Section E - Hydraulics
Fault Finding
Hydrostatic Transmission
E - 40 E - 40
9803-9450-2
Checking Motor Leakage Rate
If the motor speed is low and the pump output is normal,
the cause could be excessive internal wear in the motor
which would result in high leakage of oil into the motor
casing. By measuring the amount of oil leaking from the
motor casing back to tank, it is possible to determine if the
motor is worn.
1 Stop the engine.
2 Remove the seat and floorplate to expose the motors.
3 Connect a flowmeter into the top motor drain hose A
or bottom motor drain hose B as required.
4 Install a 0 - 400 bar (0 - 6000 lb/in
2
, 0 - 422 kg/cm
2
)
pressure gauge into the appropriate point on the
pump to measure the pressure generated in the
motor feed line K
Pump Main Relief Pressure Test
Points ( T E-41)
5 Start the engine and drive the machine forward
against a solid, immovable object as shown at C.
Measure the amount of oil expelled from the motor
during one minute’s operation.
At the maximum pressure of 385 bar (5582 lbf/in
2
) the
normal oil leakage should be approx. 17 l/min (3.75 UK gal/
min, 4.5 US gal/min).
Note: The motor leakage at zero pressure is much less
than the rate at higher pressures. This is because at higher
pressures the motor flushing spool is actuated causing the
oil flow through the motor casing to increase. The figure
quoted above is the combined leakage and flushing flows.
If the flow rate is higher than normal, the motor should be
dismantled for repair.
Fig 30.
Fig 31.
A
B
C
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