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Tractor Performance

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Title: Tractor Performance


1
WELCOME
2
Tire inflation and its influence on drawbar
characteristics and performance
  • Presented by
    - Utpal Kumar Mishra

  • 12AG61R05

3
Need Of Research
  • Drawbar performance Ability of tractor to
    develop sufficient drawbar pull, within the
    acceptable range of slip in the on road or
    off-road condition.
  • About 20-55 of energy transferred to drive wheel
    is wasted in soil-tire interaction. This energy
    is useless or causes soil compaction.
  • Common speed of tractor during field operation is
    3kph to 15 kph, unfortunately within this range
    slip gets its maximum value.(Reducing slip means
    more Tractive efficiency ).
  • Ways to reduce slip -

4
Need cont
  • Enlargement of the tire contact area reduces
    negative effect of tractors movement on the
    field and it restricts physical degradation of
    soil characteristics (structure damage,
    compaction, etc.).
  • On deformable surfaces, high inflation pressure
    results in increased ground penetration work ,
    thus higher rolling resistance.
  • Tire inflation has significant effect on contact
    area between tire and soil and so on the tractive
    efficiency.

5
Objective
  • To evaluate the advantages of low inflation
    pressure and its effect on drawbar pull.
  • Application of obtained results in measurement
    with a mounted plough.

6
Theoretical analysis
  • Gross traction, moving the tractor forward is a
    result of interaction between soil and the engine
    toque transferred onto tires Circumference.
  • The transfer circumference force causes the soil
    shear stress, which is a direct proportional to
    the tangential force, and the indirect
    proportional to shear area, in which the force
    acts.

7

Theoretical analysis
contda. Shear plate apparatus for measuring
soil strength b. Shear force versus shear
displacement curve for various loads
8

Theoretical analysis contdFmax AC
W tan f Fmax / A C (W/A) tan f
C p tan fFor loose sand and most of the
soil, the shear stress increases rapidly with
shear displacement and then approaches a constant
value. This shear stress shear displacement
relationship is proposed by Janosi and
Hanamoto.(2 , 8)
Here, j Shear displacement and
K Shear deformation modulus
9
K is the measure of magnitude of the shear
displacement required to develop maximum shear
stress. Value of K determines the shape of the
curve. Its value is
represented by the distance between the vertical
axis and the point of intersection of the
straight line tangent to the shear curve at
origin and Horizontal line represent maximum
shear stress.
Theoretical analysis contd..
10
Total tractive force
  • i is slip

11

Theoretical analysis
contd..Measured surface pressure distribution
(in psi) under a smooth tire for the same
vertical load but different inflation pressure.
Above at 10 psi, below 6 psi. (off road Vehicle
engineering principles, C E Goering, M L Stone, D
Smith P K Turnquist)
12


Theoretical analysis contd..Three - dimensional
views of pressure distribution under a smooth
tire on soil A, Inflation pressure, 14 p.s.i.
B,10 p.s.i. C, 6 p.s.i. (Vanden Berg and Gill,
Amer. Soc. Agr. Engin. Trans. (460).(soil
dynamics in tillage traction, W R Gill )
13
Drawbar performance curve
(Theory of ground vehicles, J Y Wong.)
14
Relation between drawbar power and slip
with drawbar pull
(Theory of ground vehicles, J Y Wong.)
15
Tire Description
  • Measurements of tire in?ation in?uence on drawbar
    characteristics and performance, were performed
    with the use of radial tire sets. The ?rst step
    in the research was to measure drawbar
    characteristics. In the next stage, the tractor
    was equipped with a plough under the same
    conditions.
  • The following radial-ply tires were used
  • I. Tires with narrow treads
  • Front tire 14.9 R28
  • Rear tire 18.4 R38
  • II. Tires with wide treads
  • Front tire 520/60 R28
  • Rear tire 650/60 R38

16
Tires and inflation pressure used during test
Axle Tire description Inflation pressure (kpa) Static weight (kg)
Front wheel 14.9 R28 170 4540
Rear wheel 18.4 R38 170 3240
Front wheel 14.9 R28 255 4540
Rear wheel 18.4 R38 255 3240
Front wheel 520/60 R28 75 4580
Rear wheel 650/60 R38 65 3360
Front wheel 520/60 R28 180 4580
Rear wheel 650/60 R38 180 3360
17
Soil and other sensors used
  • Soil type loam soil, moisture content from
    21.69 to 22.9.
  • Speed range of 5, 8 and 10 kph with full fuel
    supply.
  • A RDS TGSS radar sensor was mounted onto tractor
    frame for measuring actual velocity of tractor.
  • Tire footprint was obtained by multiple elevating
    and lowering of wheel along horizontal plane till
    clear footprint profile was obtained.
  • Lucia G evaluation software was used for
    measurement of contact area.
  • After drawbar test, measurements with a plough
    were carried out with same inflation and
    adjustment settings.
  • Real and theoretical velocity, fuel consumption,
    engine speed, depth and width of plough were
    recorded.

18
Measured and calculated parameters at testing tire
Tires with narrow tread
Tires with wide tread
Axle Inflation pressure (kpa) Tire footprint (cm²)
Front wheel 75 2123
Rear wheel 65 2390
Front wheel 180 1702.1
Rear wheel 180 1822.5
Axle Inflation pressure (kpa) Tire footprint (cm²)
Front wheel 170 1527.8
Rear wheel 170 1569.5
Front wheel 250 1373.1
Rear wheel 250 1181.4
19
Vehicle traction ratio versus
slipHighest values 0.57 0.61 .VTR increased by
7.01 and tire footprint area by 21.25.
(Tire with narrow tread )
20
Drawbar power specific fuel consumption
characteristics versus drawbar pull.
(Tire with narrow tread)
21
  • Highest values 0.66 0.74. VTR increased by
    12.12 and tire footprint area by 28.23.
  • (Tire with Wide tread)

22
Tire with wide tread
23
Results contd
  • The maximum drawbar power is increased at 5, 8
    and 10 kph by 9.1, 9.6, and 14.6,
    respectively.
  • The tire footprint increased at the rear and
    front tires by 31.1 and 24.7, respectively.
  • The specific fuel consumption at maximum drawbar
    power was reduced at 5, 8, 10 kph by 3.4, 8.1,
    and 16, respectively in comparison with higher
    inflation pressures.
  • If the tractor works with lower tire inflation by
    setting travel speed at 5 kph, it reaches fuel
    consumption saving up to 1.64 l h1.

24
Result of ploughing set measurement
Width (mean) (m) Depth (mean) (m) Tractor speed (kph) Slip Effective performance (ha/h) Fuel consumption ( l/ha)
2.71 ( with wide tread, front 75kpa, rear 65kpa ) 0.25 4.70 19.11 (13 ) 1.27 (8.5 ) 24.33 (8.8)
2.68 ( Both tire 180 kpa ) 0.26 4.35 21.99 1.17 26.68
2.64 ( with narrow tread, 250 kpa) 0.25 4.44 24.73 1.17 26.55
2.60 ( 170 kpa ) 0.25 4.66 20.74 (16 ) 1.21 (3.4 ) 25.53 (3.8 )
25
Conclusion
  • The results of test measurements revealed that
    reducing tire inflation of appropriate tire types
    can improve the drawbar characteristics and,
    consequently, fuel consumption.
  • However, low tire inflation does not guarantee
    better drawbar characteristics in all cases.
  • From the results of the above-mentioned
    experiment, it can be concluded that lower tire
    inflation has the largest influence on
    performance at aggregation with implements,
    requiring a lower working speed and a large
    demand of drawbar force, therefore practical
    benefits are in the case of field operations with
    increased drawbar pull requirements.

26
Conclusion contd
  • The tractor should only be operated until the
    value of slip where VTR reaches its maximum.
  • In case the VTR grows monotonously, the slip
    should not go over the transitional zone into the
    linear part of the curve.
  • The results show that the slip should not exceed
    15 because it causes a decrease of engine power
    efficiency transmitted to the surface.
  • As follows from the presented characteristics,
    the tractor transferred larger drawbar pull to
    the surface at the same ground speed and lower
    inflation pressure.
  • Larger transferred drawbar pull means an increase
    of drawbar power and thus tractor performance.

27
References
  • 1 Grec?enko A. Vlastnosti terennich vozidel.
    VS?Z v Praze 1994 118 s.ISBN 80-
  • 213-0190-2 in Czech.
  • 2 Bekker MG. Introduction to terrain-vehicle
    systems. MichiganUniversity of
  • Michigan Press 1969.
  • 3 Burt EC, Lyne PW, Meiring P, Keen JF.
    Ballast and inflation effect on tyre efficiency.
  • Trans ASAE 198326(5)13524.
  • 4 Gaultney L, Krutz GW, Steinhardt GC,
    Liljedahl JB. Effects of subsoil compaction on
  • corn yields. Trans ASAE 1982(3)5639.
  • 5 Lyasko M. Slip sinkage effect in soilvehicle
    mechanics. doi10.1016/
  • j.jterra.2009.08.005.
  • 6 Vermeulen GD, Perdok UD. Soil compaction in
    crop production. Amsterdam
  • Elsevier 1994. p. 44778.
  • 7 Wong JY, Huang W. Wheels vs. tracks a
    fundamental evaluation from the traction
  • perspective. J Terramech 2006432742.
  • 8 Wong JY. Terramechanics and off-road
    vehicles. Amsterdam Elsevier 1989.
  • 9 Wong JY. Theory of ground vehicles. 3rd ed.
    New York Wiley 2001.

28
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