Contitech-ConveyorBeltDesign

7/23/2019 Contitech-ConveyorBeltDesign

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Edition

Conveyor Belt System Design

CONTI Conveyor Belt Service Manual

ContiTech Division of Continental AG


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Conveyor Belt Service Manual

Conveyor BeltSystem DesignEdited by:Dr.-lng. Rainer Alles

Contributors:Obering. W. ErnstProf. Dr.-lng. W.S.W. Lubrich andthe followingContiTech engineersDr.-lng. R. AllesDipl.-lng. G. BottcherDipl.-lng. H. SimonsenDipl.-lng. H. Zintarra

Published by

ContiTech Transportbandsysteme GmbHD-30001 Hannover, Germany

Status 1994

a reversed version will be available

at autum 1995

The ContiTech Group

is a development partner and

original equipment manufac-

turer for numerous branches

of industry with high grade

functional parts, components

and systems It is part of

the Continental Corporation

with over 26 companies in

Europe specialising in rubber

and plastics technology

and utilising their commonknow-how.

That's what the ContiTechbrand is all about.

ContiTechSpecialist in rubber andplastic technology


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Table of Contents

Page Page

1 Basic expressions and definitions ................. 6

2 Stipulation of principal data .......................... 9

2.1 Material handled.......................................... 10

2.2 Flolw of material handled ........................... 12

2.3 Conveying track .......................................... 13

2.4 Type of belt conveyor.................... . ............. 14

2.4.1 Belt width ........................................ ............ 15

2.4.2 Belt speed ................................................... 16

2.4.3 Belt support ................................................. 18

2.5 Conveying capacity ..................................... 20

3 Calculation of belt conveyor ........................ 27

3.1 Masses..................................... ........... ........ 29

3.1.1 Idlers............................................................ 30

3.1.2 Conveyor belt .............................................. 32

3.1.3 Drive elements ............................................ 33

3.2 Coefficients................................ .... ............. 34

3.3 Motional resistance of sections ................... 36

3.4 Required power......................... ...... ............ 41

3.5 Peripheral force................................ .. ......... 44

3.5.1 Starting and stopping .................................. 473.5.2 Multiple pulley drive..................................... 50

3.6 Calculation example ................. .. ................ 53

4 Stipulation of tgension member ...................56

4.1 Belt tensions....................................... ......... 61

4.1.1 Belt tensions in operation ............................ 66

4.1.2 Belt tensions on starting and stopping ........ 68

4.1.3 Belt tensions with regard to sections............70

4.2 Additional strains ......................................... 71

4.2.1 Flat-to-trough transition and vice versa....... 73

4.2.2 Transition curves ......................................... 75

4.2.3 Turnover .......................................................77

4.3 Selection criteria.......................................... 78

4.3.1 Pulley diameter.............................................79

4.3.2 Troughing properties ................................... 81

4.3.3 Centre distance and takeups ...................... 82

4.3.4 Effects of material handled.......................... 83

4.3.5 Feeding strain.............................................. 85

4.4 Tension member data ................................ 87

4.4.1 Textile tension members ............................. 90

4.4.2 Steel cable tension members ...................... 91

4.4.3 Splice dimensions ....................................... 92

5 Selection of covers ..................................... 96

5.1 Cover material ............................................ 98

5.2 Cover gauge ............................................. 100

5.2.1 Abrasion resistance................................... 101

5.2.2 Impact resistance ...................................... 1025.3 Special cover structures ........................... 103

6 Steep angle conveyor belts ...................... 105

6.1 Chevron cleated belt ................................ 107

6.2 Box-section belt ........................................ 108

6.2.1 Conveying capacity ................................... 110

6.2.2 Constructional data ................................... 111

6.3 Fin-type belt and belt withbonded partitions ...................................... 113

7 Elevator-belts ................................ .... ....... 1157.1 Conveying capacity .................................. 116

7.2 Power requirement and belt tensions........ 117

7.3 Selection of bucket elevator belts ............ 119

7.3.1 Tension member ....................................... 120

7.3.2 Covers ....................................................... 122

7.3.3 Buckets and bucket attachments .............. 123

8 Piece goods handlingand belts for sliding bed operation ............ 125

8.1 Conveying capacity .................................. 126

8.2 Calculation of required power ................... 1278.3 Conveyor belt desing................................. 129

9 Appendix ........................................ ..... ..... 130

9.1 Index ........................................ ................. 131

9.2 Symbols ...................................... .............. 134

9.3 Questionnaires ...........................................

9.4 Printed forms for calculation.......................


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An insignificant side-note for all those who are already accustomed tousing Sl units or units derived from them and who take advantage of this"standard" settlement by the international units system.

For all other readers it is pointed out that an "Act on Units in MeasuringProcedure", regulating the use of technical units in business and officialtransactions, was passed on 2nd July 1969 and became mandatory forus when the transitional period expired on 1st January 1978.

The effects of this Act on materials handling technology are minimal asmost of the units already widely used in this sphere have undergone nochange. One essential point is the uniform stipulation of the

kilogram (kg) as a unit for mass

It was furthermore stipulated that the word "weight" may be used only asa mass quantity. The weights listed in a large number of tables andreference books thus retain their numerical value. Other units of weight orof mass are the gram (g) and the ton (t).

We recall: one kilogram was accelerated by the gravitational attraction ofthe earth at approx. 9.81 m/s2 and thus exercised on the base it is resting

upon a weight of one kilogram-force. In the Space Age we now departfrom this unit of force, that applied solely under the gravitationalconditions of the earth, and use exclusively the

Newton (N) as a unit for force

One kilogram is accelerated by one Newton at 1 m/s2 or one kilogramacts under the influence of the acceleration due to gravity on its basewith the force of approx. 9.81 Newton. All forces that were formerlyexpressed in kilogram-force attain a numerical value increased approx-imately by the factor 10 with Newton as a unit.

The breaking strength of a conveyor belt in kilogram-force related to theunit of width in cm retains approximately its familiar numerical value if the

breaking strength in N is related, as practised below, to the width in mm.

1 kilogram-force/cm 1 N/mm

It follows from the introduction of the Newton as a unit for force that theacceleration due to gravity g occurs in all calculation formulae in whichweights are determined or other forces with their origin in weights arecalculated. For this purpose

Acceleration due to gravity g = 9,81 m/s2

can be inserted with sufficient accuracy. A simplification results in thecalculation of power in W (Watt) by the multiplication of force in N andspeed in m/s. A conversion factor is then superfluous.

This short introduction is aimed at drawing your attention to thechangeover resulting from these regulations for the following calcula-tion principles and data.


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D - Conveyor belt calculation D

This section of the ContiTech Conveyor Belt Service Manual comprisesdesign fundamentals and data essential for the designing of a conveyorbelt system. The calculation procedures and data stated take the currentlevel of technology largely into account with regard to the latest researchresults and independent tests, provided that these give sufficiently well-founded information. Advice is given to enable the appropriate conveyor

belt from the Conti-range to be selected for each individual project and tohelp both the designer and the user to attain optimum coordinationbetween the conveyor belt, the design of the beltsystem and the practicalapplication.

The calculation of the belt conveyor for bulk material set out at thebeginning of these calculation principles is based on specificationscontained in DIN standard 22101 (February 1982) and is supplementedby extending design procedures. Essential calculation stages not inclu-ded in the DIN 22101 standard specifications have been described forinstance in publications by Vierling*

The designations of formula quantities have been adapted as far aspossible to general guidelines. Designations already well known from

technical literature in this field have also been used, however, where wefelt them to be beneficial.

Only the "statutory units" (Sl units or units derived therefrom) on whichthe "International Units System" (Sl) is based are used in the formulae,tables and diagrams. To facilitate comprehension, the units used in thefurther course of the calculation are stated after the respective formulae,whereby the units listed in the index of symbols are to be used. A briefdimensional consideration helps in cases of doubt. The units to be usedare stated in the case of formulae with conversion factors or dimension-affected constants.

* Vierling, A Zum Stand der Berechnungsgrundlagen fur Gurtforderer Braunkohle Warme und Energie19 (1967) No 9,P 309-315Vierling, A Zur Theorie der Bandfrderung Continental-Transportband-Dienst 1972, 3rd edition.


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D In general, the following data are known before a belt conveyor isdesigned:

Type of material to be conveyed(e. g. bulk weight, lump size, angle of repose)Flow of material to be conveyed (e. g. mass flow, volume flow)Conveying track (e. g. conveying length, conveying height).

These data are a basis for selection of the type of belt conveyor and thusfor the type of conveyor belt. The decision on whether it is a plainstandard conveyor belt, a steep-angle conveyor belt or a specialconveyor with the corresponding special-purpose belt serves as areference point for the stipulation of the principal data, in particular ofconveying speed and belt width, but may necessitate for instance inaddition the stipulation of the troughing design, the belt surface profile orthe pitch of elevator buckets.

The next factors to be determined are motional resistances and requiredpower of the belt conveyor. If the design is already established, it is thesize, position and type of the driving motors that have to be recordedbesides the data stated hitherto, as these may have a decisive influence

on the selection of the conveyor belt. The calculation of the beltconveyor leads on to the peripheral forces at the driving pulleys. Theirmagnitude depends on the extent of the motional resistances but variesfor temporary operating conditions such as starting and stopping.

The design of the tension memberin the conveyor belt then follows. Itstensile strength is determined mainly by the magnitude of the belttensions. Further influences result from a variety of criteria relating tooperation and design.

As the strength of the tension member must always have a specificsafety margin over the maximum stress, it is essential to stipulate thesafety coefficient or to check the available safety margin on selection ofthe tension member. Special attention must be paid here to the durability

of the conveyor belt at the joints.

The tension member of the conveyor belt is enclosed in the covers, whichthus form an effective protection against external influences. For thisreason the material and construction are selected to counteract theeffects of the material conveyed and of the environment. Conformity tothe tension member must also be observed on selection of the covers.

Conti conveyor belts are supplied to all parts of the world, using thosedispatch facilities best suited to the destination; the packagingguarantees safe transport even in exceptional cases. The optimum partlengths can be determined for each particular instance to provideinexpensive shipment and simple assembly. The thickness, width and

weight of the belt are to be given special consideration.The conveyor belt calculation process described also conforms with thearrangement of the following chapters. The chart shows both the normalsequence of design stages and the feasibility of starting at any section,provided that specific data or parameters are known. In general thesingle chapters go deeper into the respective subject with increasing sub-division, so that a rough assessment of the belt structure can be made byconsulting the general chapter alone. Special reference is made to thosecalculation points at which an assessment is recommended.


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Basic expressions and definitions D - 1 D

Stipulation of principal data D - 2

Material handled ............. 2.1

Flow of material 2.2 Conveying track............. 2.3

Type of belt conveyor ..... 2.4Conveying capacity ........ 2.5

Calculation of belt conveyor D - 3

Masses ........................... 3.1

Coefficients 3.2 Motional resistance ....... 3.3

Required power .............. 3.4

Peripheral forces............. 3.5

Calculation example ....... 3.6

Stipulation of tension member D - 4

Tensile forces of belt ...... 4.1

Additional strains 4.2 Selection criteria ............ 4.3

Tension member data..... 4.4

Selection of covers D - 5

Cover material 5.1 Cover gauge.................. 5.2

Special cover structures...................... 5.3

Steep-angle conveyor belts D - 6

Elevator belts D - 7

Piece goods handling and belts for sliding bed operation D - 8

Appendix D - 9

The staff of the ContiTech Transportbandsysteme GmbH with itssophisticated research and development resources is available for directconsultation and to answer any questions.

Please address enquiries to:

ContiTech Transportbandsysteme GmbHPostfach 169, D-30001 HannoverBttnerstrae 25, D-30165 HannoverTelefon (0511)938-07Telefax (0511)938-2580Telex 92170 con d

The computer programmes filed in the constantly expanding library of theDepartment for Application Technique enable enquiries to be dealt withpromptly Apart from specific individual problems, this facility permitsabove all extensive calculations and design alternatives to be

investigated without loss of time Reference can be made to the currentlycomplied programmes at those points of the conveyor belt calculationmarked with the key word 'CONTI-COM'.


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D - 1 D - 1 Basic expressions and definitions

Continuous conveyors: Continuous conveyors are mechanical, pneu-matic and hydraulic conveying devices with which the material to behandled can be moved continuously on a fixed conveying track ofrestricted length from feeding point to discharge point, possibly atvarying speed or in a fixed cycle. These conveyors are available instationary or mobile versions and are used for the handling of bulk

materials or piece goods.

Belt conveyors: Continuous conveyors whose belts have a tensionmember consisting of synthetic fabrics or steel cables with rubber orsynthetic covers; the belts are supported by straight or trough-shapedidlers or have sliding support on a smooth base as a tension and supportmember. The actual conveying is done on the top run, in special caseson the top run and the return run. Belts with cleated top covers, special-purpose belts or sandwich belts are used for steep-angle conveying.

11 10 1 13 8 6 12 2

17 5 15 7 9 16 4 3 14

1 Feed2 Discharge3 Head pulley (drive pulley)

4 Snub or deflecting pulley5 Tail pulley (takeup pulley)6 Top run (tight side)7 Return run (slack side)8 Rop run idlers9 Return run idlers10 Feed rollers11 Flat-to-trough transition12 Trough-to-flat transition13 Feed chute14 Belt cleaner (transverse scraper)15 Belt cleaner (plough-type scraper)16 Drive unit17 Counterweight

Belt-type elevators: Continuous conveyors with buckets or similarcontainers as carriers; these either scoop the material or are filled bymetering hoppers and emptied at specific discharge points. The tensionunit consists of belts to which the containers are attached. Transport iseffected at any angle from vertical to horizontal.

Flow of material: Mass or volume of the conveyed bulk material or piecegoods per unit of time in continuous conveying. In contrast, the capacityis not time-related.

Conveying capacity: The volume capacity or capacity of material

conveyed that can be attained with the given conveying speed and theavailable cross-section area or the container volume and spacing.


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Conveying speed: Speed of the material conveyed. The conveyor beltas the support member determines the speed of the material on it.

D - 1

Centre distance: The distance between head and tail pulley of theconveyor. The belt length as the inside circumference of the endless,slack belt results from this distance only when the pulley circumferenceand any belt loops (tension loops, discharge loops etc.) present are takeninto account.

Conveying length: The distance between the centre of the materialfeeding point and the axle of the discharge pulley. If the materialconveyed is stripped off, the centre of the material discharge is to betaken instead. In general the conveying length is approximately equal tothe centre distance. The conveying length may, however, besmallerthanthe centre distance or be variable during the conveying process.

Conveying height: The difference in height between material feed andmaterial discharge. Belt conveyors with sections at different gradientsyield the section heights allocated to the section lengths.

Belt support: The belt is generally supported by fixed idlers or bysuspended idlers. The belt can be flat or troughed by multi-roll idlers.Troughing permits a greaterflow of material and promotes improved belttraining. The idler spacing is normally larger on the return run than on thetop run and can also be graduated within one belt conveyor. Special idlerdesigns or arrangements are frequently selected at the feeding pointsand for belt cleaning.

Flat belt V-trough 3-roll troughing(with CONTIWELL-side wall)

Square-troughing belt 5-part troughing

Conveyor belt: The task of the conveyor belt is to carry the materialhandled and simultaneously to transmit the driving forces to overcomethe motional resistances. The conveyor belt consists in general of thetension member and the top and bottom covers, which form a core-protecting covering.

Those conveyor belts used in belt conveyors are to be regarded ascontinuous conveying elements composed of one or more belt sections

joined together at their ends. Short conveyor belts can also bemanufactured in endless versions.


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D - 1

Steep angle conveyor belts: Rollback of the material handled can beprevented by means of chevron cleats, fins or cross partitions on thecarrier side when the conveying gradient is steep. The design can beadapted to the material to be conveyed and to the transverse stabilityrequired. Cross partitions and corrugated sidewalls can be combined to

form the corrugated box-section belt.

Steep angleconveyor belt with HCKER CONTIWELLchevron cleats Conveyor belt Box-section belt

Elevator belts: These are used in belt-type bucket elevators and areprovided with special brackets for the attachment of containers, bucketsor belt slings.

Tension member: The task of the tension member is to transmit theforces induced at the drives for overcoming the system resistances to thepoint where they are needed. In the fabric ply belt, the tension memberconsists of one or more plied fabrics. In the case of a steel cable belt, thetension member consists of steel cables arranged on a single plane andrunning parallel to each other longitudinally; these cables are imbeddedin core rubber.

Core rubber: The core rubber envelops the steel cables of the steelcable tension member, providing good adhesion to the cover materialwith a high dynamic carrying capacity. The physical properties aremaintained even after repeated curing, for instance on splicing.

Belt covers: The covers protect the tension member from damage andother environmental influences. The top and bottom covers may vary inthickness. The bottom cover can be omitted from bare-bottom-ply beltsfor sliding bed operation. Additional elements designed to increaseimpact resistance or for monitoring purposes may be located in thecovers. The cover materials can be selected to suit any application.

Surface patterning: For improved holding of materials on gradients orfor special applications, the top cover can be manufactured in a patternedor a cleated version.


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D - 2 Stipulation of principal data D - 2

Material handled 2.1

Flow of material handled 2.2 Conveying track 2.3

Type of belt conveyor 2.4

Belt width 2.4.1

Belt speed 2.4.2 Belt support 2.4.3

Carrying capacity 2.5

The designing of a conveyor belt begins with an investigation into the

service requirements and the stipulation of the principal data characte-rizing the specific application. Data already available can be checkedagainst the guide values stated in this section.

The optimum conveyor belt cannot be selected by means of the principaldata alone, as the operating method and the belt conveyor design alsohave a considerable influence. If the stress and strain on the conveyorbelt are not known in detail, a calculation of the belt conveyor must beexecuted with reference to the bulk material transport up to approx. 30system gradient in section D - 3. Sections D - 6 to D - 8 containsupplementary data for the calculation of steep-angle conveyors for bulkmaterials, of elevators and piece goods conveyors.


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D 2.1 D - 2.1 Material handled

The physical and chemical properties of the material to be handled mustbe taken into account when selecting the belt conveyor and designing theconveyor belt.

Properties of material to be handled (guide values)

Material to be handled

Bulkdensity

in t/m3

Angleof

reposein

Max.gradientof fight

Possible effect

mech. chem. temp.

Ammonium sulphateArtificial fertilizersAsh, dryAsh, wetAsphalt, crushed

0.75-0.950.9-1.2

0.65-0.750.90.7

12

15

2212-15

161822

+ + +

Bauxit, crushedBauxit, fineBerry und Lorraine iron, fineBeetBeet chip, wetBlast furnace slag

1.2-1.41.9-2.0

3.20.65-0.75

0.51.2-1.4

151018

18-201818

15-1715-17

18

+ ++

+ ++

+

CementCereals (not oats)Clay, dampClinkerCoal, fineCoal, rawCokeConcrete, wetCopper oreCrushed rock

1.2-1.50.7-0.85

1.81.2-1.50.8-0.9

0.75-0.850.45-0.61.8-2.41.9-2.41.5-1.8

0-1010-1215-1810-15

1018150-515

10-15

15-2014

18-2018

18-2018

17-1816-22

1816-20

+ +

+++++++++

+++

++

++

Felspar, crushedFish meal

FlourFoundry sandFoundry wasteFruit

1,60.55-0.65

0.5-0.61.2-1.31.2-1.6

0.35

15

10

1825

15-182016

12-15

+ +

+++

+

+ +

+

Glass, crushedGranite, crushedGraphite, powderGravel and sand, wetGravel, graded, washedGravel, ungradedGypsum, crushedGypsum, powdered

1.3-1.61.5-1.6

0.52.0-2.41.5-2.5

1.81.35

0.95-1.0

151815

12-15202020

12-1518-20

1823

++++

+

Household refuse 0,6 18-20 + +

Iron ore

Iron ore, pellets

1.7-2.5

2.5-3.0

15

12

18

15

++

Lignite briquettes ovalLignite, dryLignite, wetLime, lumpsLimestone, crushed

0.7-0.850.5-0.9

0.91.0-1.41.3-1.6

1515

15-201515

12-1315-1718-2015-2016-18 +

+

MaizeManganeseMatchwood

0.7-0.752.0-2.20.2-0.35

1215

1518-2222-24

+++

Oil cakeOil sandOverburden

0.7-0.81.6-1.81.6-1.7

101515

152017 ++

++++

PeatPhosphate, crushedPhosphate, finePotash

0.4-0.61.2-1.4

2.01.1-1.6

1512-15

15

1618-20

1818

++++ +


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Material to be handled

Bulkdensity

in t/m3

Angleof

reposein

Max.gradientof fight

Possible effect

mech. chem. temp.

D 2.1

Rock saltRubber, pellets

1.20.8-0.9

15 1812

++

Salt, coarse

Salt, fineSand, drySand, wetSandstone, crushedScrap metalSlagSlate, crushedSludgeSoap flakesSoil, dampSugar caneSugar, rawSugar, refined

1.2

1.2-1.31.3-1.41.4-1.91.3-1.51.2-2.0

1.31.4-1.6

1.00.15-0.351.5-1.90.2-0.30.9-1.10.8-0.9

15

151515

0

15-20

18-20

15-1816-2020-25

18

1518-20

1520

++++++++++

+

+

+

+

Timber, pieces 0.25-0.5 20-25

Key:+ medium wear + + heavy wear

chemically aggressive chemically highly aggressivetemperatures above 70 temperatures above 120C

The dynamic angle of repose is in general lower than the natural angle ofincline of the material handled and depends on

the type of material handled,the conveying speed,the design of the feeding point andthe gradient of the system.

It permits an assessment of the cross-sectional form of the bulk materialon the belt. The maximum gradient stated for the flight applies to astandard, uncleated belt surface.


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D 2.2 D - 2.2 Flow of material handled

If a specific quantity of material is to be handled in a prescribed time, the

Mass flow Qm in t/h

results with the mass of the material handled, and the

Volume flow QV=Qm/ in m/h.

for bulk materials with bulk density .

The necessary conveying capacity of the conveyor belt or belt conveyorto be selected is determined by these two values. To what extentdowntime may occur through maintenance, breakdown and repairs andto operation-related interruptions in conveying must be taken into accountwhen making the selection.

Operating hours per year

Working days per year 1 shift* 2 shifts 3 shifts

365

250200

2920

20001600

5840

40003200

8760

60004800

* 1 shift = 8 hours

Guide values for maximum material flows

QV in m/h Qm in t/h

Belt conveyorsSteep angle conveyor beltsElevators

approx. 25.000approx. 1.400approx. 1.500

approx. 40.000approx. 3.000approx. 2.500


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D - 2.3 Conveying track D 2.3

Owing to its continuous conveying process, the belt conveyor hasrelatively low flight loads and can consequently be adapted to anyrouting. The belt gradient can be changed at random, which may providethe most economic solution for longhaul conveying systems in particular.Certain minimum radii of the concave or convex curves must be adheredto. Laying in horizontal curves is also feasible with belt conveyors. The

use of a high-strength tension member permits considerable conveyinglengths and conveying heights to be attained. Centre distances in themagnitude of 5 to 10 kilometers and conveying heights of up to severalhundred meters are no longer a rarity.

Belt conveyors with steep angle belts are normally designed for shorterflights at a very steep gradient. The belt guidance can be adapted largelyto the specific application in this case too with the use of appropriatesupporting elements.

Belt elevators are used almost exclusively for vertical transport withconveying heights of up to almost 100 meters. The operating principlepermits no curves or significant gradients in the flight. The use of steepangle conveyor belts and elevator belts overlaps in the range of verysteep to vertical transport. Individual adaptation of the conveyor elementis frequently essential in this instance.


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D 2.4 D - 2.4 Type of belt conveyor

The transport of bulk material and piece goods on conveyor belts with nosurface partitioning or on hugger belts is restricted by the gradient atwhich the material being handled begins to slip or to roll. Nor is faultlesstransport guaranteed if starting or stopping induces this process. Thecritical conveying gradient angle for a smooth belt is between 15 and 20for the majority of different types of material handled. Furthermore,

special belts permitting steeper gradients have to be used. The statedguide values apply to ascending transport.

1 Conveyor belts with no surface partitioning(Conveyor belts with cover patterning for bulk materials)

2 Piece goods conveyor belts with cover patterning , Rollgurt*3 Belts with chevron cleats4 Fin belts, box-section belts with corrugated sidewalls5 Conveyor belts in sandwich design6 Elevator belts

The maximum gradients are to be selected on the small side, if easilyflowing bulk material is to be conveyed at an angle on conveyor belts ofgroups 1,2 or 3. With increasing surface pattern depth and with transportin buckets etc., the type of material handled is of essential significance

only with regard to granularity or piece size.

The velocity data, too, represent guide values that are intended to help inselecting the appropriate type of belt but have to be determined moreprecisely in the subsequent design. If a steep angle conveyor belt or anelevator belt is found to be suitable for the application or if belts for piecegoods or for sliding bed operation are to be designed, special attentionshould be paid to the information in the relevant chapters.

For bulk material transport on conveyor belts with cover patterning(group 1) the maximum conveying gradients can be set approx. 5 higherthan corresponding to the respective angle of the material concerned.

If a control of all requirements has led to the selection of a conveyor with

a belt from groups 2 to 6, the layout information given for these specialconveyor belts in Sections D - 6, D - 7 und D - 8 is to be observed.

* Tubular belt, developed by Continental and PWH AS (please ask for special literature).


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D - 2.4.1 Belt width D 2.4.1

The belt width should be selected as far as possible from standardized orcustomary widths as the dimensions of the idlers and other constructionalelements of the belt conveyor are coordinated with these widths.

Standard belt widths*

300 400 500 600 650 8001000 1200 1400 1600 1800

Belt width Bin mm 2000 2200 2400 2600 2800

3000 3200

In the case of troughed belts, the belt width must not fall short of certaindimensions, depending on the lump size (edge length) of the material tobe handled, as the material can otherwise not be transported safely. Withstrongly eccentric pieces there is furthermore the risk of the beltmistracking and of idlers being damaged by material projecting beyondthe belt.

Minimum belt widthsSize k of lumps

in mmMind. belt width B

in mm

100 400

150 500

200 650

300 800

400 1000

500 1200

550 1400

650 1600

700 1800

800 2000

This data applies to approximately cubic lumps. Narrower widths are alsoadmissible for oblong lumps (so-called "slabbies") or when single piecesare imbedded in mainly fine material.

It is to be observed that the troughability too is influenced by the beltwidth. The troughability decreases with diminishing belt width. On finaldetermination of the belt structure, the troughability (D - 4.3.2) is to be

checked.

* CONTINENTAL conveyor belts are currently available in widths of up to 6400 mm. Textile carcassbelts are available from stock in widths of 400 to 1000 mm.


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D 2.4.2 D - 2.4.2 Belt speed

The selection of the belt speed is of decisive significance for the furtherdesigning of the belt conveyor and of the belt.

Application featuresConveying speed

v in m/s

Special cases, process-related(e. g. cooling conveyors) 0.5

Small flows of material, protective transport(e. g. coke bench conveyors) 0.5-1.5

Standard application conditions and materialhandled(e. g. gravel conveyance)

1.5-3.5

Large flows of material, long conveying lengths(e. g. overburden conveyance) 3.5-6.5

Special cases(e. g. jet conveyors) 6.5 and more

In general a more economic design can be achieved with higherconveying speeds. The greater the conveying lengths and thus the beltlengths, the more significant this is, so that maximum conveying speedswill be selected especially in such cases. The limits imposed first andforemost by the type and nature of the material to be handled can beexceeded in many instances if, for example, additional measures aretaken at the feeding points to eliminate or diminish the drawbacks of highconveying speeds.

Bulk material features

strongly abrasivefine and lightfragilecoarse grained (sized) and heavy

low conveyingspeeds

slightly abrasivemedium bulk weightmedium granularity (unsized)

higher conveyingspeeds

Increased conveying speed results in an increased conveying capacitywith a constant belt width. It may thus be possible to select a narrowerbelt width or a simpler troughing design for a given flow of material. In

addition, reduced drive tractions and consequently reduced dimensioningof all elements constituting the belt conveyor may result. Drawbacks areincreased belt wear, to which special attention should be paid in shortbelt conveyors, an increased risk of damage to the material handled andincreasing power requirements for large capacities.

Reduced conveying speed correspondingly results in a larger belt widthor a higher-capacity troughing design with the given flow of material. Theincreased drive tractions are offset by reduced belt wear and a reducedrisk of damage to the material handled.


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Belt speedsguide values from systems in operation

D 2.4.2

Bulk materials Application

Coal (fine, dusty)Filter ashHousehold refuse

Power stationsRefuse dressing

Cement clinkerCoke

Cement plantsSteel worksCoking plants

Raw salt (fine)Residual salt (damp)Gravel, sand

Potash industryPit and quarryindustry

Cement, chalkLimesetone (crushed)Cereals

Dressing plantsGrain silos

Pit coal (crushed)Marl

Underground plantsPower stationsCement industry

OreCoal

Loading plantsStockyards

Raw salt (crushed)BauxiteRock phosphate

Long-distanceconveying systems

Crude lignite (damp)OverburdenConcentrated phosphate

Raw materialextractionOpen cast mines

Belt speed in m/s


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D 2.4.3 D - 2.4.3 Belt support

The cross section of the conveyor belt is formed by the arrangement ofits supporting elements - idlers or slip planes - and thus adapted to theapplication conditions and the necessary conveying capacity.

The supporting system is generally effected by idlers with largelystandardized lengths and diameters. The lengths are prescribed so as to

ensure reliable belt support even with the mistracking that is permittedwithin certain limits. The selection of the idler diameter is influenced bythe conveying speed. Further data to help determine idler weights andspacings are given in the relevant chapters.

Belts for bulk material transport are supported almost exclusively byrigidly mounted idlers or suspended (garland) idlers.

Application features for belt support systems

Bulk materials Piece goods

Support Rollers Plane-borneor rollers

as hopperdrawing deviceand conveyortype scales

laterally chutedor with corrugatedsidewalls asskirting

belt width dependenton piece goodsdimensions

as beltwith corrugatedsidewalls

with corrugatedsidewalls to increaseconveying capacity

single piece shouldnot project beyondsidewall

Flat belt

as partitionedbelt withcorrugatedsidewalls forsteep angletransport

with transversepartitions or withcorrugated sidewalls

for all bulk

materialsvarious troughdesigns

with fins or partitions or

with patterned coverfor steep angletransport

transport of billets

or tree trunks, reelsand barrels to preventlateral rolling

troughedbelt

Trough belt with turned-up sides construction as forbulk materials

The design of multiple troughs is determined essentially by the troughingangle.

Troughing angle of multiple belt supports

Troughing Top run Return run

V-trough

for belt widths up to 800 mm.Troughing angle up to 30 depend-ing on belt construction. Beltwidths up to 1200 mm and trough-ing angle up to 45 in special cases.With stepped fabric plies at beltcentre where appropriate

in any width required for bettertracking; standard troughingangle 10-15

3-part

Classical version for all beltwidths; standard troughing angle:20 - 30 - 35 - 40 - 45"Deep trough" with shortenedcentre idler

with double strand, material andpassenger transport with the con-ventional top run troughings

5-part

In top run, preferred as close-setgarland idler assembly in the mate-rial feeding area. Troughing angle

dependent on load distribution,belt rigidity and belt tension:25/55 or 30/60


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19

Troughing designs D 2.4.3(The clearance d must not exceed 10 mm; from 2000 mm belt width ist must not exceed 15 mm.)

Standard idler tube lengths in mm

Troughingdesign

Belt widthB inmm

300 400 500 600 650 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200

flat I 380 500 600 700 750 950 1150 1400 1600 1800 2000 2200 2500 2800

V-trough I 200 250 315 340 380 465 600 700 800 900 1000 1100 1250 1400 1500 1600 1700 1800

3-part I 160 200 250 250 315 380 465 530 600 670 750 800 900 950 1050 1120 1150

l1 200 250 315 380 465 530 600 640 670 700 800 900 9003-part(deep trough) l2 380 465 550 600 670 700 800 900 1000 1100 1150 1150 1250

3-part I 165 205 250 290 340 380 420 460 500 540 580 640 670

When selecting the idler diameter, care should be taken that no excessively high numbers of revolutions result fromthe belt speed. 600-700 r. p. m. should not be exceeded.

Standard idler diameter in mm

Carrier idlers 88,9 108 133 159 193.7

Impact idlers 156 180 215 250 290

Return run support discs 120 133 150 180 215 250 290

Idler speed

v.60

nR = . DR in min-1

DR in mm

The economic efficiency of a belt conveyor can be considerablyinfluenced by the selection of an optimum idler spacing in the top and thereturn run. The capital expenses and the maintenance expenditure arealso reduced by a smaller number of idlers. Approximate standard valuesof the idlerspacing lo in the top run can be calculated from the empiricalrelationship*

IO 5.(k

. ) 0,2 in m

max. grain size k in mmbulk density in t/m

The idler spacing in the return run should be about 2 bis 3 x IO.

A detailed investigation, e. g. towards graduating the idler spacings whencentre distances are greater, may be advisable and can be undertaken atany time by the staff of the Continental Application TechniqueDepartment.

* The following effects should be observed in particular:Loading capacity of the idlers

(Service life of the idler depending on bearingload and axial deflection)Troughing properties of the belt(Safe material intake and adequate belt support)Drive traction and belt sag (cf. D - 4.1)(Prevention of shear vibrations of the belt and excessive motional resistances due to higher flexing stress)


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D 2.5CONTI-COM

D - 2.5 Conveying capacity

The conveying capacity of the belt conveyor is determined by the fillingcross-section area A and the conveying speed v. The theoretical volumecapacity thus amounts to

QV th = A.v

.3600 in m/h

an the theoretical capacity to

Qm th = A.v

.3600

. in t/h

A = A1 + A2 in m

The filling cross-section area A is based on the effective belt widt

b = 0,9 B - 50 mm for B 2000 mm

b = B - 250 mm for B > 2000 mm

For belts with corrugates sidewalls the maximum effective belt widthamounts to

bn = B - 100 mm for a corrugated sidewall height hK 80 mm

bn = B - 120 mm for a corrugated sidewall height hK > 80 mm

which is reduced by the corresponding amount for a plain skirting zone.The effective filling height heff is approx. 0,9

.hK.

With feeding rate 1 the effective conveying capacity amounts to

QV eff= A.v

.3600

.1 in m/h

or

Qm eff= A.v

.3600

.

.1 in t/h

The deviation of the filling cross-section form from the straight-side fill

assumed with angle , which occurs above all in non-horizontal transport,can be taken into account with feeding rate 1.

Guide values for1 in non-horizontal transport

Gradient in 2 4 6 8 10 12 14 16 18 20

H/L 0.035 0.070 0.105 0.140 0.174 0.208 0.242 0.276 0.310 0.342

Feeding rate 1 1.0 0.99 0.98 0.97 0.95 0.93 0.91 0.89 0.85 0.81

The values stated apply only to strongly troughed conveyor belts andbulk material with high internal friction. For untroughed belts andV-troughs in particular, non-horizontal transport results in considerablyreducedfeeding rates 1 that have to be calculated by the approximation

method* or determined empirically.

* ' A mathematical formulation is given for instance in DIN 22 101


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Gradients exceeding 20 can generally be attained only with conveyorbelts with a partitioned or patterned cover. The stated values of1 applywith the same restrictions as above.

D 2.5

Guide values for1 with gradients exceeding 20

Gradient in 21 22 23 24 25 26 27 28 29 30

H/L 0.358 0.375 0.391 0.407 0.423 0.438 0.454 0.469 0.485 0.500Feeding rate 1 0.78 0.76 0.73 0.71 0.68 0.66 0.64 0.61 0.59 0.56

Short flights deviating in their gradient from the overall conveying angle ofthe belt conveyor need not be taken into account with reduction factor1unless the filling cross-section changes on a brief run-through.

The necessary filling cross-section results from the above equations witha given flow of material Qm (mass flow in t/h) and taking into accountwhere relevant a uniformity coefficient 2 1 in feeding, in

in m

and thus enables the trough design to be selected from the tablesshowing the values for A with the corresponding parameters

Flat Square trough ( = 80)

hk* = 100 mm hk* = 150 mm

Angle of repose Angle of repose Angle of repose

Beltwidth

Bin mm 5 10 15 20

Beltwidth

Bin mm 5 10 15 20

Beltwidth

Bin mm 5 10 15 20

300400500650800

10001200140016001800200022002400

0.00100.00210.00340.00620.00980.01580.02320.03200.04220.05390.06690.08310.1011

0.00210.00420.00700.01260.01970.03180.04670.06450.08510.10860.13500.16760.2037

0.00320.00640.01070.01910.03000.04830.07100.09800.12940.16510.20510.25470.3096

0.00440.00870.01450.02600.04080.06570.09650.13320.17580.22420.27860.34590.4206

400500650800

1000120014001600

0.01710.02580.03970.05460.07590.09900.12390.1505

0.01830.02820.04470.06330.09110.12240.15730.1957

0.01940.03060.04990.07230.10670.14660.19180.2423

0.02070.03320.05540.08170.12310.17190.22790.2911

650800

1000120014001600

0.04990.07170.10240.13470.16890.2048

0.05340.07830.11470.15450.19800.2449

0.05690.08510.12730.17500.22790.2863

0.06060.09220.14060.19640.25940.3296

* hk = hn + 25 mm


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22

D 2.5

in m

Corrugated sidewall

Angle of repose = 0 Angle of repose = 10

Height of corrugated Heigth of corrugated

sidewalls hk in mm sidewalls hk in mm

Beltwidth

Bin mm

60 80 125 160 60 80 125 160

300400500650800

10001200140016001800200022002400

0.00970.01510.02050.02860.03670.04750.05830.06910.07990.09070.10150.11230.1231

0.01290.02010.02730.03810.04890.06330.07770.09210.10650.12090.13530.14970.1641

0.01800.02920.04050.05730.07420.09670.11920.14170.16420.18670.20920.23170.2542

0.02300.03740.05180.07340.09500.12380.15260.18140.21020.23900.26780.29660.3254

0.01110.01850.02680.04100.05710.08160.10970.14130.17640.21510.25730.30300.3522

0.01430.02360.03370.05050.06930.09740.12910.16430.20310.24530.291

0.34040.3933

0.01910.03220.04620.06880.09340.12930.16870.21170.25820.30820.36170.41880.4794

0.02410.04040.05750.08490.11420.15640.20210.25140.30420.36050.42030.48370.5505


Height of corrugated Height of corrugated

sidewalls hk in mm sidewalls hk in mm

Beltwidth

Bin mm

60 80 125 160 60 80 125 160

300400500650800

10001200140016001800200022002400

0.01180.02030.03010.04740.06760.09930.13640.17880.22660.27970.33820.40210.4713

0.01510.02540.03700.05690.07990.11520.15580.20190.25320.31000.37210.43950.5123

0.01970.03370.04910.07470.10340.14620.19450.24800.30700.3713044090.51600.5963

0.02470.04190.06050.09080.12420.17330.22790.28770.35300.42360.49950.58090.6675

0.01260.02220.03360.05410.07870.11790.16440.21820.27920.34750.42310.50590.5961

0.01590.02720.04040.06370.09100.13380.18380.24120.30580.37770.45690.54340.6371

0.02030.03540.05220.08100.11380.16400.22140.28620.35820.43740.52400.61780.7190

0.02530.04350.06360.09710.13460.19110.25480.32580.40410.48970.58260.68270.7901


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D 2.5

in m

V-trough


Troughing angle Troughing angle

Beltwidth

B

in mm 20 30 35 40 45 20 30 35 40 45

300400500650800

10001200140016001800200022002400

0.00380.00770.01280.02290.03600.05800.08520.11760.15520.19800.24600.30550.3714

0.00520.01040.01730.03090.04850.07820.11480.15840.20910.26680.33150.41160.5004

0.00560.01120.01870.03360.05270.08480.12460.17190.22690.28950.35970.44660.5429

0.00590.01180.01960.03520.05520.08890.13050.18020.23780.30340.37690.46800.5690

0.00600.01200.01990.03570.05610.09030.13260.18300.24150.30810.38280.47530.5778

0.00570.01140.01900.03410.05350.08610.12650.17460.23040.29390.36520.45350.5513

0.00680.01350.02260.04040.06340.10200.14990.20680.27300.34830.43270.53730.6532

0.00710.01410.02350.04200.06600.10620.15590.21520.28400.36240.45030.55910.6796

0.00720.01430.02380.04260.06680.10760.15800.21810.28780.36710.45620.56640.6886

0.00710.01410.02350.04200.06600.10620.15590.21520.28400.36240.45030.55910.6796



Beltwidth

Bin mm 20 30 35 40 45 20 30 35 40 45

30040050065080010001200140016001800

200022002400

0.00670.01340.02230.03990.06260.10070.14790.20420.26950.3438

0.42720.53040.6448

0.00760.01520.02530.04530.07110.11450.16810.23200.30620.3906

0.48530.60260.7326

0.00780.01560.02590.04640.07290.11730.17230.23770.31370.4003

0.49730.61750.7507

0.00780.01560.02590.04640.07290.11730.17230.23770.31370.4003

0.49730.61750.7507

0.00760.01520.02530.04530.07110.11450.16810.23200.30620.3906

0.48530.60260.7326

0.00770.01540.02570.04590.07210.11610.17040.23520.31040.3961

0.49210.61100.7428

0.00850.01690.02820.05050.07920.12750.18720.25840.34100.4350

0.54050.67110.8156

0.00860.01710.02850.05100.08010.12890.18930.26130.34490.4400

0.54670.67880.8252

0.00850.01690.02820.05050.07920.12750.18720.25840.34100.4350

0.54050.67110.8158

0.00820.01630.02720.04880.07650.12310.18080.24960.32940.4202

0.52210.64830.7881


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D 2.5

3-part



Beltwidth

Bin mm 20 30 35 40 45 20 30 35 40 45

400500650800

100012001400160018002000220024002600280030003200

0.00590.01000.01870.0292

0.04820.07050.09870.13120.16820.20860.26350.31790.38490.45010.52560.6143

0.00840.01430.02660.0415

0.06850.10020.14010.18600.23840.29570.37310.45030.54460.63730.74400.8682

0.00950.01610.02990.0468

0.07710.11280.15760.20920.26800.33250.41910.50610.61160.71590.83560.9742

0.01040.01770.03280.0514

0.08450.12370.17270.22910.29350.36410.45840.55390.66870.78310.91381.0641

0.01120.01910.03530.0552

0.09070.13270.18520.24550.31440.39010.49050.59300.71520.83800.97751.1368

0.00990.01660.03050.0477

0.07800.11430.15900.21060.26940.33440.41940.50760.61110.71670.83560.9702

0.01210.02040.03740.0586

0.09580.14030.19530.25870.33100.41080.51530.62360.75080.88051.02651.1917

0.01300.02200.04020.0630

0.10290.15070.20970.27780.35530.44100.55290.66930.80540.94481.10131.2778

0.01380.02320.04250.0666

0.10870.15920.22140.29310.37490.46540.58300.70600.84900.99631.16111.3460

0.01440.02420.04430.0694

0.11310.16570.23020.30470.38960.48370.60520.73330.88111.03441.20521.3956



Beltwidth

Bin mm 20 30 35 40 45 20 30 35 40 45

400500650800100012001400160018002000220024002600

280030003200

0.01190.02010.03660.05740.09350.13700.19030.25190.32200.39980.50050.60620.7287

0.85530.99661.1551

0.01400.02360.04310.06750.11000.16120.22400.29650.37910.47060.58920.71360.8579

1.00691.17331.3597

0.01480.02500.04560.07140.11630.17050.23680.31340.40070.49740.62240.75410.9061

1.06381.23941.4356

0.01550.02610.04750.07450.12120.17770.24670.32640.41730.51810.64770.78500.9427

1.10711.28961.4925

0.01600.02690.04900.07670.12470.18280.25360.33550.42870.53230.66490.80620.9673

1.13651.32351.5300

0.01410.02370.04310.06750.10970.16080.22310.29510.37720.46830.58540.70950.8519

1.00051.16541.3489

0.01600.02700.04900.07680.12490.18310.25400.33610.42950.53330.66660.80800.9701

1.13941.32711.5359

0.01680.02820.05120.08020.13040.19110.26510.35070.44820.55650.69530.84291.0117

1.18841.38411.6009

0.01730.02910.05280.08280.13440.19700.27320.36130.46160.57320.71550.86781.0409

1.22321.42431.6460

0.01770.02970.05380.08440.13690.20070.27810.36770.46970.58330.72730.88261.0576

1.24341.44751.6709


29/140

25

D 2-5

3-part (deep trough)



Beltwidth

Bin mm 20 30 35 40 45 20 30 35 40 45

100012001400160018002000220024002600280030003200

0.05450.07950.10920.14230.18110.22420.28120.34550.41620.48540.55970.6531

0.07640.11160.15340.20010.25480.31560.39530.48500.58340.68150.78670.9161

0.08530.12460.17130.22380.28510.35320.44200.54160.65100.76120.87951.0227

0.09250.13530.18610.24350.31020.38450.48070.58830.70630.82690.95641.1103

0.09800.14350.19760.25900.33000.40920.51090.62430.74860.87771.01641.1776

0.08370.12250.16850.22070.28130.34870.43550.53270.63950.74880.86651.0053

0.10250.15010.20660.27080.34510.42790.53410.65290.78320.91781.06271.2316

0.10950.16040.22080.28970.36930.45800.57130.69780.83650.98111.13671.3160

0.11470.16810.23160.30420.38780.48120.59970.73170.87631.02891.19311.3793

0.11800.17320.23880.31420.40060.49720.61900.75420.90221.06071.23141.4209



Beltwidth

Bin mm 20 30 35 40 45 20 30 35 40 45

100012001400160018002000220024002600

280030003200

0.09890.14480.19940.26150.33330.41340.51570.63000.7555

0.88571.02601.1882

0.11610.17010.23430.30750.39190.48620.60630.74010.8870

1.04061.20611.3956

0.12210.17890.24660.32400.41300.51250.63860.77900.9329

1.09541.27031.4683

0.12620.18510.25520.33580.42820.53140.66160.80620.9647

1.13381.31611.5191

0.12840.18860.26020.34290.43730.54300.67520.82170.9820

1.15581.34311.5474

0.11480.16820.23170.30420.38780.48120.59970.73190.8771

1.02911.19311.3800

0.13030.19100.26320.34600.44110.54740.68180.83160.9958

1.16941.35641.5674

0.13530.19840.27350.35980.45880.56950.70900.86401.0340

1.21511.41031.6280

0.13830.20300.28000.36880.47040.58410.72640.88431.0573

1.24381.44501.6656

0.13940.20480.28260.37290.47570.59090.73410.89241.0657

1.25551.46011.6799


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26

D 2.5

5-part

Troughing angle 1 / 225 / 55

Angle of repose

Beltwidth

Bin mm 0 10 15 20

100012001400160018002000220024002600280030003200

0.09580.14020.19490.25410.32620.40730.51060.62540.75160.88921.02281.1909

0.11810.17300.23990.31430.40250.50160.62640.76490.91711.08921.25121.4498

0.12970.19010.26330.34550.44210.55060.68660.83741.00311.18351.36981.5844

0.14180.20800.28780.37830.48370.60190.74970.91341.09321.28901.49421.7254

Troughing angle 1 / 2

30 / 60

Angle of repose

Beltwidth

Bin mm 0 10 15 20

100012001400160018002000220024002600280030003200

0.10210.14960.20760.27140.34800.43400.54270.66340.79600.94061.08511.2595

0.12240.17940.24840.32610.41720.51950.64750.78950.94531.11511.29141.4928

0.13290.19490.26960.35460.45320.56390.70200.85501.02291.20581.39871.6140

0.14390.21120.29180.38430.49090.61040.75900.92361.10421.30081.51101.7410


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D - 3 Calculation of belt conveyor D - 3

Masses 3.1

Idlers 3.1.1 Conveyor belt 3.1.2

Drive elements 3.1.3

Coefficients 3.2

Motional resistance 3.3

Resistive forcecomponents 3.3.1

Motional resistancesof sections 3.3.2

Required power 3.4

Peripheral forces 3.5

Starting and stopping 3.5.1 Multi-pulley drive 3.5.2

Example of calculation 3.6

When designing conveyor belts for low-powered conveyor systems, arough calculation of the belt conveyor may be adequate in many cases.

For this purpose it is quite sufficient to work with the standard formulaeand guide values given in the main chapters of this section. The guidevalues listed there can also be used to achieve an initial roughassessment of the belt structure, the data of which can then be applied inthe more precise calculation. It is therefore advisable to observe the mainchapters of Sections D - 4 (tension members) and D - 5 (covers) prior tothe more detailed investigations in the subchapters.

The technical staff of the ContiTech GmbH guarantee to undertake ameticulous investigation of both simple and extremely intricateapplications at any time. The prompt preparation of a quotation can befacilitated considerably by use of the questionnaire attached in theappendix (D - 9).


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D 3 An essential step in conveyor belt calculation is the determination of thepower requirements from the overall motional resistances, taking intoaccount where relevant temporary operating conditions such as starting,stopping or section loading in systems with varying gradients.

Motional resistances of a belt conveyor

1 Rolling resistance of idlers2 Belt flexing resistance3 Flexing resistance of material conveyed4 Feeding resistance5 Skirting friction resistance6 Scraper friction resistance7 Belt deflection resistance at pulleys8 Gradient resistance

The different components of the motional resistance can in general becalculated comprehensively by means of empirical coefficients. In specialcases, however, it may be advisable to ascertain the essentialcomponents of the motional resistance individually.

The size of the drives and their quantity, if the power is to be generatedby more than one drive, can be determined from the required power. Astatement on the optimum arrangement too can be made as soon as themotional resistances have been ascertained. When the number of drivesand their arrangement have been stipulated, the peripheral forces actingon the drive pulleys and having a decisive effect on the extent of the belttensions can be determined.


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D - 3.1 Masses*

D 3.1

In order to calculate the motional resistance, the sum total of all massesmoved on the flight must be determined. These include not only the loadmass but also the belt mass and the rotating idler parts. A more preciseinvestigation of the intermittent'operating conditions in starting andstopping furthermore involves reducing all rotating masses, including themasses of rotating drive parts, to the pulley circumference.

The mass mL of the material handled, burdening one meter of the flight,amounts from the capacity and the conveying speed to

in kg/m

If transport is effected on the top and return runs simultaneously, themass mL is to be ascertained from the sum total of the two capacities.

Mass flow Qm in t / h

Mass in mL in kg / m

In cases where the belt structure has not yet been assessed or furtherdata on the intended design of the conveying system are not yetavailable, guide values for the mass mG of the belt and nip of the rotatingidler parts can be inserted according to the loading of the system.

Guide values for the mass (2 mG + mR ) of the moving parts of a belt conveyor in kg / m

B in mm 300 400 500 650 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 3000 3200

light systems 8.5 15.0 18.5 22.5 30 37 54 63 81 106 118 128 140 161 180 200

standard system 10 16.5 21 25.5 35 52 77 89 130 154 192 207 242 256 302 345

heavy-duty system 13.0 18 24 28.5 40 67 100 115 179 202 266 287 344 371 425 490

* In general usage the term "weight" can also be used for "mass". In all instances, however, it Is only the

unit "kilogram" (kg) that is admissible.

I


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D 3.1.1 D - 3.1.1 Idlers

In order to ascertain with precision the mass of all moving idler parts,related to 1 m of the centre distance, the mass of one idler or idler troughset is to be taken from the table below and to be divided by therespective idler spacing lo or lu. If the idler spacings are graduated, theaverage idler spacing is to be taken as a basis.

in kg/m

Guide values for masses of rotating parts of idlers (trough assemblies)

Mass in kgBelt width B

in mmIdler diameter

in mm 1-part V-trough 3-part 5-part

300 88.9 3.2 4.1

40088.9

108133

3.95.67.6

4.76.68.7

5.47.39.6

500 88.9108133

4.56.68.9

5.57.8

10.4

6.18.4

11.1

65088.9

108133

5.58.0

10.8

6.39.0

12.1

7.09.8

13.1

80088.9

108133

6.79.8

13.3

7.410.614.2

8.311.615.6

9.012.416.3

1000108133159

11.715.921.9

13.217.824.7

13.618.226.3

14.218.928.0

1200

108

133159

14.2

19.326.1

15.0

20.528.0

16.3

22.329.8

16.3

21.731.9

1400133159

21.829.3

23.331.6

25.035.5

24.335.0

1600 133159

25.133.4

26.535.0

28.038.7

28.539.3

1800 133159

27.637.8

29.139.5

30.742.4

31.542.5

2000133159193.7

30.240.269.1

31.843.376.4

33.347.080.1

33.546.589.5

2200 159193.2

46.577.8

49.082.6

50.193.2

49.595.5

2400 159193.7

50.786.6

51.591.4

53.593.2

53.0100.5

2600 159193.7

55.197.2

57.597.6

56.5107.0

2800 159193.7

58.5103.0

59.1106.4

60.0113.0

3000 159193.7

63.0109.0

65.5112.5

65.0121.5

3200 159193.7

70.0120.0

71.5123.0

68.0126.5


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Idlers with supporting discs are frequently used in the return run in orderto keep the system clean.

D 3.1.1

Masses of rotating parts of return run idlers with supporting discs in kg

Belt widthB

in mm

Tubediameter

in mm

Discdiameterin mm

1-part 2-part

400 51 120 4.0 5.0

500 57 133 5.7 6.8

650 51 133 6.8 8.1

800 63.5 150 11.7 13.2

1000 63.5 150 13.0 14.5

1200 88.9 180 22.2 23.9

1400 88.9 180 24.2 25.9

1600 108 180215

31.942.0

33.944.5

1800 108 180215

34.344.9

36.347.3

2000 198 100215 31.348.8 39.351.8

2200 133 215250

59.873.8

62.876.8

2400 133 215250

62.477.5

67.282.3

2600 133 215250

68.784.9

71.787.9

2800 159 290 130.6 138.2

3000 159 290 138.4 146.3

3200 159 290 146.2 154.4

In the case of heavy-duty systems with centre distances below 80 m, themasses of the feeding idlers that may be fitted with impact rings are to begiven special consideration where applicable.

Masses of rotating parts of feeding idlers with impact rings

Beltwidth B

Tubediamter

Impact idlerdiameter

Mass in kg

in mm in mm in mm 1-part 3-part

100012001400160018002000220024002600280030003200

88.9108108108133133133159159193.7193.7193.7

156180180180215215215250250290290290

19.130.835.742.267.173.680.1

117.5127.3201.0214.0230.0

21.132.840.545.071.177.684.1

127.5137.5221.0234.0252.0

As the mass of the rotating idler parts is concentrated mainly in the idlertube, the idler mass reduced to the belt speed amounts approx. to

in kg/m

and

in kg


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D 3.1.2 D - 3.1.2 Conveyor belt

The mass of the conveyor belt results from the mass mz of the tensionmember and the mass mo of the covers. If the type and structure of theconveyor belt are not stated, the belt construction must first be assessed.For this purpose an estimated calculation can be executed as describedearlier, using the standard formulae and guide values stated in the mainchapters.

Guide values to determine the tension member mass

The mass mD depends on the density of the cover compound and on thethickness of the top and bottom covers. For standard applications, themass with cover thickness s2 orS3in mm amounts approx. to

in kg/m

A density of D= 1,1 kg/dm3 can be assumed in cover rubber compounds

for standard application.

20% to 30% higher cover weights have to be taken into account for covermaterials designed for the handling of material containing oil, for hotmaterials or for application in underground mining. The precise valuesare stated in Section D - 5.1.

The belt weight mG with B in m consequently amounts to

in kg/m

For conveyor belts with a special structure and for special applications,

the precise data are to be obtained from the manufacturer. If it becomesapparent in the course of continued calculation or designing that adeviating belt structure has to be selected, the value of mG is to becorrected where applicable.

I


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D - 3.1.3 Drive elements D 3.1.3

The masses of the drive elements such as motor armature, clutch,brakes, gear mechanism and pulleys are not taken into account in thecalculation of the motional resistance of a belt conveyor.

The operating conditions on starting and stopping (D - 3.5.1) may,however, be considerably influenced by the masses as these also have

to be accelerated or decelerated by the starting or braking torque. Themass moments of inertia must be reduced to the pulley circumferenceand, if they attain a significant quantity in comparison with the othermoving masses, must be taken into account in the calculation of theperipheral forces.

The mass of a drive element rotating at speed n in min-1 reduced to thepulley circumference rotating at belt speed v is

in kg

with the mass moment of inertia J = GD/4g in kgm2. In obsolescent

catalogues GD2

is frequently still stated as a so-called "flywheel effect" inkpm2.

If the masses of the individual drive elements cannot be reducedseparately, the mass me red of a drive pulley with clutches and possiblywith a brake results approximately from the mass moment of inertia of themotor JM, the motor speed nM and a standard factor KM.

in kg

Rotational inertia coefficient KM

Slipring motor Squirrel-cage motorDrive with brake 0.58 1.2

Drive without brake 0.28 0.65

Guide values of mass moments of inertia for electromotors with a ratedspeed of 1000 min-1


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D 3.2 D - 3.2 Coefficients

The resistance coefficient f, resulting from a correlation between theweights and the motional resistances, yields the primary resistances FHofthe belt conveyor. The f-values take into account the sum of the motionalresistances in the top run and the return run and are applicableapproximately in the range from 70% to 110% rated load.

Guide values for f+

f with v in m/sConveying systems with

ascending, horizontal orslightly descending transport(motor-driven)

1 2 3 4 5 6

Standard versionHandling of material withaverage internal friction

0.016 0.165 0.017 0.018 0.02 0.022

Well laid-out and withsmoothly rotating idlers.Handling of material withlow internal friction

0.0135 0.014 0.015 0.016 0.017 0.019

Unfavourable operating

conditions.Handling of materialwith high internal friction

0.023 to 0.027

The guide values of f+ include a safety margin for the design as the actualmotional resistances are dependent on numerous factors, some of whichcannot be precisely determined. A safety margin is also to be taken intoaccount in the designing of braked systems for descending transport. Inthis case, however, the resistance coefficient is to be assumed to be notlarger but correspondingly smaller.

Guide value for f-

Conveyor systems for steeply descendingtransport (generator-induced braking)

f

Well laid-out conveying systems with normal operatingconditions.Handling of material with low to medium internal friction

0.012 to 0.016

Special account can be taken of certain limiting quantities. The guidevalues stated are based on a minimum belt sag of approx. 1 % so thatthe f-values can be reduced where applicable when the sag: idler spacingratio is low, i. e. when the belt tensions are high. Overdimensioned idlerdiameters also lead to lower f-values.

Quantatively the influence of the outdoor temperature can be taken moreexactly into consideration, provided that f-values not deviating consid-

erably from the guide values result from the multiplication of f by factorCT.

Influence of outdoor temperature

Temperature in C 20 +10 +0 -10 -2 -30

Factor CT 1 1.01 1.04 1.10 1.16 1.27


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The secondary resistances FN are determined by the length coefficient D 3.2

the accuracy of which, however, is adequate only for conveying systemswith centre distances or conveying lengths exceeding 80 m.

Length coefficient C* depending on conveying length L

L in m C L in m C L in m C L in m C

346

1016202532405063

9.07.65.94.53.63.22.92.62.42.22.0

8090

100120140160180200

1.921.861.781.701.631.561.501.45

250300350400450500550600

1.381.311.271.251.221.201.181.17

700800900

10001500200025005000

1.141.121.101.091.061.051.041.03

Coefficient C*

Conveying length L in m

* For conveying lengths below 80 m and In individual cases for relatively high secondary resistances, itis advisable to check and, where relevant, to correct coefficient C in the light of the secondaryresistance components.

2,0


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D 3.3 D - 3.3 Motional resistanceCONTI-COM

The motional resistance F of a belt conveyor is calculated with thecoefficients C and f.

In the case of conveying systems with slighter gradients ( < 18) cos

can be equated with I as an approximation..

The motional resistance F consists of various components.

Primary resistance FH

The primary resistance is that resistive force component that occurs inthe top run and in the normally unloaded return run, irrespective ofconveying height H. It is equivalent to a frictional force.

Secondary resistance FN*

The secondary resistance is due mainly to frictional and accelerationforces in the feeding area and can generally be expressed with sufficientaccuracy by the coefficient C as a fraction of the primary resistance forbelt conveyors with a conveying length in excess of 80 m.

* When ascertaining the secondary resistances precisely, it is above all the following components that haveto be taken into account:

Acceleration resistance FNa at the feeding point

In this equation VO is the relative speed of the material handled on feeding.

Frictional resistance FNsch at the feeding chute

In this equation hsch is the height in m of the material filling between the chute sidewalls.

The frictional resistance of belt cleaning equipment can be taken into account by

with belt width B in m. This component, however, does not normally occur in concentrated form at thefeeding point.

The precise determination of FNis thus based on


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Gradient rfesistance FSt D 3.3

Considering the belt conveyor as a whole, the gradient resistance resultssolely from the drop forces of the load masses, as the forces from thedownward pressure of the conveyor belt (top run against return run) arecounterbalanced.

As a further component of motional resistance F, special resistances FSmay occur; these are due, for example, to tilted idlers* skirtboards locatedon the flight or to scrapers for discharging the material conveyed. Theirmagnitude can be ascertained in individual cases from data in technicalliterature.

With the stated components, the overall motional resistance becomes

and must be overcome in operation by a peripheral force FU generated atone or more than one drive pulley.

The conveying height H is to be inserted with a positive sign forascending transport and with a negative sign for descending transport.When the gradient of the conveying system is slight, a prediction cannotalways be made in the latter case as to whether a positive or a negativeoverall motional resistance will result. The calculation must then beexecuted with the selected values f(+) and f(-) respectively. The largestnumerical value then states the decisive (positive or negative) motionalresistance for further calculation.

In a borderline case, operation of the belt conveyor with no load may leadto the maximum motional resistance. A calculation of the motionalresistances in no-load operation too is therefore essential for low-gradientdownhill conveying systems.

The layout of the belt conveyor in accordance with this schedule can beexecuted by means of the table used in the calculation example inSection D - 3.6 (cf. also D - 9.3). If a precise investigation of the belttension is to be made in the further course of the calculation, possiblywith starting and stopping taken into account, the motional resistance canno longer be considered totally but must be allotted to top run and returnrun according to its origins.

It is also in the investigation of belt conveyors with an alternating flightgradient or varying section loads that the motional resistances have to bedetermined separately and allocated locally to the individual sections ofthe conveying system in order to ascertain the exact belt tensions(D - 3.3.2).

* According to Vierling, the tilt resistance for 3-part (roughing sets In the top run and 2-part (roughingsets in the return run can be determined as follows (with = 0 3 to 0.4):

and

In these equations, the trouhing factor is c = 0,4 for 30-troughingc = 0,5 for 45-troughing

and the angle of tilt.


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D 3.3.1 D - 3.3.1 Resistive force components

Components of the primary resistance FH occur in the top run and in thenormally unloaded return run of the belt conveyor. The resistancecoefficients fO or fU to be inserted for this purpose can be set atapproximately equal to f.

with

For loading states deviating considerably from the rated load or from no-load operation of the belt, the values of f can be corrected in accordancewith an empirically determined correlation.

Resistance coefficient

Nominal load mLnom in %

If the return run is also used for transport, the load mass m LU is to betaken correspondingly into account in component FHU.

The secondary resistance FN is determined separately from the individualcomponents or calculated with coefficient C from the primary resistanceFH

and can be allocated locally to the feeding point with sufficient accuracy.

The gradient resistances are also to be considered separately for top runand return run, so that

and

now results with regard to belt mass mG. In this case too the load massmLU is to be taken into account where relevant in component FStu if thereturn run is used for transport.

The tabular schedule shown in the calculation example can be used inallocating the motional resistances. FHO and FSto1, or FHU and FStu arecombined in the schedule.

and


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D - 3.3.2 Motional resistances of sections D 3.3.2

If the motional resistances, the required power and the belt tensions of abelt conveyor with a layout including sections with varying gradients orloads are to be determined, a division into section lengths LN andcorresponding section heights HN is undertaken in order to obtain moreaccurate results. Those sections too that result from variable feeding ordischarge points are also to be distinguished in this process.

In order to facilitate recognition of critical operating conditions, thosesection lengths that have an approximately constant gradient or at leastrun at a continuous upward or downward inclination are selected. Initialfeeding of the belt conveyor or interruptions in transport may result inloading states that lead to higher or lower motional resistances inconveying systems with such layouts than when loading is continuous. Inaddition, the motional resistances at vertices or saddle points of thesystem layout may lead to critical belt tensions that do not emerge from acalculation with the overall conveying height H. This calculation, however,must nevertheless be executed in order to determine whether theconveying system is to be regarded as braked or motor-driven in normaloperation with continuous loading. In accordance with this, either the

large or the small f-value is to be inserted uniformly in the subsequentcalculation of the motional resistances by sections.

The motional resistance in the top run or return run of a section n resultswith primary resistance FHN and gradient resistance FStn as

*

Any special resistances present must be taken into account additionally.The same f-value can be assumed here too for the loaded or unloadedbelt if no data of greater accuracy are available.

The secondary resistances FN amounting from the calculation executed

above to

or needing to be determined in special cases from the individualcomponents, can be added with sufficient accuracy to the section at thebeginning of which the material is loaded onto the belt.

The chart shown in chapter D - 3.6 can be used for the systematicrecording of all calculated values. It is advisable to calculate first thevalues of the sections for the normal loading state and for unloadedoperation, beginning with the return run in the belt driving direction, asthe critical operating instance can frequently not be recognized from theoutset. For this reason the moving masses required for calculation ofintermittent operating states are to be determined at this point.

If the reduced masses mEred of the drive elements or pulleys are notnegligible in relation to the moving masses of the flight, they are to berecorded at the point at which they are effective.

* For sections of the return run, Hn is to be inserted with an inverse sign (negative for ascendingtransport).


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D 3.3.2 Apart from the normal case, in which the conveying flights arecontinuously loaded, further operating states arise from the section loadsthat may be critical for design and that lead to the largest or smallest (i.e. negative) motional resistances. The respective loading states areidentified as follows.

a continuously loaded

b continuously non-loaded

c transport starting

d transport ending

Whilst these loading states are to be taken into account in all instances,there is a slight probability of extreme operating conditions occurringthrough accidental interruptions in the feeding of the conveyor. Suchcases, that might lead to considerably increased dimensioning, can beprevented with appropriate control systems.

e loaded on uphill gradient

f loaded on downhill gradient

Low-gradient sections with a positive motional resistance even whenloaded are to be regarded as loaded in case e and as unloaded in case f.

The maximum motional resistance to be taken into account in the designresults from the sum total of the motional resistances.

FN = 0 is to be set in the consideration of the critical case with thesmallest, i. e. negative motional resistances (mainly loading of downhillsections).


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D - 3.4 Required power D 3.4 CONTI-COM

The power required by a belt conveyor that has to be transmitted to theconveyor belt by one or simultaneously by more than one drive pulleyamounts from the motional resistance F to

The power capacity PM to be installed for driven conveying systems (withpositive F) results from the power required PTr with the mechanicalefficiency

for braked conveying systems (with negative F)

Guide values for mechanical efficiencies

Driven conveying systemEfficiency

+

Single-pulleydrive

+

Multiple pulleydrive

Brakedconveyingsystem

-

Drive with pulley motor 0.96

Drive via secondary transmisson 0.94 0.92

via secondary transmissionand fluid cluth

0.9 0.85 0.95-1.0

with pump / hydraulic motor 0.86 0.80

Whilst the mechanical efficiency leads to the power to be installed PMhaving to be greater in the case of a positive power PTr on the pulley,

braked conveying systems can possibly be provided with a drive whoseoutput PM is equal to or slightly lower than the required power PTr on thedrive pulley. For safety reasons a somewhat higher efficiency factor isassumed on braking.

The power capacity of the motors to be provided for the drive isfurthermore influenced by the ambient temperature (coolant temperature)and the altitude above mean sea level (coolant density). The instructionsof the specific manufacturer should be observed. For air-cooled motors,standard conditions imply a coolant temperature of between 30 and 40Cand installation altitudes of up to 1000 m above mean sea level. Whererelevant, special requirements concerning starting-up of the system orextreme power peaks due to section loading are to be taken into accountin selection of the motor construction.


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D 3.4 Selection from the rated output values (acc. to DIN 42 973 standards)

Outputin kW

Outputin kW

Outputin kW

1.52.2

34

5.57.51115

18.5

22303745557590

110132

160200250315400500630

In order to attain favourable starting and operating properties, the type ofmotor (squirrel cage rotor or slipring rotor) and of clutch are to beadapted to the specific application. The decisive factor here is startingfactor KA, by which the ratio of maximum starting torque to rated torque isdetermined, so that the maximum torque on starting amounts to

The magnitude of the rated driving torque is determined by the enginesize selected or - when a fluid clutch is used - by the clutch size selected.In order not to generate any unnecessarily high belt tensions on starting,it is advisable to coordinate the motor or clutch size as precisely aspossible with the required power PM.

Guide values for starting factors KA

Drive Applicatin Starting factor

Squirrel cage motor withspecial-purpose fluid clutches Large-scale conveying systems 1.2

Slipring motor or thyristorcontrolled start-up

Medium to large-scaleconveying systems 1.2 - 1.4

Squirrel cage motor with fluidclutch

Standard conveyingsystems (from approx.30 kW per motor)

1.5

Squirrel cage motorwith Y-delta connection

Only for conveying systemsstarting up unloaded 1.6

Squirrel cage motor withfull-voltage starting

Small-scale conveying systems(up to approx. 30 kW) 2.0 - 3.0

The torque required for the breakaway and acceleration of a beltconveyor on start-up, which must normally be somewhat greater than theload torque in operation, can be designated by the so-called breakawayfactor.

Guide values for breakaway factor KIDownhill conveying systems, long-distance systems,systems starting up unloaded below 1.3

Standard systems 1.3 - 1.5

Heavy-running systems with high friction above 1.5

For conventionally designed conveying systemsKA> KIis to be selected.If, however, a higher power capacity is installed (PMon> PM) for reasons ofdrive uniformity or owing to only one specific size of drive being available,the starting factor can be determined with the equation

and can be reduced if necessary by the selection of an appropriate fluidclutch or starting circuit.


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In the case of drives with more than one motor, the start-up can beinfluenced by switching on the individual motors with time delay Thestart-up of conveying systems is dealt with in detail in Chapter D - 3.5.1.

D 3.4

When considering sections, the rating of the drives to be installed is to belaid out in the light of the maximum required power, i.e. in accordancewith the criteria set out in Chapter D - 3.3.2.

and when Fmax is positive

or when Fmax is negative

In the least favourable case a start-up process may coincide with themotional resistances Fmax, resulting in the starting factor


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D 3.5 D - 3.5 Peripheral forceCONTI-COM

The peripheral forces occur at the driven or braked drive pulleys and aretransmitted there to the belt to overcome all motional resistances actingon the conveyor belt.

in N

The peripheral forces can act on the belt at one pulley or distributed overa number of pulleys.

The belt tensions on the entry side and the leaving side of the drivepulleys are of decisive significance for further calculation. On the onehand the greater belt tension, generally T1 on the entry side, affects thetensile strength calculation of the conveyor belt; on the other hand theheight of the smaller belt tension, generally T2 on the leaving side,

determines whether power transmission is feasible at all. The target ofthe calculation is thus to determine the necessary magnitude of the belttension on the entry side and the leaving side. These belt tensions arethe outcome of this chapter.

Regardless of whether it is a driving or braking drive mechanism that isbeing investigated, whether the operating state concerned is starting orstopping, or whether it is a multiple pulley drive that is underconsideration, the following designation should be retained under allcircumstances.

in operation T2

On Starting T2ABelt tension at the leaving side of the beltfrom the last pulley at the head

of the conveying system (start of return run) On braking T2B

Setting out from this belt tension that is designated with T2, T2A oder T2Bthe level of the further belt tensions is to be determined in the followingsection D - 4. A design of the tension member in the conveyor belt basedon belt tension T1 or T1A sufficiently accurate only for the standard case ofa horizontal or constant-gradient belt conveyor, ignoring stopping andany additional strains in the case of exclusive head drive.

In the case of a driven belt, the peripheral force FU is positive; thus T1 isgreater than T2. In the case of negative peripheral forces, i. e. of a brakedbelt, T2 is greater than T1.


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For the case of a driven conveyor belt, the belt tensions required forfriction transmission of peripheral force FU result from marginal condition

D 3.5

In this formula is the friction coefficient between the pulley circum-

ference and the belt surface and the degree of wr

Documents

Contitech-ConveyorBeltDesign