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2.3 Hydraulic system fault diagnosis and correction
Fault Probable cause Corrective action
No oil pumps
from the pump
Low oil level Fill to the specified oil level.
Blocking of strainer
Clean oil pipe and oil tank. If hydraulic oil is dirty,
please change it.
Low oil
pressure of oil
pump output
Bearing worn; retainer, O-ring
damage
Change the bad spare parts
Adjustment failure of safety valve Rise pressure with pressure gage.
Air in the oil pump
Fill hydraulic oil to the oil tank, use the pump after
bubble vanishing
Noise of oil
pump
Cavitation arising from the strainer
blocking
Adjust or replace soft tube and clean the strainer
Cavity caused by the high viscosity
of hydraulic oil
Replace new hydraulic oil, whose viscosity suits pump
running speed. Work only when the oil temperature is
normal
Bubble in the hydraulic oil
Check the reason for the bubble and then take
measures
Forks can’ t lift
Gear
pump
works
Oil way block or damage Repair or replace
Gear
pump no
work
Lifting inching switch loosen or
damage
Re-fix or replace
Motor or circuit fault Repair
Forks do not
drop down
Solenoid valve block or damage Repair or replace
Pressure of
safety valve is
unstable or
can’t be
adjusted
Pressure adjusting screw loosen Re-adjust and lock.
Pressure adjusting spring
deformation or damage.
Replace
Safety valve spool wear or sticking Replace or clean to reassemble.
Pump failure Repair pump
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