14 - 8
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 Disconnect the motor drain hose A. Connect a hose to
the drain adapter on the motor and insert the end of the
hose into a 6 litres (minimum) measuring jug or
container. Blank the open hose A.
4 On machines from serial no. 678000 a motor flush line B
is connected to the motor casing which must be
disconnected and plugged before proceeding otherwise a
true leakage reading cannot be obtained.
5 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
(see next page for pressure test points).
6 Start the engine and, with the parking brake ON, operate
the motor service. Measure the amount of oil expelled
from the motor during one minute’s operation and
compare with the figures shown in the table below.
Note: If the parking brake will not hold the machine
sufficiently to achieve the necessary line pressure, the
machine should be driven against a solid, immovable object
as shown at C.
If the flow rate is higher than normal, the motor should be
dismantled for repair as the distributor seals are probably
worn.
Section E
Hydraulics
9803/8500
Section E
14 - 8
Issue 1
Problem Solving
Illustration shows typical machine installation.
AA
AA
BB
w
Average motor leakage rate
Pressure - bar (lbf/in
2
)
20 (290) 50 (725) 100 (1450) 150 (2175) 200 (2900) 300 (4350) 400 (5800)
Servo - l/min (UK gal/min) 2.2 (0.48) 2.3 (0.50) 2.4 (0.53) 2.8 (0.62) 3.0 (0.66) 3.7 (0.81) 4.0 (0.88)
US gal/min 0.58 0.60 0.64 0.74 0.79 0.97 1.06
Manual - l/min (UK gal/min) 3.3 (0.73) 3.4 (0.75) 3.5 (0.77) 3.9 (0.86) 4.1 (0.90) 4.8 (1.06) 5.1 (1.12)
US gal/min 0.88 0.90 0.92 1.03 1.08 1.27 1.35
C
325430
325400
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