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Hydraulic System
After the machine has been kept stored for a long time, air in the oil may be separated and accumulate in the upper
section in the cylinder, causing slow response time in operation or reducing cylinder power.
In case these symptoms appear, repeatedly operate all actuators several times.
Symptom
Loader front function is inoperable.
(Hydraulic pump noise level increases)
All actuators have no power.
Only one actuator is inoperable.
Only one cylinder is inoperable or has
no power.
Oil overheats
Oil leak from low pressure hose
TROUBLESHOOTING
Cause
Faulty hydraulic pump
Lack of hydraulic oil
Broken suction pipe and/or hose
Malfunction due to worn hydraulic pump
Decrease in set pressure of main relief valve in
control valve
Lack of hydraulic oil
Trapped foreign matter in hydraulic oil tank
suction filter
Aeration in suction side
Broken control valve spool
Trapped foreign matter in valve spool
Broken pipe and/or hose
Loose pipe line joint
Broken O-ring at pipe line joint
Broken actuator
Broken oil seal in cylinder
Oil leak due to damage to cylinder rod
Contaminated oil cooler
Faulty fan motor and pump
Abnormal fan rotation
Loose clamp
Faulty suction pipe
11-3
Solution
* Repair, Replace
Refill
* Repair, Replace
* Replace
* Adjust
Refill
Clean
Retighten
* Replace
* Repair, Replace
* Repair, Replace
Retighten
* Replace
* Repair, Replace
* Repair, Replace
* Repair, Replace
Clean
* Repair, Replace
* Repair, Adjust
Retighten
* Repair, Replace
* Consult your authorized Hitachi dealer.
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