GENERAL REQUIREMENTS
1. The tractor shall be clean and shall be tested in normal working conditions.
2. The Radiator, Sump, Hydraulic and other reservoirs shall be filled to the specified levels.
3. Tools, Spare Tyre and Loose accessories and equipment shall be complete as supplied and shall be in normal storage positions.
4. Tyre pressure shall be as per specifications.
5. In conducting the test, Following measuring tolerances shall be observed :
* Distance => ±0.5%.
* Mass => ±0.5%.
* Tyre pressure => ±5%.
PROCEDURE
A – Determination of Horizontal Co-ordinate of C.G.:
1. Determine the mass (m) of the whole tractor, Front Reaction Rf, Rear Reaction Rr, RHS Reaction RRh, and LHS Reaction RLh of the Tractor.
2. Measure the Wheel base (b) of the Tractor.
3. Measure the Rear wheel Track width (t) of the Tractor.
4. Calculate the x co-ordinate (along the plain of symmetry of the tractor) of C.G., by following formula :
Rf
x = ---------- b
m
5. Calculate the y co-ordinate (across the plain of symmetry of the tractor) of C.G., by following formula:
RRh
y = -------- t
m
OR
RLh
y = ------------ t
m
B – Determination of Vertical co-ordinate (z):
1. Suspend the Tractor from front end, by putting a load cell in between the suspension rope / wire.
2. Measure the distance D, from the axis of the rear wheels to the plane containing the point of lifting of the tractor in horizontal position.
3. Put 75 kg mass on the operators seat to compensate the operator’s weight.
4. Measure the Rolling Radius of the Rear Tyre (R).
5. Just lift the tractor from the ground, so that the front wheels are just above the ground level. Measure the load P0, required for lifting, by load cell.
6. Measure the tilt angle α0 at this condition.
7. Now Lift the Tractor at different angles (upto 25º ), from horizontal.
8. As the Tractor is lifted, part of the mass of the tractor at the front will be transferred to the rear and the load Req to lift the tractor get reduced. Measure these loads P0, P1, P2, P3, P4, …………. Pn.
9. Measure the Corresponding Tilt angles α0, α1, α2, α3, α4 ……….., αn.
10. The Vertical co-ordinate z is determined by the following formula :
D ( P0 – Pn )
z = R + ------------------------- t
m ( tan αn - tan α0 )
11. The value of z are determined at different angles and then average of all represents the vertical co-ordinate of the C.G.
