Jacobsen SLF 1880, Technical/Repair Manual

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8F-42
hydrostatic drive circuit, including the traction pump,
front wheel motors or 4WD valve. Proceed with an
Instrument Test (Section 8G).
Figure 8F-1. Tow Valve
FRONT TRACTION MOTOR TEST
The front traction motor case drain is used to return
internally bypassed hydraulic oil to the hydraulic tank.
1. Shut off the engine and remove the ignition key.
2. Install wheel restraints or with the tractor on con-
crete or asphalt, secure the mower to a stationary
object, such as a pole or tree.
3. Remove the case drain hose from the front trac-
tion motor to be tested. Immediately plug the
hose.
4. Position a drain pan (minimum capacity 1 gallon
(3.8 liters)) near the wheel motor.
5. Install a separate test hose on the case drain fit-
ting and place the free end in the container.
6. Start the engine, set engine to high idle speed and
in two wheel drive, push the traction pedal forward
for 15 seconds.
7. Shut off the engine and remove the ignition key.
8. Measure the amount of oil collected from the case
drain leakage from the 15 second test and multiply
x 4 to get gallon per minute of oil internally
bypassing the wheel motor.
Conclusion
• If oil from the case drain is less than 0.5 gpm (1.9
lpm), the motor is not at fault. Perform same test on
other front traction motor. Proceed to instrument test
(Section 8G)
• If the oil from the case drain is 0.5 to 1.5 gpm (1.9 to
5.7 lpm), the traction motor is marginal.
• If the oil from the case drain is more than 1.5 gpm
(5.7 lpm), the traction motor should be repaired or
replaced.
9. Remove the test hose from the motor and plug
from the hydraulic hose. Connect the hydraulic
hose to the traction motor (Figure 8F-2).
Figure 8F-2. Traction Motor Case Drain (Left Front Motor Shown)
Tow Valve
Separate Hose Traction Motor Case Drain (Left Front Motor Shown)