Seminar on “The Effect of Gang Angle of offset Disc Harrows on Soil

Tilth, Work Rate and Fuel Consumption” By

SHAIKH AMIR JAMEER2012AE/54B

DEPARTMENT OF FARM MACHINERY AND POWERCOLLEGE OF AGRICULTURAL ENGINEERING AND

TECHNOLOGYVASANTRAO NAIK MARATHWADA KRISHI VIDYAPEETH

PARBHANI 431 402

INTRODUCTIONOffset disc harrow:-

It is a secondary tillage implement which pulverises, smoothens, and packs the soil in seed bed preparation and control weeds.

In offset disc harrow two gangs are fitted one behind the other.

The soil is thrown in both directions because discs of both gangs faces in opposite directions.

The angels between the gangs of disc harrow can be adjusted to meet field condition.

Components of Disc Harrow

Disc :-

Gang:-

Gang axel:-

Gang angle:-

Gang control lever:-

Fig 1. Offset Disc Harrow

Working Principle

off-set disc harrow is based on the working principle that side thrust against the front gangs is opposed by the side thrust of the rear gang.

Objective:- The effect of gang angle of offset disc harrow on

Soil tilth,Theoretical work rate, andFuel consumption

Material and Methods 1) Tractor

A four-wheel drive, 59 kW (44 hp) tractor equipped with a tractor performance monitor, which provide relevant information such as: engine speed, actual forward speed, wheel slip and fuel consumption per hour.

Tyres

Axial Load kn

Inflation pressure kpa

Dimensions of tyres

Front 29.15 152 13.6R 24Rear 29.10 124 16.9R 34

2) ImplementA trailed-type medium-weight offset disc harrow with the following specifications was used in the field trials.

3) Data acquisition systemA portable computer-based recording system was developed, which analyses the signals from the tractor performance monitor sensors as well as the information from a 50 kN load cell based pull measuring system.

Disc Diameter, mm

Number of discs

Static weight per

disc, N

Disc spacing,

mm

Max. working

width, mm610 20 650 230 2350

RADAR Actual forward speed

FUAL FLOWConsumption per hour

MAGNETIC PROXIMITYEngine speed

MAGNETIC PROXIMITYWheel speed

POSITIONtiming active

SENSORSTractor performance

monitor

LOAD CELLDrawbar pull

TERMINAL BORARD AND CONDITIONER

Data acquisition board

PORTABLE COMPUTER

DERIVATION

4)Soils

Two fields with different soil types were selected(a) Site 1:- clay loam; and(b) Site 2:- loamy sand. These fields, located on private farms, soil conditions in each

site are presented in following Table.

Soil condition: Average result in the 200 mm top layer

5) Test Procedure

At the maximum angle between disc gangs, and throttle set to 1800 rpm, a preliminary test was run, with the operator shifting to a higher gear, step by step.Same test was repeated at a lower angle between disc gangs.After the two combinations of throttle, gear and gang angle were set, defining two treatments, the actual measurements were taken in 50m runs, with four replications.Average depth of soil layer was obtained from at least 20 value along 50m run Average working width was obtained from 12 direct measurements across each 50 m harrowed path .

Result and Discussion

At site 1 (clay loam), the maximum gang angle between the disc gangs was found to be 46o ,while at the site 2 (loamy sand) it was found to be 33o.

The gang angles were re-adjusted to 37o and 25o at site 1 and site 2 respectively. At the same time, the speed was increased from 5.8 to 6.9 km/h at site 1 and from 4.9 to 6.6 km/h at site 2. and the results observed are tabulated in table no 4.

Average results from four replications at each gang angle, at sites 1 & 2.

Angel between gangs, degree

Engine

speed

under

load, rpm

gear

Forward

speed,

km/h

Working

depth, m

Wheel

slip%

Theoretic

al work rate ha/ hr.

Fuel consumption, l/ha

Drawbar pull Kn

Drawbar

power

Kw

Site 146

(Max.)

1670 15 5.80 0.194 7 1.21 11.69 18.68 3.11

37 1681 17 6.90 0.188 5 1.46 9.96 15.16

29.05

Site 233

(Max.)

1712 13 4.93 0.270 16 1.09 11.06 15.28

21.67

25 1626 17 6.61 0.270 11 1.46 9.34 11.79

20.91

Angle between disc gangs ,deg

Mean ,mm Standard deviation ,mm

46 44.2 7.437 42.8 12.7

Table 5 Adjusted MWD at each angle between disc gangs at site 1

Table 7 .Adjusted MWD : At each angle between disc gangs at site2

Angle between disc gangs ,deg

Mean ,mm Standard deviation ,mm

33 12.9 7.925 11.1 4.8

K value SourceDegree

s of freedo

m

Sum of square

s Mean

square F value prob

1 Replications 7 759.037 108.434 1.0048 0.4976

2 Angle 1 8.702 8.702 0.0806-3 Error 7 755.418 107.914

total 15 1523.157

Table 6Adjusted MWD : analysis factorial ANOVA for replications (1-8) and angles (46 and 37)at site 1.

Forw

ard

spee

d km

/h

Fig. 1:- Variation in forward speed at each gang angles

Theo

retic

al w

ork

rate

ha/

hr

Fig. 2:- Variation in theoretical work rate at each gang angles

Fig. 3:- Variation in fuel consumption at each gang angles

Fuel

con

sum

ptio

n l/h

a

Fig. 4:- Variation (%), after reducing the angle between the gangs

Conclusion

In the light soils tested, higher work rates and lower values of fuel consumption per unit of cultivated area were attained with no visible difference in soil tilth.

operating the disc harrows at a lower gang angle and shifting to a higher gear in the tractor.

References:-

The effect of gang angle of Offset disc harrows on soil tilth, work, and rate and fuel consumption by Joao M.serrano; J.O. Peca; M.Carvalho; M. Nunes; Ribeiro; F.santos

Universidad de Evora, Departamento de Engeharia Rural, Nucleoli da Mitra Apartado 94, 7002-554 Evora, Portugal.

White WM (1993) Dry aggregate distribution in soil sampling and method of analysis, pp 659- 662. Levis publisher Canada

Singh jay; Ganguly Purnima; Singh K N (1978) Effect of soil and implement parameter on the depth of penetration of disc harrow.

Topic Is Open For Discussion