Hydraulic System Fault Diagnosis And Correction - HANGCHA Mini Range CDD12-A2MJ-SZ Operation And Maintenance Manual

2.3 Hydraulic system fault diagnosis and correction

Fault
No oil pumps
from the pump
Low oil pressure
of oil pump output
Noise of oil pump
Gear pump
works
Gear pump
no work
Forks do not
drop down
Pressure of
safety valve is
unstable or can't
be adjusted
Probable cause
Low oil level
Blocking of strainer
Bearing worn; retainer,
O-ring damage
Adjustment failure of safety
valve
Air in the oil pump
Cavitation arising from the
strainer blocking
Cavity caused by the high
viscosity of hydraulic oil
Bubble in the hydraulic oil
Oil way block or damage
Lifting inching switch loosen
or damage
Motor or circuit fault
Solenoid valve block
damage
Pressure adjusting
loosen
Pressure adjusting spring
deformation or damage.
Safety valve spool wear or
sticking
Pump failure
Corrective action
Fill to the specified oil level
Clean oil pipe and oil tank. If hydraulic oil is
dirty, please change it.
Change the bad spare parts
Rise pressure with pressure gage
Fill hydraulic oil to the oil tank, use the pump
after bubble vanishing
Adjust or replace soft tube and clean the
strainer
Replace new hydraulic oil, whose viscosity
suits pump running speed. Work only when
the oil temperature is normal
Check the reason for the bubble and then
take measures
Repair or replace
Re-fix or replace
Repair
or
Repair or replace
screw
Re-adjust and lock.
Replace
Replace or clean to reassemble.
Repair pump
67