HANGCHA CPD10J, Руководство по обслуживанию

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4 . Hydraulic system
The high pressure oil from main pump goes to control valve and divide it to two parts by dividing
valve inside control valve: one of them goes to lifting cylinder or tilting cylinder, another part goes to
steering gear with invariable flow to control steering cylinder. When lifting and tilting spool is in
neutral, high pressure oil return oil tank directly from pass way. When pulling lifting spool, high
pressure oil goes by throttle valve and then push piston rod under lifting cylinder piston. When pushing
lifting spool, it is that bottom of lifting cylinder piston connects with low pressure line and then piston
rod drops by deadweight and weight of cargo. In this time, oil from lifting cylinder goes by
unidirectional speed limiting valve so as to control the falling speed. When operating tilting spool, high
pressure oil goes to front house of tilting cylinder and another connects with low pressure line so as to
make mast tilt forward or backward.
Main pump
Trouble Probable cause Corrective action
No oil from oil
pump
Low oil level in tank. Add oil to specified level.
Clogged suction pipe or strainer.
Clean oil line and tank. If oil is dirty,
change.
Low discharge
pressure on oil
pump.
Worn bearing damaged backup
ring and O-ring.
Replace faulty parts.
Maladjusted relief valve.
Readjust to specified pressure using
pressure gauge.
Air in oil pump.
Retighten suction side pipe.
Add oil in oil tank.
Check pump oil seal.
Do not operate pump until bubbles in tank
disappear.
Noisy oil pump
Cavitation due to crushed suction
hose or clogged strainer.
Adjust or replace crushed hose and clean
strainer.
Air being sucked from loose
suction side joint.
Retighten each joint.
Cavitation due to too high oil
viscosity.
· replace with new oil having proper
viscosity for temperature at which pump is
to be operate.
· to operate when oil temperature is normal.
Bubbles in hydraulic oil. Determine cause of bubbles and remedy.
Oil leaking from
oil pump
Faulty oil seal on pump, faulty
O-ring or worn sliding surfaces on
pump.
Replace faulty parts.