Section 4
MAINTENANCE
4-57
785 Motor Grader
TROUBLESHOOTNG CHARTS
HYDRAULIC SYSTEM
SYMPTOM CAUSE REMEDY
Grader Will Not Move Transmission fluid low Add transmission fluid.
Parking brake engaged Disengage parking brake.
Throttle not at idle Set throttle to idle.
Check that rpm is less than 1200 Lower rpm to 1200 or less.
No power to shifter Check for power at shifter and
correct if defective.
Check that APC is operating Correct defect.
No Hydraulic Steering Power Steering pump bad Replace pump.
Relief valve bad Replace valve.
Brake charge valve bad Replace valve.
Steering valve bad Replace valve.
Slow Hydraulic Functions Low oil level Add oil.
Air in hydraulic oil Inspect suction side hoses and
fittings.
Engine rpm low Inspect and adjust speed control.
Hydraulic strainer clogged Change strainer.
Hydraulic standby pressure too low Adjust. See your authorized dealer.
Low pump flow (worn pump) See your authorized dealer.
Hydraulics Overheat Excessive load Reduce load.
Low oil level Fill to proper level.
Oil cooler clogged Clean and check airflow.
Max pressure on the valve is set Adjust pressure setting.
lower than the maximum pressure
on the pump causing pump to
operate all the time
Hydraulic Functions Drift or Settle Cylinder or control valve leaking Repair leakage.
Contamination in valve bore See your authorized dealer.
Score valve bore or bent valve spool See your authorized dealer.
Foaming Oil Incorrect type of oil Use recommended oil.
Air leak on suction side of pump Tighten fittings and inspect hoses for
damage.
Oil level too high or low Adjust to FULL mark on dipstick.
Hydraulic Pump Leaking Worn shaft seal See your authorized dealer.
Capscrews holding pump housing Tighten capscrews.
loose
Courtesy of Machine.Market
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