation we have primarily utilised the A(8) method but, during ‘on-farm’ exposure measurement, vibration dose values have also been derived (see Figures 5.29 – 5.32 inclusive and Appendix 2.8). At the time of writing the HSE is undertaking a public consultation exercise regarding implementation of the PA(V)D in the UK. Whilst it is highly likely that the ELV will be specified by the A(8) technique, debate is currently ongoing as to whether the EAV will be implemented in VDV or A(8) terms: the implications of this stance are discussed in Sections 3.1 & 7.4. An important aspect of results interpretation concerns how estimates for a whole day’s vibration exposure can be made from values measured over a shorter period (see also Appendix 4). Nominal half-day (approx. 4-hour) measurement periods were used ‘on-farm’ to ensure the data acquired were characteristic of the operation. If using the r.m.s. A(8) approach, the resultant overall average frequency-weighted r.m.s. acceleration (Aeq) value, measured for the shorter (~4-hour) period, can be considered to extend throughout the entire day’s use of the machine. The Aeq value becomes equivalent to the daily occupational vibration exposure (A(8)) value for that operation, if the vehicle in question were to be operated for 8 hours. Consequently the Aeq values generated by this investigation may be compared directly with the A(8) EAV and ELV values stipulated by the PA(V)D whenever the working day length approximates to 8 hours. For shorter or longer working days the respective A(8) value for the daily exposure period in question may be calculated from the Aeq value, prior to comparison with the EAV or ELV (see Section 3.1.2, Equation 3). A similar approach is necessary for the VDV; its cumulative nature requires a value for a shorter period be re-calculated to estimate the VDV after the full day’s exposure. This is performed by assuming subsequent WBV emission

84

levels are similar to those recorded during the (~4 hour) measurement period (see Appendix 4). Examples of estimated 8-hour VDV’s appear in Tables 5.5 & 5.6, Figures 5.29 – 5.32 and Appendix 2.8.

Table 5.4 WBV exposure values specified by the EU PA(V)D

8-hour energy-equivalent

r.m.s. acceleration – A(8)

(m/s2)

Vibration Dose Value

(m/s1.75)

Exposure Action Value (EAV) 0.5 9.1

Exposure Limit Value (ELV) 1.15 21

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Tractor

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

Figure 5.23 Range of average ‘energy-equivalent’ r.m.s. seat acceleration (Aeq) values recorded during ‘on-farm’ WBV measurement programme The range of energy-equivalent WBV (Aeq) levels (largest single axis only) recorded upon the seats of ‘on-farm’ agricultural tractor-implement combinations is depicted in Figure 5.23, highlighting the spread of overall average WBV magnitudes (0.36 – 1.39 m/s2) present within typical agricultural operations. It would appear that only a minority of the applications would exceed the PA(V)D-prescribed A(8) exposure limit value (ELV) if operated for 8 hours per day (see Figures 5.24, 5.25 & 5.35). Seat WBV data arising from the ‘on-farm’ tractor investigation are summarised in Table 5.5 and Figure 5.24 (suspended front axle & cab tractor) and Table 5.6 and Figure 5.25 (fully suspended (front & rear axle) tractor). Corresponding cab floor results appear in Appendix 2.7, and are presented graphically for comparison with operator seat WBV levels in Figures 5.26 & 5.27 (largest single axis only). Generally the individual ‘on-farm’ operations reflect similar relative WBV magnitudes to those obtained from SRI ‘in-field’ measurements (see Figure 5.28), especially in the case of the fully suspended (front & rear axle) tractor.

85

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Tasks

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

X-axis Y-axis Z-axis EAV (A(8) ELV (A(8)

Spraying Ploughing Trailer Transport Cultivating

Figure 5.24 Range of ‘energy-equivalent’ r.m.s. (Aeq) seat acceleration levels

recorded upon ‘on-farm’ suspended front axle and cab tractors: (displayed by measurement axis & task performed)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Tasks

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

X-axis Y-axis Z-axis EAV (A(8) ELV (A(8)

Spraying Ploughing Trailer Transport Cultivating

Figure 5.25 Range of ‘energy-equivalent’ r.m.s. (Aeq) seat acceleration levels

recorded upon ‘on-farm’ fully suspended (front & rear axle) tractors: (displayed by measurement axis & task performed)

86

Seat acceleration levels were in all instances higher than those recorded upon the cab floor (see Figures 5.26 & 5.27). In largest single-axis magnitude terms, highest overall average (Aeq) levels were, once more, primarily encountered in the transverse (Y) axis during most field operations, with the exception of trailer transport when the longitudinal (X) axis levels took precedence. However, as previously discussed, whilst the Directive requires WBV exposure levels to be assessed separately in each axial direction, and the measurement axis with the greatest (overall average) magnitude be identified, action is required to reduce WBV exposure in all axial directions where the EAV is exceeded (see Section 3.1.3). In practical terms whilst, for a given vehicle / application, the longitudinal (X) or transverse (Y) measurement axes may exhibit the highest axis-weighted overall-average acceleration levels, marginally lower Aeq levels in the remaining axial directions may still require vibration-reducing actions on the part of the employer, if above the EAV, especially if significant peak acceleration events (shocks and jolts) are present (see Figures 5.30 – 5.32). Following this methodology it can be seen from the limited ‘on-farm’ survey performed during this investigation (see Figures 5.24 & 5.25 and Tables 5.5 & 5.6)) that the EAV would be reached or exceeded after 8 hours operation, due to WBV levels present in the following axes upon the following machine / task combinations:- Suspended Front Axle & Cab Tractor:-

o Spraying / fertiliser spreading:- X & Y-axes o Ploughing:- X & Y-axes o Trailer transport:- X & Y-axes o Cultivating:- Y-axis

Fully Suspended (front & rear axle) Tractor:-

o Spraying / fertiliser spreading:- Y-axis o Ploughing:- X & Y-axes o Trailer transport:- X & Y-axes o Cultivating:- X, Y & Z-axes

Seat r.m.s. acceleration levels were of sufficient magnitude in certain examples of the fully suspended (front & rear axle) tractor to approach or exceed the ELV after 8 hours operation upon trailer transport and cultivating operations (see Figure 5.25 & Table 5.6): a potential situation predicted for all the test vehicles following the SRI ‘in-field’ programme. However, these same operations resulted in only moderate / low WBV levels upon the suspended front axle & cab tractor (see Figure 5.24 & Table 5.5), spraying and ploughing operations frequently generating higher WBV levels upon examples of this vehicle. This evidence raises a number of important issues. ISO test track and SRI ‘in-field’ investigations with representative examples of these vehicles found that, in the majority of agricultural field operations, these machines generated comparable WBV emission levels upon both the cab floor and operator’s seat: the fully suspended tractor delivering reduced WBV levels during (road / farm track) trailer transport operations. Why therefore were these findings not reflected in the ‘on-farm’ data?

87

Table 5.5 ‘On-farm’ WBV seat data: suspended front axle & cab tractor

X Y Z Major axis

Ploughing (1) 4.25 0.35 0.62 0.32 Y 0.62 11.7 5.16 2.96 >24

Ploughing (2) 3.25 0.58 0.86 0.47 Y 0.86 15.3 2.72 0.99 14.39

Ploughing (3) 4.25 0.39 0.49 0.26 Y 0.49 10.2 8.29 5.13 >24

Cultivating (1) 5.25 0.35 0.53 0.27 Y 0.53 13.3 7.04 1.74 >24

Cultivating (2) 4.75 0.45 0.67 0.31 Y 0.67 16.9 4.51 0.68 23.84

Spraying (1) 4.50 0.50 0.66 0.40 Y 0.66 16.0 4.63 0.84 >24

Spraying (2) 4.25 0.41 0.49 0.29 Y 0.49 12.1 8.39 2.55 >24

Spraying (3) 4.50 0.48 0.78 0.42 Y 0.78 20.7 3.27 0.30 17.32

Trailer Work (1) 3.75 0.55 0.50 0.34 X 0.55 12.0 6.61 2.63 >24

Trailer Work (2) 4.75 0.52 0.58 0.37 Y 0.58 14.3 6.00 1.31 >24

Trailer Work (3) 4.00 0.47 0.38 0.29 X 0.47 11.7 9.10 2.94 >24

Time to EAV (hr)

(A(8))

Time to ELV (hr)

(A(8))Task Duration

(hr)Average r.m.s. acceleration (m/s 2 ) Aeq

(m/s 2 )

Est. 8 hr VDV

(m/s 1.75 )

Time to EAV (hr)

(VDV)

Table 5.6 ‘On-farm’ WBV seat data: fully suspended (front & rear axle) tractor

X Y Z Major axis

Ploughing (1) 4.00 0.54 0.93 0.33 Y 0.93 19.9 2.31 0.35 12.24

Ploughing (2) 5.75 0.34 0.81 0.30 Y 0.81 21.9 3.06 0.24 16.18

Ploughing (3) 4.50 0.59 0.76 0.39 Y 0.76 16.4 3.47 0.76 18.37

Cultivating (1) 3.75 0.54 0.85 0.46 Y 0.85 21.7 2.79 0.25 14.75

Cultivating (2) 4.50 0.86 1.36 0.65 Y 1.36 29.4 1.09 0.07 5.76

Cultivating (3) 4.00 0.89 1.39 0.63 Y 1.39 26.2 1.04 0.12 5.51

Spraying (1) 4.75 0.48 0.58 0.41 Y 0.58 14.6 5.86 1.20 >24

Spraying (2) 6.00 0.27 0.36 0.26 Y 0.36 8.5 15.32 10.72 >24

Trailer Work (1) 5.50 0.71 0.65 0.38 X 0.71 18.2 3.93 0.50 20.79

Trailer Work (2) 5.00 1.12 0.85 0.48 X 1.12 28.9 1.60 0.08 8.49

Trailer Work (3) 4.50 0.54 0.64 0.33 Y 0.64 25.3 4.94 0.13 >24

Time to EAV (hr)

(A(8))Task Duration

(hr)

Time to EAV (hr)

(VDV)

Est. 8 hr VDV

(m/s 1.75 )

Aeq (m/s 2 )

Average r.m.s. acceleration (m/s 2 ) Time to ELV (hr)

(A(8))

Vehicle WBV emission levels are dependent not only upon vehicle design and the presence of vibration reduction features (e.g. suspended seats, cabs & axles), but also upon operating surface, forward speed and personal driving technique / direction. It was noted during the ‘on-farm’ investigation that certain of the suspended front axle & cab tractor operating conditions were not as severe as those being experienced by the fully suspended (front & rear axle) machines. This was particularly noticeable during cultivating and trailer transport operations. The ‘intensity’ of use of the fully suspended machines, in terms of demanded cycle times and haul distances, also appeared to be greater. It is appropriate to highlight that the latter are solely observations of a relatively small sample of tractors / operations, albeit made by experienced agricultural field test personnel. Nonetheless it is probably inappropriate to conclude that a suspended front axle & cab tractor will frequently deliver lower WBV levels than a fully suspended (front & rear axle) machine.

88

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Tasks

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

Seat Floor EAV (A(8)) ELV (A(8))

Spraying Ploughing Trailer Cultivating (Y-axis) (Y-axis) transport (X-axis) (Y-axis)

Figure 5.26 Range of ‘energy-equivalent’ r.m.s. (Aeq) seat & floor acceleration

values recorded upon ‘on-farm’ suspended front axle and cab tractors (largest axis denoted beside ‘task’)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Tasks

Wei

ghte

d r.m

.s. a

ccel

erat

ion

(m/s

2 )

Seat Floor EAV (A(8)) ELV (A(8))

Spraying Ploughing Trailer Cultivating (Y-axis) (Y-axis) transport (X-axis) (Y-axis)

Figure 5.27 Range of ‘energy-equivalent’ r.m.s. (Aeq) seat & floor acceleration

values recorded upon ‘on-farm’ fully suspended (front & rear axle) tractors (largest axis denoted beside ‘task’)

89

Average rms acceleration values - TM 165 Seat

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field) Farm 1 Farm 2 Farm 3

Average rms acceleration values - JCB Seat

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field) Farm 1 Farm 2 Farm 3 Figure 5.28 Comparison between SRI ‘in-field’ and ‘on-farm’ WBV levels, by vehicle and operation (largest axis denoted beside ‘operation’)

Average rms acceleration values - TM 165 Floor

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field) Farm 1 Farm 2 Farm 3

Average rms acceleration values - JCB Floor

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

SRI (field) Farm 1 Farm 2 Farm 3

90

A more precise comparison between the WBV emission levels generated by the suspended front axle & cab tractor and the fully suspended (front & rear axle) machine is provided by the SRI ‘in-field’ test programme (see Figure 5.28), but no doubt performance of a greater number of ‘on-farm’ test replications in the future would enable greater statistical confidence to placed in data from this potentially variable (‘on-farm’) source. Figures 5.29 – 5.32 depict the parameters arising from the ‘on-farm’ WBV measurement programme in a generic presentation format. Figures 5.29 & 5.30 depict seat WBV data arising from a suspended front axle & cab tractor performing ploughing and fertiliser spreading (spraying) operations, respectively. Figures 5.31 & 5.32 depict comparable data arising from a fully suspended (front & rear axle) tractor undertaking trailer transport and cultivating. Tabular data specifies the measurement location (seat or floor), tractor model, geographical location, date, operation type and measurement duration. The corresponding graph depicts a time history of frequency-weighted 1-minute average r.m.s. acceleration values, as recorded in the orthogonal axis which consistently generated the largest overall average values throughout the operating period. This is supplemented by traces depicting 15-minute vibration dose values (VDV) and development of equivalent continuous frequency-weighted r.m.s. acceleration (Aeq) which, as previously discussed, may be related to the A(8) value. Tabular WBV data are presented in terms of overall average frequency-weighted r.m.s. acceleration (Aeq) and peak values for each measurement axis, together with corresponding root-sum-of-squares (RSS) values. Individual axis and RSS VDV values for the measurement duration, and estimated (VDV) values for an 8-hour period, are also included. Finally, estimated operating periods until the EAV and ELV are reached, are shown both in relation to the A(8) and VDV calculation methods. Comments relating specifically to each of these ‘on-farm’ WBV measurement examples appear at the base of each Figure (5.29 – 5.32 inclusive). A summary of cab floor and seat WBV data from the entire ‘on-farm’ programme is presented in Appendix 2.8. The traces shown within Figures 5.33 & 5.34 depict the development of equivalent continuous r.m.s. (Aeq) seat acceleration (in the largest single (major) axis) for all ‘on-farm’ tractor type / operation WBV exposure measurement replicates, thereby indicating the degree of variation present within each ‘target’ task. The important parameter is the Aeq value at the end of each measurement period for a particular operation: these values are also presented in Tables 5.5 & 5.6 and their range depicted in Figures 5.24 & 5.25 (for all measurement axes). Little WBV exposure variation is present within certain operations (suspended front axle & cab tractor – trailer transport and cultivating; fully suspended tractor – ploughing and spraying). Greater variation is present within the other tractor / task combinations (suspended front axle & cab tractor – ploughing and spraying; fully suspended tractor - trailer transport and cultivating). This absence of pattern suggests that WBV exposure levels are less operation-dependent than the findings of the SRI ‘in-field’ programme suggest. An alternative explanation is that insufficient ‘on-farm’ tractor / task measurement replicates were performed to enable the ‘operation’ dependency of WBV exposure to be determined. This also restricts generation of a robust, generic WBV emissions database for agricultural tractor operations, which is undoubtedly a requirement to assist implementation of the Directive within UK agriculture.

91

92

Lar

son Davis HVM100 SN:00215 Day Month YearLocation: Seat 15 Jan 2Machine: TM165Reg No: AO51HMY Start time: 13:47Task: PloughingPlace: Edwards, Farmers/Contractors, Mattishall

otal VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:15 8.6 12.3 6.7 16.4hr est tot 10.8 15.3 8.4 20.5

T

0.58 0.86 0.47 1.138

EstimTT

-

ated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )ime to EAV (hr): 0.99 2.72 X Y Z Sumime to ELV (hr): >24 14.39 5.08 5.56 5.06 6.35

Figure 5.29

Comments •

•

•

s relatively constant throughout, having once attained a representative value in the first 15 minutes of operation (see Appendix 4);

• The VDV Exposure Action Value (EAV) is exceeded in approx. 1-hour operation; • The A(8) Exposure Action Value (EAV) is exceeded in approx. 2¾ hours operation; • The (A(8)) Exposure Limit Value (ELV) is exceeded in approx. 14½ hours operation.

Typical time history of weighted 1-minute r.m.s. accelerations (Y-axis, TM 165 seat – ploughing) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV) and table of seat WBV parameters

A relatively consistent vibration record (Y-axis largest) with few peaks in any axis; however the overall acceleration level is moderate to high; The abovementioned characteristics result in a relatively constant, high Y-axis Aeq value, which reflects the overall WBV history well; The VDV ramps steadily throughout the measurement period, reflecting its cumulative nature. The Aeq is the level of equivalent continuous acceleration experienced since the beginning ofthe measurement period: it therefore remain

2

2.5

tion

(m/s

2 ) 16.0

20.0

0

0.5

1

0:00 0:30 1:00 1:30 2:00 2:30 3:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

0.0

4.0

8.0 VDV

(m/s

1.

era

1.5 12.0 75)

Transverse (Y) Aeq VDV

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0.0

4.0

8.0

12.0

16.0

20.0

VDV

(m/s

1.75

)

Transverse (Y) Aeq VDV

Larson Davis HVM 0 SN:00215 Day Month Year

Location: Seat 5 Mar10

2Machine:Reg No:Task:

TM165W271DNO Start time: 08:45Fertiliser spreading

Place: R Melbourne, Contractor, Stevenage

Total VDV (m/s 1.

Time X

75 ) Average r.m.s. (Aeq) (m/s 2 )Y Z Sum X Y Z Sum

0h

mTim 7.95 10.15 13.10 13.30

4:30 10.1 13.8 9.8 19.3 0.50 0.66 0.40 0.928- r est tot 11.7 16.0 11.3 22.3

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Ti e to EAV (hr): 0.84 4.63 X Y Z Sum

e to ELV (hr): 23.93 >24

ure 5.30 Typical time history of weighted 1-minute r.m.s. accelerations (Y-axis, TM 165 seat – fertiliser spreading) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibrati

Fig

on

• A variable vibration record (Y-axis largest), reflecting the cyclical (refilling, transport,

field travel) nature of the operation; • Moderate peaks, troughs and periods of inactivity (refilling) are present: the highest peaks

occur in the Y and Z-axes; • The equivalent continuous acceleration (Aeq) level is moderate: this calculation method

smoothes the time history to a degree and does not respond to the peak events as significantly as the VDV method (see trace);

• The VDV Exposure Action Value (EAV) is exceeded in less than 1-hour operation; • The A(8) Exposure Action Value (EAV) is exceeded in approx. 4½ hours operation; • The (A(8)) Exposure Limit Value (ELV) will not be exceeded in a 24-hour period

(Methods of calculating estimated exposure values are discussed in Appendix 4);

Dose Value (VDV) and table of seat WBV parameters Comments

93

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0.0

4.0

8.0

12.0

16.0

20.0

VDV

(m/s

1.75

)

Transverse (X) Aeq VDV

Larson Davis HVM100 SN:00215 Day Month Year

Location: Seat 17 Jan 2Machine: JCB FastracReg No: W193BAV Start time: 11:47Task: Trailer Work (Sugar Beet Haulage)Place: David Russell Contractor (Downham Market)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:30 16.3 16.6 9.6 24.4 0.71 0.65 0.38 1.03

8-hr est tot 17.9 18.2 10.6 26.8

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.50 3.93 X Y Z SumTime to ELV (hr): 14.06 20.79 11.09 9.84 18.10 18.10 Figure 5.31 Typical time history of weighted 1-minute r.m.s. accelerations (X-axis,

JCB 3185 seat – trailer transport) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV) and table of seat WBV parameters

C • A te,

f reafter harvester to clamp field transport; • W

a• T

s• T eeded in approx. 30 minutes operation; • T• T ion; • W task,

p site travel and harvester maintenance breaks must regularly occur in practice.

omments

variable vibration time history (X-axis largest), reflecting initial road travel to a new siollowed by an inactive period and the

hilst the overall average r.m.s. (Aeq) values identify the X-axis as largest, greatest peaks ctually occur in the Z-axis;

he Aeq reduces significantly during the idle period, but increases substantially during ubsequent fieldwork: the overall value would be higher for an entire day’s fieldwork; he VDV Exposure Action Value (EAV) is exc

he A(8) Exposure Action Value (EAV) is exceeded in approx. 4 hours operation he (A(8)) Exposure Limit Value (ELV) is likely to be exceeded in ~20¾ hours operat hilst the ELV appears unlikely to be reached during the daily performance of this

erhaps this example is not a truly representative working day ? Nonetheless, inter-

94

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0.0

4.0

8.0

12.0

16.0

20.0

VDV

(m/s

1.75

)

Transverse (Y) Aeq VDV

Larson Davis HVM100 SN:00215 Day Month Year

Location: Seat 26 Mar 2Machine: JCB Fastrac 3185Reg No W193BA: V Start time: 09:19

CultivatinTask: gPlace:

Total VDV (m/s 1.75 )Time X Y Z Sum X Y Z Sum

18.0 9.5 22.4 0.54 0.85 0.46 1.1121.7 11.5 27.1

mm

Russell Contractors, Downham Market

Average r.m.s. (Aeq) (m/s 2 )

03:45 10.6hr est tot 12.88-

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Ti e to EAV (hr): 0.25 2.79 X Y Z Sum

e to ELV (hr): 7.01 14.75 7.34 11.21 13.7Ti 0 13.60

Fig tory of weighted 1-minute r.m.s. accelerations (Y-axis, us

• s

• Moderate to high overall average r.m.s. (Aeq) and 8-hour estimated VDV values; • Substantial (1-minute average) peaks occur early on, causing a rapid increase in the VDV:

the Aeq does not respond to these events as significantly and reduces during subsequent periods of lower r.m.s. acceleration levels;

• The VDV Exposure Action Value (EAV) is exceeded in approx. 15 minutes; • The A(8) Exposure Action Value (EAV) is exceeded in approx. 2¾ hours operation; • The (A(8)) Exposure Limit Value (ELV) is likely to be exceeded in 14¾ hours operation; • Whilst it appears the ELV would only be reached during a long working day, this point

could in fact be reached much sooner if the initial high acceleration levels were maintained through a greater proportion of the working day (see Appendix 4).

ure 5.32 Typical time his

JCB 3185 seat – cultivating) plus development of equivalent continuor.m.s. acceleration (Aeq) & 15 minute record of Vibration Dose Value(VDV) and table of seat WBV parameters

Comments

An extremely variable vibration record (Y-axis largest) reflecting fieldwork in conditionof different severity / location, plus a period of inactivity;

95

Equivalent Continuous r.m.s. Acceleration (Aeq) (TM 165 seat, Y-axis - Cultivation)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

CT1 - Y CT2 - Y Equivalent Continuous r.m.s. Acceleration (Aeq) (TM 165 seat, Y-axis - Spraying)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

DR1 - Y DR2 - Y DR3 - Y Figure tion traces for suspended front axle & cab tractor (TM 165) ‘on-farm’

operations

96

Equivalent Continuous r.m.s. Acceleration (Aeq) (TM 165 seat, X-axis - Trailer Transport)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0:00

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

)1.0

30 3:0 00 4:30 5:00

Time (hrs)

2

0:30 1:00 1:30 2:00 2:

Elapsed0 3:30 4:

TR1 - X TR2 - X TR3 - X

Eq

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0:00

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

)

uiva

0:3

lent

0

Conti

1:

nuous r.m.s.

1:30

Acceleration

2:00

apsed

(Aeq) (TM oughing)

00 2:30 4:00 4:30

El Time (hrs)

2

165 seat, Y-axis - Pl

3:00 3:30

PL1 - Y PL2 - Y PL3 - Y

Equivalent continuous r.m.s. (Aeq) seat accelera 5.33

Equivalent Continuous r.m.s. Acceleration (Aeq) (JCB 3185 seat, X-axis - Trailer Transport)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

TR1 - X TR2 - X TR3 - X

Equivalent Continuous r.m.s. Acceleration (Aeq) (JCB 3185 seat, Y-axis - Cultivation)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

CT1 - Y CT2 - Y CT3 - Y Equivalent Continuous r.m.s. Acceleration (Aeq) (JCB 3185 seat, Y-axis - Ploughing)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

PL1 - Y PL2 - Y PL3 - Y

Equivalent Continuous r.m.s. Acceleration (Aeq) (JCB 3185 seat, Y-axis - Spraying)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

DR1 - Y DR2 - Y Figure 5.34 Equivalent continuous r.m.s. (Aeq) seat acceleration traces for fully suspended (front & rear axle) tractor (JCB Fastrac

97

3185) ‘on-farm’ operations

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Tractor

Dai

ly v

ibra

tion

expo

sure

(A(8

)) (m

/s2 )

A(8) EAV (A(8)) ELV (A(8))

Figure 5.35 Daily WBV exposure (A(8)) likely to be received by operators of

surveyed ‘on-farm’ tractors, if operated for 8 hours per day

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Tractor

Dai

ly v

ibra

tion

expo

sure

(A(8

)) (m

/s2 )

A(8) value for 12 hr shift EAV (A(8)) ELV (A(8))

98

Figure 5.36 Daily WBV exposure (A(8)) likely to be received by operators of

surveyed ‘on-farm’ tractors, if operated for 12 hours per day

As discussed earlier, whilst few (~ 9%) of the ‘on-farm’ tractor - operations surveyed would exceed the PA(V)D A(8) exposure limit value (ELV) if worked for 8 hours per day, virtually all the machine examples (~ 95%) would exceed the exposure action value (EAV) during the same working period (if specified in VDV terms), but fewer (~ 82%) would reach the EAV if it were to be specified by the A(8) method (see Tables 5.5 & 5.6 and Figures 5.35 & 5.37). However, as discussed in Section 3.1.3, if the vehicle operating period extends beyond 8 hours per day, the weighted r.m.s. acceleration and VDV magnitudes associated with the ELV and EAV values progressively reduce (see Figure 3.1). Alternatively the A(8) value for a non-8-hour working day must be calculated from the prevailing Aeq value (see Section 3.1.2, Equation 3 (reproduced below)) to reflect the (shorter or longer) exposure period. The effect of a longer working day upon operation of the tractor – operations surveyed can be seen by comparing Figures 5.35 & 5.36, which depict the daily WBV exposures likely to be received by the operators if the vehicles were worked for an 8 or 12-hour period. It will be noted that the longer operating period effectively increases the A(8) value of each vehicle, increasing the likelihood of exceeding the EAV and ELV, but the nature of this increase (or decrease) with exposure period (time) is not linear (see Figure 3.1 and equation below).

A(8) = Aeq 8t

where:-

t = daily exposure period (hours)

Aeq = the energy-equivalent continuous r.m.s. acceleration which is representative of the exposure period (m/s2)

To this end Tables 5.5 & 5.6 and Figures 5.37 & 5.38 present the estimated operating periods required for each surveyed tractor / task combination to reach the EAV (VDV & A(8)) and the ELV (A(8)) respectively. The likelihood of exceeding the EAV during a normal (8-hour) agricultural operating day is therefore very high, necessitating employers implement WBV exposure reduction / management actions discussed in Section 3.1.3. The ELV would, at first, not appear to be a significant restriction to normal use of modern, state-of-the-art tractors during an 8-hour working day, but such a working day is hardly normal practice in agriculture, especially regarding operation of tractors of this size. If the working day were to increase, 14% of the surveyed examples would exceed the ELV in 9 hours operation, 18% in 13 hours and 27% in 15 hours operation. Such operating periods may appear extreme, but as part of the ‘on-farm’ investigation, drivers recorded both their driving hours and the operation(s) performed by their tractors during the (5-day) working week, which encompassed the WBV measurement day. This effectively produced a survey of 110 tractor-days, of which 90 days (82%) were operational: the results obtained are summarised in Table 5.7 and Figure 5.39. Whilst 57% of tractor-days exceeded 8 hours operation per day, a significant proportion reached 12, 14 or even 16 hours per day. Additionally, these operating hours would probably extend over a

g ed as a busy period in e may well restrict UK agricultural tractor operating patterns, in terms of permissible daily operating period (greater than 8 hours).

6 day workin week and the survey period (December – March) is not usually regard the farming year. Consequently, the requirements of the Directiv

99

12

13

14

15

16

0

1

2

3

4

5

6

7

8

9

10

11

Ope

ratin

g Pe

riod

(hou

rs)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Tractor

EA DV)V (V EAV (A(8))

Figure 5.37 Operating period required of surveyed ‘on-farm’ tractors / tasks in order

to exceed the Exposure Action Value (EAV)

F

igure 5.38 Operating period required of surveyed ‘on-farm’ tractors / tasks in orderto exceed the A(8) Exposure Limit Value (ELV)

0

2

4

6

8

10

12

14

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Tractor

Ope

ratin

g Pe

riod

(hou

rs)

18

20

22

24

26

28

ELV (A(8))

100

Table 5.7 ‘On-farm’ daily usage of suspended front axle & cab (TM 165) and fully suspended (front & rear axle) (JCB 3185) tractors

Tractor Number of

days surveyedNumber of

operational daysNumber of

operational days <= 8 hrs

Number of operational days

> 8 hrs

Average operational day length (hours)

JCB 55 45 22 23 9.5 TM 55 45 17 28 8.3

-hour (half-day) measurement period, as utilised in the ‘on-farm’ WBV programme, will ly

0

5

10

15

20

25

4 6 8 10 12 14 16

Period of daily operation (hrs)

Num

ber o

f wor

king

day

s

JCB 3185 TM 165

Figure 5.39 ‘On-farm’ daily usage of suspended front axle & cab (TM 165) and fully

suspended (front & rear axle) (JCB 3185) tractors Mitigating against these findings is the fact that this was a limited survey. Whilst the WBV exposure measurement days were found to be representative of vehicle usage, the survey was performed during only one seasonal period. Also of consequence is the likely daily working pattern of the vehicle in question: rest breaks, machine maintenance and periods of general inactivity can all contribute to a reduction in the Aeq WBV exposure value (see Figure 5.31). This characteristic also has consequences for ‘in-field’ WBV exposure measurement. A 30 minute measurement period, as used during the SRI ‘in-field’ WBV programme, will encompass normal variations present within an agricultural tractor field task. However, such a period of operation will be ‘continuous’ and will not include rest or maintenance breaks. The 4almost certain identify such breaks if they are a common / regular feature.

101

102

m’ WBV

uous-operation’ WBV levels

Figure 5.40 Comparison between SRI ‘in-field’ and ‘as-recorded’ ‘on-far

levels

SRI (field) Farm 1 Farm 2 Farm 3

Average rms acceleration values - JCB Floor

0.5

0.6

0.8

0.9

1

Wei

ghte

d r.m

.s. A

ccel

era

s2 )

0.7tion

(m/

igure 5.41 Comparison between SRI ‘in-field’ and ‘on-farm’ ‘continF

0

0.1

0.2

0.3

0.4

0.5

0.6

0.9

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

Wei

ghte

d r.m

.s. A

ccel

erat

io

0.7n (m

0.8

/s2 )

1

0

0.1

Ploughing (Y) Cultivating (Y) Spraying (Y) Trailer transport (X)

0.2

0.3

0.4

Average rms acceleration values - JCB Floor

SRI (field) Farm 1 Farm 2 Farm 3

103

The potential effect of sampling duration is highlighted in Figures 5.40 & 5.41 and discussed further in Appendix 4. Figure 5.40 indicates the degree of similarity between WBV levels recorded SRI ‘in-field’ and comparable ‘on-farm’ measurements. Figure 5.41 depicts the same SRI ‘in-field’ values, but the ‘on-farm’ WBV data has been processed to reflect only periods of continuous operation. Consequently, whilst certain of the WBV levels recorded during the SRI ‘in-field’ work may initially appear somewhat excessive and unrepresentative of ‘on-farm’ machine operation, comparison with ‘continuous’ ‘on-farm’ operation shows this not to be the case. Nonetheless, as far as the Directive is concerned, it is the lower, ‘interrupted’ ‘on-farm’ WBV daily exposure levels which are evaluated against the prescribed action and limit values. 5.4.4 ‘On-Farm WBV Exposure Measurement - Summary The objectives of the ‘on-farm’ tractor WBV investigation were to:-

• Verify the practical applicability of the detailed agricultural tractor WBV emissions data derived from the SRI ‘in-field’ and (possibly) ISO Test Track measurement programmes;

• Explore the variation in (and magnitudes of) WBV emission and resultant exposure levels encountered upon ‘on-farm’ agricultural tractors during typical half-day (4 hour) work periods;

selecte ctor designs included in the overall investigation.

The findings of the ‘on-farm’ tractor WBV exposure measurement programme may be summarised as follows:-

• Specific ‘on-farm’ tractor / operation combinations generated WBV emission levels similar to those experienced during the SRI ‘in-field’ measurement programme. This was particularly true of the fully suspended (front & rear axle) tractor;

• Cultivating and trailer transport generated the highest WBV emission levels upon the fully suspended (front & rear axle) tractors, confirming the findings of the SRI ‘in-field’ programme (see Figure 5.25);

• Largest overall average r.m.s. (Aeq) seat acceleration levels were usually found in the transverse (Y) axis during the majority of ‘on-farm’ operations, with the exception of trailer transport when longitudinal (X) axis WBV took precedence (see Figures 5.24 & 5.25). However, frequently the maximum peak acceleration was found to occur in the vertical (Z) axis;

• In all instances seat acceleration levels were higher than those recorded upon the tractor cab floor (see Figures 5.26 and 5.27);

• During certain operations (cultivating and trailer transport), ‘on-farm’ examples of the suspended front axle & cab tractor generated lower WBV emission levels than the comparable SRI ‘in-field’ tractor and the ‘on-farm’ fully suspended (front & rear axle) tractors. This was deemed to be due to disparate operating conditions and intensity of machine operation;

• It was considered that, in general, the ‘on-farm’ fully suspended (front & rear axle)

greater f ‘farm contractor’ rather than ‘owner-operator’ ownership of these machines;

• Enable limited investigation of typical usage patterns of ‘on-farm’ examples ofd test tra

tractors were operated at higher forward speeds, over rougher surface conditions, thanthe suspended front axle & cab tractors. This may, however, be a consequence of a

proportion o

• Virtually all (~ 95%) of the ‘on-farm’ tractor-operations surveyed exceeded the PA(V)D 8-hour Exposure Action Value (EAV) within 8 hours operation, and will require management of employee daily WBV exposure if 8 or more hours operation per day are common place. Possible measures are outlined in Section 3.1.3;

• Few ‘on-farm’ tractor-operations (~ 9%) exceeded the Exposure Limit Value (ELV) within 8 hours operation. However, if the working day length were to increase to 15 hours, up to 27% of the vehicles surveyed would probably exceed the ELV;

• A majority (57%) of the tractors surveyed were operated for more than 8 hours per day. A number of machines were operated for up to 16 hours per day (see Figure 5.39);

• The PA(V)D is not likely to restrict the operation of large, modern, ‘state-of-the-art’

V is reached in a 5.37). During part-day

eded the VDV EAV in 8 hours operation, whilst ~82% exceeded the

• ll contribute to a reduction in the Aeq WBV exposure value;

not assisted by the relatively small number of individual tractor / operation combinations investigated;

ls, but ermine the degree of WBV emission variability between supposedly

identical tractors / operations;

/ implement

tractors during an 8-hour day, but it will become a limitation if the working daylengthens significantly (see Figure 5.38);

• During agricultural tractor operations, the VDV-specified EAconsiderably shorter period than the A(8) EAV (see Figureoperation, the EAV is more likely to be exceeded (requiring implementation of WBV exposure reduction / management measures) if specified in VDV terms. However, over a full (8-hour) day the difference appears less significant; ~95% of the tractors surveyed exceA(8) EAV in the same period; Daily working patterns, including rest breaks, machine maintenance and periods of general inactivity, can a

• Variation in WBV daily exposure level was found to be present between certain examples of similar ‘on-farm’ tractors / operations. This is

the 3 replicates performed being adequate to indicate ‘on-farm’ WBV leveinsufficient to det

• A more detailed study of similar ‘on-farm’ format, but comprising a larger number of measurement replications, is required to enable creation of a robust database of generic WBV emission data for modern agricultural tractor combinations.

104

6. ALL-TERRAIN VEHICLES

ain vehicles (ATVs or “Quad Bikes”) were arguably the greatest unknowAll-terr n in this inve gWhere as had o the instATVs a 6.1 A r eand n‘in-fieldwheel-dreflecteThree eon work(see cin T le

sti ation, but their undeniable popularity in agriculture necessitated their inclusion. possible the same testing and measurement techniques were employed upon the ATVs been used on the other vehicles in the investigation. Modifications t

rumentation used have been described (see Section 3.2) and procedures specific to the re also described below.

TEST VEHICLES

ang of four modern, state-of-the-art 300 – 400cc ATVs (see Figure 6.1) were identified ki dly loaned by their respective manufacturers for the purposes of the ISO test track and

’ vibration investigations at SRI (see Sections 6.2 & 6.3). All machines were four-rive models with the exception of the Honda, which was two-wheel-drive: a fact d in its slightly different weight distribution and lower overall mass (see Table 6.1). xamples of one of the ATVs tested at SRI (Machine ‘A’) were subsequently located ing farms and subjected to vibration measurements during typical ‘on-farm’ operation

Se tion 6.4). A summary of the relevant specifications of the four ATV models is given ab 6.1 below.

Table 6.1 ATVs used in the investigation at SRI

Make Honda Kawasaki Suzuki Yamaha

Model (Four Trax) KLF300 (-C)

4x4 LT-F-300

(King Quad) 400

Big Bear TRX 350 TM

Weighop

FrRear (kg) Total (kg)

140 186 326

173 200 373

182 211 393

171 207 378

t with 77 kg erator:-

ont (kg)

Wheelbase (m) 1.25 1.20 1.16 1.23

Track width (m) 0.85 0.84F / 0.86R 0.86 0.82

Front tyres AT24 8-12 AT24 8-11 AT24 8-11 AT25 8-12

Pressure (lb/in2) 2.8 5.0 4.4 3.6

Rear tyres AT24 9-11 AT24 10-11 AT25 10-12 AT25 10-12

Pressure (lb/in2) 2.8 4.0 4.0 3.6

Front suspension Independent,

twin coil spring & damper

Independent, twin coil spring

& damper

Independent, twin coil spring

& damper

Independent, twin coil spring

& damper

Rear suspension Trailing live

axle, single coil spring & damper

Trailing live axle, twin coil

spring & damper

Independent, twin coil spring

& damper

Trailing live axle, single coil spring & damper

105

Figure 6.1 ATVs used in the investigation at SRI

Figure 6.2 ATV traversing the ISO 100 m (smooth ation

er) ride vibr test track

106

6.2

ISO TEST TRACK VIBRATION EM MEASUREMENT

.2.1 Procedur

hole-body vibration (WBV) emission levels were recorded in three mutually-perpendicular irections (X-longitudinal, Y-transverse, Z-vertical), both upon the seat and the right-hand

footrest of each machine (see Figures 3.5 & 3.6 respectively), as a 77 kg (mass) operator rode each over the SRI ISO 100 m (smoother) ride vibration test track, as defined in ISO 5008:2002. Three measurement replications were made of each ATV traversing the ISO track at each of the ISO 5008:2002-defined forward speeds (10, 12 & 14 km/h). Additional measurements were also made at 16, 18 and 20 km/h. WBV data was acquired and analysed by the methods previously described in Sections 3.2 & 3.3, in accordance with the recommendations of ISO 2631-1:1997. After some preliminary trials, measurements when driving over the ISO 35m (rougher) track were abandoned, because of the difficulty of maintaining a constant forward speed upon the test vehicles. Hand-arm (transmitted) vibration (HAV) was measured upon both handlebars of each ATV, using equipment described in Section 3.2, whilst driving over the ISO 100 m (smoother) track at the same range of speeds specified above. HAV was also measured during constant forward speed tests whilst driving upon a smooth concrete surface, during which the maximum forward speed attainable in each forward gear was held for at least 10 seconds whilst vibration measurements were made. Because of the differences in gear ratios between the test vehicles, a simple average of the frequency-weighted overall three-axis sum (Root-Sum-of-Squares - RSS) r.m.s. acceleration levels at all forward speeds was calculated for each machine.

.2.2 Results

Whole-body vibration - Seat Operator seat WBV emission levels recorded upon each of the four ATVs whilst traversing the ISO 100 m test track, are presented graphically within the line graph sections of Figures 6.3 – 6.6 inclusive. For three of the machines the vertical (Z) axis WBV component was consistently greater than those recorded upon the longitudinal (X) and transverse (Y) axes, despite the effect of the PA(V)D-stipulated 1.4 multiplying factor that increases the magnitude of the horizontal acceleration components. However, for one machine the transverse (Y) axis acceleration levels were of similar magnitude because, in that particular case, the Z-axis component was of lower magnitude than those recorded upon the other machines. In all cases, Z-axis acceleration levels increased steadily with increasing forward speed, at least up to approx. 15 km/h: however, two machines exhibited a tendency to lower acceleration magnitudes at 20 km/h. Across the test vehicles, Z-axis frequency-weighted acceleration magnitudes at 15 km/h forward speed ranged from less than 1.5 m/s2 to more than 3 m/s2.

(Continued)

ISSION

6 e Wd

6

107

Speed (km/h)

108

Figure 6.4 ATV ‘B’ seat acceleration (1.4 multiplier)

Figure 6.3 ATV ‘A’ seat acceleration (1.4 multiplier)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(

1.6

1.8

m/s

2 )

2.08 10 12 14 16 18 20 22 24 26 28 30

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0.0

2.08 10 12 14 16 18 20 22 24 26 28 30

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Road Track Field OverallTask Segments

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

Figure 6.5 ATV ‘C’ seat acceleration (1.4 multiplier)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

Figure 6.6 ATV ‘D’ seat acceleration (1.4 multiplier)

109

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

F

F

F

igure 6.7 ATV ‘A’ footrest acceleration (1.4 multiplier)ure 6.7 ATV ‘A’ footrest acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

igure 6.8 ATV ‘B’ footrest acceleration (1.4 multiplier)igure 6.8 ATV ‘B’ footrest acceleration (1.4 multiplier)

110

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

Figure 6.9 ATV ‘C’ footrest acceleration (1.4 multiplier)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Road Track Field OverallTask Segments

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Task Longitudinal (X) Task Transverse (Y) Task Vertical (Z)Track Longitudinal (X) Track Transverse (Y) Track Vertical (Z)

ISO 100m Test Track

0

Figure 6.10 ATV ‘D’ footrest acceleration (1.4 multiplier)

111

6.2.2 Results (continued) Whole-body vibration - Footrests WBV emission levels recorded upon the footrests of the four test ATVs whilst traversing the ISO 100 m test track, are presented graphically within the line graph sections of Figures 6.7 – 6.10 inclusive. In all cases, the vertical (Z) axis acceleration component was of far greater magnitude than either X- or Y-axis components, reaching a maximum of 3 - 3.5 m/s2 for all the test machines. Without the smoothing effect produced by the saddle, one ATV demonstrates a complex relationship between footrest WBV emission levels and forward speed (see Figure 6.9). This is thought to be a result of the spacing of the wooden slats of which the ISO test track is constructed (see Figure 6.2), insofar as the vibration generated by the slats interacts with the dynamic response of the test vehicles. Hand-arm vibration (handlebars) The frequency-weighted RSS handlebar (hand-arm) vibration levels derived from the ISO test track, range from 5 m/s2 to nearly 10 m/s2, as depicted by the line graph sections of Figures 6.11 – 6.14. These HAV emission levels are considerably greater than the average levels recorded upon the smooth concrete surface, as shown by the left-hand bar graph pair in Figures 6.11 – 6.14. The difference in vibration magnitudes is thought to result from excitation receiv which form the ISO track (see Figure 6.2), this being at a frequency that can pass through the HAV weighting filter with little or no attenuation. 6.2.3 ISO Test Track Vibration Emission Measurement - Summary The results of the ATV ISO test track vibration measurement programme may be summarised as follows:-

• Seat WBV emission levels in the vertical (Z) axis were significantly greater than those in the longitudinal (X) or transverse (Y) axes, irrespective of vehicle forward speed, with the exception of Machine D whose Y-axis WBV levels initially shadowed and then marginally exceeded those of the Z-axis above 14 km/h;

• Seat Z-axis WBV emission levels at 15 km/h forward speed ranged from less than 1.5 m/s2 to more than 3.0 m/s2, depending upon the ATV model;

• In the majority of instances seat X and Y-axis WBV levels were not affected substantially by forward speed (9 – 19 km/h) (see Figures 6.3 – 6.6);

• Footrest longitudinal (X) and transverse (Y) axis WBV emission levels were consistently low (0.5 – 0.8 m/s2) and not affected by vehicle forward speed. Generally footrest Z-axis WBV levels increased significantly with forward speed, frequently approaching 3.0 – 3.5 m/s2 (see Figures 6.7 – 6.10);

• Hand-arm RSS vibration emission levels increased significantly at higher forward speeds, doubling in many instances (e.g. ~5 to ~10 m/s2) (see Figures 6.11 – 6.14);

• ISO test track (wooden) slat spacing is believed to affect (increase) ATV footrest WBV & ere substan e;

• The ISO 5008 test track was not conceived for vibration measurement on small vehicles such as ATVs (low mass & small diameter tyres), and consequently would benefit from modification to better-suit vehicles of this type.

ed by the ATV tyres as they ran over the spaced wooden slats

handlebar HAV levels. ISO test track HAV emission levels wtially greater than those recorded upon a smooth concrete surfac

112

113

Figure 6.11 ATV ‘A’ hand-arm vibration emission levels

Figure 6.12 ATV ‘B’ hand-arm vibration emission levels

0.0

1.0

Concrete Field Farm

We

8 20 22 24 26 28 30

Speed (km/h)

10.08 10 12 14 16 1

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

ight

ed r.

m.s

. Acc

eler

atio

n (m

/s2 )

Driving Surface

Left Handgrip Right HandgripLeft Handgrip Right Handgrip

ISO 100m Test Track

0.Concrete

Driving Surface

0

1.0

0

0

4.0

5.0

9.0

Field

Wei

ghte

d r.m

.s. A

ccel

erat

)

8 10 12 14 16 18 20 22 24 26 28 30

Speed (km/h)

10.0

2

7.0

8.0

ion

(m/s

6.0

3.

2.

ISO 100m Test Track

Left Handgrip Right HandgripLeft Handgrip Right Handgrip

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Concrete Field

Driving Surface

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 3

Speed (km/h)

Left Handgrip Right HandgripLeft Handgrip Right Handgrip

ISO 100m Test Track

0

Figure 6.13 ATV ‘C’ hand-arm vibration emission levels

Figure 6.14 ATV ‘D’ hand-arm vibration emission levels

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Concrete Field

Driving Surface

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

8 10 12 14 16 18 20 22 24 26 28 30

Speed (km/h)

Left Handgrip Right HandgripLeft Handgrip Right Handgrip

ISO 100m Test Track

114

6.3 SRI ‘IN-FIELD’ VIBRATION EMISSION MEASUREMENT 6.3.1 Procedure A repeatable, composite ‘in-field’ test circuit was devised comprising 0.5 km each of smooth road and farm track, followed by driving twice around a field headland. The headland was chosen for the (tractor) wheel ruts present upon it, which provided an approximate simulation of off-road conditions for the ATVs under test. The entire circuit took approx. 10 minutes to complete, the test rider selecting a consistent forward speed between the vehicles. For each machine, seat and footrest WBV emission levels were recorded in three mutually-perpendicular axes during two circuits of the test route: HAV emission levels were recorded during one circuit. Frequency-weighted r.m.s. WBV emission levels were calculated for both the complete (overall) circuit and for each individual section (road, track and field). Vibration Dose Values (VDV) were also calculated these tests. Frequency-weighted RSS (r.m.s.) hand-arm vibration (HAV) emission levels were calculated for the complete (overall) test circuit, but the resulting values are labelled as ‘field’ in Figures 6.11 – 6.14 inclusive. During this phase of the investigation, a device was developed to enable operator presence upon the ATV seat to be recorded upon the 8th channel of the PC card recorder. However, consistent operation of this device was not achieved early enough for it to be used during the ‘in-field’ test programme, so any effect of th losing contact with the ATV seat was ignored. 6.3.2 Results Whole-body vibration - Seat The bar graph sections of Figures 6.3 – 6.6 inclusive, depict operator seat WBV emission levels for the four ATVs. In general, ‘overall’ ‘in-field’ WBV emission levels were of the same orders of magnitude as those arising from the ISO 100 m test track: overall levels of the vertical (Z) axis component being around 1.5 m/s2, and the longitudinal (X) and transverse (Y) axis components both being lower. The expected trend can be seen where ‘field’ seat WBV emission levels are greater than those recorded upon the (farm) ‘track’, which in turn are greater than those resulting from the ‘road’ section of the composite test circuit. Whole-body vibration - Footrests Footrest WBV emission levels for the four machines are depicted by the bar graph sections of Figures 6.7 – 6.10 inclusive. As in the case of the ISO test track measurements, the vertical (Z) axis component dominates, but the ‘overall’ ‘in-field’ footrest vibration magnitudes were somewhat lower, between 2.0 – 2.5 m/s2. Differences between ‘road’, ‘track’ and ‘field’ emission levels are smaller than those between corresponding WBV values recorded upon the operator’ he footrests (and t s that the ISO test track vibration emission values are affecte spaced wooden slat construction of the track (see Section 6.2.2), the characteristic vibration frequency of which would also feed through the wk filter.

e driver

s seat. This suggests that some engine vibration feeds through through the wk weighting filter). It also supports the hypothesi

d by the

115

Hand-arm vibration (handlebars) Handlebar (hand-arm) vibration emections of Figures 6.1

ission levels are depicted by the right-hand bar graph 1 – 6.14 inclusive. These frequency-weighted sum (root-sum-of-

nt. An overall average of the vibration levels arising from the different sections of

levels upon tractors and other field machines. However, these vehicles are typically eavier and have larger diameter tyres than ATVs, and consequently it is possible that the

the spaced wooden slats, of which the test track is constructed, may have the frequency-weighted vibration emission values recorded on this test

ult in ISO track vibration levels being unduly high.

’ seat WBV levels between these other machines (A, B & D) did not correlate very ell with their comparison gained upon the ISO test track. However, the differences between

O track and ‘in-field’ instances, and it would perhaps to be distinguished by the ISO track test, given its

pothesis whereby the ISO test track provides an additional vibrational input (from the slat spacing), this being common to all the machines tested.

ssquares - RSS) r.m.s. HAV values, recorded over the entire (overall) composite ‘in-field’ test circuit (see Section 6.3.1) were generally found, at 3 - 4 m/s2, to be only slightly greater than those obtained from the smooth concrete surface (see Section 6.2.1). 6.3.3 ATV ‘in-field’ and ISO test track performance comparison The four models of ATV included in the study at SRI (see Figure 6.1 & Table 6.1) may be compared by means of the vibration data arising from the SRI ‘in-field’ or ISO 5008 test track investigations (see Figures 6.15 – 6.18). It is also of interest to evaluate the ISO test track data as a potential predictor of ‘in-field’ vibration emission levels. To provide a consistent basis for machine comparison, an average of vibration emission levels recorded at 10, 12 and 14 km/h upon the ISO test track are depicted, as directed by ISO 5008 for tractor driver WBV

easurememthe SRI ‘in-field’ composite test circuit (road, farm track & field) are depicted for each machine. An average of RSS hand-arm vibration levels recorded at all forward speeds upon the smooth concrete track, are also displayed (see Figures 6.17 & 6.18). The ISO test track was developed to enable consistent, comparative measurement of WBV mission e

hpassing frequency ofa large influence onsurface. This could potentially res Whole-body vibration - Seat Although the ‘overall in-field’ vertical (Z) axis seat WBV magnitudes from the different machines were of a similar order of magnitude, it can be seen from Figure 6.15 that one of the ATVs (Machine C) amplified the ISO test track-induced vibration nearly twice as much as the others. Although this machine also generated higher seat WBV emission levels than the other vehicles ‘in-field’, the difference was very much smaller. Additionally, any comparison of in-field‘

wmachines were quite small in both the IS

e unreasonable to expect the machinesbquestionable suitability for machines of this type. Whole-body vibration - Footrests A closer correlation exists between the vertical (Z) axis footrest WBV emission levels of the ATVs resulting from the ISO test track and ‘in-field’ measurements (see Figure 6.16). In the case of footrest vibration, it may be that engine vibration has a greater influence than ground-induced (tyre) vibration: otherwise, similar relative differences in WBV levels to those found upon the seats would be expected (see Figure 6.15). The footrest WBV results are also consistent with the hy

116

3

2

2.5

m/s

2 )

117

Figure 6.15 ATV seat vertical (Z) axis whole-body vibration: machines A, B, C & D

Figure 6.16 ATV footrest vertical (Z) axis vibration: machines A, B, C & D

0

0.5

1

ISO 100m Track Overall 'In-Field'

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(

1.5

Machine A Machine B Machine C Machine D

0

3

Overall 'In-Field'

3.5

0.5

1

1.5

2

Wei

ghte

d r.m

.s. A

ccel

erat

ion

( 2.5m/s

2 )

ISO 100m Track

Machine A Machine B Machine C Machine D

0

1

2

3

4

5

6

Smooth Concrete ISO 100m Track Overall 'In-Field'

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Machine A Machine B Machine C Machine D

Figure 6.17 ATV left handgrip vibration (RSS): machines A, B, C & D

0

1

2

3

4

5

6

Smooth Concrete ISO 100m Track Overall 'In-Field'

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Machine A Machine B Machine C Machine D

Figure 6.18 ATV right handgrip vibration (RSS): machines A, B, C & D ATV right handgrip vibration (RSS): machines A, B, C & D

118

Hand-arm vibration (handlebars) In this case, the ISO 100 m (smoother) test track data again exhibits a characteristic that does not correlate with the SRI ‘overall’ ‘in-field’ results (see Figures 6.17 & 6.18). On the ISO track, one machine exhibits a lower level of RSS vibration emission than the other three, yet in the field the differences between the test machines are smaller and they are rated in a different relative order. However, the ‘in-field’ HAV magnitudes compare more favourably with those arising from the tests on a smooth concrete surface, particularly with regard to rating by magnitude. The ‘in-field’ HAV emission levels were slightly higher than those from the smooth concrete surface. This could indicate that some ground-induced vibration from the (predictably rougher) field surface is feeding through the frequency-weighting filter. Alternatively, the ‘in-field’ tests may have included periods of operation at engine speeds other than maximum, whereas the smooth surface tests were all conducted at full throttle. 6.3.4 Comments (conclusions) regarding standardised tests The ISO 5008 100 m (smoother) test track is not suitable in its present (constructional) form for providing a representative comparison of different ATVs, whether the interest is whole-body or hand-arm vibration. If the present (wooden slat) construction, which is currently endorsed by ISO 5008, were replaced with a smoothed concrete surface of appropriate contour – a method which has been used at some test facilities - then the vibrational problems arising f aviour

As ‘in-field’ levels of handlebar (hand-arm) vibration were best predicted by that measured when the machines were driven over a smooth surface, it may well be that a static test (albeit with the engine running) would provide an adequate prediction. In that case, it would be useful to investigate what engine speed settings would be most appropriate, as vibration emission values derived from a single-speed test could be compromised by resonance effects in the machine structure. 6.3.5 ‘In-Field’ Vibration Emission Measurement - Summary The objectives of this specific part of the investigation were:-

• To quantify for each model of ATV the WBV and HAV emission levels, averaged over a set of controlled conditions that were representative of a common use of these machines in UK agriculture;

• To investigate the similarity between these vibration levels and those found during tests on the ISO 5008 track (Section 6.2).

The results may be summarised as follows:-

• The largest seat WBV emission levels were generally evident in the vertical (Z) axis, typically being in the region of 1.5 m/s2;

• Footrest WBV emission levels were minated by the vertical (Z) axis component, 2

• e only slightly greater than those values recorded upon a smooth concrete surface;

rom slat spacing would be eliminated, and better correlation with ‘in-field’ behmight be achieved.

doand were in the range 2.0 - 2.5 m/s ; ‘Overall’ ‘in-field’ HAV levels (RSS) were between 3.0 – 4.0 m/s2 and wer

119

• Seat (Z-axis) WBV levels recorded upon the ISO 5008 track were of a similar magnitude to those recorded ‘in-field’, but did they not reflect differences between

• An ISO test track of wooden slat construction is of questionable suitability for ype (ATVs); V upon ATVs.

the machines in the same manner; ‘in-field’ differences between machines being much smaller than those arising from the ISO track (see Figure 6.15);

• Footrest (Z-axis) WBV levels recorded upon the ISO track were slightly higher than those recorded ‘in-field’, but reflected differences between the individual machines quite closely (see Figure 6.16);

• HAV (RSS) emission levels recorded upon a smooth concrete surface were slightly lower than those measured ‘in-field’, but demonstrated very similar differences in magnitude between the machines (see Figures 6.17 & 6.18);

• ISO track HAV values were higher than those recorded ‘in-field’, and demonstrated larger differences between individual machines, which were not consistent with those found ‘in-field’;

quantification of vibration emission levels from machines of this t• A static test may be suitable for assessment of engine-induced HA

120

6.4 6.4.1 In a cparticipTwo of ne (Hill Farm#1) of approx. 230 hectares, the other (Hil aBorders Hill Farstockmaimmedi for work. Generally this ‘round’ took ½ – 1-hour. Hill Fafarm ’ nd’,

hi w

he Gamekeeper (estimated weight ~90 kg) used his ATV for two slightly different tasks. In ne case a game feed distributor was attached to the rear load-carrying rack. The operator ould then drive out to a given plantation, slow down whilst spreading food, before returning

t high speed to re-fill the hopper. The other task involved placing sacks of feed on the load-carrying rack and driving around plantations, dismounting frequently to re-fill freestanding feeders in these locations. Between ½ & 1-hour was required for either operation, which were performed as the first task each morning. Sometimes both tasks would be performed on the same day, the feed distributor being removed during a break. This was the case on the WBV measurement day. All the above routines would vary with the season and if there was also a need to move stock around the enterprises. However, the days on which measurements were made were considered by the drivers to be typical of most working days. The only exception to this was the WBV recording for the Gamekeeper, who had held back some work from the previous day “to make sure that there was enough work to measure”, resulting in a recording period in excess of 2 hours on the day in question (see Table 6.3). 6.4.2 Procedure A preliminary visit was made to each enterprise to confirm the farmer’s agreement to participate and the suitability of the machine on-site. Also to check upon the daily routine of ATV use and in particular when it was convenient to fit and remove the measurement instrumentation. In some cases the instrumentation was fitted at the end of the preceding day; otherwise it was installed early in the morning before the machine was needed. The equipment was checked in the laboratory before travel to each farm. The Human Vibration Meters and PC card recorder (see Section 3.2.3) were set to record as close to the start of each daily ‘round’ as practicable, and stopped at the end of the ‘round’, the aim being to obtain one dataset each of WBV (seat & footrest) and HAV (handlebar) on each farm, this necessitating measurement on successive days. Because of the terrain, it was not possible to observe the use of the machine once it had left the farmyard. Only in the case of the Gamekeeper’s machine could progress be monitored, because of frequent returns to the farmyard to re-fill the feed distributor or to collect further sacks of feed.

‘ON-FARM’ VIBRATION EXPOSURE MEASUREMENT

Farm description and ATV utilisation

sso iation with an ATV manufacturer’s agent, a number of farmers were approached to ate in an investigation of admittedly restricted scope: three enterprises kindly agreed. these were Welsh hill farms; o

l F rm#2) rather smaller. The third enterprise was a 200-hectare holding in the Welsh , which operated as a commercial shoot, the ATV being used by the Gamekeeper.

m#1 was operated by the farmer/owner, with the assistance of one stockman. The n (estimated weight ~70 kg) generally used the ATV, primarily to inspect the stock

ately after arriving

rm#2 was run by a young farmer, with help from his mother. In this instance the er s mother (estimated weight ~70 kg) used the ATV for the stock inspection ‘rou

ch as undertaken at whatever time was convenient and took about ½-hour. w Towa

121

6.4.3 Results As discussed previously (Section 3.1), the European Union Physical Agents (Vibration)

irective (PA(V)D) (EEC, 2002) defines the WBV Exposure Action Value (EAV) and

or (8) method produces a value which is an average vibration level adjusted to represent an

.s. acceleration vels recorded upon the operator’s seat are relatively consistent, the resultant Aeq value

s of vibration ith reasonable accuracy but gives poor representation of shocks and jolts, whereas the VDV

in VDV or A(8) terms: the implications of this stance are discussed Sections 3.1 & 7.4.

proach is used, the resultant overall verage frequency-weighted r.m.s. acceleration (Aeq) value measured for a shorter period, an be considered to extend throughout the entire day’s use of the machine. If this use

e Aeq value becomes equivalent to the daily occupational vibration xposure (A(8)) value for that operation. Consequently the Aeq values generated by this

y’s exposure. his is performed by assuming subsequent WBV emission levels are similar to those recorded

DExposure Limit Value (ELV) in two alternative ways. Either as an 8-hour energy-equivalent frequency-weighted r.m.s. acceleration value (A(8)), or as a vibration dose value (VDV). Member States are given the option of implementing the Directive using either method, using the values stated below (see Table 6.2). Specific details are discussed in Section 3.1, but an important difference between the methods is as follows. The root-mean-square (r.m.s.) A8 hour working day, whereas the vibration dose value represents cumulative exposure to vibration over the working day. The practical significance of this is clearly depicted by Figure 5.29 & 6.19. If, over a given period of work, frequency-weighted r.mle(only A(8) if duration equals 8 hours) changes little, having once reached an average ‘plateau’ value. However, in the same circumstances, the VDV increases throughout the work period in a cumulative manner. Additionally, the A(8) method represents steady levelwmethod performs well in both instances (Griffin, 1998; Coles, 2002). These issues, and those of data sampling duration, are discussed in Appendix 4. Throughout this investigation we have primarily utilised the A(8) method but, during ‘on-farm’ exposure measurement, vibration dose values have also been derived (see Figures 6.19 and Appendix 3.3). At the time of writing the HSE is undertaking a public consultation exercise regarding implementation of the PA(V)D in the UK. Whilst it is highly likely that the ELV will be specified by the A(8) technique, debate is currently ongoing as to whether the EAV will be implementedin An important aspect of results interpretation concerns how estimates for a whole day’s vibration exposure can be made from values measured over a shorter period (see also Appendix 4). In the case of the ATV’s, the ‘on-farm’ measurement period of ½ - 1-hour encompassed the entire day’s exposure for each vehicle, but in other businesses longer exposures might be involved. Where the r.m.s. A(8) apacextends for 8 hours, theinvestigation may be compared directly with the A(8) EAV and ELV values stipulated by the PA(V)D whenever the working day length approximates to 8 hours. For shorter or longer working days the respective A(8) value for the daily exposure period in question may be calculated from the Aeq value, prior to comparison with the EAV or ELV (see Section 3.1.2, Equation 3). A similar approach is necessary for the VDV; its cumulative nature requires a value for a shorter period be re-calculated to estimate the VDV after the full daTduring the (~4 hour) measurement period (see Appendix 4). . This, however, is not the case for the VDV: its cumulative nature requires a value for non-8 hour period be re-calculated to estimate the VDV after 8 hours exposure, this being performed by assuming subsequent WBV emission levels are similar to those recorded during the (½ - 1 hour) measurement period. Estimated 8-hour (seat WBV) VDV’s for the ‘on-farm’ ATVs appear in Table 6.5 and Appendix 3.3.

122

Table 6.2 WBV exposure values specified by the EU PA(V)D

8-hour energy-equivalent

r.m.s. acceleration – A(8)

(m/s2)

Vibration Dose Value

(m/s1.75)

Exposure Action Value (EAV) 0.5 9.1

Exposure Limit Value (ELV) 1.15 21

Following the procedure used during both the ISO test track and SRI ‘in-field’ measurement programmes, WBV was recorded both upon the ATV seat and footrests. However, no guidance is provided by the PA(V)D regarding evaluation of WBV which originates from multiple sources (e.g. the operator’s posterior and feet). Given that it is common practice to ride ATV’s whilst standing upon the footrests, particularly when traversing rough terrain, ‘simple’ acceleration data from a seat-mounted accelerometer may be misleading. To guard against this an array of thin-film force transducers was incorporated into the accelerometer

eat-pad’ installation (see Figure 3.5), their output being recorded by the data acquisition

she had dismounted from the machine. Further analysis of vehicle rward speed time-histories could possibly clarify this issue, but unfortunately this was

perative, WBV emission and xposure levels were recorded once more on a second day, with hand-arm vibration being

‘ssystem. This device was able to indicate the operator’s presence upon the seat and consequently the periods when he/she was being exposed to the WBV being recorded by the seat accelerometer pad. The difference between ‘overall’ (total) seat WBV exposure and that received during ‘seat contact’ is highlighted for each ‘on-farm’ application within Tables 6.4 & 6.5. Regrettably, whilst this technique indicated ‘seat presence’, it was unable to differentiate between periods of ‘seat absence’ when the operator was standing on the footrests, or when he/fobeyond the resources of this particular investigation. In the interim, estimated operating periods to reach the (seat WBV) EAV and ELV (see Table 6.6) were calculated using driver ‘on-seat’ WBV data. Footrest WBV emission and exposure levels were recorded & calculated and are depicted for the reader’s information (see Tables 6.7 & 6.8), but further evaluation is restricted by the current form of the PA(V)D, namely a lack of guidance regarding how to evaluate whole-body vibration exposure in instances where an individual receives vibration both through his/her seat and feet.. The Directive specifies an EAV and ELV for hand-arm vibration (HAV), these being 2.5 m/s2 and 5 m/s2 respectively. However, in instances where an operator is subjected simultaneously to both HAV and WBV, these physical agents are considered separately. If either should exceed the EAV, the preventative steps stated in Section 3.1 must be implemented, and under no circumstances should either WBV or HAV exposure levels be allowed to exceed the ELV. Because of a suspicion concerning the data resulting from the first WBV measurement on Hill Farm#1, and because the farmer was particularly co-oemeasured on a third day. Both WBV and HAV were also recorded for the Gamekeeper. However, there were time constraints on Hill Farm#2, so that only one day was available and this was used for WBV measurement purposes. The activities associated with each recording are illustrated in Appendix 3.4 in the form of time-history graphs of forward speed and operator ‘seat presence’.

123

0.0

0.5

0:00 0:15 0:30 0:45 1:00

Elapsed Time (hrs)

0

3

1.0

1.5

2.0

2.5

3.0W

eigh

ted

r.m.s

. Acc

eler

atio

n (m

/s2 )

6

9

12

15

18

VDV

(m/s

1.75

)

Vertical (Z-axis) seat Aeq VDV

Larson Davis HVM100 SN:00215 Day Month Year

Location: Seat 24 Sep

2Machine: ATVReg No: Start time: 07:55Task: Stock tourPlace: Hill Farm #1 (1)

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z Sum00:45 12.6 16.1 17.0 26.5 1.06 1.39 1.39 2.20

8-hr est tot 22.8 29.1 30.7 48.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.06 1.03 X Y Z SumTime to ELV (hr): 1.75 5.46 8.53 12.84 22.10 22.10 Figure 6.19 Typical time history of weighted 1-minute r.m.s. accelerations (Z-axis, ATV

seat – Hill Farm#1 (1)) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV) and table of seat WBV parameters

Table 6.3 ATV ‘on-farm’ WBV recording durations and forward speeds used

Forward speed (km/h) Farm

Measurement

duration (hours:mins)

Average Maximum

Hill Farm#1 (1) 0:55 10.8 46

Hill Farm#1 (2) 1:10 10.1 53

Hill Farm#2 0:35 9.4 34

Gamekeeper 2:20* 7.5 41 * Included 20-minute break for removing the feed distributor

124

Table 6.4 ‘On-farm’ ATV weighted r.m.s. (Aeq) seat WBV exposure values

Energy-equivalent weighted r.m.s. (Aeq) seat acceleration (m/s2)

Farm

Circumstance X-axis Y-axis Z-axis

Major axis

‘Overall’ 1.06 1.39 1.39

Driver ‘on-seat’ 1.00 1.32 1.26 Y/Z

Hill Farm#1 (1)

Difference (%) 6 5 9 -

‘Overall’ 0.90 1.29 1.21

Driver ‘on-seat’ 0.84 1.20 1.09 Y/Z

Hill Farm# 2)

Difference (%) 7 7 10 -

1 (

‘Overall’ 0.72 0.65 0.87

Driver ‘on-seat’ 0.69 0.62 0.77 Z

Hill Farm#2

Difference (%) 4 4 12 -

‘Ov 0.55 erall’ 0.76 0.85

Driver 0.53 0.Y/Z

‘on-seat’ 0.74 66 Gamekeeper

Difference 4 3 22 - (%)

Whole-body vibration - Seat As mentioned previously, the AT ’ WBV exposure data acquired mainly resulted

ion, with the exception of the Gamekeeper who provided an unusually long period of use (see Table 6.3). The seat WBV (Aeq) exposure values recorded upon the ‘on-farm’ ATVs are shown in Table 6.4, highlighting the range of (‘on-seat’) WBV magnitudes (0.62 – 1.32 m/s2) common during typical ‘on-farm’ ATV operations. In the majority of ‘on-farm’ applications, the vertical (Z) and transverse (Y) axis vibration components were greater than those present in the longitudinal (X) axis. This departs somewhat from the findings of the SRI ‘in-field’ test programme (see Section 6.3), where longitudinal (X) and transverse (Y) axis vibration magnitudes were similar and markedly lower than those experienced in the Z-axis. However, in these ‘in-field’ test conditions the Z-axis vibration levels were generally higher than those encountered ‘on-farm’, suggesting that the SRI ‘in-field’ composite test circuit probably provided a smoother operating surface for the test vehicles, which generated less vehicle (Y-axis) roll, but conversely higher vertical (Z) axis vibration levels because of higher forward speed. In ‘on-farm’ conditions, longitudinal (X) axis vibration magnitudes appear to be approximately 10 - 30% lower than the levels experienced in the transverse (Y) or vertical (Z) axes. Differences in acceleration levels between individual farms appear to be as great as two to one, irrespective of the measurement axis: this is probably attributable to differences in personal driving style.

V ‘on-farmfrom stock monitoring rounds of ½ - 1-hour durat

125

It would appear that only one of the ‘on-farm’ ATV applications investigated (two measurement instances) ld exceed the PA(V)D-prescribed A(8 operat e Table 6.6). It seems that the operator in question (Hill Farm#1) rode his ATV in a rather harder manner than the rators, e result that he returned higher values of both energy-equivalent r.m.s. acceleration (Aeq) and VDV (see Tables 6.4 & 6.5 respectively). This cons led to considerably shorter operating periods unti e PA(V)D-prescribed WBV (EAV) and Exposure Limit Value ) wo see wever he ‘on-fa TVs ex d the PA(V)D Exposure Action Value in less than ½-hour operation when this parame expressed in terms of VDV (see Tab

‘O at wh ody vibr exposu lues:- Vibration Dose Value (VDV)

eat vibrat se value ( (m/s1.75)

generated actual daily WBV exposure levels that wou) Exposure Limit Value (ELV) during 8 hours of ion (se

other two ope with th

equently l th (ELVExposure Action Valu

Table 6.6). Hoe

, all tuld be reached ( rm’ A ceedeter is

les 6.2 & 6.6).

Table 6.5 n-farm’ ATV se ole-b ation re va

ATV s ion do VDV)Farm

xis is s

Major

Circumstance X-a Y-ax Z-axi axis

‘Overall’ VDV 2.6 16.1 1 17.0

D eat’ 7 Z/Y

river ‘on-s 11. 15.1 15.5

Difference (%) 7 6 9 Hill Farm#1 (1)

1.1 27.3 -

Est 8-hr VDV 2 28.0

‘Overall’ VDV 12.4 17.5 18.4

Driver ‘on-seat’ 11.5 16.1 16.0 Z/Y

Difference (%) 7 8 13 Hill Farm#1 (2)

Est 8-hr VDV on seat 18.3 25.6 25.4 -

‘Overall’ VDV 10.0 8.1 10.9

Driver ‘on-seat’ 9.5 7.9 10.2 Z/X

Difference (%) 5 3 6 Hill Farm#2

Est 8-hr VDV 17.2 14.3 18.4 -

‘Overall’ VDV 11.3 11.9 15.6

Driver ‘on-seat’ 11.0 11.7 14.7 Z

Difference (%) 3 2 6 Gamekeeper

Est 8-hr VDV 15.1 16.1 20.2 -

126

Table 6.6 Estimated ‘on-farm’ ATV operating periods to reach PA(V)D-prescribed WBV Exposure Action Value (EAV) & Exposure Limit Value (ELV)

(based upon seat ‘overall’ Z-axis WBV magnitudes)

Estimated time to EAV (hours:mins) Estimated time to ELV (hours:mins) Farm

VDV A(8) VDV A(8)

Hill Farm#1 (1) 0:5 1:2 2:8 5:29

Hill Farm#1 (2) 0:4 1:22 1:59 7:14

Hill Farm#2 0:17 2:39 8:2 13:59

Gam ekeeper 0:16 7:40 14:392.46 NB:- HSE is proposing to utilise A(8) for the ELV and is consulting regarding either A(8) or VDV for the EAV In general, the effect of calculating WBV exp alues ring driv at presence’ was a reduction of less than 10% (see Tables 6.4 & 6.5). An exception was found in the case of the Gamek e ‘over . ‘on-se fference e vertical (Z) axis was more than 20%. In this case the dr visible vib V se he was ounted he engine was idling. This wo o the ulation w never the ver dismounted to fill a sack or feed hopper, as he the eng for this. It would n however have contributed much to the figures, values g domi by the eak acceleration events encount off-road travel. Wh ation Whole-body vibration m ned from footrests the ‘on-fa ATVs ar lso consistent with the ‘in-f experim progra , in tha the vertical (Z) axis component is greatest and considerably larg ng value recorded upon the seat. & 6.8 ese valu ave not been corrected for times when the driver had dismounted from the ATV seat because, as discussed previously, such periods of ‘seat ab always sistent w e opera feet being off the footrests. As discussed earlier, it is currently unclear how to evaluate whole-body vibration exposure in in vidual receives vibration both through his/her seat and feet. Consequently, the information provided in Tables for the reader’s information.

osure v only du times of er ‘se

eeper, when th all’ vs at’ di in thiver himself pointed out the clearly dismration of the AT

uld have added tat cushion when and t Aeq WBV calcseldom stopped

heine

driot

VDV WBV ered during

these bein nated p

ole-body vibr - Footrests

agnitudes obtai the of rm’ e at results of the SRI ield’ ental

er than the correspondimme

(see Tables 6.7 ). Th es h

sence’ were not con ith th tor’s

stances where an indi6.7 & 6.8 is primarily

127

Table 6.7 ‘On-farm’ ATV footrest weighted r.m.s. (Aeq) vibration exposure values

Ene ation (m/s2) rgy-equivalent weighted r.m.s.(Aeq) footrest accelerFarm

X-axis Y-axis Z-axis

Major axis

Hill F (1) 0.71 0.76 3.62 Z arm#1

Hill Farm#1 (2) 0.64 0.74 3.05 Z

Hill Farm#2 43 2.07 Z 0.49 0.

Gamekeeper 0.57 .53 3.30 0 Z

le 6.8 ‘On-farm’ ATV footrest vibration exposure values:-

ATV footrest vibration dose value (VDV) (m/s1.75)

Tab Vibration Dose Value (VDV)

Farm X-axis Y-axis Z-axis

Major axis

Hill Farm#1 (1) 9.3 8.9 38.7 Z

Hill Farm#1 (2) 9.6 9.8 37.8 Z

Hill Farm#2 7.7 5.2 23.5 Z

Gamekeeper 10.1 9.0 47.5 Z

Hand-arm vibration Vibration of the ATV handlebars was measured for durations of 35 and 45 minutes respectively at Hill Farm#1 and for the Gamekeeper. In the first of these instances, the PC card recorder shut down at an early stage, necessitating some improvement to the mounting arrangement. However, the short-term frequency-weighted r.m.s. acceleration values stored in the human vibration meters were available, and so these have been used for both sets of recordings. The overall three-axis sum (Root-Sum-of-Squares - RSS) values are shown in Table 6.9 below.

Table 6.9 ‘On-farm’ ATV hand-arm vibration exposure

RSS weighted r.m.s. (Aeq) hand-arm acceleration (m/s2) Farm

Left h Right hand and

Hill Farm#1 8.1 9.3

Gamekeeper 3.9 4.8

The machine used by the Gamekeeper was very much newer than that used at Hill Farm#1, which may partially account for the higher acceleration magnitudes found on the latter. However, the Gamekeeper’s machine exhibited unusually large vibration at idle, as

128

m tockman on Hill Farm#1 led to some ground-induced vibration being transmitted through to

the handlebars. If filter with relativ le attenuation.Farm#1 machine were gr ose arisin simulated field tests at S ee Figure 6.3), almost certainly due to higher levels of ground surface-induced vibration on the fa in this a ation from this source was able to pass through the WBV signal filter, it is likely that it was also able to pass through the HAV filter, possibly re recorded ation levels. In e e have to conclude that a HAV magnitude spread of two to ay be expected in typical ‘on-farm’ use of ATVs. Table 6.10 Estimated ‘on-farm’ ATV operating periods to reach PA(V)D-prescribed

HAV Exposure Action Value (EAV) & Exposure Limit Value (ELV)

Farm Estimated time to EAV Estimated time to ELV s)

entioned earlier. An alternative explanation could be that the hard-driving technique of thes

that were the case, it would pass through the HAV weighting Certainly the whole-body vibration levels recorded upon the Hill ely litt

eater than th g from the RI (s

rm. Given that, pplication, the vibr

sulting in higher vibr ither case, w one m

(based upon weighted RSS r.m.s .vibration magnitude upon worst hand)

(hours:minutes) (hours:minute

Hill F 0:36 2:18 arm #1

Ga 2:12 8:42 mekeeper

The HAV emission levels generated by the majority of the ATV’s during the SRI ‘in-field’ tests ightly greater than those arising from the smooth concrete test surface (see Figu 4 inclusive ically being in the range 3.0 – 4.0 2 However, one ATV (Ma he model targeted during the ‘on-farm’ test programme - disp ed a ignificant increase in HAV emission levels between the smooth concrete, the SRI ‘in-field’ nd the Hill Farm#1 test conditions (see bar-graph sections of Figure 6.11), whereas HAV

Gamekeeper’s machine (see Table 6.9) were comparable with those xperienced during the SRI ‘in-field’ test programme (see Figures 6.17 & 6.18).

sures (see Section 3.1.3). As previously discussed, on no account should workers receive daily exposure to vibration (e er HAV or WBV) in excess of the Exposure Limit Value (EL aken to reduce vibration exposure below the ELV and measures be implemented to prevent it being exceeded again. Consequently regarding l V are considered separately in relation to their respective ELV’s, on a “first-past-the-post” basis. As stated earlier, at the time of writing the HSE is undertaking a public consultation exercise regarding implem UK. It appears likely that the WBV ELV will be spec s. A(8) value (1.15 m but debate is currently ongo as to whether the WBV EAV will be implemented in VD .1 m/s1.75) or A(8) (0.5 m/s2) terms. No option is provided f the Directive, the EAV and ELV being the A(8) values stated above.

were only slres 6.12 - 6.1chine A) – t

), typ m/s . lay

salevels recorded upon thee As discussed earlier, the PA(V)D does specify an EAV and ELV for hand-arm vibration (HAV), these being 2.5 m/s2 and 5 m/s2 (A(8)) respectively. However, in instances where an operator is subjected simultaneously to both HAV and WBV, these physical agents are considered separately, exposure to vibration exceeding either the HAV or WBV Exposure Action Value (EAV) necessitating the implementation of vibration reduction and management mea

ithV). If the ELV is exceeded, immediate action must be t

imitation of machine operating period, HAV and WB

entation of the PA(V)D in the ified as a r.m. /s2), ing

V (9or HAV by

129

Consequently, in the two ‘on-farm’ instances where HAV was recorded (see Tables 6.9 & 6.10), seat (whole-body) vibration caused the (WBV) EAV to be exceeded first, in less than 20 minutes. The HAV EAV was not reached until between 30 minutes and 1-hour 50 minutes later. However, on both farm ATVs, hand-arm vibration levels caused the (HAV) ELV to be reached in a shorter period than the WBV ELV (see Tables 6.6 & 6.10). However, given the short daily use periods of these vehicles, neither WBV nor HAV exposure is likely to present an operational restriction to typical stock farmers. The ELV could possibly pose a restraint to daily use of ATVs by more intensive users, but the vibration exposures likely in these applications and their consequent risk are not currently known. 6.4.4 ‘On-Farm’ Vibration Exposure Measurement - Summary The object ere:-

• To quantify typical daily exposure to WBV and HAV of farmers who use ATVs for work whilst t

• nvestigate the r een vibration levels m controlled conditions, either ‘in-field’ or on a (ISO) test track, and what characterises daily

n exposure ‘on-farms’. The findings may be summarised as follows:-

• ‘On-farm’ ATV seat WBV levels vary y at least ±50%, giving anything from 0.66 -

ed the ELV.

arising from the controlled (SRI) ‘in-field’ conditions generally provide a fairly good indication of ‘on-farm’ longitudinal (X) axis WBV levels, averaged over the daily exposure period, but ‘on-farm’ transverse (Y) axis values were greater and conversely vertical (Z) axis values lower than the corresponding ‘in-field’ levels;

ives of the ‘on-farm’ ATV vibration exposure measurement programme w

fieldTo i

ending livestock; elationship betw easured under

vibratio

b1.26 m/s2 in the vertical (Z) axis, depending upon the application;

• Short daily exposure times, generally of less than 1½ hours, ensure that even the highest of these WBV levels does not cause the PA(V)D Exposure Limit Value (ELV) to be exceeded during normal daily use;

• In several instances, the WBV Exposure Action Value (EAV) is not exceeded (during typical daily use) if expressed in r.m.s. A(8) terms. However, if specified as a VDV, the EAV is exceeded in all cases;

• Hand-arm vibration (HAV) levels also vary widely, and approach or exceIt is not clear how much of this difference in levels is the result of differences in ground conditions, driving technique or machine (condition) between the enterprises studied;

• In the case of HAV, the short daily exposure periods ensure that the ELV is not exceeded in typical ‘on-farm’ use, but the EAV may well be exceeded, and if so will require management of employee daily vibration exposure. Possible measures are outlined in Section 3.1.3;;

• Footrest WBV levels are greater than those generated upon the seat (saddle); • If footrest vibration is treated in the same way as seat vibration, then even the short

daily exposure times found on farms will result in transgression of the ELV; • Given that the WBV requirements of the PA(V)D have been determined according to

what is needed to protect the worker’s lower back, and that there is very little data for transmission of vibration from the feet to the lumbar spine in postures similar to those of ATV riders, nor to correlate foot vibration with low back problems, it is suggested that this result provides a reason for further research rather than for restricting the use of these vehicles;

• On the basis of the limited evidence available from the investigation, vibration values

130

• On the basis of even more limited evidence, HAV measured in controlled ‘in-field’ conditions is of a similar order of magnitude to that found on some farms;

• Results from the ISO 5008 test track do not provide a good indication of vibration magnitudes in controlled (SRI) ‘in-field’ conditions, and are therefore even less useful for predicting ‘on-farm’ vibration exposures. Given that an ISO test track of wooden slat construction is of questionable suitability for quantification of vibration emission levels from machines of this type (ATVs), arguably this is to be expected.

131

132

7. DISCUSSION The overall objective of this investigation was to determine Whole-Body Vibration (WBV) emission and exposure levels associated with representative ‘state-of-the-art’ agricultural vehicles, both whilst traversing ISO 5008 standard ride vibration test tracks and whilst performing typical agricultural operations, both in (representative) controlled ‘in-field’ conditions and during normal operation on working farms. Additionally, the investigation considered the consequences of prescribing limits for operator WBV daily exposure, upon agricultural vehicle usage patterns in the U.K. The investigation targeted three generic types of agricultural vehicle (self-propelled sprayers, all-terrain vehicles (ATVs), and agricultural tractors), all whilst operating (‘in-field’ and ‘on-farm’), the latter with a range of attached agricultural implements. 7.1 SELF-PROPELLED SPRAYERS The section of the investigation concerning self-propelled sprayers (Section 4) followed the established format described above, studying two suspension design variants of otherwise identical machines. When attempting to compare WBV emission levels recorded ‘in-field’ and upon the ISO test tracks, it is important to select appropriate track and field test conditions (and vehicle states) for comparison. Fortunately, this was probably one of the few instances where a degree of comparability existed between certain of the test conditions, namely the ISO 100 m ‘smoother’ track (at approx. 12 km/h) and the SRI ‘farm track’, the former having originally been designed to represent something rather like the latter. Additionally, the ‘laden’ sprayer condition in which some of the ISO track work was conducted was identical to that used during the SRI ‘in-field’ work. The resulting similarity (or lack of it) between results is therefore of interest. Upon the ISO test track (only the 100 m ‘smoother’ version used), vertical (Z) axis WBV emission levels were consistently higher than those recorded in the longitudinal (X) or transverse (Y) axes, irrespective of vehicle forward speed or suspension system capability. However, in many instances, Y-axis WBV levels approached those recorded in the Z-axis. The (forward control) position of the operator’s cab, well forward of the sprayer’s pitch centre, probably caused a proportion of vehicle pitch to be translated into near vertical movement of the cab floor, hence the high acceleration levels in this axis. Fitting softer ‘flotation’ tyres, rather than the stiffer ‘standard’ variants, caused significant increases in cab floor transverse (Y) axis acceleration levels during both the ISO track and ‘in-field’ test programmes, almost certainly because the lower inflation pressures of the flotation tyres resulted in lower dynamic stiffness and hence greater low-frequency transverse roll motion of the vehicle. Consequently, during the ‘in-field’ test programme, when fitted with ‘flotation’ tyres, machine transverse (Y) axis WBV emission levels were almost always the largest. The most significant physical difference between the test machines concerned the designs of their suspension systems (coil spring & hydraulic damper and self-levelling air spring & hydraulic damper). In theory the ISO track provided a good opportunity to investigate the relative practical benefits of these designs. Whilst longitudinal (X) and transverse (Y) axis cab floor acceleration levels upon the ISO track were comparable between the vehicles, the vertical (Z) axis WBV levels recorded upon the air spring suspension vehicle were significantly (up to 30%) lower than those of the coil spring suspension machine. ‘In-field’ performance indicated lower WBV levels upon the air spring vehicle in both vertical (Z) and longitudinal (X) axial directions.

133

Additionally, WBV emission levels upon the coil spring suspension vehicle were found to crease when in ‘laden’ conditio machine did not exhibit this

ms (24 m) extended (rather than ‘stowed’), requently, vertical (Z) axis WBV levels.

d’ travel and ‘spraying’ operations but,

in n, whereas the air suspensionundesirable characteristic. However, one word of caution when comparing vehicle WBV emission levels: the air spring suspension seat fitted to the air spring suspension vehicle was more effective in reducing vertical (Z) axis vibration than the (rather ‘tired’) mechanical suspension seat fitted to the coil spring suspension machine. Operator ‘seat’ WBV emission levels were always higher than those measured upon the cab floor, but this trend was less pronounced upon the air suspension machine, almost certainly due to the disparate suspension seats (of both different design and age) fitted to the test machines. Consequently, the degree of effectiveness of different suspension seats upon ‘seat’ WBV level reduction should not be confused with the performance of the vehicle suspension system. For this reason, cab floor WBV levels often provide a more reliable basis for vehicle suspension system evaluation (but

ot operator WBV exposure assessment). n Travelling over the ISO track with the sprayer booonsistently increased longitudinal (X) axis and, less fc

Transverse (Y) axis levels decreased slightly or remained the same. The coil spring suspension machine demonstrated these trends more consistently than air spring suspension vehicle. Vehicle loading condition (laden or unladen) had no effect upon these trends, which are probably a result of the sprayer weight distribution and pitch centre moving rearwards when the booms are unfolded, their stowed position being forwards alongside the operator’s cab. During the SRI ‘in-field’ programme, farm ‘track’ travel was understandably found to generate the highest WBV emission levels of all test conditions investigated, irrespective of vehicle suspension system design, tyre fitment or the measurement location. During farm ‘track’ travel the largest WBV levels were always found in the transverse (Y) axial direction.

BV emission levels were lower during both ‘roaWwhen fitted with ‘flotation’ tyres, the highest overall average r.m.s. (Aeq) WBV levels generated upon the vehicles in these conditions were still found in the transverse (Y) axis. However, when fitted with ‘standard’ tyres, the behaviour of the vehicles changed, vertical (Z) axis WBV emissions becoming greater than those of the longitudinal (X) or transverse (Y) axes during ‘road’ travel and ‘spraying’, irrespective of the vehicle design or measurement location (floor or seat). The apparent superiority of transverse (Y) axis WBV would not necessarily have been so prevalent were it not for the 1.4x multiplying factor, stipulated by the Directive for application to horizontal axes values (see Section 3.1.2). Comparison of ‘in-field’ and ISO test track data (as discussed above) illustrated very good agreement between transverse (Y) axis WBV levels, but a less agreement between longitudinal (X) axis WBV and very poor agreement in the vertical (Z) axis. Vehicle tyre equipment was found to have no effect upon the degree of agreement observed. The majority of ‘on-farm’ self-propelled sprayers, all of which were fitted with ‘standard’ tyres, were found to generate similar WBV emission levels to those experienced during the SRI ‘in-field’ programme, vibration magnitudes being significantly different in only one ‘on-farm’ instance, which was deemed a result of disparate (unusually rough) ‘on-farm’ operating conditions. ‘On-farm’ seat acceleration levels were higher than those recorded upon the sprayer cab floor in all instances, transverse (Y) axis WBV emissions generally being the largest of those measured upon the operator’s seat, but vertical (Z) axis emissions frequently taking precedence amongst measurements made upon the cab floor. However, in many instances the differences between individual axis WBV magnitudes was small (see Tables 4.5

134

& 4.6). The greater (vertical) distance between the vehicle’s roll centre and the seat surface undoubtedly assists the apparent superiority of the ‘operator’s seat’ Y-axis values. Of the ‘on-farm’ sprayers surveyed, a majority (57%) were operated for more than 8 hours per day during the survey week, a number being operated for up to 14 hours per day. Despite this, the total weekly operation period was a remarkably consistent average of 45 hours. Considering the likely impact of the PA(V)D, all of the ‘on-farm’ sprayers surveyed exceeded the 8-hour Exposure Action Value (EAV) within 8 hours operation, and will require implementation of measures to reduce and manage employee daily WBV exposure if 8 or more hours operation per day are common place. Possible measures are outlined in Section 3.1.3. Only one example exceeded the Exposure Limit Value (ELV) within 8 hours operation, in an uncommonly rough application. Working day length would have to increase to unsustainable levels (greater than 22 hours per day) for the other sprayers surveyed to xceed the A(8) ELV. Consequently, the requirements of the PA(V)D are not likely to

example sprayers. This was not assisted by the relatively small number of individual achines investigated; the 3 replicates performed being adequate to indicate ‘on-farm’ WBV

ent ethodologies are to be developed to assist the industry to embrace the Directive.

erestrict the operation of large, modern, ‘state-of-the-art’ self-propelled sprayers during an 8 hour day, and will not become a limitation even if the working day were to lengthen significantly (see Table 7.1). Daily working patterns, including rest breaks, machine maintenance, re-filling and periods of general inactivity, can all contribute to a reduction in the Aeq WBV exposure value. However, variation in WBV exposure levels was found to be present between certain ‘on-farm’mlevels, but insufficient to determine the degree of WBV emission level variability between supposedly identical vehicles / operations. Therefore, whilst the consistency between WBV emissions encountered during ‘on-farm’ sprayer operation is encouraging, a more detailed investigation of similar format, but comprising a larger number of measurement replications, is advisable in order to enable creation of a robust database of generic WBV emission data for modern self-propelled agricultural sprayers. Additionally, differences between ISO test track and ‘in-field’ WBV data require closer investigation if improved test track WBV assessmmNonetheless, given the evidence provided by this investigation, it seems unlikely that the requirements of the Directive will restrict the daily or weekly usage of self-propelled agricultural sprayers in the UK.

135

7.2 AGRICULTURAL TRACTORS As discussed previously in greater detail (see Section 5), four 4wd tractors in the 90 – 130 kW

asurement programme demonstrated that the type of gricultural operation / task performed has a greater influence upon resulting WBV emission

osed PA(V)D A(8) Exposure Limit Value (ELV) to be xceeded during an 8-hour working period, potentially necessitating changes in operating

methods or equipment to reduce WBV levels or, alternatively, limitation of daily operating duration. Ploughing may also cause the ELV to be exceeded, but only if the work period extends to approx. 12 – 14 hours per day. In all instances seat acceleration levels were higher than those recorded upon the tractor cab floor (see Figures 5.13 & 5.22 and Appendices 2.5 & 2.6). With the exception of cultivating and trailer transport, little significant difference was found between the cab floor WBV emission levels of the test tractors (suspension system designs) whilst performing the selected ‘in-field’ operations (see Figure 5.13); at least when WBV levels were evaluated by the ISO 2631-1:1997 “Effect of Vibration on Health” methodology favoured by the Directive (‘largest single weighted axis’: see Section 3.1.2). Arguably the point vibration total value (vector sum or root-sum-of-squares: see Appendices 2.5 & 2.6), which represents the acceleration levels present in all axial directions as opposed to solely the axis of the largest magnitude, is a better indicator of the differences in vehicle ride comfort perceived by the operator during fieldwork. The technique employed also relates more closely to the ISO 2631-1:1997 “Effect of Vibration on Comfort” evaluation methodology, but retains the additional weighting of horizontal axis values.

engine power range were selected for WBV measurement during travel upon ISO ride vibration test tracks and operation in controlled (SRI) ‘in-field’ conditions. Each vehicle embodied different levels of suspension system complexity, these being:-

• Unsuspended • Suspended cab • Suspended front axle & cab • Fully suspended (front & rear axle).

Only examples of the suspended front axle & cab tractor and the fully suspended (front & rear axle) tractor participated in the subsequent ‘on-farm’ WBV evaluation, but these vehicles performed field operations largely identical to those undertaken previously at SRI, namely ploughing, plough transport, cultivating, spraying / fertiliser spreading, and trailer transport, thereby providing a direct comparison with the SRI ‘in-field’ work. The SRI ‘in-field’ WBV emission mealevels than the suspension system capability of the test tractors performing each task (see Figures 5.13 & 5.22 and Appendices 2.5 & 2.6). Spraying and plough transport generated low WBV emission levels: ploughing generated moderate levels, whereas trailer transport generated moderate to high levels and cultivating generated high WBV levels (see Tables 7.1 & 7.2). This confirmed the previous belief that the WBV levels generated during moderate-higher speed operations are highly dependent upon prevailing surface conditions. The WBV levels recorded upon the operator’s seat during the SRI controlled ‘in-field’ test programme (see Figure 5.22) suggested that operators performing any of the tractor-operations with any of the surveyed vehicles will exceed the proposed PA(V)D A(8) Exposure Action Value (EAV) within 8 hours operation, requiring implementation of measures to reduce and manage employee daily WBV exposure if 8 or more hours operation per day are commonplace. Additionally, (rough ground) cultivating and trailer transport operations will cause the prope

136

Table 7.1 Relative WBV magnitudes arising from agricultural tractor operations performed during the SRI ‘in-field’ investigation

WBV Emission Level (energy-equivalent continuous (overall average) r.m.s. acceleration)

Low Moderate High

Ploughing Cultivating (rough ground) Spraying / Ferti r

Plough T ailer Transport

lise Spreading

ransport Tr

Calculation of cab floor vector sum acceleration levels by this method returned the same relative ranking and distribution of individual field operations, clarifying the relative differences between suspension system performance (resultant WBV emission levels) as being small during spraying and plough transport; moderate during ploughing and trailer

Evaluation

ion dose value (VDV). Removal of these periods of inactivity resulted in much greater

transport; and large during cultivating: a case of the more extreme the application, the greater the difference between the suspension systems. Whilst no vehicle / suspension system design appeared to be particularly superior for all the field operations investigated, and it should be noted that during certain operations the differences between the vehicles were small, evaluation of cab floor or operator seat WBV levels by the vector sum (RSS) method did suggest the ride comfort of the fully suspended (front & rear axle) tractor and the suspended front axle & cab tractor to be marginally superior to that of the other test vehicles in the majority of instances. of cab floor WBV levels by the largest single axis method displayed a similar trend between vehicle types, but this was not so apparent amongst operator seat WBV values derived by this technique: and the latter are, of course, the WBV emission levels from which operator daily exposure would be derived. Specific ‘on-farm’ tractor / operation combinations generated WBV emission levels similar to those experienced during the SRI ‘in-field’ measurement programme, particularly in the case of ‘on-farm’ examples of the fully suspended (front & rear axle) tractor, which generated its highest WBV levels during cultivating and trailer transport operations. However, whilst SRI ‘in-field’ WBV levels initially appeared higher than those from corresponding ‘on-farm’ machines / operations (see Figure 5.40), closer investigation showed that ‘on-farm’ daily working patterns, including rest breaks, machine maintenance and periods of general inactivity, all contributed to a reduction in the r.m.s. Aeq WBV exposure value, but not in the vibratsimilarity between SRI ‘in-field’ and ‘on-farm’ WBV levels (see Figure 5.41). During the majority of field operations (spraying / fertiliser spreading, ploughing & cultivating) and plough transport, the largest operator seat WBV levels (overall average r.m.s. (Aeq) acceleration) were mainly encountered in the transverse (Y) axis, when WBV was evaluated by the largest single weighted axis method. However, during trailer transport longitudinal (X) axis acceleration took precedence (see Figures 5.24 & 5.25), probably a result of vertical force input to the tractor pickup hitch (from the trailer drawbar) accentuating vehicle pitch, as discussed in Section 5.3.6. Horizontal (X & Y) axis seat Aeq acceleration levels were in all instances higher than those recorded upon the cab floor (see Figures 5.26 &

137

5.2 re frequently found to o

The his inves 31-1:1997 “Effect of Vibration on Health” ogy favoured by the Directive (‘largest single weighted axis’: see Section 3.1.2). WBV e compared individually with the EAV and ELV following application of frequency weightings and axis w & Y axes): effectively increasing the magnitudes of the horizontal However, as previously discussed, whilst the Directive requires WBV exposure levels to be ssessed separately in each axial direction, nd the measurement axis with the greatest

(shocks and jolts) are present.

reshold than the corresponding A(8) EAV (see Figure 5.37).

ction, in terms

7 and further discussion in Section 7.4). Nonetheless, maximum peak accelerations weccur in the vertical (Z-axis) direction.

apparent importance of the horizontal (X & Y) axes WBV levels reported in ttigation is undoubtedly accentuated (and arguably distorted) by use of the ISO 26

methodollevels in each axial direction ar

eighting factors (1.4x for X the latter (X & Y) axes WBV values.

a a(overall average) magnitude be identified, action is required to reduce WBV exposure in all axial directions where the EAV is exceeded (see Section 3.1.3). In practical terms whilst, for a given vehicle / application, the longitudinal (X) or transverse (Y) measurement axes may exhibit the highest axis-weighted overall-average acceleration levels, marginally lower Aeq levels in the remaining axial directions will also require implementation of appropriate vibration exposure-reducing measures if daily exposure levels exceed the EAV, and specially if significant peak acceleration eventse

Virtually all (~ 95%) of the ‘on-farm’ tractor-operations surveyed exceeded the PA(V)D 8 hour Exposure Action Value (EAV) within 8 hours operation, and will require implementation of measures to reduce and manage employee daily WBV exposure if 8 or more hours operation per day are common place. Possible measures are outlined in Section 3.1.3. Relatively few tractor-operations (~ 9%) exceeded the Exposure Limit Value (ELV) within 8 hours operation. However, if the working day length were to increase to 15 hours, up to 27% of the vehicles surveyed would probably exceed the ELV. During agricultural tractor operations, the VDV-specified EAV represents a considerably ower operating duration thl

Arguably this disparity offers greater overall protection to the vehicle operator. For instance, during part-day operation the EAV is more likely to be exceeded (requiring implementation of WBV exposure reduction / management measures) if specified in VDV terms. However, over a full (8-hour) working day the difference appears less significant; ~95% of the ‘on-farm’ tractors surveyed exceeded the VDV EAV in 8 hours operation, whilst ~82% exceeded the A(8) EAV in the same period. This issue is discussed further in Section 7.4. A majority (57%) of the tractors surveyed were operated for more than 8 hours per day and a number were used for up to 16 hours per day (see Figure 5.39). Consequently, whilst the requirements of the Directive are not likely to restrict the operation of large, modern, ‘state-

f-the-art’ tractors during an 8-hour working day, they may well pose a restriomaximum permissible daily operating period, if the working day were to lengthen significantly (greater than 8 hours). The onset of this limitation would be more rapid if the vehicles in question are smaller (lighter) or offer lower levels of operator comfort, WBV levels having been shown to be higher on smaller, more basic tractors in comparable operating conditions (Scarlett et al., 2002). Nonetheless over 50% of the ‘on-farm’ tractors / operations surveyed would have to work for approaching 24 hours per day to reach the ELV (see Figure 5.38).

138

As discussed earlier (see Section 3.1.2), the Directive provides a derogation permitting weekly averaging of daily personal vibration exposures, but this is intended for use in ircumstances where occasional high vibration exposure levels (greater than the ELV) are

times. Issues of seasonal timeliness, primarily lating to utilisation of favourable soil and weather conditions, place somewhat unique

els than the omparable model SRI ‘in-field’ tractor and also the ‘on-farm’ examples of the fully

s of more onventional’ design.

ent of WBV mission levels upon a solo tractor traversing these tracks bears no relation to practical

clikely to be encountered during the working week, but otherwise levels are usually low (below the EAV). Such qualifying circumstances would appear to be extremely rare in agricultural tractor operations. The situation is (possibly) complicated further by the fact that the resulting weekly average personal vibration exposure (A(8)week) represents the total exposure occurring within a period of seven consecutive days, but normalised to a reference duration of 40 hours, whereas modern agricultural practices can frequently cause the working week duration to exceed 80 hours at peakredemands upon agricultural operations, requiring extended working day lengths at peak times. The true extent of the impact the PA(V)D will have upon industries which interact strongly with the natural environment will not be realised until some time after the attempted implementation of the Directive. However, it is probable that by selection of appropriate work equipment and the provision of adequate operator training in methods of WBV exposure reduction, the impact of the Directive upon such industries may be minimised. During certain operations (cultivating and trailer transport), ‘on-farm’ examples of the suspended front axle & cab tractor generated lower WBV emission levcsuspended (front & rear axle) tractor. This was deemed to be due to disparate operating conditions and intensity of machine operation, the ‘on-farm’ fully suspended (front & rear axle) tractors being, in general, operated at higher forward speeds, over rougher surface conditions, than the suspended front axle & cab tractors. This may, however, be a consequence of a greater proportion of farm contractor rather than owner-operator ownership of these (fully suspended) machines. Additionally, the higher cost of these vehicles frequently necessitates more intense ‘on-farm’ utilisation compared with tractor‘c Comparison of ISO test track WBV emission levels with those recorded during SRI ‘in-field’ operations is fraught with difficulty, mainly due to differences in vehicle mass, axle weight distributions, tyre inflation pressures and external force systems between the test conditions. The ISO ride vibration tracks were originally developed as a research tool and a method of assessing tractor suspension seat performance. As such it is still useful in comparative testing of axle and cab suspension systems, although suspension seat testing has long since been transferred to the laboratory (ISO 5007:2003). The (current ISO 5008) measuremeagricultural operating conditions, to the extent that any significant correlation between ‘track’ and ‘field’ results would be a cause for concern. The recent updating of ISO 5008 (ISO, 2002) has done little to improve this situation. Nonetheless, defined, repeatable WBV test conditions and methodologies are required for agricultural tractors and other ‘off-road’ vehicles. In the future (2007 onwards) it is probable that new tractor customers, particularly high intensity users who expect their employees’ daily WBV exposure to frequently exceed the EAV, will favour cost-effective equipment embodying WBV-reducing design features, thereby assisting compliance with the PA(V)D.

139

It seems reasonable to expect those customers will also desire WBV emission data from manufacturers to support the claimed effectiveness of the aforesaid features and assist justification of purchase decisions. If so, that data should:-

i) Enable direct comparison between different vehicle models, ranges and competitive brands;

ii) Relate closely to the likely WBV emissions of the said vehicle(s) in agricultural applications / operating conditions.

The ISO 5008 test methodology currently satisfies (i) but falls significantly short of (ii). The PA(V)D does not require equipment manufacturers to state likely WBV emission levels of their products, but the EU Machinery Directive (98/37/EC) (EEC, 1998) does require such a declaration in the operators handbook if WBV emission levels equal or exceed 0.5 m/s2. These emission levels were regularly exceeded by all tractors during the SRI ‘in-field’ trials see Figure 5.22). However, agricultural tractors are not currently included w( ithin the scope

ctor / operation combinations investigated; the 3 replicates performed

daily WBV exposure levels (and their

target specific operations of concern in greater detail, whilst utilising recommended WBV estimation / calculation techniques for other (lower exposure level) operations, with confidence.

of the Machinery Directive, but all other agricultural machinery (self-propelled or otherwise) is, i.e. both self-propelled sprayers and ATVs. Consequently there is scope for further analysis of the results obtained from this investigation and development / refinement of ride vibration track test methodologies, with a view to providing a consistent, realistic, ideally independent method of agricultural tractor WBV assessment. Without such a reliable method, vehicle customers will be unable to have confidence in the relative WBV emission levels stated by manufacturers (either voluntarily or for legislative compliance) for their respective machines. Variation in WBV exposure values was found between certain examples of similar ‘on-farm’ tractors / operations (see Figures 5.33 & 5.34). This was not assisted by the relatively small

umber of individual tranbeing adequate to indicate ‘on-farm’ WBV levels, but insufficient to determine the degree of WBV emission variability between supposedly identical tractors & operations. A more detailed study of similar ‘on-farm’ format, but comprising a larger number of measurement replications, is required to enable creation of a robust database of generic WBV emission data for modern agricultural tractor / implement combinations, in order to enable employers to estimate the potential daily occupational vibration exposure of their employee’s and thereby comply with the requirements of the Directive. In theory such a database need only be sufficiently detailed to enable an employer to determine whether exceedance of the EAV and/or ELV during a given (typical) operating period is unlikely, possible or probable. However, as indicated by Table 7.3, the ecommended methods for determining employee r

subsequent complexity & cost) are dependent upon the magnitudes of the exposure levels likely to be encountered. If daily vibration exposure is likely to approach the ELV (and most certainly if it may exceed it), then a representative workplace measurement of vibration exposure may be either advisable or necessary. For this reason, especially given the location of tractor operation WBV daily exposure levels between the EAV and ELV (see Table 7.2), a robust database of generic WBV emission data would be of value, enabling an employer to

140

7.3 ALL-TERRAIN VEHICLES (ATVs) It is the case with drivers of ATVs, probably more so than those of any other farm vehicle,

at they have freedom of choice with regard to travel speed. They may also have to cross the rou stsimilar vehicles performing similar tasks is of the order of ±50% (see Section 6). This is gr gr amay be t vibration exposure. However, it is just as likely

be transformed into higher operating speeds for those who control their speed according to o be

thghe ground. It is therefore not surprising that the range of seat WBV magnitudes for

eater than the difference between different machines (ATVs) travelling over the same ound t the same speed (see Figure 6.15). The advantage of the lower vibration machines

aken by drivers in the form of lowertotheir personal comfort. Therefore the exposure levels that we have measured are likely t

presentative of all ATVs of this size (300-400 cc engine capacity). re As long as stock farmers use these machines for only ½ - 1 hour per day, they are unlikely to exceed the PA(V)D 8-hour Exposure Limit Value: whether they exceed the Exposure Action Value depends on whether one uses the VDV or the A(8) assessment criterion. However, ATVs are also used for recreational purposes, often by hill farmers seeking to diversify into a sport or entertainment enterprise. In such cases it is to be expected that drivers, particularly instructors, will use such machines for considerably longer than 1-hour per day. In these cases they will require management of vibration exposure, including advising of the vibration risk to health. It is also likely that drivers will intentionally seek to travel at higher speeds and/or over rougher terrain as part of the desired ‘experience’. Such vehicle use is beyond the scope of the present study, but it would be irresponsible not to mention the probability that it could lead to vibration exposures in excess of the ELV. One reason for recording driver presence upon the seat had been to exclude those rough parts of any journey during which the driver stood up to make his/her ride more comfortable. In the event, eliminating periods when the driver was not on the vehicle seat made only a small difference (generally less than 10%) to his/her overall exposure, and the difference was no greater when measured in terms of VDV rather than as r.m.s. (A(8)). Therefore, the anticipated effect was not found. However, the drivers did spend some time out of the saddle, and this did reduce their overall exposure slightly. Time off the seat does not equate to time spent standing on the footrests, but rather was mostly time during which the operator dismounted. From the records obtained in this investigation, it is not possible to identify any time the operator spent standing on the footrests. In the ‘on-farm’ data, both transverse (Y) and vertical (Z) axes exhibited similar magnitudes of WBV on the seat, with longitudinal (X) axis WBV being rather lower. This would not have been the case without the 1.4x multiplying factor stipulated for the horizontal axes (see Section 3.1.2). It was also different from what was found in the SRI controlled ‘in-field’ trials, where WBV levels in the vertical (Z) axis clearly dominated. A likely explanation is that the operating surfaces at SRI were not as severe as those found on the farms. This would have allowed higher vehicle forward speeds, with more vertical (Z) and less roll (Y-axis) motion than on the farms. A similar effect has been observed with tractors driven over the two different ISO 5008 tracks. The ‘rougher’ (35 m) track, traversed at lower speeds, produces more transverse (y-axis) and less vertical (Z-axis) vibration than the ‘smoother’ (100 m) track. It may be concluded that the SRI ‘in-field’ test circuit was not rough enough to be representative of ‘on-farm’ conditions. Nevertheless, that circuit did provide a better comparison between the different machines than did the ISO 5008 track.

141

ISO 5008 specifies ordinates for two pairs of test tracks, each pair being the left and right heel tracks. The standard allows the tracks to be constructed of separate slats, usually

008 could be adapted to e suitable for ATV WBV measurement.

ggests that the AV and ELV are likely to be reached sooner for hand-arm vibration than for whole-body

alent? eople stand up to enable their legs to cushion the effect of rough rides, and subjectively it

r annual utilisation of these vehicles, which anslates into a greater number of working hours spent ‘in the driving seat’. A similar

wwooden, for each ordinate, or of moulded concrete, which can be smoothed between ordinates. The separate slats were deemed to be acceptable for use by tractors and other vehicles with tyres of large diameter. The results obtained in this study suggest that they are not suitable for ATVs, whose tyre diameter and chassis structural stiffness are different to that of a ‘conventional’ tractor. A moulded concrete track may well have been more appropriate for ATV evaluation, but unfortunately could not be compared in this study. However, while the ‘smoother’ (100 m) track did not produce the equivalent transverse (Y-axis) motion found on farms, attempts to use the ‘rougher’ (35 m) track had to be abandoned because of the difficulty of maintaining a constant forward speed, and because the driver had to stand out of the seat in order to control the vehicle. It is difficult to see how ISO 5b Although only two sets of hand-arm vibration data were obtained from farms, these were consistent with data obtained from the controlled ‘in-field’ tests. The data suEvibration on these machines. However, as for WBV, the short durations of use encountered on livestock farms enables the vehicles to be used without exceeding the daily ELV. The same cannot be said for the vibration on the footrests. If the directive is followed precisely, this has to be assessed as whole-body vibration in the same way as that on the seat. And in that case, all the ‘on-farm’ example vehicles exceeded the ELV. However, a layman who is concerned about the amount of vibration reaching the lower back might be moved to ask how it is that the two inputs of seat and footrest(s) come to be considered equivPworks. The authors of this study believe more research relevant to this condition is required. 7.4 OVERALL DISCUSSION Although the UK agricultural workforce has reduced substantially in recent years, the remaining workers are spending a greater proportion of their time operating mobile machines which can create exposure to whole-body vibration. This is primarily a result of the use of fewer, larger (higher power) tractors in the UK (see Figures 2.9 & 2.10). Their smaller number and their higher initial cost requires greatetrscenario applies to specialist self-propelled vehicles such as self-propelled sprayers, forage and sugar beet harvesters. The increased popularity of agricultural contractors and contract farming operations may potentially lead to operators spending a greater number of longer working days performing specific operations at peak times of the year. Whole-body vibration exposure data for the ‘on-farm’ tractors in this survey suggests that there is a wide variation of exposure levels for similar agricultural operations / tasks (see Table 7.2). One possible (but unsubstantiated) explanation for this is the potential difference in driver operating technique / style between farmers who may perhaps be owner-drivers of the machines in question, and have fixed volumes of work to undertake without excessive time pressures (in a normal season). Alternatively, the staff of contractors may need to work more intensely / faster and for longer periods in each day, in order to maximise work volumes and potential business income.

142

Table 7.2 Summary of ‘on-farm’ agricultural vehicle operations investigated

Likelihood of Exceeding Value in a Normal

Working Day:- Vehicle / Activity

Seat overall average r.m.s.

(Aeq) WBV level (m/s2)

Time to EAV (A(8))

(hrs:mins)

Time to ELV (A(8))

(hrs:mins)

Average Working

Day (hrs) EAV ELV

S.P. Sprayer 0.53 – 0.69 4:12 – 7:7 22 - >24 10.1 Yes No

Tractor – Spraying 0.36 – 0.78

(0.5 – 0.74)

3:17 – 15:26 17:23 - >24 8.9 Probably No

Tractor - Ploughing 0.49 – 0.93

(0.73 – 0.89)

2:19 – 8:20 12:14 - >24 8.9 Yes Unlikely

Tractor – Trailer Transport

0.47 – 1.12 1:36 – 9:3 8:26 - >24 8.9 Yes (1.05 – 1.32)

Possibly

Tractor – Cultivating 0.53 – 1.39

(1.2 – 1.49)

1:2 – 7:7 5:29 - >24 8.9 Yes Possibly

ATV 0.85 – 1.39 1:2 – 2:46 5:29 – 14:39 1 - 2 Possibly V.unlikely

NB:- Tractor WBV data in parentheses originates from SRI ‘in-field’ measurements (performed in controlled or suspension system designs investigated;

m’ measurements and, in the case of tractors, only includes

ur, the ATVs would have exceeded the EAV only if specified according to the VDV criterion (see Table 6.6). However, these vehicles may also exceed the EAV for hand-arm vibration (see Section 6.4.3). In all of these instances, daily vibration exposure in

field conditions) and encompasses all tract

All other WBV data above relates to ‘on-far suspended front axle & cab, and fully suspended (front & rear axle) tractor models.

This limited survey has provided reasonable indication of the factors that affect WBV daily exposure during ‘on-farm’ use of selected agricultural vehicles, but the range of WBV levels within operations is large (frequently +/- 50%: see Table 7.2), particularly in the case of specific ‘on-farm’ tractor-implement operations. If a comprehensive, generic database of agricultural vehicle WBV emission levels is deemed desirable, to provide farmers with adequately robust data to enable estimation of likely WBV daily exposure levels (as required by the Directive), or alternatively to identify the need for workplace measurement of WBV exposure levels (see Table 7.3), then a more comprehensive study is required, embodying a greater number of measurement replications. This issue, which applies primarily to tractor-implement operations, is discussed in greater detail in Section 7.2. Operators of virtually all the ‘on-farm’ examples of tractor operations and the self-propelled sprayers would have received WBV daily exposures in excess of the Exposure Action Value (EAV) within 8 hours operation, whether the EAV was evaluated according to the r.m.s. (A(8)) or the VDV criterion (see Table 7.2). Given their generally short daily operating periods of ½ - 1 ho

143

exce ing plementation of measures to reduce and manage worker vibration exposure, and advising

workers of the associated health risk (see Section 3.1.3). W e osur lue ), o tor o ied ‘on-farm’, only cultivating provid es ker exposure would have exceeded the ELV within an 8-hour working day, although trailer tra rt ope s approached the ELV in certain instances (see Table 7.2). Longer working days, extending to 12- uld l e p ailer port o tions causing operator WBV exposure to exceed the ELV. Of the self-propelled sprayers, only on one, brief occasion were ‘on-farm’ WBV exposure levels severe enough to exceed the ELV, if the e tin hou ver icula plic med be sufficiently unusual treme conditions to be experienced for the entire (~4-hour) measurement period. Finally, the ATVs used on stock farms were not operated for sufficiently long (tot in da LV to be exceeded, although the

re ational use of these vehicles. The controlled ‘in-field’ tests performed at SRI generally produced average weighted r.m.s. (Aeq) acceleration levels of a similar order of ma tho und ‘ ’. For the agricultural tractor operations, the SRI ‘in-field’ WBV levels were slightly higher than those from ‘on-farm’, as would be expected because of the lack of (maintenance or rest) breaks during the measurement p ers, one farm record

ab V than SRI -field’ he other ‘on-farm’ instances (see 9). This may have been, and indeed is believed to be, an unusual occurrence, but it indicates the need for some care in establishing generic vibration values rtain ope ith tio bly to c thacontrolled ‘in-field’ tests were reasonably representative of more general farm work.

e ly

he ISnd self-propelled sprayers, than were found in the controlled field trials. This is a natural

ration levels, and in some

ss of the EAV will require action to be taken on the part of the employer, includim

ith regard to th PA(V)D Exp e Limit Vaed exampl

(ELVwhere wor

f the trac daily

perations stud

nspo ration

14 hours, co ead to som loughing and some tr trans pera

xposure had con ued for 8 rs. Howe , that part r ap ation see to for such ex

al) periods each given y for the Ecase might be diffe nt for recre

gnitude to se fo on-farm

eriods at SRIly higher WB

. For the s levels

elf-propelled sprayeither thegenerated consider ‘in or t

Figure 4.1

for ce rations. W that excep n, it is proba fair onclude t the SRI

However, for the ATVs a more severe ground surface might have given more representativtransverse (Y-axis) motion, with the necessarily lower forward speeds leading to relativelower vertical (Z-axis) vibration levels (see Section 6.4.3).

O 5008:2002 WBV test tracks yielded much larger WBV magnitudes for the tractors Taresult of the origins of the track, these being to represent the most severe ride conditions found in normal farm vehicle operation. The relevance to WBV levels found upon tractors in normal work is further compromised by the lack of any attached implements or trailers, the applied forces from which can have a large effect on the dynamics of the tractor. Consideration needs to be given to practical ways of including these aspects within future attempts to improve this standardised test methodology, and indeed the role such a methodology can play in off-road vehicle WBV emissions assessment (discussed in greater detail within Section 7.2). ATVs, whose use is more usually over rough ground surfaces, were tested more appropriately by the ISO 5008 (100 m ‘smoother’) track. However, the current form of SRI ISO 5008 track construction, comprising separate wooden slats, was a

robable cause of discrepancies in the footrest and handlebar vibpcases possibly also in the seat vibration. This difficulty might be overcome if a moulded concrete form of the track construction (an intended future modification at SRI) were to be used.

144

Table 7.3 Proposed method(s) for determination of WBV daily exposure level

Likely WBV daily exposure level

Less than EAV ~ EAV → ELV

Calculate likely daily exposure level from manufacturer’s stated

WBV emission values

Or Derive from published WBV exposure data for the generic

machine type/operation (via proposed HSE website

calculator)

Calculate likely daily exposure level from manufacturer’s stated

WBV emission values

Or Derive from published WBV exposure data for the generic

machine type/operation (via proposed HSE website

calculator)

Measure WBV exposure levels in the workplace

ar axle) tractor and the suspended ont axle & cab tractor to be marginally superior to that of the other test vehicles in the

in the transverse (Y) axial direction. The apparent importance of the horizontal (X & Y) axes WBV levels reported in this investigation is undoubtedly accentuated (and arguably distorted) by use of the ISO 2631-1:1997 “Effect of Vibration on Health” methodology favoured by the Directive (‘largest single weighted axis’: see Section 3.1.2). WBV levels in each axial direction are compared individually with the EAV and ELV following application of frequency weightings and axis weighting factors (1.4x for X & Y axes): the latter

The differences between WBV emission levels generated by individual tractor (axle and cab) suspension designs were generally less than those evident between the different agricultural tasks performed (spraying / fertiliser spreading, ploughing, plough transport, cultivating, trailer transport), particularly when evaluated by the ‘largest single weighted axis’ methodology favoured by the Directive. Every effort was made to minimise variation in the controlled ‘in-field’ test conditions, in order to highlight differences in tractor (suspension system) performance, but small differences no doubt existed between ground surface conditions for the same field task. Nonetheless, whilst no vehicle / suspension system design appeared to be particularly superior for all the field operations investigated, and it should be noted that during certain operations the differences between the vehicles were small, evaluation of cab floor or operator seat WBV levels by the vector sum (RSS) method did suggest the ride comfort of the fully suspended (front & refrmajority of instances. Evaluation of cab floor WBV levels by the largest single axis method displayed a similar trend between vehicle types, but this was not so apparent amongst operator seat WBV values derived by this technique: and the latter are, of course, the WBV emission levels from which operator daily exposure would be derived. Nonetheless, it is possible to conclude that, for a given task and given operating conditions, there are advantages in selecting the tractor with the most appropriate suspension system capability. For the self-propelled sprayers, the recently developed self-levelling air spring suspension system was found to offer useful advantages over the earlier mechanical coil spring and damper design in both ISO track and controlled ‘in-field’ trials. The flotation tyres, despite the apparent advantage of being softer, actually contributed to greater levels of WBV by increasing the vehicles’ transverse (Y-axis) roll motion. A feature common to whole-body vibration on the tractor and self-propelled sprayer operations investigated is the predominance of high (axis-weighted) overall average WBV levels

145

effe er, some of the instances the transverse (Y) axis would have produced the largest WBV levels

prior to the addition of 40% he remaining (majority of) instances do raise a question regarding the foundation upon which use of the 1.4x multiplier is based, as this factor is not found in the near alent British Standard, BS 6841:1987.

ch alts ir

axis erall avera magnitude be identified, action is required to reduce WBV exposure in all ax exceeded (see Section 3.1.3 n practical terms whilst lon inal (X) or transverse (Y) axes may exhibit th erall levels, marginally lower levels in tions ntation of appropriate vibration ex s if daily exposure levels exceed the EAV (as outlined in Se cularl vehicle / application, significant peak acceler hocks and jolts), po not well represented by the r.m.s. (A(8)) evaluation method, are present in any of the other axial directions.

ss is problem to an extent. In the future engineering solutions to these problems may well be

ration between the cab floor and the eat above the suspension. For horizontal motion, this can mainly be explained by the

ctively increasing the magnitudes of the horizontal (X & Y) axes WBV values. Howevin

from the multiplying factor. T

ly-equiv

This is, however, a largely teWBV exposure levels to be as

with the greatest (ov

nical (procedural) issue, for essed separately in each axial d

ge) r.m.s. acceleration

hough the Directive requires ection, and the measurement

ial directions where the EAV is gitud). I

e highest axis-weighted ov the remaining axial direcposure-reducing measurection 3.1.3). This is parti

ation events (s

-average (Aeq) acceleration will also require impleme

y pertinent if, for a givenssibly

A feature that is highlighted, if not exaggerated, by the horizontal axes multiplying factors, is the importance of height of the operator’s position above ground level, and above the vehicles’ roll centre. The gradual increase in this height as agricultural vehicles (particularly tractors) have become more powerful / larger is not a desirable development from the point of view of whole-body vibration. Furthermore, it is a motion whose effect it is difficult to mitigate by additional seat suspension capability. Horizontal (Y-axis) seat suspensions are now available, and indeed an example was fitted upon a test tractor in this investigation. During operations typified by high transverse (Y-axis) acceleration levels, this facility appeared to moderate the increase between cab floor and operator seat WBV levels in that axial direction. However, this characteristic was not investigated in isolation and further study would be required to determine its significance. In practice there are a number of factors that may complicate and potentially limit the effectiveness of this solution. Firstly, there is restricted space within the majority of agricultural vehicle cabs for transverse (Y-axis) suspension travel, and the low roll frequencies of these vehicles requires long suspension travel in order to be effective. Secondly, were such long suspension travels to be practical, there would be the ergonomic problem of relative movement between the operator and cab-mounted controls, although the current tendency to mount vehicle controls upon the operator’s seat could potentially addrethfound. There is not the scope within the constraints of this investigation to thoroughly analyse the part played by seat suspension systems in the WBV exposure of the tractor driver. What has given some concern is the apparent amplification of vibsincrease in height above the vehicle’s roll centre. The position regarding vertical (Z) axis vibration is more complex. Seat vertical suspension systems have traditionally been designed to protect the occupant from relatively large magnitude motion, between approx. 1.0 - 2.0 m/s2 weighted r.m.s. magnitude (ISO 5007:2003). For larger motions, it is possible that the suspension travel limits will be reached. For lower level motions, friction will progressively reduce the suspension system’s effectiveness.

146

Another issue of relevance to seat suspension performance is the appropriateness of the e-marking system. This was originally based upon ensuring the suitability of seat suspension system performance when fitted upon unsuspended tractors, but was extended to include tractors fitted with forms of axle and/or cab suspension without adequate technical verification. This may have led to suspended seats being fitted into cabs where the primary

ertical motion may be at a frequency lower than that for which the seat was designed,

rts to satisfy the Directive ould result in drivers being more exposed to shocks / jolts than they may have otherwise

quire particular control measures and, by consequence, may well provide better

vleading to the possibility of resonant amplification. When there is a strong likelihood of seat suspension over-travel, operators often adjust the suspension seat mid-ride position to a position higher than is optimum, sometimes even jamming the suspension system against the upper travel limit stop, thereby reducing the risk of a jarring blow at the bottom of suspension travel, but also leading to greater transmission of low-level vibration. If seat suspension systems are to protect the driver against the more severe shocks / jolts, they will require generally higher damping than is consistent with achieving low transmission of vibration in the standard (ISO 5007) tests. It also poses a problem for implementation of the PA(V)D, as this is predicated upon reducing average vibration levels rather than shocks. It is entirely possible that effocbeen, even if the criterion VDV is used rather than the A(8). The difference between the r.m.s. (A(8)) and VDV assessment criteria is very large for this application area (agricultural vehicles), manifesting itself in terms of the exposure duration required to reach the EAV or ELV. This probably arises because the equivalence was based on a calculation of estimated vibration dose values, or eVDVs, which can be derived from r.m.s. acceleration data (see ISO 2631-1:1997 & Section 3.1.2). Real, measured VDVs are intended for use with vibration signals that fail by a long way to satisfy the criteria for using eVDV, the latter being namely:-

• Crest factor greater than 6; • Nearly constant level of r.m.s. acceleration (stationary data)

WBV measurement upon agricultural vehicles can generate crest factors as high as 20, and the time-histories of 1-minute r.m.s. acceleration recorded in this investigation (see Figures 5.30, 5.31 and 5.32) display very wide variations in level. Issues concerning estimation of WBV exposure levels (in A(8) & VDV format) from measured data are explored further in Appendix 4. The VDV criterion does provide a better indication of shocks and transients in WBV exposure than the simpler r.m.s. (A(8)) evaluation method (Coles, 2002). It is also more able to identify short-duration / high vibration intensity incidents which

ay remindication of WBV risks present and the effectiveness of subsequent control measures. However, there is the issue of the strange units (m/s1.75) and the more complex method of calculation of VDV, if more widespread / general use is desired. A(8) daily exposure values may be estimated more easily and accurately from manufacturer’s stated machine WBV emissions values and, as shown, the A(8) EAV and ELV are likely to be less stringent where shocks and jolts are present in the acceleration time history. It has been proposed elsewhere (Stayner, 2001) that some feature of the amplitude or peak distribution of a vibration time signal might be a more appropriate measure of WBV health risk than those presently in use. However, this matter is not at present open for discussion.

147

148

8. CONCLUSIONS AND RECOMMENDATIONS At the potential risk of over-simplification, the following may be concluded from this substantial investigation:-

• Virtually all the agricultural vehicle operations investigated, involving modern, state-of-the-art tractors, self-propelled sprayers or ATVs, will result in operator WBV daily exposure exceeding the PA(V)D Exposure Action Value (EAV) during a normal working day (see Table 7.2), thereby requiring employers to implement measures to reduce & manage worker vibration exposure, as proposed by the Directive (see Section 3.1.3);

• During the majority of agricultural vehicle operations investigated, WBV daily exposure

is unlikely to exceed the Exposure Limit Value (ELV) during a typical working day, either due to sufficiently low WBV emission levels upon the vehicles concerned, or suitably short (total) periods of exposure within the day (see Table 7.2). However, exceptions include tractors cultivating (on rough ground) and tractor-trailer transport operations. Longer shifts, extending to 12 – 14 hours per day, which are common at peak times in agriculture, could result in other tractor operations (e.g. ploughing) causing operator WBV exposure to exceed the ELV. In longer days such as these, over 25% of the large, modern ‘on-farm’ tractor-operations surveyed would cause the ELV to be exceeded. Also, under comparable operating conditions, WBV emission levels upon smaller tractors are likely to be higher than upon the larger models investigated here, resulting in higher WBV daily exposure levels. However, over 50% of the ‘on-farm’ tractors / operations surveyed would have to work for approaching 24 hours per day to exceed the ELV (see Figure 5.38);

• It should be stressed that the WBV Exposure Limit Value (ELV) should not be

considered a ‘safe’ level of vibration exposure in the workplace, but rather as a high, undesirable level of vibration exposure (and a legal threshold) to be avoided at all costs. It is for this reason the Directive requires action to be taken, so far as is reasonably practicable, to minimise vibration exposure once levels exceed the Exposure Action Value (EAV);

• Differences between overall average (Aeq) WBV emission levels generated by individual

tractor (axle and cab) suspension designs were generally less than those evident between the different agricultural operations performed (spraying / fertiliser spreading, ploughing, plough transport, cultivating, trailer transport), particularly when evaluated by the ‘largest single weighted axis’ (ISO 2631-1:1997 ‘Effect of Vibration on Health’) methodology favoured by the Directive;

• Developments in suspension system design have been shown to reduce the WBV

emission levels of self-propelled sprayers. Developments in tractor (cab and axle) suspension systems appear to yield improvements in subjective ride comfort: a fact confirmed by evaluation of cab floor and operator seat WBV levels by the vector sum (RSS) method. The latter suggested the ride comfort of the fully suspended (front & rear axle) tractor and the suspended front axle & cab tractor to be marginally superior to that of the other test vehicles in the majority of instances. Cab floor WBV levels derived by the largest single axis method displayed a similar trend between tractor designs, but this was not so apparent amongst operator seat WBV values derived by the technique: and the latter are, of course, the WBV emission levels from which operator daily exposure would be derived;

149

• WBV po ary by as much as ±50% or more for the same task, depending upon ground conditions, driving

rences in WBV levels generated by alternative types (capabilities) of tractor cab and/or axle suspension system, whilst operating in similar conditions;

•

all average longitudinal (X) or transverse (Y) axis WBV levels, whilst significant peak

•

levels would be the largest for a greater number of vehicles / operations investigated;

•

the ELV (see Table 7.3), then a more comprehensive study is required, embodying a greater number of measurement replications. This issue is particularly

ex sure levels during ‘on-farm’ agricultural vehicle operations can v

technique and operational requirements (‘the need for speed’). This is much greater than the likely diffe

The Directive requires WBV levels in each axial direction to be assessed separately, and the axis with greatest (overall average) magnitude be identified. However, action is required to reduce exposure to vibration in all axial directions in which the EAV is exceeded (see Section 7.4). A given vehicle / application may exhibit high over

acceleration events (shocks and jolts) are generated in one or more of the other axial directions, and are possibly not well represented by the r.m.s. (A(8)) evaluation method;

During the majority of self-propelled sprayer and tractor-implement operations, largest (overall average, axis weighted) WBV magnitudes were generated in the transverse (Y) axis: during tractor-trailer transport the longitudinal (X) axis WBV took precedence. However, maximum peak acceleration levels frequently occurred in the vertical (Z) axis, and vertical (Z) axis WBV levels dominated ATV operation. The apparent importance of horizontal (X & Y) axes WBV levels reported in this investigation is undoubtedly accentuated (and arguably distorted) by use of the ‘largest single weighted axis’ (ISO 2631-1:1997 ‘Effect of Vibration on Health’) methodology favoured by the Directive. Were 1.4x multiplying factors not applied to horizontal vibration components, vertical (Z) axis WBV

If a comprehensive, generic database of agricultural vehicle WBV emission levels is deemed desirable, to provide farmers with adequately robust data to enable estimation / calculation of likely WBV daily exposure levels (as required by the Directive) and/or to identify the need for workplace measurement of WBV exposure levels, where these may approach

pertinent to tractor-implement operations, which typically generate WBV daily exposure levels between the EAV and ELV (see Table 7.2). Such a database would be of value, enabling an employer to target specific operations of concern in greater detail (workplace exposure measurement), whilst permitting recommended WBV estimation / calculation techniques to be used for other (lower exposure level) operations, with confidence;

• For agricultural operating conditions, there is little equivalence between the 8-hour

energy-equivalent, frequency-weighted r.m.s. acceleration (A(8)) and vibration dose value (VDV) methods of WBV exposure assessment, as specified by the Directive. This is because the equivalence is based upon the estimated vibration dose value (eVDV), and the requirements for use of the eVDV are not met by the WBV encountered in real agricultural conditions. In agricultural operating conditions the A(8) EAV and ELV appear to be less stringent (equate to longer operating durations) than their VDV-specified equivalents;

150

• The ISO 5008 ride vibration track tests provide a reasonable basis for comparing self-propelled sprayer WBV emission levels. However, for agricultural tractors, the results of the ISO 5008 tests bear little resemblance to WBV levels measured under ‘in-field’ or ‘on-farm’ conditions. This is largely because of the lack of attached implements or trailers and consequent differences in vehicle mass, weight distribution, tyre inflation pressures and external force systems acting upon the vehicle. Consequently, current

•

duration (due to exposure in excess of the ELV), rather than exposure to whole-body vibration. The slatted construction form of the ISO 5008 test track is

test track techniques require development / adaptation to improve their suitability for tractor-implement combination WBV emission assessment. Such developments would ideally deliver standardised testing methodologies, capable of quantifying the effectiveness of tractor WBV-reducing design features when operating in typical agricultural conditions (see Section 7.2);

For ATVs, hand-arm vibration exposure is more likely to restrict vehicle daily operating

inappropriate for ATVs, because of vibration generated by the inter-slat spacing. The suitability of the alternative moulded concrete type of track has not as yet been evaluated.

151

152

9. REFERENCES BSI (1997) BS 6841 Guide to Measurement and Evaluation of Human Exposure to Whole-Body Mechanical Vibration and Repeated Shock. British Standards Institution, London. Bovenzi, M. & Betta, A. (1994) Low Back Disorders in Agricultural Tractor Drivers Exposed to Whole-Body Vibration and Postural Stress. Applied Ergonomics 25, 231-240. Coles, B. (2002) The Physical Agents (Vibration) Directive. Exposure Action and Limit Values for Whole-Body Vibration: an important choice. HSE Discussion Paper (unpubl.), Southwark, UK. Crolla, D.A. (1976) The Effect of Cultivation Implements on Tractor Ride Vibration and Implications for Implement Control. J agric Engng Res 21, 247-261. Crolla, D.A. & Dale, A.K. (1979) The Ride Vibration of Tractor and Trailer Combinations. NIAE Departmental Note No. DN/ER/915/05005 (unpubl.), Silsoe, UK. DEFRA (Department for Environment, Food & Rural Affairs) (2001) Agriculture in the United Kingdom: 2000 (and previous years). Dufner, D.L. & Schick, T.E. (2002) John Deere Active SeatTM: a new level of seat performance. Proc. VDI Agritechnik Conference ‘Agricultural Engineering for Environmental Protection’, Martin Luther Universitat, Halle-Wirttenburg, Germany. EEC (1978) Council Directive on the Approximation of the Laws of Member States Relating to the Driver’s Seat on Wheeled Agricultural and Forestry Tractors (78/764/EEC). Journal of the European Communities No. L 183/9-32. EEC (1998) Council Directive on the Approximation of the Laws of Member States Relating to Machinery (98/37/EC). Journal of the European Communities No. L 207, 23rd July, 46pp EEC (2002) Council Directive on the Minimum Health and Safety Requirements Regarding the Exposure of Workers to the Risks Arising from Physical Agents (Vibration) (2002/44/EC). Journal of the European Communities No. OJ L 177, 6th July, 13pp. Griffin, M.J. (1998) A Comparison of Standardised Methods for Predicting the Hazards of Whole-Body Vibration and Repeated Shocks. Journal of Sound and Vibration, 215 (4), 883-914. ISO (1997) ISO 2631-1:1997 Mechanical Vibration and Shock - Evaluation of Human Exposure to Whole-Body Vibration - Part 1: General requirements. International Organisation for Standardisation, Geneva. ISO (2001) ISO 5349-1:2001 Mechanical Vibration – Measurement and Evaluation of Human Exposure to Hand-Transmitted Vibration - Part 1: General requirements. International Organisation for Standardisation, Geneva. ISO (2002) ISO 5008:2002 Agricultural Wheeled Tractors and Field Machinery - Measurement of Whole-Body Vibration of the Operator. International Organisation for Standardisation, Geneva.

153

+ISO (2003) ISO 5007:2003 A perator’s Seat – Laboratory valuation of Transmitted Vibration. Int Standardisation, Geneva.

ch

Tractors. J agric Engng Res 9(2), 147-158.

ain. HSE Contract

spensions:

gricultural Wheeled Tractors – Oernational Organisation forE

Lines, J.A.; Whyte, R.T. & Stayner, R.M. (1989) Agricultural Vehicle Suspensions:

uspensions for Tractor Cabs. Proc. 3rd Int. Symposium of Int. Section of ISSA for ResearSon Prevention of Occupational Risks, Vienna.

ines, J.A.; Stiles, M. & Whyte, R.T. (1995) Whole Body Vibration During Tractor LDriving. Journal of Low Frequency Noise and Vibration, 14(2), 87-104. Matthews, J. (1966) Ride Comfort for Tractor Operators: II Analysis of Ride Vibrations on

neumatic TyredP Paddan, G.S.; Haward, B.M.; Griffin, M.J. & Palmer, K.T. (1999) Whole-Body

ibration: Evaluation of Some Common Sources of Exposure in Great BritVResearch Report 235/1999. HSE Books, ISBN 0 7176 2481 1, 70pp.

eachey, R.O.; Lines, J.A. & Stayner, R.M. (1989) Agricultural Vehicle SuPTractor Front Axle Suspension. Proc. 3rd Int. Symposium of Int. Section of ISSA for Research on Prevention of Occupational Risks, Vienna. Scarlett, A. J.; Price, J.S. & Stayner, R.M. (2002) Whole-Body Vibration: Initial Evaluation of Emissions Originating from Agricultural Tractors. HSE Contract Research Report 413/2002. HSE Books, ISBN 0 7176 2276 2, 18pp. Stayner, R.M. & Bean, A.G.M. (1975) Tractor Ride Investigations: A survey of vibrations experienced by drivers during field work. NIAE Departmental Note No. DN/E/578/1445 (unpubl.), Silsoe, UK. Stayner, R.M.; Hilton, D.J. & Moran, P. (1975) Protecting the Tractor Driver from Low-Frequency Ride Vibration. Proc. IMechE Conf. “Off-Highway Vehicles”, Tractors &

quipment, CP 11/75, IMechE, London. E Stayner, R.M. (2001) Whole-Body Vibration and Shock - A Literature Review. HSE Contract Research Report 333/2001. HSE Books, ISBN 0 7176 2004 2.

154

APPENDICES APPENDIX 1.1: Self-Propelled Sprayer Specifications:– ISO Test

Track and SRI ‘In-Field’ Test Programmes

ble

on both front & rear axles

al ’ linkage suspension system

system:- Equal wheel four wheel drive

A1.1.1 Coil Spring Suspension Sprayer

Make:- Househam Model:- Super Sprint Year of manufacture:- 1997

Registration No.:- P820 BCT Spray tank capacity:- 2500 l Spray boom width:- 24 m Engine:- 118 kW 6-cylinder turbocharged diesel

Driveline:- 2-speed hydrostatic, infinitely-varia Wheelbase:- 3.10 m Track width:- 1.83 m

Suspension features (in addition to operator’s seat):- Twin coil springs & dampers

Front axle may oscillate relative to chassis – lateral location provided by a Panhard rod

Operator’s seat:- Isringhausen – Vertical (Z)-axis adjustable mechanicspring & damper; ‘scissor(tired)

Operator’s mass:- 77.5 kg Ground drive

Axle loadings, tyre equipment & tyre pressures:-

tandard Tyres, Unladen S Front Rear Total kg nd

(16 lb/in2)

Standard Tyres, Laden (~2000 l) Front

Axle loadings:- 3000 kg 2320 kg 5320 Tyre sizes:- Continental Contract AC90 12.4 R32 radials all rou

Tyres pressures:- 1.6 bar (24 lb/in2) 1.1 bar

Rear Total Axle loadings:- 3642 kg 3699 kg 7341 kg Tyre sizes:- Continental Contract AC90 12.4 R32 radials all round Tyres pressures:- 2.1 bar (31 lb/in2) 2.1 bar (31 lb/in2) Flotation Tyres, Unladen Front Rear Total Axle loadings:- 3150 kg 2514 kg 5664 kg Tyre sizes:- Nokian ELS 600/55 R26.5 tubeless radials all round Tyres pressures:- 0.9 bar (13 lb/in2) 0.8 bar (12 lb/in2) Flotation Tyres, Laden (~2000 l) Front Rear Total Axle loadings:- 3708 kg 3734 kg 7442 kg Tyre sizes:- Nokian ELS 600/55 R26.5 tubeless radials all round Tyres pressures:- 1.2 bar (17 lb/in2) 1.2 bar (17 lb/in2)

155

A1.1.2 Air Spring Suspension S

Year of manufRegistration No.:- FY02 GPU

turbocharged diesel infinitely-variable

o operator’s seat):- rings & dampers on both front & rear axles

ation provided

xis adjustable air spring & fixed damper; ge su pension system

pring & fixed

Operat

em:-

Axle lo pressures:- Standa

prayer Make:- Househam Model:- AR 2500 (Super Sprint Air-Ride)

acture:- 2002 Spray tank capacity:- 2500 l

Spray boom width:- 24 m Engine:- 118 kW 6-cylinder Driveline:- 2-speed hydrostatic,

Wheelbase:- 3.10 m Track width:- 1.83 m

on tSuspension features (in additielling air sp Twin, self-lev

Front axle may oscillate relative to chassis – lateral locby a Panhard rod

air suspension seat Operator’s seat:- KAB 856 series– Vertical (Z)-a

‘scissor’ linka s- Longitudinal (X)-axis fixed mechanical s

damper or’s mass:- 77.5 kg

Ground drive syst Equal wheel four wheel drive

adings, tyre equipment & tyre

rd Tyres, Unladen Front Rear Total 5828 kg

90 12.4 R32 radials all round ) 1.2 bar (18 lb/in2)

2000 l)

Axle loadings:- 3314 kg 2514 kg Tyre sizes:- Continental Contract AC

Tyres pressures:- 1.9 bar (27 lb/in2

tanda (~S rd Tyres, Laden Front Rear Total Axle loadings:- 4064 kg 3784 kg 7848 kg

12 ound Tyre sizes:- Continental Contract AC90 .4 R32 radials all rTyres pressures:- 2.4 bar (35 lb/in2) 2.2 bar (32 lb/in2)

lotatio n F n Tyres, Unlade Front Rear Total

Axle loadings:- 3429 kg 2616 kg 6045 kg und Tyre sizes:- Nokian ELS 600/55 R26.5 tubeless radials all ro

Tyres pressures:- 1.0 bar (15 lb/in2) 0.8 bar (12 lb/in2)

lotatio ~F n Tyres, Laden ( 2000 l) Front Rear Total Axle loadings:- 4140 kg 3835 kg 7975 kg

und Tyre sizes:- Nokian ELS 600/55 R26.5 tubeless radials all roTyres pressures:- 1.3 bar (19.5 lb/in2 1.2 bar (18 lb/in2) )

156

APPENDIX 1.2: Self-Propelled Sprayer WBV Emission Data:- ISO Test Track Programme

A Systems:- Unladen C l Spri tandard tyres – Unladen (Empty tank) Spray bo

2)

1.2.1 Coil Spring and Air Spring Suspension

oi ng Suspension Sprayer - S

oms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 9.93 0.288 0.68 0.128 2.08 0.738 1.33 .080 1 2.60 0.535

12.00 8 0.246 0.83 0.062 2.59 0.575 1.43 0.030 3.09 0.4813 0.84 0.010 2.69 0.454 1.42 0.021 3.16 0.37.99 0.265 2

Spray bo d)

oms closed (stowe

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean ean SD Mean SD SD M10.17 0. 1.28 0.150 1.08 0.004 1.74 0.115 0.029 0.48 009 12.22 0.063 0.58 0.040 1.15 0.222 1.21 0.020 1.77 0.149 13.04 1.64 0.56 0.91 1.24 14.25 0.142 0.60 0.020 0.96 0.007 1.30 0.025 1.72 0.020 15.00 0.73 1.38 1.33 2.05 16.22 0.72 1.30 2.00 1.34 18.09 0.78 1.54 5 2.32 1.5 20 1 1.56 1.71 2.49 .45 0.9

Spray booms open (e

ge r ccele (m/s

xtended)

Avera .m.s. floor a ration (1.4 multiplier) 2) Actual speed (km/h) Y Z RSS X

Mea SD Mean SD Mean SD an SD Mea Me n SD n 9.93 0. 2 1.29 0.030 0.288 0.47 01 0.70 0.013 0.038 1.54

12.00 0.246 0.54 .0 0.69 0. 1 0.016 1.57 0 12 028 1.3 0.014 13 0.265 0.56 0 0.68 9 0.00 1.64 0.01.99 0. 12 0.017 1.3 9 1

Closed (S er

ge r ccele (m/s2

towed), 1.4 multipli

Avera .m.s. floor a ration (1.4 multiplier) )

Actual spe X ed (km/h) Y Z RSS Mea SD Mean SD Mean SD Mean SD Mean SDn 10 0.029 0.38 0 0.72 0.017 1 6 0.021 1.42.17 0. 09 .1 0.014 12.22 0.063 0.42 0.003 0.72 0.018 1.29 0.018 1.53 0.010 13.04 0.41 0.68 1.34 1.56 14.25 0.142 0.43 0.008 0.66 0.018 1.34 0.012 1.56 0.011 15.00 0.48 0.64 1.36 1.58 16.22 0.46 0.67 1.42 1.64 18.09 0.44 0.61 1.72 1.87 20.45 0.48 0.59 1.75 1.91

157

Air Spring Suspension Sprayer - Standard tyres – Unladen (Empty tank) Spray booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 9.83 0.201 0.51 08 0.018 0.015 0.68 0.013 0.67 0.008 1.

11.74 0.117 0.53 0.006 0.72 0.004 0.73 0.003 1.15 0.002 13.33 0.085 0.62 0.016 0.73 0.032 0.79 0.011 1.24 006 0.

Sp om ed ed)

ge r.m.s. seat a on ultip /s2

ray bo s clos (stow

Avera ccelerati (1.4 m lier) (m )

Actual spee (km/h) X Y RSS d Z Mean SD Mean SD Mean SD Mean SD Mean SD 9.94 0.057 0.40 99 0.016 0.002 0.66 0.025 0.63 0.004 0.

11.70 0.058 0.42 0.003 0.71 0.009 0.69 0.009 1.07 002 0.12.77 0.52 0.74 0.72 1.16 13.74 0 .090 0.51 0 .009 0.72 0 .013 0.75 0 .016 1.16 0 .00314.52 0.49 0.69 0.74 1.12 15.86 0.48 0.74 0.80 1.19 17.82 0.53 0.68 0.87 1.22 19.67 0.60 0.64 0.98 1.32

Sp oms en (e ed)

Averag acceleration (1.4 mu tiplier) (m 2)

ray bo op xtend

e r.m.s. floor l /s

Actual speed (km/h) X Y Z RSS Mean SD Mean an SD SD Mean SD Mean SD Me9.83 0.201 0.37 0.002 0.65 0.010 0.80 0.005 1.10 004 0.

11.74 0.117 0.38 0. 0. 0.006 0.67 013 0.90 022 1.18 0.023 13.33 0 .085 0.42 0 .016 0.65 0 .023 1.02 0 .017 1.27 0 .022

Cl Sto 1.4 m lier

Averag acceleration (1.4 mu tiplier) (m 2)

osed ( wed), ultip

e r.m.s. floor l /s

Actual speed (km/h) X Y RSS Z Mean SD Mean an SD SD Mean SD Mean SD Me9.94 0.057 0.32 0.002 0.69 0.020 0.73 0.002 1.05 015 0.

11.70 0.058 0.34 0. 0. 0.008 0.68 025 0.83 006 1.13 0.013 12.77 0.37 0.70 0.91 1.21 13.74 0.090 0.38 0.004 0.64 0.043 0.92 0.015 1.18 0.020 14.52 0.36 0.65 0.93 1.19 15.86 0.37 0.66 1.02 1.27 17.82 0.40 0.64 1.11 1.34 19.67 0.45 0.58 1.23 1.43

158

Coil Spring Suspension Sprayer - Flotation tyres – Unladen (Empty tank)

Spray booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 10.20 0.307 0.69 0.029 1.05 0.032 1.26 0.019 1.78 0.026 12.21 0.207 0.73 0.006 0.98 0.074 1.18 0.010 1.70 0.047 14.21 0.262 0.76 0.004 0.91 0.090 1.31 0.026 1.77 0.064

Spray booms closed (stowed)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.18 0.144 0.52 0.011 0.75 0.034 0.96 0.011 1.33 0.028 12.39 0.193 0.54 0.012 0.83 0.013 1.04 0.007 1.43 0.008 13.28 0.54 0.96 1.08 1.54 14.34 0.152 0.55 0.007 0.85 0.029 1.10 0.018 1.49 0.019 15.13 0.55 0.83 1.10 1.48 16.29 0.60 0.81 1.12 1.50 18.27 0.74 0.87 1.29 1.72 20.57 0.90 0.91 1.50 1.97

Spray booms open (extended)

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.20 0.307 0.44 0.006 0.66 0.024 1.12 0.009 1.37 0.018 12.21 0.207 0.46 0.004 0.71 0.063 1.14 0.008 1.42 0.038 14.21 0.262 0.48 0.002 0.70 0.043 1.28 0.022 1.54 0.030

Closed (Stowed), 1.4 multiplier

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.18 0.144 0.37 0.006 0.75 0.010 1.12 0.015 1.40 0.009 12.39 0.193 0.38 0.010 0.78 0.045 1.22 0.005 1.50 0.023 13.28 0.38 0.87 1.25 1.57 14.34 0.152 0.38 0.007 0.79 0.020 1.24 0.003 1.52 0.011 15.13 0.39 0.77 1.24 1.51 16.29 0.42 0.75 1.30 1.56 18.27 0.44 0.72 1.43 1.66 20.57 0.51 0.76 1.53 1.79

159

Air Spring Suspension Sprayer - Flotation tyres – Unladen (Empty tank) Spray booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 9.80 0.085 0.51 0.015 0.78 0.027 0.63 0.013 1.13 0.023

11.74 0.144 0.52 0.014 0.72 0.030 0.69 0.013 1.12 0.030 13.38 0.149 0.59 0.001 0.78 0.016 0.78 0.020 1.25 0.012

Spray booms closed (stowed)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 9.93 0.129 0.44 0.011 0.89 0.053 0.62 0.010 1.17 0.047

11.83 0.081 0.43 0.005 0.76 0.018 0.68 0.007 1.11 0.016 12.72 0.47 0.77 0.71 1.14 13.83 0.111 0.54 0.015 0.81 0.037 0.75 0.014 1.23 0.031 14.75 0.55 0.89 0.76 1.30 15.72 0.56 0.84 0.84 1.31 17.82 0.59 0.86 0.91 1.38 19.35 0.68 0.88 0.96 1.47

Spray booms open (extended)

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 9.80 0.085 0.36 0.009 0.81 0.025 0.71 0.005 1.14 0.015

11.74 0.144 0.37 0.002 0.84 0.038 0.78 0.013 1.20 0.034 13.38 0.149 0.41 0.016 0.90 0.050 0.93 0.006 1.36 0.041

Closed (Stowed), 1.4 multiplier

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 9.93 0.129 0.32 0.006 0.96 0.012 0.70 0.015 1.24 0.002

11.83 0.081 0.34 0.001 0.88 0.027 0.81 0.005 1.24 0.022 12.72 0.36 0.96 0.84 1.33 13.83 0.111 0.38 0.007 0.98 0.065 0.92 0.010 1.40 0.039 14.75 0.38 1.08 0.97 1.50 15.72 0.41 1.04 1.04 1.53 17.82 0.42 1.09 1.20 1.68 19.35 0.46 1.09 1.28 1.74

160

A1.2.2

Suspension Sprayer - Standard tyres – Laden (Full tank)

y booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Coil Spring and Air Spring Suspension Systems:- Laden

Coil Spring

Spra

Actual speed ( ) X Y Z RSSkm/h

SD Mean M M MSD SD SD SD ean ean ean Mean 0.148 0.031 0.155 0.057 0.103 9.86 0.78 1.11 1.35 1.92 0.260 0.058 0.173 0.048 0.156 11.99 0.92 1.40 1.56 2.28

13.85 0.092 1.04 0.037 1.62 0.062 1.75 0.068 2.61 0.097 Spray booms closed (stowed)

Average r.m.s. se ation (1.4 multiplier) (m/s2)

at acceler Actual speed ( ) X Y Z Skm/h RS

SD Mean M M MSD SD SD SD ean ean ean Mean 0.110 0.019 0.194 0.014 0.156 9.90 0.60 1.47 1.09 1.93 0. 4 0. 8 0. 5 0. 2 0. 6 02 00 18 02 1312.19 0.71 1.37 1.37 2.07

13.43 0.77 1.56 1.50 2.30 0. 0 0. 0 0. 4 0. 6 0. 1 18 03 13 04 0814.14 0.84 1.70 1.52 2.43

15.19 0.76 1.43 1.49 2.20 16.36 0.79 1.71 1.52 2.42 18.56 0.91 1.78 1.79 2.68 20.57 1.09 1.90 2.04 2.99

Spray booms open (extended)

Average r.m.s. flo acceleration (1.4 m iplier) (m/s2)

or ult Actual speed (km/h) X Y Z RSS

SD Mean M M MSD SD SD SD ean ean ean Mean 0.148 0.012 0.027 0.016 0.006 9.86 0.43 0.78 1.26 1.54 0.260 0.028 0.021 0.083 0.083 11.99 0.51 0.73 1.44 1.69

13.85 0.092 0.60 0.046 0.78 0.023 1.64 0.111 1.91 0.116 Closed (Stowed), 1.4 multiplier

Average r.m.s. flo acceleration (1.4 m iplier) (m/s2)

or ult Actual speed (km/h) X Y Z SRS

Mean SD Mean SD Mean SD Mean SD Mean SD 0.110 0.005 0.022 0.027 0.035 9.90 0.36 0.84 1.13 1.45 0. 4 0. 6 0. 6 0. 5 0. 9 02 01 0.74 03 02 0212.19 0.43 1.38 1.62

0.75 1.52 1.76 13.43 0.47 0. 0 0. 3 0. 2 0. 9 0. 0 18 0.53 03 0.78 03 1.53 00 1.79 0314.14

15.19 0.48 0.74 1.51 1.74 16.36 0.50 0.74 1.60 1.83 18.56 0.53 0.73 1.96 2.16 20.57 0.60 0.74 2.17 2.37

161

Air Spring Suspension Sprayer - Standard tyres – Laden (Full tank)

Averag r.m.s. sea ati n (1.4 mu iplier) (m/ )

y booms open (extended) Spra

s2e t acceler o lt

Actual spee (km/h) X RSS d Y Z

Mean SD Mean SD Mean SD Mean SD Mean SD 10.04 0 0 0 0 0 .063 0.53 .031 0.76 .082 0.75 .009 .0671.20 11.80 0.113 0.58 0.011 0.75 0.020 0.80 0.002 1.24 0.016 13.63 0.198 0.63 0.018 0.79 0.028 0.84 0.019 1.31 0.016

Spray booms closed (stowed

Averag r.m.s. sea ati n (1.4 mu iplier) (m/ )

)

e t acceler o lt s2

Actual spee (km/h) X RSS d Y Z Mean SD Mean SD Mean SD Mean SD Mean SD 10.03 0 0 0 0 0 .159 0.39 .002 0.71 .006 0.72 .008 1.08 .00612.01 0.195 0.44 0.017 0.70 0.020 0.76 0.006 1.13 0.011 13.07 0.54 0.79 0.79 1.24 13.79 0. 4 0. 0 0. 7 0. 2 0. 1 02 0.52 02 0.81 03 0.81 00 1.26 0314.63 0.50 0.78 0.86 1.27 16.00 0.48 0.70 0.94 1.26 17.78 0.49 0.73 0.98 1.32 19.81 0.61 0.77 1.15 1.51

Spray booms open (extended)

verag acceleration (1.4 mu tiplier) (m 2)

A e r.m.s. floor l /s

Actual spee (km/h) X RSS d Y Z Mean SD Mean SD Mean SD Mean SD Mean SD 10.04 0 0 0 0 0 .063 0.39 .007 0.72 .014 0.95 .023 1.26 .02511.80 0.113 0.40 0.001 0.69 0.015 1.10 0.018 1.36 0.020 13.63 0.198 0.44 0.011 0.71 0.017 1.13 0.016 1.41 0.021

Closed (Stowed), 1.4 multiplier

verag acceleration (1.4 mu tiplier) (m 2)

A e r.m.s. floor l /s

Actual spee (km/h) X RSS d Y Z Mean SD Mean SD Mean SD Mean SD Mea n SD10.03 0 0 0 0 0 .159 0.33 .006 0.80 .028 0.85 .020 1.22 .00912.01 0.195 0.35 0.012 0.74 0.027 1.01 0.020 1.30 0.031 13.07 0.39 0.72 1.04 1.32 13.79 0. 4 0. 8 0. 6 0. 9 0. 5 02 0.40 00 0.73 01 1.10 00 1.38 0114.63 0.40 0.78 1.05 1.37 16.00 0.39 0.69 1.06 1.32 17.78 0.40 0.69 1.14 1.40 19.81 0.50 0.67 1.28 1.53

162

Coil Spring Suspension Sprayer - Flotation tyres – Laden (Full tank)

Spray booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 10.22 0.146 0.79 0.084 1.28 0.188 1.33 0.067 2.01 0.196 12.18 0.331 0.81 0.020 1.05 0.055 1.35 0.009 1.89 0.036 13.71 0.080 0.87 0.041 1.04 0.104 1.43 0.038 1.97 0.094

Spray booms closed (stowed)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.45 0.114 0.57 0.004 1.13 0.019 1.14 0.010 1.70 0.019 12.16 0.143 0.59 0.007 0.94 0.073 1.22 0.012 1.65 0.037 13.28 0.64 1.03 1.29 1.77 14.29 0.098 0.64 0.011 1.04 0.100 1.22 0.016 1.73 0.053 15.38 0.67 1.04 1.27 1.77 16.36 0.67 1.01 1.33 1.80 18.00 0.79 1.06 1.59 2.07 20.57 1.01 1.11 1.74 2.30

Spray booms open (extended)

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.22 0.146 0.44 0.032 0.97 0.031 1.28 0.031 1.67 0.050 12.18 0.331 0.49 0.002 0.99 0.019 1.40 0.020 1.79 0.019 13.71 0.080 0.51 0.018 1.01 0.067 1.49 0.004 1.87 0.031

Closed (Stowed), 1.4 multiplier

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean SD Mean SD Mean SD Mean SD 10.45 0.114 0.38 0.006 1.16 0.046 1.33 0.025 1.81 0.043 12.16 0.143 0.41 0.010 1.00 0.040 1.46 0.022 1.82 0.025 13.28 0.44 1.10 1.47 1.89 14.29 0.098 0.45 0.010 1.18 0.068 1.43 0.005 1.90 0.047 15.38 0.45 1.14 1.43 1.88 16.36 0.46 1.16 1.49 1.94 18.00 0.51 1.09 1.79 2.15 20.57 0.56 1.08 1.77 2.15

163

Air Spring Suspension Sprayer - Flotation tyres – Laden (Full tank) Spray booms open (extended)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS

Mean SD Mean SD Mean SD Mean SD Mean SD 9.64 0.127 0.52 1.02 0.81 1.40 0.048 0.025 0.076 0.016

11.48 0.009 0.029 0.172 0.52 0.99 0.033 0.83 0.014 1.39 13.65 0.060 0.66 0.007 1.06 0.016 0.89 0.010 1.54 0.008

Spray booms closed (stowed)

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y Z RSS Mean SD Mean Mean Mean SD SD SD Mean SD 9.95 0.079 0.48 0.002 0.95 0.073 0.81 0.013 1.34 0.058

11.91 0.239 0.49 0.018 0.84 0.013 0.79 0.009 1.25 0.019 12.90 0.55 0.88 0.79 1.30 13.76 0.170 0.62 0.006 0.93 0.035 0.83 0.017 1.39 0.012 15.00 0.66 0.96 0.95 1.50 15.86 0.63 0.91 0.95 1.46 17.82 0.66 1.22 1.13 1.78 20.11 0.78 1.06 1.15 1.75

Spray booms open (extended)

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) X Y RSS Z Mean SD SD Mean SD SD Mean SD Mean Mean 9.64 0.127 0.36 0.012 0.91 0.055 0.91 0.010 1.34 0.045

11.48 0.172 0.37 0.007 0.90 0.037 0.99 0.010 1.39 0.033 13.65 0.060 0.43 0.008 0.93 0.005 1.07 0.009 1.48 0.008

Closed (Stowed), 1.4 multiplier

Average r.m.s. floor acceleration (1.4 multiplier) (m/s2)

Actual speed (km/h) Y RSS X Z Mean Mean Mean Mean SD Mean SD SD SD SD 9.95 0.079 0.34 0.005 1.03 0.046 0.94 0.039 1.44 0.053

11.91 0.239 0.35 0.008 0.96 0.030 0.96 0.010 1.40 0.026 12.90 0.37 0.99 0.99 1.45 13.76 0.170 0.40 0.004 0.98 0.054 1.01 0.010 1.47 0.032 15.00 0.42 1.02 1.06 1.54 15.86 0.39 0.97 1.12 1.54 17.82 0.44 1.05 1.23 1.68 20.11 0.48 1.03 1.30 1.73

164

APPENDIX 1.3: Self-Propelled Spra er WB Emiss n Data -Fiel ’ Progr mme

Coil spring suspension - Standard tyres

e r.m.s. floor a tion

.4 m er) (

A .m.s. acc

(1.4 mul (m/

y V io :-SRI ‘In

d a

Averag ccelera

(1 ultipli m/s2)

verage r seat eleration

tiplier) s2)

Z RSS X Y Z RSS X Y

Ro 0.10 0.19 0.38 0.43 0.14 0.26 0.43 53 ad 0.

Track 0.31 0.73 65 1. 0 0 98 0. 6 30 0. 02 .39 . 7 1.

Spraying 0.34 0.3 1.04 8 0.64 0.82 0.43 0.52 0.80

Overal 0.43 0.6 81 0.4 0.57 0.7 1.03 l 0.32 1 0. 0 5

ring en - Sta d ty

Average r.m.s. floor ac

.4 mu lier) (

Av acce n

(1.4 multip r) (m/

Air sp s spu sion n ard res

celeration

(1 ltip m/s2)

erage r.m.s. seat leratio

lie s2)

Y Z RSS X Y Z RSS X

Ro 0.09 0.17 28 0. 0 0.21 0. 0 0.53 ad 0. 34 .09 3

Track 0.28 0.68 0.49 0. 0.28 0.80 0.56 1.02 88

Spraying 0.29 0.40 0.44 0.66 0.31 0.46 0.47 0.72

Overal 0.43 0.4 67 0.29 0.50 0.4 0.74 l 0.28 3 0. 7

rin pen - F n t

Average r.m.s. floor acceleration

(1.4 multiplier) (m/s2)

Average r.m.s. seat acceleratio

(1.4 multiplier) (m/s2)

Coil sp g sus sion lotatio yres

n

X Y Z RSS X Y Z RSS

Road 0 0 0.33 0.51 0.17 0.5 0.39 0. .10 .37 5 69

Track 0 0. 62 1.14 0.33 1.23 0.70 1..27 92 0. 45

Sprayi 0 0 0.51 0.73 0.31 0.6 0.60 0.ng .26 .46 3 92

Overall 0 0.55 0.51 0.79 0.31 0.75 0.59 1.00 .25

165

Air spring suspension - Flotation tyres

Average r.m.s. seat acceleration

(1.4 multiplier) (m/s2)

Average r.m.s. floor acceleration

(1.4 multiplier) (m/s2)

SS X Y Z RSS X Y Z R

Road 0.08 0.28 0.21 0.36 0.09 0.37 0.23 0.44

Track 0.26 0 0.48 0.26 1 0.54 .95 1.10 .08 1.23

Spraying 0.21 0.37 0.64 0.41 0.48 0.24 0.55 0.72

Overall 0.21 0.56 0.38 0.71 0.23 0.64 0.41 0.80

166

APPENDIX 1.4: Self-Propelled Sprayer ‘On-Farm’ WBV Exposure Data:- Synopsis of Results

Larson Davis HVM100 SN:00272 Day Month Year

Location: Floor 23 May 2Machine: HouseReg No: FY02GAO : 08:40Task: SprayingPlace: H L Crops (Contr s)

Total VD 1.7

ham Air SuspendedStart time

actor

V (m/s 5 ) verag . (Aeq)A e r.m.s (m/s 2 )Time Y S X Y Z Sum03:30 6.0 8.6 8.7 13.5 0.26 0.39 0.39 0.61

Maximum peak value (m/s

X Z um

2 )X

6.20 2

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 23 May

Y5.4

Z12.80

Sum12.80

2Machine: Househam Air SuspendedReg No: FY02GAO Start time: 08:47Task: SprayingPlace: H L Crops (Contractors)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:30 6.3 11.2 10.1 16.0 0.28 0.52 0.53 0.79

8-hr est tot 7.7 13.8 12.4 19.7

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 1.52 7.12 X Y Z SumTime to ELV (hr): >24 >24 6.38 6.99 14.80 14.80

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.3

0.5

0.8

1.0

1.3

1.5

1.8

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

167

Larson Davis HVM100 SN:00272Floor

Day Month YearLocation: 29 May 2Machine: Househam Air SuspendedReg No: FY02GRU Start time: 08:49Task: SprayingPlace: Bush & Sons (Farmers)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 7.4 8.0 7.5 12.9 0.31 0.36 0.37 0.61

Maximum peak value (m/s 2 )X Y Z Sum

4.42 4.76 7.13 7.29

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 29 May 2Machine: Househam Air SuspendedReg No: FY02GRU Start time: 08:50Task: SprayingPlace: Bush & Sons (Farmers)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 8.6 13.7 8.8 17.7 0.38 0.59 0.37 0.80

8-hr est tot 9.9 15.8 10.2 20.5

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.88 5.73 X Y Z SumTime to ELV (hr): >24 >24 5.12 9.44 17.20 17.10

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

168

Larson Davis HVM100 SN:00215 Day Month YearLocation: Floor 18 Jun 2Machine: Househam Air SuspendedReg No: FY02VFK Start time: 10:50Task: SprayingPlace: R Lane (Contractor)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum01:45 8.5 8.4 11.4 16.3 0.57 0.59 0.78 1.13

Maximum peak value (m/s 2 )X Y Z Sum

4.72 5.29 8.55 8.95

Larson Davis HVM100 SN:00272 Day Month YearLocation: Seat 18 Jun 2Machine: Househam Air SuspendedReg No: FY02VFK Start time: 10:49Task: SprayingPlace: R Lane (Contractor)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum01:45 13.9 22.8 16.8 30.1 0.94 1.27 0.88 1.81

8-hr est tot 20.3 33.3 24.5 44.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.04 1.23 X Y Z SumTime to ELV (hr): 1.27 6.52 8.76 14.98 30.80 31.80

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0:00 0:30 1:00 1:30 2:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

169

Larson Davis HVM100 SN:00215 Day Month YearLocation: Floor 18 Jun 2Machine: Househam Air SuspendedReg No: FY02VFK Start time: 19:08Task: Spraying (second part)Place: R Lane (Contractor)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum02:00 6.7 7.6 9.5 13.8 0.44 0.54 0.65 0.95

Maximum peak value (m/s 2 )X Y Z Sum

4.52 4.16 8.46 8.57

Larson Davis HVM100 SN:00272 Day Month YearLocation: Seat 18 Jun 2Machine: Househam Air SuspendedReg No: FY02VFK Start time: 19:07Task: Spraying (second part)Place: R Lane (Contractor)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum02:00 10.5 11.2 13.2 19.7 0.69 0.68 0.68 1.18

8-hr est tot 14.8 15.9 18.6 27.8

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.46 4.23 X Y Z SumTime to ELV (hr): 12.96 22.39 6.64 13.73 25.50 25.50

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.3

0.5

0.8

1.0

1.3

1.5

0:00 0:30 1:00 1:30 2:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

170

APPENDIX 2.1: Agricultural Tractor Specifications:– ISO Test Track Programme

A2.1.1 Unsuspended Tractor Make:- John Deere Model:- 7810 Year of manufacture:- 2001 Engine:- 129 kW 6-cylinder turbocharged diesel Transmission:- 18-speed full powershift Wheelbase:- 2.80 m Track width:- 1.86 m

Suspension features (in addition to operator’s seat):- None

Operator’s mass:- 77 kg Ground drive system:- Unequal wheel four-wheel-drive Goodyear Super Traction Radial tyres

Front Rear Total Axle loadings:- 2565 kg 4471 kg 7036 kg Tyre sizes:- 16.9 R28 20.8 R38 Tyres pressures:- 0.6 bar (8.7 lb/in2) 0.6 bar (8.7 lb/in2) A2.1.2 Suspended Cab Tractor Make:- Renault Model:- Ares 630 RZ Year of manufacture:- 2001 Engine:- 88 kW 6-cylinder diesel Transmission:- 16-speed semi-powershift Wheelbase:- 2.75 m Track width:- 1.90 m

Suspension features (in addition to operator’s seat):- ‘Hydrostable RZ’ cab suspension

system, comprising coil spring/damper units, Panhard rods, longitudinal struts & rear anti-roll bar (see Section 2.1.2)

Operator’s mass:- 77 kg Ground drive system:- Unequal wheel four-wheel-drive Michelin Agri Bib tyres

Front Rear Total Axle loadings:- 2577 kg 2960 kg 5537 kg Tyre sizes:- 14.9 R28 18.4 R38 Tyres pressures:- 0.7 bar (10.2 lb/in2) 0.6 bar (8.7 lb/in2)

171

A2.1.3 Suspended Front Axle & Cab Tractor

Holland

Make:- New 5

urbocharged diesel

m th:-

ures ‘Comfort Ride’ cab suspension system, comprising coil spring/damper units &

e Section 2.1.2) ‘Terraglide’ self-levelling, gas-over-oil, hydro-pneumatic front axle suspension

Operator’s mass:- 77 kg Ground drive system:- Unequal wheel four-wheel-drive Michelin XM108 tyres

Model:- TM 16

Year of manufacture:- 2001 Engine:- 120 kW 6-cylinder t Transmission:- 18-speed semi-powershift Wheelbase:- 2.787 Track wid 1.925 m

Suspension feat(in addition to operator’s seat):-

Panhard rods at cab rear (se

system (see Section 2.1.3)

Front Rear Total

2 kg Tyre sizes:- 540/65 R28 650/65 R38 Tyres pressures:- 0.6 bar (8.7 lb/in2) 0.6 bar (8.7 lb/in2)

A2.1.4 Fully Suspended (front & rear axle) Tractor

Model:- Fastrac 3185

Engine:- 127 kW 6-cylinder turbocharged diesel -powershift

Wheelbase:- 3.05 m

Suspension features (in addition to operator’s seat):-

Rear axle:- self-levelling, gas-over-oil, hydro-pneumatic suspension system (see Section 2.1.3)

7 kg

Alliance Super Power Drive A-360 tyres

Axle loadings:- 2765 kg 3737 kg 650

Make:- JCB

Year of manufacture:- 2001

Transmission:- 54-speed semi

Track width:- 2.01 m

Front axle:- twin coil springs, telescopic dampers, radius rods & Panhard rod

Operator’s mass:- 7Ground drive system:- Equal wheel four-wheel-drive

Front Rear Total Axle loadings:- 3762 kg 3483 kg 7245 kg

Tyres pressures:- 1.2 bar (17.4 lb/in ) 1.2 bar (17.4 lb/in )

Tyre sizes:- 540/65 R30 540/65 R30 2 2

172

APPENDIX 2.2: Tractor Suspension Seat Specifications

0)

Sear Manufacturing Co. Model:-

Suspen Z) axis:- air spring (adjustable) & damper

Longitudinal (X) axis:-

Transverse (Y) axis:- ing (fixed) & damper (fixed)

A2.2.2 Tr Renault Operat Model:- MSG 85/731

I No.:-

al ( axis: sp damper (fixed), ‘scissor’ linkage

spring (fixed) & damper

None

2.2.3 65)

Air Suspension Seat 3 seat unit

Serial No.:- CNH 82 Suspension type:- Vertical (Z) axis:-

r’ linkage d) & damper

Tr nsvers (Y) a

A2.2.1 Unsuspended Tractor (John Deere 781 Operator’s seat:- Manufacturer:- JD Air FS 92/01 e11 – I, II & III. 0445 Serial No.:- 2873960

sion type:- Vertical ((adjustable), ‘scissor’ linkage mechanical spring (fixed) & damper (fixed) mechanical spr

Suspended Cab actor ( Ares 630 RZ)

or’s seat:- Manufacturer:- Grammer

e1 – II & II Serial - Suspension type:- Vertic Z) - mechanical ring (adjustable) &

Longitudinal (X) axis:- mechanical (fixed)

Transverse (Y) axis:- A Suspended Front Axle & Cab Tractor (New Holland TM 1

anufacturing Co. Operator’s seat:- Manufacturer:- Sear M Model:- De Luxe SA1580

SA15748 suspension unit e11 – I, II & III. 1294

016027

air spring (adjustable) & damper (adjustable), ‘scisso

Longitudin axis:- mechanical spring (fixeal (X) (adjustable)

a e xis:- None

173

A2.2.4 Fully Suspended (front & rear axle) Tractor (JCB Fastrac 3185)

Model:- MSG 95A/721 12V

uspension type:- ertical (Z) axis: stable) & damper (fixed),

Longitudinal (X) axis:- mechanical spring (fixed) & damper

Transverse (Y) axis:-

Operator’s seat:- Manufacturer:- Grammer e1 – II & III. S V - air spring (adju

‘scissor’ linkage

(adjustable) None

174

A est Track Programme

2.3.1 Unsuspen d Tractor (John Deere 7810)

eed (km/h)Mean SD Mean SD

4.0 0.97 0 0.55 0.02 1.66 0.0655.1 1.09 0.022 1.62 0.006 0.68 0.01 2.08 0.0156.1 1.18 1.78 0.79 2.277.0 1.31 0.025 1.72 0.011 0.88 0.01 2.34 0.001

10.1 0.53 0.025 0.91 0.035 0.69 0.00 1.26 0.03312.0 0.61 0.040 1.04 0.025 0.67 0.00 1.38 0.03113.0 0.66 1.10 0.70 1.4614.1 0.74 0.051 1.22 0.014 0.77 0.01 1.62 0.01015.4 0.75 1.27 0.86 1.7016.1 0.81 1.26 1.00 1.8018.0 0.82 1.35 1.10 1.9319.8 0.91 1.41 1.42 2.2024.3 1.00 1.43 1.64 2.4030.5 1.56 1.27 1.94 2.79

ActualSpeed (km/h)

Mean SD Mean SD Mean SD Mean SD4.0 1.43 0.041 1.53 0.052 0.63 0.017 2.19 0.0605.1 1.59 0.037 1.98 0.049 0.78 0.012 2.66 0.0566.1 1.77 2.31 0.87 3.047.0 1.96 0.029 2.04 0.093 1.03 0.018 3.01 0.076

10.1 0.83 0.061 1.10 0.080 0.69 0.024 1.54 0.05112.0 0.86 0.083 1.29 0.032 0.60 0.009 1.67 0.03413.0 0.95 1.27 0.60 1.7014.1 1.13 0.030 1.46 0.074 0.71 0.023 1.98 0.03915.4 1.25 1.61 0.73 2.1616.1 1.46 1.54 1.01 2.3618.0 1.46 1.68 1.05 2.4619.8 1.76 1.79 1.52 2.9424.3 1.69 1.66 1.71 2.9330.5 2.53 1.55 1.97 3.56

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )

a 2

RSSX Y Z

PPENDIX 2.3: Agricultural Tractor WBV Emission Data:- ISO T

A de

ActualSp

Mean

Average r.m.s. floor iplier) (m/s ) X Y Z RSS

SD Mean SD0.025 1.23 .059

cceleration (1.4 mult

175

A2.3.2 Suspended Cab Tractor (Renault Ares 630 RZ)

Actual

Mean SD Mean SD Mean SD Mean SD4.1 0.99 0.045 1.19 0.074 0.44 0.01 1.61 0.0525.1 1.15 0.009 1.53 0.015 0.52 0.01 1.98 0.0166.0 1.32 1.55 0.65 2.147.1 1.41 0.017 1.48 0.019 0.90 0.01 2.23 0.005

10.6 0.50 0.006 0.82 0.008 0.62 0.01 1.14 0.00912.7 0.57 0.013 0.89 0.015 0.55 0.01 1.19 0.00213.8 0.62 0.99 0.54 1.2914.9 0.69 0.019 1.04 0.029 0.62 0.01 1.39 0.02416.1 0.74 1.02 0.71 1.4417.1 0.72 1.11 0.83 1.5619.1 0.69 1.07 1.03 1.6421.6 0.68 1.13 1.24 1.8124.0 0.93 1.10 1.41 2.0130.0 1.37 0.97 1.42 2.19

ActualSpeed (km/h)

Mean SD Mean SD Mean SD Mean SD4.1 1.41 0.066 1.33 0.070 0.62 0.022 2.04 0.0405.1 1.74 0.030 1.75 0.053 0.71 0.041 2.57 0.0406.0 2.07 1.70 0.91 2.837.1 2.46 0.012 1.66 0.017 1.29 0.020 3.23 0.011

10.6 0.88 0.024 1.03 0.087 0.80 0.016 1.57 0.07712.7 1.04 0.019 1.13 0.090 0.64 0.015 1.66 0.07813.8 1.14 1.25 0.70 1.8314.9 1.28 0.046 1.32 0.101 0.78 0.024 1.99 0.08116.1 1.46 1.34 0.93 2.1917.1 1.31 1.28 1.13 2.1519.1 1.25 1.23 1.42 2.2621.6 1.27 1.66 1.66 2.6724.0 1.88 1.56 1.82 3.0430.0 2.61 1.33 1.75 3.41

Average r.m.s. floor acceleration (1.4 multiplier) (m/s 2 ) Y RSS

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 ) X Y Y RSS

Speed (km/h) X Y

176

A2.3.3 Suspended Front Axle & Cab Tractor (New Holland TM 165)

S

S

ActualSpeed (km/h)

Mean SD Mean SD Mean SD Mean SD3.9 0.90 0.044 1.21 0.074 0.50 0.01 1.59 0.0504.8 1.02 0.007 1.83 0.061 0.72 0.02 2.21 0.0465.9 1.20 1.74 1.02 2.346.7 1.25 0.021 1.73 0.021 1.07 0.04 2.39 0.021

9.7 0.45 0.008 0.92 0.053 0.82 0.02 1.31 0.02611.8 0.51 0.002 0.97 0.046 0.72 0.03 1.31 0.02012.5 0.55 1.01 0.70 1.3513.7 0.57 0.011 1.10 0.040 0.79 0.02 1.47 0.01914.6 0.59 1.17 0.91 1.6015.6 0.57 1.14 1.07 1.6717.5 0.60 1.34 1.10 1.8419.6 0.63 1.24 1.28 1.8924.2 0.84 1.21 1.81 2.3328.7 1.03 1.34 1.81 2.47

ActualSpeed (km/h)

Mean SD Mean SD Mean SD Mean SD3.9 1.22 0.055 1.30 0.136 0.55 0.024 1.86 0.0894.8 1.43 0.020 1.99 0.130 0.76 0.030 2.57 0.0985.9 1.75 1.74 1.12 2.716.7 1.85 0.045 1.88 0.020 1.23 0.084 2.91 0.027

9.7 0.68 0.009 1.16 0.181 0.78 0.015 1.55 0.13311.8 0.78 0.006 1.22 0.230 0.65 0.024 1.59 0.16712.5 0.84 1.16 0.67 1.5813.7 0.88 0.028 1.38 0.233 0.74 0.013 1.79 0.17114.6 0.91 1.36 0.93 1.8815.6 0.91 1.31 1.09 1.9317.5 1.05 1.91 1.11 2.4519.6 1.10 1.51 1.27 2.2624.2 1.51 1.55 1.46 2.6128.7 1.87 1.57 1.42 2.82

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 ) X Y Y RS

Average r.m.s. floor acceleration (1.4 multiplier) (m/s 2 ) X Y Y RS

177

A2.3.4 Fully Suspended (front & rear axle) Tractor (JCB Fastrac 3185)

Actual

Speed (km/h)Mean SD Mean SD Mean SD Mean SD

4.0 1.17 0.041 1.32 0.025 0.35 0.01 1.79 0.0144.8 1.21 0.023 1.67 0.019 0.50 0.01 2.12 0.0245.8 1.20 1.75 0.65 2.226.8 1.25 0.011 1.59 0.029 0.82 0.02 2.18 0.022

10.0 0.43 0.010 0.64 0.027 0.41 0.01 0.87 0.02511.7 0.52 0.008 0.73 0.030 0.46 0.01 1.00 0.02612.9 0.53 0.75 0.48 1.0313.8 0.58 0.008 0.79 0.018 0.52 0.01 1.10 0.01514.8 0.62 0.81 0.55 1.1615.9 0.67 0.84 0.59 1.2217.7 0.68 0.87 0.64 1.2719.9 0.71 0.89 0.70 1.3323.8 0.93 0.90 0.78 1.5130.0 1.09 0.86 0.89 1.65

ActualSpeed (km/h)

Mean SD Mean SD Mean SD Mean SD4.0 1.61 0.074 1.53 0.101 0.44 0.037 2.27 0.0194.8 1.82 0.015 2.04 0.085 0.71 0.023 2.82 0.0655.8 2.00 2.14 1.01 3.096.8 2.23 0.020 1.97 0.070 1.27 0.054 3.24 0.026

10.0 0.64 0.018 0.76 0.039 0.53 0.007 1.13 0.02711.7 0.81 0.034 0.92 0.151 0.62 0.015 1.37 0.08912.9 0.74 0.88 0.66 1.3213.8 0.87 0.076 0.95 0.062 0.75 0.021 1.49 0.02214.8 0.94 1.01 0.83 1.6115.9 1.12 1.18 0.90 1.8617.7 1.07 1.04 0.89 1.7419.9 1.03 1.11 0.92 1.7823.8 1.59 1.14 0.88 2.1430.0 2.13 1.24 1.00 2.66

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 ) X Y Y RSS

Average r.m.s. floor acceleration (1.4 multiplier) (m/s 2 ) X Y Y RSS

178

APPENDIX 2.4: Agricultural Test Tractor Set-up:- SRI ‘In-Field’ Programme

A2.4.1 Unsuspended Tractor (John Deere 7810) Spraying (tractor plus front weights) Implement:- Hardi 1000 litre 3pt. linkage-mounted, air-assisted sprayer 12 m spray booms Front

Rear Total Axle loadings:- 2412 kg 7886 kg 10299 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.6 bar (23.2 lb/in2) Ploughing / Plough Transport (tractor plus front weights) Implement:- Dowdeswell DP7 5-furrow, fully-mounted reversible plough Front Rear Total Axle loadings:- 1968 kg 7582 kg 9550 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.3 bar (19 lb/in2) Cultivating (tractor plus front weights) Implement:- Cousins 4 m 3pt.linkage-mounted pigtail cultivator Front Rear Total Axle loadings:- 3115 kg 5889 kg 9004 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 0.9 bar (13 lb/in2) Trailer Transport (tractor less front weights) Implement:- Wootton 12 tonne tandem axle tipping trailer Sprung drawbar, sprung axles

Trailer gross weight:- 17145 kg Drawbar load:- 2921 kg Bogie load:- 14224 kg Tyre pressures:- 5.2 bar (76 lb/in2) Front

Rear Total Tractor Axle loadings:- 2247 kg 7772 kg 10019 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.6 bar (11.6 lb/in2) Tractor – Trailer Gross Train Weight:- 10019 + 14224 = 24243 kg

179

A2.4.2 Suspended Cab Tractor (Renault Ares 630 RZ)

praying

- Hardi 1000 litre 3pt. linkage-mounted, air-assisted sprayer 12 m spray booms

Front

S(tractor plus front weights) Implement:

Rear Total

1924 kg 6623 kg 8547 kg

lough spo t ractor plus front weights)

-furrow, fully-mounted reversible plough

Front

Axle loadings:- Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.6 bar (23.2 lb/in2) P ing / Plough Tran r(t Implement:- Dowdeswell DP7 5 Rear Total

Axle loadings:- 1352 kg 6344 kg 7696 kg .6 lb 2)

ractor plus front weights)

Cousins 4 m 3pt.linkage-mounted pigtail cultivator

Front

Tyres pressures:- 0.8 bar (11 /in 1.6 bar (23.2 lb/in2) Cultivating (t Implement:- Rear Total

Axle loadings:- 2937 kg 3654 kg 6591 kg .6 lb 2)

ractor less front weights)

tton 12 tonne tandem axle tipping trailer g drawbar, sprung axles

2921 kg ogie load:- 14224 kg

Tyre pressures:- 5.2 bar (76 lb/in2)

Front

Tyres pressures:- 0.8 bar (11 /in 0.8 bar (11.6 lb/in2) Trailer Transport (t Implement:- Woo Sprun Trailer gross weight:- 17145 kg Drawbar load:- B Rea r Total

Tractor Axle loadings:- 2080 kg 6300 kg 8380 kg

t:

Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.6 bar (11.6 lb/in2) Tractor – Trailer Gross Train Weigh - 8380 + 14224 = 22604 kg

180

A2.4.3 Suspended Front Axle & Cab Tractor (New Holland TM 165) Spraying (tractor plus front weights) Implement:- Hardi 1000 litre 3pt. linkage-mounted, air-assisted sprayer 12 m spray booms Front Rear Total

)

(tractor plus front weights)

Axle loadings:- 2235 kg 7138 kg 9373 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 0.95 bar (13.8 lb/in2

Ploughing / Plough Transport

Implement:- Dowdeswell DP7 5-furrow, fully-mounted reversible plough

Front Rear Total Axle loadings:- 2369 kg 6750 kg 9119 kg

Tyres pressures:- 0.6 bar (8.7 lb/in2) 0.8 bar (11.6 lb/in2) Cultivating (tractor plus front weights)

Implement:- Cousins 4 m 3pt.linkage-mounted pigtail cultivator

Front Rear Total Axle loadings:- 3479 kg 5042 kg 8521 kg Tyres pressures:- 0.8 bar (11.6 lb/in2) 0.6 bar (8.7 lb/in2) Trailer Transport (tractor less front weights) Implement:- Wootton 12 tonne tandem axle tipping trailer Sprung drawbar, sprung axles Trailer gross weight:- 17145 kg Drawbar load:- 2921 kg Bogie load:- 14224 kg Tyre pressures:- 5.2 bar (76 lb/in2) Front Rear Total

kg

Tractor Axle loadings:- 2220 kg 7067 kg 9287 kg Tyres pressures:- 0.6 bar (8.7 lb/in2) 1.1 bar (17.6 lb/in2) Tractor – Trailer Gross Train Weight:- 9287 + 14224 = 23511

181

A2.4.4 Fully Suspended (front & rear axle) Tractor(JCB Fastrac 3185) Spraying (tractor less front weights) Implement:- Hardi 1000 litre 3pt. linkage-mounted, air-assisted sprayer 12 m spray booms Front Rear Total Axle loadings:- 2577 kg 6813 kg 9390 kg Tyres pressures:- 1.2 bar (17.4 lb/in2) 2.2 bar (32 lb/in2) Ploughing / Plough Transport (tractor plus front weights)

Implement:- Dowdeswell DP7 5-furrow, fully-mounted reversible plough

Front Rear Total Axle loadings:- 3038 kg 6350 kg 9388 kg Tyres pressures:- 1.2 bar (17.4 lb/in2) 1.75 bar (25.4 lb/in2)

Cultivating (tractor less front weights)

Implement:- Cousins 4 m 3pt.linkage-mounted pigtail cultivator

Front Rear Total Axle loadings:- 3073 kg 5047 kg 8120 kg Tyres pressures:- 1.2 bar (17.4 lb/in2) 1.4 bar (20.3 lb/in2)

Trailer Transport (tractor less front weights) Implement:- Wootton 12 tonne tandem axle tipping trailer Sprung drawbar, sprung axles Trailer gross weight:- 17145 kg Drawbar load:- 2921 kg Bogie load:- 14224 kg Tyre pressures:- 5.2 bar (76 lb/in2)

Front Rear Total Tractor Axle loadings:- 3448 kg 6452 kg 9900 kg Tyres pressures:- 1.4 bar (20.3 lb/in2) 2.4 bar (34.8 lb/in2)

Tractor – Trailer Gross Train Weight:- 9900 + 14224 = 24124 kg

182

AP ISRI ‘In-Field’ Programme

Tractor Model Key

• Tractor ‘A’ = Unsuspended • Tractor ‘B’ = Suspended Cab • Tractor ‘C’ = Suspended Front Axle & Cab • Tractor ‘D’ = Fully Suspended (Front & Rear Axle)

ltivatin 1.14 0 5 50

ltivatin 0.90 0 .75

Cultivating 0.93 0. 1 6.84

P ugh Transport A 0.42 0.51 0.49 0.82 0.52 0.58 0.48 0.92 20.72

P 0.47 0.76 0.61 0.60 0.56 1.02 20.77

Pl 0.29 0.48 0.46 0.72 0.35 0.65 0.44 0.86 22.54

Pl ugh Transport D 0.38 0.45 0.39 0.70 0.48 0.59 0.46 0.88 24.12

6 5.33

0.55 0.65 0.49 0.98 0.74 0.83 0.53 1.24 4.97

5.18

Ploughing 0.60 0. 0.55 0 .08

Spraying 0.47 0 67

Spraying 0.44 0 10.19

Spraying C 0.30 0.41 0.32 0.60 0.38 0.50 0.36 0.72 9.79

D 0.34 0.48 0.37 0.70 0.49 0.74 0.54 1.04 9.94

T 0.89 0.78 0.54 1.30 1.32 0.84 0.49 1.64 19.40

T ler Transport B 0.81 0.69 0.46 1.16 1.35 0.94 0.53 1.73 18.68

T 0.48 1.58 19.71

Trailer Transport D 0.78 0.59 0.40 1.06 1.32 0.74 0.48 1.58 20.77

Speed (km/h)

PEND X 2.5: Agricultural Tractor WBV Emission Data:-

Task Tractor

X Y Z RSS X Y Z RSS

ltivating A 0.73 0.99 0.57 1.35 0.81 1.20 0.63 1.59Cu 6.71

Cu g B 1.00 .70 1.67 1.4 1.49 0.79 2.22 6.

6Cu g C 0.72 .75 1.38 0.89 1.46 0.61 1.82

D 0.77 48 1.30 1.01 .28 0.69 1.78

lo

lough Transport B 0.37 0.47

ough Transport C

o

Ploughing A 0.53 0.64 0.36 0.90 0.63 0.77 0.36 1.0

Ploughing B

Ploughing C 0.57 0.70 0.41 0.99 0.71 0.89 0.43 1.22

D 0.46 31 0.81 .73 0.36 0.99 5

A 0.39 .40 0.73 0.5 0.56 0.49 0.90 9.0

B 0.35 .37 0.67 0.57 0.53 0.53 0.94

Spraying

railer Transport A

rai

railer Transport C 0.72 0.77 0.53 1.18 1.05 1.09

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )

Average r.m.s. floor acceleration (1.4 multiplier) (m/s 2 )

183

APPENDIX 2.6: Agricultural Tractor WBV Emission Data:- nsport

Tractor Model Key

• Tractor ‘A’ = Unsuspended

SRI ‘In-Field’ - Trailer Tra

X Y Z RSS X Y Z RSS

Field surface A 1.03 0.94 0.56 1.50 1.43 0.96 0.55 1.81 12.13

Field surface B 1.14 0.89 0.59 1.56 2.02 1.28 0.67 2.48 11.79

Field surface C 0.88 0.80 0.58 1.32 1.26 1.23 0.54 1.84 11.20

Field surface D 1.12 0.81 0.53 1.48 2.03 1.01 0.68 2.37 10.91

Farm track A 0.98 1.04 0.64 1.57 1.43 1.17 0.52 1.92 12.69

Farm track B 0.88 0.89 0.47 1.34 1.47 1.18 0.55 1.96 13.07

Farm track C 0.77 0.97 0.60 1.37 1.10 1.44 0.51 1.88 12.53

Farm track D 0.85 0.77 0.46 1.24 1.43 1.02 0.61 1.86 16.11

Country road A 1.02 0.75 0.56 1.38 1.59 0.81 0.57 1.88 28.42

Country road B 0.83 0.64 0.50 1.17 1.41 0.83 0.55 1.73 30.31

Country road C 0.88 0.91 0.58 1.39 1.33 1.19 0.53 1.87 32.22

Country road D 0.78 0.49 0.37 0.99 1.31 0.60 0.38 1.49 36.14

Smooth road A 0.60 0.44 0.30 0.80 0.94 0.50 0.32 1.11 40.39

Smooth road B 0.46 0.35 0.28 0.64 0.74 0.42 0.32 0.91 38.84

Smooth road C 0.40 0.50 0.35 0.73 0.59 0.73 0.36 1.00 40.03

Smooth road D 0.46 0.42 0.33 0.70 0.74 0.56 0.31 0.97 57.13

Overall A 0.89 0.78 0.54 1.30 1.32 0.84 0.49 1.64 19.40

Overall B 0.81 0.69 0.46 1.16 1.35 0.94 0.53 1.73 18.68

Overall C 0.72 0.77 0.53 1.18 1.05 1.09 0.48 1.58 19.71

Overall D 0.78 0.59 0.40 1.06 1.32 0.74 0.48 1.58 20.77

Speed (km/h)Task Tractor

Average r.m.s. floor acceleration (1.4 multiplier) (m/s 2 )

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )

• Tractor ‘B’ = Suspended Cab • Tractor ‘C’ = Suspended Front Axle & Cab • Tractor ‘D’ = Fully Suspended (Front & Rear Axle)

184

APPENDIX 2.7: ‘On-Farm’ Agricultural Tractor Cab Floor W BV

A2.7.1 Suspended Cab & Front Axle Tractor (New Holland TM 165)

Emission Data

X Y Z Major axis

TM 165 Ploughing (1) 4.25 0.28 0.44 0.34 Y 0.62

Ploughing (2) 3.25 0.43 0.67 0.52 Y 0.95

Ploughing (3) 4.25 0.38 0.47 0.31 Y 0.68

Cultivating (1) 4.75 0.31 0.39 0.34 Y 0.61

Cultivating (2) 5.25 0.28 0.37 0.28 Y 0.54

Dressing (1) 4.25 0.33 0.45 0.33 Y 0.65

Dressing (2) 4.50 0.35 0.29 0.31 X 0.54

Dressing (3) 4.50 0.30 0.46 0.38 Y 0.67

Trailer Work (1) 3.75 0.37 0.32 0.46 Z 0.67

Trailer Work (2) 4.75 0.37 0.37 0.38 X / Y / Z 0.65

Trailer Work (3) 4.00 0.30 0.30 0.26 X / Y 0.50

RSS (m/s 2 )

Tractor Task Duration (hr)

Average r.m.s. acceleration (m/s 2 )

A2.7.2 Fully Suspended (Front & Rear Axle) Tractor (JCB Fastrac 3185)

X YJCB Ploughing (1) 4.00 0.44 0.57

Z Major axis

0.27 Y 0.77

Ploughing (2) 5.75 0.29 0.39 0.30 Y 0.57

Ploughing (3) 4.50 0.48 0.65 0.34 Y 0.87

Cultivating (1) 3.75 0.38 0.61 0.37 Y 0.80

Cultivating (2) 4.50 0.69 0.88 0.64 Y 1.28

Cultivating (3) 4.00 0.67 0.92 0.50 Y 1.24

Dressing (1) 4.75 0.35 0.45 0.31 Y 0.64

Dressing (2) 6.00 0.23 0.29 0.21 Y 0.43

Trailer Work (1) 5.50 0.50 0.44 0.33 X 0.74

Trailer Work (2) 5.00 0.70 0.59 0.39 X 0.99

Trailer Work (3) 4.50 0.39 0.38 0.24 X 0.59

RSS (m/s 2 )

Average r.m.s. acceleration (m/s 2 )Duration Tractor Task (hr)

185

APPENDIX 2.8: Agricultural Tractor ‘On-Farm’ WBV Exposure Data:- Synopsis of Results

Appendix 2.8.1 Suspended Cab & Front Axle Tractor (New Holland TM 165)

Jan

Larson Davis HVM100 SN:00272 Day M

ocation: Floor 11onth Year

L 2Machine: TM165Reg No: AO51CWC Start time: 11:17Task: PloughingPlace: Sparrow, Farmers, Soham

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:15 6.2 7.3 6.6 11.6 0.28 0.44 0.34 0.62

Maximum peak value (m/s 2 )X Y Z Sum

4.21 4.48 6.65 6.77

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 11 Jan 2Machine: TM165Reg No: AO51CWC Start time: 11:17Task: PloughingPlace: Sparrow, Farmers, Soham

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:15 7.0 10.0 5.7 13.3 0.35 0.62 0.32 0.78

8-hr est tot 8.2 11.7 6.6 15.6

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 2.96 5.16 X Y Z Sum

ime to ELV (hr): >24 >24 4.23 4.97 10.40 10.40

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

T

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

186

Larson Davis HVM100 SN:00272Floor

Day Month YearLocation: 15 Jan 2Machine: TM165Reg No: AO :4751HMY Start time: 13Task: PloughingPlace: Edwards, Farmers/Contractors, Mattis ll

Total VDV (m/s 1.7

ha

5 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:15 6.6 9.6 7.9 14.1 0.43 0.67 0.52 0.95

Maximum peak value (m/s 2 )X Y Z Sum

4.10 4.20 6.08 6.57

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 15 Jan 2Machine: TM165Reg No: AO51HMY Start time: 13:47Task: PloughingPlace: Edwards, Farmers/Contractors, Mattishall

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:15 8.6 12.3 6.7 16.4 0.58 0.86 0.47 1.13

8-hr est tot 10.8 15.3 8.4 20.5

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.99 2.72 X Y Z SumTime to ELV (hr): >24 14.39 5.08 5.56 5.06 6.35

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

187

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 22 Jan 2Machine: TM165Reg No: W823TPW Start time:Task: PloughingPlace: Carbrooke Estates, Norfolk

Total VDV (m/s1.75) Average r.m.s. (Aeq) (m/s2)Time X Y Z Sum X Y Z Sum

Maximum peak value (m/s2)X Y Z Sum

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 22 Jan 2Machine: TM165Reg No: W823TPW Start time: 11:24Task: PloughingPlace: Carbrooke Estates, Norfolk

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:15 7.5 8.7 4.2 12.2 0.39 0.49 0.26 0.67

8-hr est tot 8.8 10.2 4.9 14.3

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 5.13 8.29 X Y Z SumTime to ELV (hr): >24 >24 4.79 4.83 7.63 7.69

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

188

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 6 Mar 2Machine: TM165Reg No: X442NJN Start time: 08:06Task: DrillingPlace: Stevenage

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:15 6.5 7.5 5.9 11.5 0.28 0.37 0.28 0.54

Maximum peak value (m/s 2 )X Y Z Sum

4.34 3.53 4.19 4.45

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 6 Mar 2Machine: TM165Reg No: X442NJN Start time: 08:06Task: DrillingPlace: Stevenage

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:15 7.8 12.0 10.5 17.1 0.35 0.53 0.27 0.69

8-hr est tot 8.7 13.3 11.7 19.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 1.74 7.04 X Y Z SumTime to ELV (hr): >24 >24 5.95 8.18 29.10 28.90

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.4

0.8

1.2

1.6

2.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

189

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 27 Mar 2Machine: TM165Reg No: W823TPW Start time: 09:26Task: Cultivating ploughed landPlace: Carbrooke Estates

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:45 7.1 9.0 8.5 14.0 0.31 0.39 0.34 0.61

Maximum peak value (m/s 2 )X Y Z Sum

5.63 6.38 11.20 11.60

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 27 Mar 2Machine: TM165Reg No: W823TPW Start time: 09:26Task: Cultivating ploughed landPlace: Carbrooke Estates

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:45 9.9 14.8 8.0 19.1 0.45 0.67 0.31 0.86

8-hr est tot 11.3 16.9 9.1 21.8

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.68 4.51 X Y Z SumTime to ELV (hr): 19.29 23.84 8.76 9.74 15.30 15.40

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.4

0.8

1.2

1.6

2.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

190

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 5 Mar 2Machine: TM165Reg No: W271DNO Start time: 08:44Task: Fertiliser spreadingPlace: R Melbourne, Contractor, Stevenage

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 6.6 9.4 7.1 13.3 0.33 0.45 0.33 0.65

Maximum peak value (m/s 2 )X Y Z Sum

4.77 5.46 10.70 10.70

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 5 Mar 2Machine: TM165Reg No: W271DNO Start time: 08:45Task: Fertiliser spreadingPlace: R Melbourne, Contractor, Stevenage

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 10.1 13.8 9.8 19.3 0.50 0.66 0.40 0.92

8-hr est tot 11.7 16.0 11.3 22.3

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.84 4.63 X Y Z SumTime to ELV (hr): 23.93 >24 7.95 10.15 13.10 13.30

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

191

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 12 Mar 2Machine: TM#165Reg No: X701XVG Start time: 12:19Task: Fertiliser SpreaderPlace: G W Harold, Stanhoe

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:15 8.6 6.2 5.4 11.8 0.35 0.29 0.31 0.54

Maximum peak value (m/s 2 )X Y Z Sum

6.69 4.63 3.62 8.03

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 12 Mar 2Machine: TM#165Reg No: X701XVG Start time: 12:19Task: Fertiliser SpreaderPlace: G W Harold, Stanhoe

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:15 9.4 10.3 7.1 15.4 0.41 0.49 0.29 0.70

8-hr est tot 11.0 12.1 8.3 18.1

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 2.55 8.39 X Y Z SumTime to ELV (hr): >24 >24 9.62 9.83 14.00 14.00

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

192

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 13 Mar 2Machine: TM165Reg No: W241SNH Start time: 09:10Task: Fertiliser SpreadingPlace: M Cornwall, Market Harborough

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 6.4 10.5 9.1 15.2 0.30 0.46 0.38 0.67

Maximum peak value (m/s 2 )X Y Z Sum

4.28 6.82 8.98 9.37

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 13 Mar 2Machine: TM165Reg No: W241SNH Start time: 09:10Task: Fertiliser SpreadingPlace: M Cornwall, Market Harborough

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 10.1 17.9 15.1 25.0 0.48 0.78 0.42 1.01

8-hr est tot 11.6 20.7 17.4 28.9

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.30 3.27 X Y Z SumTime to ELV (hr): 8.44 17.32 7.83 12.50 23.80 24.30

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

193

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 30 Jan 2Machine: TM165Reg No: X839BAW Start time: 10:20Task: Grain haulagePlace: C Mills, Wellingborough

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:45 7.1 5.9 9.6 13.2 0.37 0.32 0.46 0.67

Maximum peak value (m/s 2 )X Y Z Sum

4.34 3.68 10.30 10.60

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 30 Jan 2Machine: TM165Reg No: X839BAW Start time: 10:20Task: Grain haulagePlace: C Mills, Wellingborough

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:45 9.9 9.8 7.8 15.7 0.55 0.50 0.34 0.82

8-hr est tot 12.0 11.8 9.5 19.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 2.63 6.61 X Y Z SumTime to ELV (hr): >24 >24 6.57 6.85 14.30 14.20

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeg

194

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 19 Feb 2Machine: TM165Reg No: AO51HMY Start time: 07:59Task: Sugar Beet HaulagePlace: Edwards, Farmer/Contractor, Mattishall

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:45 7.6 8.3 8.9 14.2 0.37 0.37 0.38 0.65

Maximum peak value (m/s 2 )X Y Z Sum

5.32 6.24 7.99 7.99

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 19 Feb 2Machine: TM165Reg No: AO51HMY Start time: 08:00Task: Sugar Beet HaulagePlace: Edwards, Farmer/Contractor, Mattishall

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:44 10.5 12.6 7.7 17.9 0.52 0.58 0.37 0.86

8-hr est tot 12.0 14.3 8.8 20.4

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 1.31 6.00 X Y Z SumTime to ELV (hr): >24 >24 6.57 10.92 7.90 11.20

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeq

195

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 13 Dec 1Machine: TM165Reg No: W823TPW Start time: 12:48Task: Trailer Work (Sugar Beet Haulage)Place: Carbrooke Estates, Norfolk

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 6.2 6.4 6.1 10.7 0.30 0.30 0.26 0.50

Maximum peak value (m/s 2 )X Y Z Sum

0.00 0.00 0.00 0.00

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 13 Dec 1Machine: TM165Reg No: W823TPW Start time: 12:48Task: Trailer Work (Sugar Beet Haulage)Place: Carbrooke Estates, Norfolk

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 9.8 8.0 6.1 14.0 0.47 0.38 0.29 0.67

8-hr est tot 11.7 9.5 7.2 16.6

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 2.94 9.10 X Y Z SumTime to ELV (hr): >24 >24 0.00 0.00 0.00 0.00

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeq

196

Appendix 2.8.2 Fully Suspended (Front & Rear Axle) Tractor (JCB Fastrac 3185) Larson Davis HVM100 SN:00272 Day Month Year

Location: Floor 22 Feb 2Machine: JCBReg No: Y585APW Start time: 11:27Task: PloughingPlace: John Orford (Contractor) Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 7.1 9.3 4.5 12.5 0.44 0.57 0.27 0.77

Maximum peak value (m/s 2 )X Y Z Sum

3.54 3.95 2.79 4.24

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 22 Feb 2Machine: JCBReg No: Y585APW Start time: 11:27Task: PloughingPlace: John Orford (Contractor) Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 8.8 16.8 6.3 19.8 0.54 0.93 0.33 1.12

8-hr est tot 10.5 19.9 7.5 23.5

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.35 2.31 X Y Z SumTime to ELV (hr): 9.85 12.24 4.89 9.56 8.05 9.58

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

197

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 19 Dec 1Machine: JCB Fastrac 3185Reg No: Y624WER Start time: 09:58Task: PloughingPlace: Fen Farming Co, Thorney, Cambs

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:45 6.8 8.5 5.9 12.4 0.29 0.39 0.30 0.57

Maximum peak value (m/s 2 )X Y Z Sum

0.00 0.00 0.00 0.00

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 19 Dec 1Machine: JCB Fastrac 3185Reg No: Y624WER Start time: 09:57Task: PloughingPlace: Fen Farming Co, Thorney, Cambs

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:45 7.7 20.2 9.1 22.9 0.34 0.81 0.30 0.93

8-hr est tot 8.3 21.9 9.8 24.9

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.24 3.06 X Y Z SumTime to ELV (hr): 6.74 16.18 0.00 0.00 0.00 0.00

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

198

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 13 Feb 2Machine: JCB Fastrac 3185Reg No: T933NEG Start time: 09:59Task: PloughingPlace: Russell, Contractor, Downham Market

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 9.5 11.9 6.1 16.3 0.48 0.65 0.34 0.87

Maximum peak value (m/s 2 )X Y Z Sum

6.27 5.74 6.49 7.78

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 13 Feb 2Machine: JCB Fastrac 3185Reg No: T933NEG Start time: 09:59Task: PloughingPlace: Russell, Contractor, Downham Market

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 11.7 14.2 10.0 20.4 0.59 0.76 0.39 1.03

8-hr est tot 13.5 16.4 11.6 23.6

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.76 3.47 X Y Z SumTime to ELV (hr): 21.52 18.37 7.34 6.94 17.70 17.80

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

199

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 26 Mar 2Machine: JCB Fastrac 3185Reg No: W193BAV Start time: 09:18Task: CultivatingPlace: Russell Contractors, Downham Market

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:45 7.2 11.2 6.7 14.8 0.38 0.61 0.37 0.80

Maximum peak value (m/s 2 )X Y Z Sum

4.27 6.01 3.87 6.98

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 26 Mar 2Machine: JCB Fastrac 3185Reg No: W193BAV Start time: 09:19Task: CultivatingPlace: Russell Contractors, Downham Market

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum03:45 10.6 18.0 9.5 22.4 0.54 0.85 0.46 1.11

8-hr est tot 12.8 21.7 11.5 27.1

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.25 2.79 X Y Z SumTime to ELV (hr): 7.01 14.75 7.34 11.21 13.70 13.60

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

200

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 3 Apr 2Machine: JCB Fastrac 3185Reg No: Y585APW Start time: 08:12Task: Dutch HarrowPlace: John Orford, Contractor, Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 11.9 15.2 11.1 22.2 0.69 0.88 0.64 1.28

Maximum peak value (m/s 2 )X Y Z Sum

7.97 9.93 11.00 12.20

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 3 Apr 2Machine: JCB Fastrac 3185Reg No: Y585APW Start time: 08:12Task: Dutch HarrowPlace: John Orford, Contractor, Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 19.2 25.5 13.4 34.1 0.86 1.36 0.65 1.73

8-hr est tot 22.1 29.4 15.5 39.3

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.07 1.09 X Y Z SumTime to ELV (hr): 2.08 5.76 15.4 16.80 15.80 21.80

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

201

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 5 Apr 2Machine: JCB Fastrac 3155Reg No: W378YGS Start time: 07:02Task: Drag HarrowPlace: Hayhill Farming, Haynes

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 10.6 14.2 7.6 19.3 0.67 0.92 0.50 1.24

Maximum peak value (m/s 2 )X Y Z Sum

4.82 5.94 6.18 6.50

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 5 Apr 2Machine: JCB Fastrac 3155Reg No: W378YGS Start time: 07:03Task: Drag HarrowPlace: Hayhill Farming, Haynes

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:00 14.2 22.0 12.1 28.5 0.89 1.39 0.63 1.76

8-hr est tot 16.9 26.2 14.4 33.9

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.12 1.04 X Y Z SumTime to ELV (hr): 3.32 5.51 6.87 10.21 26.90 27.00

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

202

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 4 Apr 2Machine: JCB Fastrac 3155Reg No: W378YGS Start time: 06:28Task: Spreading fertiliserPlace: Hayhill Farming, Haynes

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:45 7.3 9.6 6.7 13.7 0.35 0.45 0.31 0.64

Maximum peak value (m/s 2 )X Y Z Sum

5.25 5.68 10.40 10.80

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 4 Apr 2Machine: JCB Fastrac 3155Reg No: W378YGS Start time: 06:28Task: Spreading fertiliserPlace: Hayhill Farming, Haynes

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:45 10.3 12.8 12.7 20.4 0.48 0.58 0.41 0.86

8-hr est tot 11.7 14.6 14.4 23.3

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 1.20 5.86 X Y Z SumTime to ELV (hr): >24 >24 7.91 7.97 27.50 27.40

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.3

0.5

0.8

1.0

1.3

1.5

1.8

2.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

203

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 8 Apr 2Machine: JCB Fastrac 3155Reg No: W133TRP Start time: 09:31Task: Spreading fertiliserPlace: Barnes contractor, Marston

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum06:00 5.7 6.1 4.4 9.3 0.23 0.29 0.21 0.43

Maximum peak value (m/s 2 )X Y Z Sum

3.88 3.42 3.69 3.97

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 8 Apr 2Machine: JCB Fastrac 3155Reg No: W133TRP Start time: 09:16Task: Spreading fertiliserPlace: Barnes contractor, Marston

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum06:00 6.4 7.8 7.9 12.4 0.27 0.36 0.26 0.52

8-hr est tot 6.9 8.4 8.5 13.4

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 10.72 15.32 X Y Z SumTime to ELV (hr): >24 >24 3.96 7.66 17.90 17.80

One minute time history of weighted r.m.s. seat accelerations (Y-axis) and running averageof r.m.s. acceleration (Aeq) (Y-axis)

0.0

0.3

0.5

0.8

1.0

1.3

1.5

1.8

2.0

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (Y-axis) seat Aeq

204

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 17 Jan 2Machine: JCB FastracReg No: W193BAV Start time: 11:47Task: Trailer Work (Sugar Beet Haulage)Place: David Russell Contractor (Downham Market)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:30 11.5 9.3 8.8 17.1 0.50 0.44 0.33 0.74

Maximum peak value (m/s 2 )X Y Z Sum

7.25 4.27 8.55 9.40

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 17 Jan 2Machine: JCB FastracReg No: W193BAV Start time: 11:47Task: Trailer Work (Sugar Beet Haulage)Place: David Russell Contractor (Downham Market)

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:30 16.3 16.6 9.6 24.4 0.71 0.65 0.38 1.03

8-hr est tot 17.9 18.2 10.6 26.8

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.50 3.93 X Y Z SumTime to ELV (hr): 14.06 20.79 11.09 9.84 18.10 18.10

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:0

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeq

205

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 8 Jan 2Machine: JCB FastracReg No: V535SVV Start time: 11:58Task: Trailer Work (Sugar Beet Haulage)Place: David Russell Contractor, Swaffham

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:00 16.0 13.6 9.3 22.9 0.70 0.59 0.39 0.99

Maximum peak value (m/s 2 )X Y Z Sum

0.00 0.00 0.00 0.00

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 8 Jan 2Machine: JCB FastracReg No: V535SVV Start time: 11:43Task: Trailer Work (Sugar Beet Haulage)Place: David Russell Contractor, Swaffham

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum05:00 25.7 20.2 12.0 34.7 1.12 0.85 0.48 1.48

8-hr est tot 28.9 22.8 13.4 39.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.08 1.60 X Y Z SumTime to ELV (hr): 2.22 8.49 0.00 0.00 0.00 0.00

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeq

206

Larson Davis HVM100 SN:00272 Day Month YearLocation: Floor 21 Feb 2Machine: JCB Fastrac 3185Reg No: Y585APW Start time: 11:10Task: Beet haulagePlace: John Orford, Contractor, Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 9.6 10.4 6.1 15.1 0.39 0.38 0.24 0.59

Maximum peak value (m/s 2 )X Y Z Sum

6.69 6.12 8.69 9.53

Larson Davis HVM100 SN:00215 Day Month YearLocation: Seat 21 Feb 2Machine: JCB Fastrac 3185Reg No: Y585APW Start time: 11:10Task: Beet haulagePlace: John Orford, Contractor, Diss

Total VDV (m/s 1.75 ) Average r.m.s. (Aeq) (m/s 2 )Time X Y Z Sum X Y Z Sum04:30 13.2 21.9 10.6 26.4 0.54 0.64 0.33 0.90

8-hr est tot 15.3 25.3 12.2 30.5

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.13 4.94 X Y Z SumTime to ELV (hr): 3.81 >24 11.21 17.36 18.70 18.70

One minute time history of weighted r.m.s. seat accelerations (X-axis) and running averageof r.m.s. acceleration (Aeq) (X-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Transverse (X-axis) seat Aeq

207

208

209

PPENDIX 3.1: ATV WBV & HAV Emission Data:- ISO Test Track Programme

A3.1.1 Machine A

Average r.m.s. hand-arm vibration (m/s2)

A

ActualSpeed (km/h) X Y Z RSS

9.3 0.82 0.96 1.06 1.6511.4 0.96 0.98 1.21 1.8213.0 0.97 1.02 1.33 1.9414.6 1.03 1.07 1.44 2.0716.7 1.07 1.14 1.51 2.1818.5 1.14 1.13 1.57 2.25

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )

ActualSpeed (km/h) X Y Z RSS

9.3 0.51 0.75 2.36 2.5311.4 0.59 0.79 2.87 3.0313.0 0.58 0.86 3.08 3.2514.6 0.53 0.86 3.30 3.4516.7 0.48 0.87 3.46 3.6018.5 0.48 0.81 3.48 3.61

Average r.m.s. footrest acceleration (1.4 multiplier) (m/s 2 )

Left Right Surface Speed (km/h) X Y Z RSS X Y Z RSS

8.7 2.81 2.09 3.71 5.10 2.82 2.05 3.38 4.86 12.4 3.81 3.08 5.47 7.34 3.87 3.15 4.89 6.99 13.9 4.19 2.97 6.04 7.93 4.40 2.69 4.92 7.13 15.3 4.65 2.86 6.29 8.33 4.95 2.74 5.25 7.72 16.4 4.77 2.95 6.72 8.75 4.74 2.78 5.33 7.66

ISO 100m Track

19.0 5.06 3.66 7.12 9.47 5.51 3.31 6.13 8.88 4.3 1.04 0.70 1.17 1.71 1.00 1.34 1.33 2.14 8.1 1.37 1.31 3.02 3.57 1.26 1.49 1.95 2.76

11.4 0.95 1.20 1.74 2.32 0.71 1.74 1.20 2.23 14.3 0.81 0.88 1.60 2.00 0.65 1.25 1.36 1.96 16.4 0.87 1.11 1.84 2.32 0.77 1.51 1.46 2.24

Smooth Concrete

Average 2.38 2.26 Overall

Field - 1.87 2.13 2.88 4.04 1.89 1.93 2.98 4.02

209

A3.1.2 Machine B

1.99 2.07 3.11 4.522.3 2.61 0 5.1 2.57 2.46 3.42 4.93

16 2. 3. 4. 5 2.8 2.8 3. 5.621 3 3 5 6 3. 3. 42 3 3 5 7 3. 3. 5

0 0 0 1 0. 0. 10 1 1 2 1. 1. 1 2.150 1 2 2 1. 1.25 10.74 1.07 2 2 1. 1. 11 2 3 4 2. 2. 11 1 6 6 2. 3. 2

31 1 2 3 1. 2. 21 1.70 2.43 3 1. 2. 2 3.50

3Avera : Avera

Ave Ave

Smooth Concrete

-

Field Circuit

Average r.m.s. hand-arm vibration (m/s 2 )Surface Speed

(km/h)

ITrack

Left Right HandX Y Z RSS X Y Z RSS

8.4 1.29 1.53 2.24 3.00 1.39 1.46 1.97 2.8211.613.3

3.37 4.43 2.35 2.2905

3.8 5.98.0

8.05

.012

.505 3

.203 9 5 8

.779

.95 55 02 6.670.6 .11 .90 .60 .50 67 39 .11 7.15

.54 .76 .77 .21 42 73 .06 1.35

.73 .11 .66 .13 09 24 .37

.72 .08 .48 .80 26 .49 2.32.11 .48 00 09 .08 1.83

.09 .51 .10 .13 38 55 .15 3.67

.97 .76 .17 .71 31 16 .37 4.58.24 2.65

.21 .65 .42 .17 65 18 .35 3.61

.23 .21 58 03 .37.19 3.55ge ge:

rage: rage:Overall

-

SO 100m

Y Z RSS9.4 0.66 1.05 1.38 1.86

11.4 0.73 1.16 1.51 2.0413.3 0.76 1.26 1.74 2.2714.9 0.81 1.36 1.86 2.4417.7 0.84 1.42 1.89 2.5219.5 0.88 1.50 1.84 2.53

verage r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )ActualSpeed (km/h) X

A

ActualSpeed (km/h) X Y Z RSS

9.4 0.56 0.59 1.86 2.0311.4 0.58 0.64 2.13 2.3013.3 0.52 0.64 2.32 2.4614.9 0.53 0.66 2.55 2.6817.7 0.57 0.70 2.87 3.0119.5 0.72 0.77 2.98 3.16

Average r.m.s. footrest acceleration (1.4 multiplier) (m/s 2 )

210

A3.1.3 Machine C

urface

ISO 100m Track

Smooth Concrete

Overall Field

Circuit

-

-Average: Average:

Average: Average:

Speed (km/h) Left Right

Average r.m.s. hand-arm vibration (m/s 2 )

X Y Z RSS X Y Z RSS9.6 1.87 2.21 3.68 4.68 2.28 2.31 3.88 5.06

11.8 2.84 1.97 4.92 6.01 3.28 2.84 4.77 6.4513.8 3.36 2.29 5.72 7.02 3.86 3.19 5.56 7.4816.4 3.46 2.64 5.81 7.26 4.09 3.38 5.72 7.8020.0 3.71 3.00 5.91 7.60 4.35 3.42 6.14 8.2720.9 3.63 3.58 5.77 7.70 4.44 3.90 6.43 8.73

1.71 0.97 5.62 5.95 1.38 2.41 2.62 3.821.16 0.87 2.53 2.92 1.13 1.06 2.43 2.880.91 0.53 1.62 1.93 0.61 1.14 1.50 1.980.70 0.65 2.54 2.71 0.45 1.30 1.14 1.790.73 0.88 3.21 3.41 0.58 1.28 1.86 2.330.47 0.64 2.10 2.25 0.58 0.83 1.09 1.49

3.19 2.381.50 1.74 2.99 3.77 1.55 1.93 3.14 4.001.51 1.56 2.99 3.70 1.59 2.02 2.89 3.87

3.73 3.93

S

ActualSpeed (km/h) X Y Z RSS

9.3 0.77 1.54 2.29 2.8611.7 0.81 1.64 2.94 3.4613.6 0.83 1.65 3.16 3.6615.7 0.91 1.56 3.32 3.7818.0 0.92 1.62 3.15 3.6618.6 0.96 1.65 3.11 3.65

Average r.m.s. seat a tion (1.4 multiplier) (m/s 2 )ccelera

ActualSpeed (km/h) X Y Z RSS

9.3 0.74 0.73 3.40 3.5611.7 0.79 0.81 3.03 3.2413.6 0.83 0.83 2.71 2.9515.7 0.72 0.80 3.59 3.7518.0 0.69 0.86 3.43 3.6018.6 0.76 0.88 3.35 3.54

Average r.m.s. footrest cceleration (1.4 multiplier) (m/s 2 ) a

211

A3.1.4 Machine D

ActualSpeed (km/h) X Y Z RSS

9.9 0.78 1.08 1.08 1.7111.9 0.83 1.16 1.24 1.8913.5 0.84 1.24 1.26 1.9615.5 0.87 1.34 1.28 2.0518.0 0.89 1.51 1.37 2.2320.0 0.83 1.67 1.41 2.34

Average r.m.s. seat acceleration (1.4 multiplier) (m/s 2 )

ActualSpeed (km/h) X Y Z RSS

9.9 0.57 0.53 1.83 1.9911.9 0.58 0.57 2.17 2.3213.5 0.58 0.59 2.48 2.6215.5 0.58 0.56 2.47 2.6018.0 0.60 0.63 2.77 2.9020.0 0.66 0.70 3.09 3.24

Average r.m.s. footrest acceleration (1.4 multiplier) (m/s 2 )

X Y Z RSS X Y Z RSS10.3 2.38 2.39 3.56 4.90 2.84 3.27 3.88 5.8112.0 2.52 2.94 3.84 5.45 3.03 3.93 3.98 6.3613.3 2.89 2.92 4.02 5.75 3.30 3.80 3.94 6.3917.1 3.18 2.96 4.38 6.17 3.45 3.67 4.12 6.5118.5 3.54 3.54 4.97 7.05 3.87 4.34 4.62 7.4321.2 3.82 3.55 5.18 7.35 4.44 4.57 5.05 8.13

0.87 0.97 1.63 2.09 1.13 1.30 1.57 2.331.78 1.60 2.62 3.55 1.72 1.57 2.47 3.392.02 1.79 2.33 3.57 2.09 1.12 2.73 3.621.65 2.32 1.63 3.28 1.57 1.39 2.18 3.021.83 1.69 2.03 3.21 1.55 1.32 1.52 2.543.34 1.79 2.49 4.53 3.25 2.30 2.52 4.71

3.37 3.27Overall

Field Circuit

- 1.82 1.89 2.55 3.66 2.01 2.62 2.46 4.12

Average:

Average r.m.s. hand-arm vibration (m/s 2 )

-Smooth Concrete

ISO 100m Track

Average:

Left RightSurface Speed (km/h)

212

APPENDIX 3.2: ATV WBV & HAV Emission Data:- SRI ‘In-Field’ Programme

A3.2.1 Machine A

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2) Surface

X Y Z RSS Road 0.30 0.31 0.52 0.67 Track 0.87 0.98 1.21 1.78 Field 0.95 0.87 1.97 2.36

Overall 0.88 0.83 1.60 2.01

Average r.m.s. footrest acceleration (1.4 multiplier) (m/s2) Surface

X Y Z RSS Road 0.27 0.35 1.88 1.93 Track 0.39 0.59 2.38 2.48 Field 0.45 0.51 2.56 2.65

Overall 0.44 0.53 2.37 2.46 NB:- For ‘in-field’ hand-arm vibration data see Appendix A3.1.1. A3.2.2 Machine B

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2) Surface

X Y Z RSS Road 0.26 0.26 0.34 0.50 Track 0.88 0.78 1.13 1.63 Field 0.93 0.84 1.80 2.20

Overall 0.86 0.75 1.46 1.85

Average r.m.s. footrest acceleration (1.4 multiplier) (m/s2) Surface

X Y Z RSS Road 0.47 0.34 1.62 1.73 Track 0.44 0.52 1.73 1.86 Field 0.47 0.42 1.93 2.03

Overall 0.47 0.43 1.77 1.88 NB:- For ‘in-field’ hand-arm vibration data see Appendix A3.1.2.

213

A3.2.3 Machine C

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

Surface X Y Z RSS

Road 0.21 0.29 0.27 0.45 Track 0.77 0. 1.71 80 1.30 Field 0.87 2.60 0.95 2.26

Overall 0 0 1 .81 .83 .80 2.14

erage r.m.s. footrest acceleration ultiplier) (m/sAv (1.4 m 2) Surface

X Y Z RSS Road 0.72 0.23 1.50 1.68 Track 0.54 0. 40 52 2.28 2.Field 0.6 .74 6 0.44 2.63 2

Overall 0 0 2 .64 .43 .38 2.50 NB:- For ‘in-field’ hand-a bration data s pendix A3.1

3.2.4 Machine D

Average r.m.s. seat acceleration (1.4 multiplier) (m/s2)

rm vi ee Ap .3.

A

Surface X Y Z RSS

Road 0.19 0.27 0.37 0.50 Track 0.64 1. 1.53 04 0.93 Field 0.79 1.84 0.87 1.41

Overall 0 0 1 .73 .84 .19 1.63

erage r.m.s. footrest acceleration ultiplier) (m/sAv (1.4 m 2) Surface

X Y Z RSS Road 0.50 0.46 1.80 1.93 Track 0.5 .15 4 0.59 2.00 2Field 0.4 .15 7 0.46 2.05 2

Overall 0 0 1 .50 .48 .90 2.02 NB:- For ‘in-field’ hand-a bration data s pendix A3.1

rm vi ee Ap .4.

214

APPENDIX 3.3: ATV ‘On-Farm’ WBV & HAV Exposure Data:- Synopsis of Results

Year

Location: SeatMachine: VReg No: Start time:Task: ck tourPlace: m #1 (1)

V

Larson Davis HVM100 SN:00215 Day Month24 Sep 2

AT07:55

StoHill Far

Total VD Average rms (LeX Y Z Sum X Y Z

12.6 16. 17.0 26.5 1. 1.39 1.39

q)Time Sum00:45

8-hr est to1 06 2.20

t 22.8 29. 30.7 48.0

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s

1

2 )Time to EAV (hr): 0.06 Sum

LV (hr): 1.75 22.101.03 X Y Z5.46 8.53 12.84 22.10Time to E

0.0

0.5

1.0

ed r.

m.

1.5

2.0

2.5

3.0

0:00 0:15 0:30 0:45 1:00

Elapsed Time (hrs)

Wei

ght

s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) seat Aeq

Larson Davis HVM100 SN:00272 Day Month Year

Location: Footrest 24 Sep 2MaReg No:

chine: ATStart time 55

Task: Stock toure: arm #1 (1)

T

V: 07:

Plac Hill F

otal VDV Average rms (LX Y Z Sum Y Z

9.3 8.9 38.7 40.8 0 0.76 3.62

Maximum peakX Y Z Sum

7.84 5.56 26.80 26.80

eq)Time00:45

X.71

Sum3.69

value

0.0

1.0eigh

ted 2.0

3.0

4.0

5.0

6.0

7.0

0:00 0:15 0:30 0:45 1:00

Elapsed Time (hrs)

W r.

Acc

eler

atio

n (m

/s2 )

m.s

.

Vertical (Z-axis) footrest

One-minute time history of weighted r.m.s. seat & footrest accelerations (Z-axis) and running

average of seat r.m.s. acceleration (Aeq) (Z-axis)

215

YearLarson Davis HVM100 SN:00215 Day Month25 SepLocation: Seat 2

Machine: ATVReg No: Start time: 07:45Task: Stock tourPlace: Hill Farm #1 (2)

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z Sum01:15 12.4 17.5 18.4 28.1 0.90 1.29 1.21 1.98

8-hr est tot 19.8 27.8 29.2 44.7

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.08 1.21 X Y Z SumTime to ELV (hr): 2.14 6.40 9.83 14.42 31.70 32.00

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:15 0:30 0:45 1:00 1:15

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical -axis) seat Aeq (Y

Larson Davis HVM100 SN:00272 Day Month YearLocation: Footrest 25 Sep 2Machine: ATVReg No: Start time: 07:45Task: Stock tourPlace: Hill Farm #1 (2)

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z Sum01:15 9.6 9.8 37.8 40.2 0.64 0.74 3.05 3.19

Maximum peak valueX Y Z Sum

7.06 5.84 27.60 27.80

One minute time history of weighted r.m.s. seat and footrest accelerations (Z-axis) and running average of r.m.s. acceleration (Aeq) (Z-axis)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0:00 0:15 0:30 0:45 1:00 1:15

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) footrest

216

Larson Davis HVM100 SN:00215 Day Month Year

Location: Seat/Saddle 12 Dec 2Machine: ATVReg No: Start time: 09:59Task: ShepherdingPlace: Hill Farm #2

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z00:45 10.0 8.1 10.9 16.8 0.72 0.65 0.87 1.31

8-hr est tot 18.0 14.6 19.7 30.4

Estimated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )Time to EAV (hr): 0.36 2.62 X Y ZTime to ELV (hr): 10.27 13.84 8.62 6.43 11.40 12.90

Sum

Sum

0.0

0.4

0.8

1.2

1.6

2.0

0:00 0:15 0:30 0:45 1:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) seat Aeq

Larson Davis HVM100 SN:00272 Day Month YearLocation: Footrest 12 Dec 2Machine: ATVReg No: Start time: 09:58Task: ShepherdingPlace: Hill Farm #2

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z Sum00:45 7.7 5.2 23.5 25.2 0.47 0.43 2.07 2.16

Maximum peak valueX Y Z Sum

10.77 3.63 18.50 18.50

One minute time history of weighted r.m.s. seat and footrest accelerations (Z-axis) and running average of r.m.s. acceleration (Aeq) (Z-axis)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0:00 0:15 0:30 0:45 1:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) footrest

217

218

Lars

Larson Davis HVM100 SN:00272 Day Month YearLocation: Footrest 10 Dec 2Machine: ATVReg No: Start time: 07:05Task: Feeding GamePlace: Gamekeeper

Total VDV Average rms (Leq)Time X Y Z Sum X Y Z Sum02:15 10.1 9.0 45.6 47.5 0.57 0.53 3.30 3.38

Maximum peak valueX Y Z Sum

8.23 7.70 25.10 25.00

One minute time history of weighted r.m.s. seat and footrest accelerations (Z-axis) and running average of r.m.s. acceleration (Aeq) (Z-axis)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0:00 0:30 1:00 1:30 2:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) footrest

on Davis HVM100 SN:00215 Day Month YearLocation: Seat/Saddle 10 Dec 2Machine: ATVReg No: Start time: 07:06Task: Feeding GamePlace: Gamekeeper

tal VDVTo Average rms (Leq)Time X Y Z Sum X Y Z Sum02:15 11.3 11.9 15.6 22.2 0.55 0.76 0.85 1.25hr est tot 15.5 16.4 21.4 30.4

ated values VDV r.m.s./A(8) Maximum peak value (m/s 2 )me to EAV (hr): 0.26 2.77 X Y Z Summe to ELV (hr): 7.47 14.63 8.19 9.48 18.20 18.40

8-

EstimTiTi

0.0

0.4

0.8

1.2

1.6

2.0

0:00 0:30 1:00 1:30 2:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

Vertical (Z-axis) seat Aeq

APPENDIX 3.4: ATV ‘On-Farm’ WBV Programme:- Forward Speed & Operator Seat Presence Details A3.4.1 Hill Farm #1 Whole-body vibration, first day

Hill Farm #1 was a 230 hectacre upland holding operated by the farmer with one stockman. It was the stockman who drove the ATV on his morning round. On the first morning this took very nearly an hour, and the machine was out of sight for all but the first half minute and the last few seconds. The machine did not carry any load. The stockman was estimated to weigh approx. 70 kg.

ATV Record of driver presence, Hill Farm#1 WBV(1)

0.0

0.2

0.4

0.6

0.8

1.0

0 10 20 30 40 50 60

Elapsed time, minutes

Seat

sw

itch,

vol

ts

ATV Record of speed, Hill Farm#1 WBV(1)

0

10

20

30

40

50

60

0 10 20 30 40 50 6

Elapsed time, minutes

Spee

d km

/h

0

219

Whole-body vibration, second day

ATV Record of speed, Hill Farm#1 WBV(2)

0

10

20

30

40

50

0 10 20 30 40 50 60 70

Elapsed time, minutes

Spee

d km

/h

60

nutes longer.

and-arm vibration

½ - 1 hour.

ATV Record of driver presence, Hill Farm#1 WBV(2)

0.0

0.2

0.4

0.6

0.8

1.0

0 10 20 30 40 50 60 70

Elapsed time, minutes

Seat

sw

itch,

vol

ts

The second morning was a close repeat of the previous day, taking about 10 miThis was probably accounted for by a stop at 16-22 minutes for reasons not explained.

H No recording is available. The driver was away from the farmstead for only 35 minutes. I am not sure whether this was because it came on to rain, or because there were other pressing jobs (lambs to be loaded for market). It would seem reasonable to assume that daily use of the ATV varies between

220

A3.4.2 Hill Farm #2 Whole-body vibration

ill Farm #2 was a smaller farm run by a young farmer and his mother. It was the mother (estimated weight approx. 70 kg) who rode the ATV. The overall operating time of about

y typical of daily use, there being no very distant grazing areas. The me was split into two sections. That between 5 - 25 minutes (see above) was spent fetching a

ATV Record of speed, Hill Farm#2 WBV

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35 40 45

Elapsed time minutes

Spee

d km

/h

ATV Record of driver presence, Hill Farm#2 WBV

0.0

0.2

0.4

0.6

0.8

1.0

Seat

sw

itch,

vol

ts

0 5 10 15 20 25 30 35 40 45

Elapsed time minutes

H

35 minutes was probabltigroup of lambs into the yard, to be prepared for auction, with the aid of several dogs. After that, she went out alone, and at higher speed to check on the rest of the stock.

221

A3.4.3 Gamekeeper

This “farm” was bought about 12 years ago by a wealthy businessman, who lets out some of the grazing and has built-up a series of shooting plantations. The whole covers about 200 hectares on a shoulder of ground above the river Wye. There are tracks between and within the plantations which are in places only passable on foot or on the ATV. The work was split into two types of operation. For the first part (80 min) a feed hopper / dispenser was mounted on the rear rack. The machine was driven out to a plantation, and then driven more slowly for spreading feed, before returning for a refill. There were 5 such runs, but the Keeper admitted to holding some work back from the previous day “to give me a good stretch to measure”. After a 20-minute break, in which the feed hopper was removed, sacks of

Whole-body vibration

ATV Record of speed, Gamekeeper#1 WBV

0

10

20

30

40

50

60

0 15 30 45 60 75 90 105 120 135 150

Elapsed time, minutes

Spee

d km

/h

ATV Record of driver presence, Gamekeeper#1 WBV

0.0

0.2

0.4

0.6

0.8

1.0

0 15 30 45 60 75 90 105 120 135 15

Elapsed time, minutes

Switc

h vo

ltage

0

222

feed were transported out to top up standing hoppers in the plantations. This gave shorter, faster ns, with more time off the machine.

eparate calculations for the two types of operation do not show a very great difference. The

achine, and may ested. It had

As a result of the extra use of the machine on the previous day, there were only 4 runs with the feed dispenser on this visit, totalling about one hour. Note that the TEAC recording stopped after the third run. It is reasonable to assume that an average day’s use of the ATV is between 1 - 1½ hours.

ru

Sestimated weight of the gamekeeper was 90 kg. The ATV was a 2001-manufactured m

have been a more modern design than the other ‘on-farm’ ATVs tpuncture-resistant filling in the tyres, which were set to 5 psi.

Hand-arm vibration

ATV Record of speed, Gamekeeper#1 HAV

30

40

50

60

Spee

d km

/h

0

10

20

0 5 10 15 20 25 30 35 40 45

Elapsed time minutes

223

224

APPENDIX 4: Estimating WBV Exposure from Measured Data:- Particular Issues There are two features of the data reported here from commercial ‘on-farm’ work that are worthy of discussion. These are first the fact that, except in the case of ATVs, the vibration measurements did not cover the whole working day, and second the nature of the data itself. In particular, it is the non-stationary nature of the data, in a statistical sense, which is of concern. The ‘on farm’ vibration exposure data obtained in this study is based on some of the longest recording durations to be found in the literature. Nevertheless, it was restricted to approximately 4 hours for each machine / location, this being the time for half a shift, and allowing instruments to be mounted and removed before or after work or during a normal break. In practice the sampling period varied between 3 ¼ hours and 6 hours. For stationary data (i.e. limited variation of r.m.s. acceleration level and other statistical parameters with time), such as that shown in Figure 5.29 (and reproduced in Figure A4.1 below), estimation of daily exposure does not present any serious difficulties.

0

0.5

1

1.5

2

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0.0

4.0

8.0

12.0

16.0

20.0

VDV

(m/s

1.75

)

Transverse (Y) Aeq VDV

Figure A4.1 Time history of weighted 1-minute r.m.s. accelerations (Y-axis, TM 165

seat – ploughing) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV)

Using the r.m.s. approach, it can be seen that a level of equivalent continuous acceleration (Aeq) (cumulative energy-equivalent, frequency-weighted r.m.s. acceleration) is reached after about 30 minutes, and does not change significantly throughout the remaining period of work. This is explored further in Figure A4.2, where the time-base has been extended to 10 hours, and the Aeq has been extended using the assumption that the vibration magnitude on the vehicle continues as it was for the first 3¼ hours. The added curve shows the build-up of daily exposure, measured as A(8) and, if 8 hours were worked, the value would be the same as the Aeq, in this case 0.86 m/s2. If 10 hours were worked, the A(8) exposure would rise to

225

0.96 m/s2, whereas if the operator had finished ploughing when the recording finished, his ing no other work involving exposure

to WBV had been undertaken. Because of the st nature of the data, very similar

Figure A4.2 Predicted development of equivalent continuous r.m.s. acceleration

(Aeq) and daily vibration exposure level (A(8)) if machine / operation depicted in Figure A4.1 were to continue for 10 hours

Using the VDV approach, an exposure of 12.3 ms-1.75 was measured at the end of 3¼ hours (see Figure A4.1). This could be extended to a longer working day by applying the simple formula:-

VDV2 = VDV1

A(8) exposure would have been only 0.55 m/s2, assumationary

values would have been estimated had the original vibration measurement been stopped after 1 hour, or even after only 30 minutes.

0

0.25

1.5

0.5

0.75

1

1.25

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:0

Elapsed Time (hrs)

1-min r.m.s. (Y) Aeq (Y) A(8)

4

1

1

2

⎥⎦⎤

⎢⎣⎡TT

(1)

where:-

VD T2 = the actual duration of exposure (machine operation) for which an

V1 = the VDV measured (in a given axis) over measurement duration T1

(estimated) VDV is required This is illustrated in Figure A4.3, and is the method by which the “8-hour estimated total” values, as presented in the results tables within this report, were obtained. As can be seen in Figure A4.3, the estimated curve for growth of VDV approximates closely to the measured curve. This means that estimated curves that could be used for projecting VDV growth for longer periods could be based on measurements of only ½ to 1 hour, as shown in Figure A4.4.

226

0

0.5

1

1.5

2

ion

(m/s

2 )

12

14

2.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

0

2

4

6

8

10

16

VDV

(m/s

1.75

)

1-min r.m.s. (Y) Measured VDV Estimated VDV

Figure A4.3 Estimated development of VDV over an extended (theoretical) period

of machine operation (i.e. beyond 3¼ hours actually measured)

0

0.5

1.5

2.5

00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30

Wei

ght

ion

(m

0

4

10

14

16

/s1.

75)

2

/s2 )

12

1

ed r.

m.s

. Acc

eler

at

6

8

VDV

(m

2

0:

Elapsed Time (hrs)

1-mi r.m.s. (Y)n Measured VDV VDV Est 3.25hr VDV Est 1hr VDV Est 30 min

pment of VDV: measured dFigure A4.4 Develo irectly or estimated from alternative

the tank, and several short periods of higher acceleration, two of which, occurring after

durations of recorded (stationary) WBV data

However, in farm work, stationary data is the exception rather than the rule. A typical example is the WBV measurement made upon a self-propelled sprayer (see Figure 4.20), reproduced here as Figure A4.5. In this case, after a short delay, there are breaks for refilling

227

3 hours, have a strong effect on the VDV measurement. In this case, using the r.m.s. approach, the Aeq measured after 30 minutes is only about 50% of the value measured after 4¼ hours. However, the Aeq value after 1 hour operation is about 0.5 m/s2, which may be close enough to the value of 0.6 m/s2 measured at 4¼ hours for practical purposes.

Figure A4.5 Time history of weighted 1-minute r.m.s. accelerations (seat, Y-axis,

Air Spring Suspension Sprayer) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15-minute record of Vibration Dose Value (VDV)

Using this data to evaluate exposure according to the VDV method, leads to rather more anomalies. The estimated (extrapolated) VDV curve, based on the entire dataset captured over 4¼ hours of machine operation (see Figure A4.6), produces a VDV of 15.8 ms-1.75 at 8 hours (see Figure 4.20 & Table 4.5). However, it deviates by a considerable margin from the measured VDV growth curve during the first 3 hours. This leads to the effect that the estimated time to reach the EAV, of just under an hour, coincides with a measured exposure that is considerably below the EAV. It also means that estimates of exposure at 8 hours from the first 30 minutes or 1-hour of field data, at 6.8 ms-1.75 and 12.3 ms-1.75 respectively (see Figure A4.7) are lower than the measured VDV after 4¼ hours (13.7 ms-1.75) and considerably lower than the prediction for 8 hours of nearly 16 ms-1.75 estimated from the entire dataset (4¼ hours). If WBV data acquisition had not continued for the whole 4¼ hours, but had stopped before 3 hours, estimates of the driver’s WBV exposure would have been 25% lower. In this case that would not have nough to take an 8-hour day below the

y

to the overall c be seen that the 30-minute estimate of 8-hour VDV exposure is less than half the more accurate estimate, and does take

030 1:00 1:30 2:00 2:30 3:00 3:30 4:00

0.00

0.5

1

1.5

2

2.5

0:00 0:

Elapsed Time (hrs)

Wei

ghte

d r.

m.s

. Acc

eler

atio

n (m

/s2 )

3.00

6.00

9.00

12.00

15.00

VD

V (m

/s1.

75)

Transverse (Y) Aeq VDV

been eEAV, but in other cases it might well be. Whatever the reason for the high accelerations after3 hours of spra er operation, the longer measurement time must give a closer approximation

ondition from which it is only a sample. It can

the exposure below the EAV.

228

0

0.5

1

1.5

2

2.5 16

Figure A4.6 Estimated development of VDV over an extended (theoretical) period

of machine operation (i.e. beyond 4¼ hours actually measured)

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

0

2

4

6

8

10

12

14

VD

V (m

/s1.

75)

1-min r.m.s. (Y) Measured VDV Estimated VDV

2.5

14

16

0

0.5

1

1.5

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m

0

2

4

6

8

10

12

VD

V (m

/s1.

75)

2

/s2 )

1-min r.m.s. (Y) Measured VDV VDV Est 4.25hr VDV Est 1hr VDV Est 30min

229

recorded (non-stationary) WBV data

Figure A4.7 Development of VDV: measured directly or estimated from alternative

durations of

Another example of a non-stationary WBV dataset, on this occasion for a fully suspended tractor undertaking cultivating work, can be seen in Figure 5.32 and is reproduced below in Figure A4.8. In this case, a particularly rough section occurred early in the recording period. In fact, the Aeq level at 1 hour approaches the Exposure Limit Value, although by the end of 3¾ hours the Aeq has reduced to 0.85 m/s2, well within the ELV, although still well above the EAV.

Figure A4.8 Time-history of weighted 1-minute r.m.s. accelerations (seat, Y-axis,

JCB 3185 – cultivating) plus development of equivalent continuous r.m.s. acceleration (Aeq) & 15 minute record of Vibration Dose Value (VDV)

In this case the VDV exposure at 8 hours (21.7 ms-1.75) just exceeds the ELV, when estimated from the entire acceleration dataset recorded during machine operation (see Figure A4.9), but VDV estimates based upon the first hour of recorded data are significantly higher. Conversely, the estimates of VDV based upon acceleration data recorded during the first 30 minutes are very low, because of the delay between starting the recording and the machine moving off, probably as a result of additional implement preparation. If this first 30 minutes of data is excluded (see Figure A4.10) then both the 30-minute and the 1-hour estimates of VDV growth are very much higher than the estimate based on the entire dataset and, in this case, are seriously above the ELV. It can be concluded that relatively long overall sampling durations are necessary for collection of representative WBV data in conditions similar to those found in agricultural vehicle operations. There are some relatively unusual conditions in which 30 minute samples would be sufficient. However, in cases where there are breaks and changes in travel speed or surface roughness, even a sampling duration of one hour is frequently not long enough for

t can also be co acquisition, the r.m.s. easure of vibration exposure is less susceptible to change than is the VDV method.

0.00:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00

Elapsed Time (hrs)

0.0

0.5

1.0

1.5

2.0

2.5

Wei

ghte

d r.m

.s. A

ccel

erat

ion

(m/s

2 )

4.0

8.0

12.0

16.0

20.0

VDV

(m/s

1.75

)

Transverse (Y) Aeq VDV

precision better than ±25% in the VDV measure of vibration exposure.

ncluded that, given 1-hour of machine operation / dataIm

230

0.0

0.5

1.0

1.5

2.0

2.5

ion

(m/s

2 ) 25

30

Figure A4.9 Development of VDV: measured directly or estimated from alternative

durations of recorded (non-stationary) WBV data

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30

Elapsed Time (hrs)

Wei

ghte

d r.m

.s. A

ccel

erat

0

5

10

15

20

VDV

(m/s

1.75

)

1-min r.m.s. (Y) Measured VDV VDV Est 3.75hr VDV Est 1hr VDV Est 30 min

231

xcluding first 30 minutes of dataset)

Figure A4.10 Development of VDV: measured directly or estimated from alternative

durations of recorded (non-stationary) WBV data (e

0.0

0.5

1.0

0:00 0:30 1:00 1:30 2:00 2:30

Wei

ghte

d r.m

.s. A

ccel

erat

0

5

10

15VD

V (m

/s

1.5

2.5

3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00 7:30 8:00

Elapsed Time (hrs)

ion

(m/s

20

25

35

1.75

)

2.02 )

30

1-min r.m.s. (Y) Measured VDV VDV Est 3.25hr VDV Est 1hr VDV Est 30 min

Printed and published by the Health and Safety ExecutiveC30 1/98

Printed and published by the Health and Safety ExecutiveC1.10 02/05

RR 321

£35.00 9 78071 7 629701

ISBN 0-7176-2970-8

Whole

-bod

y vibra

tion o

n a

gricu

ltura

l vehicle

s: eva

luatio

n o

f em

ission a

nd

estim

ate

d e

xposu

re le

vels

HS

E BO

OK

S