Hitachi ZX27U-2, Operator'S Manual, Page: 204 / 230

TROUBLESHOOTING
11-2
3. Hydraulic System
Trouble Cause Solution
Insufficient power: all actuators
•
Insufficient engine power
•
Excessively worn hydraulic
pump
•
Main relief valve failure
•
Hydraulic oil is low
•
Suction filter restriction
•
Inspect and repair
•
Replace
•
Re-adjust pressure setting, or re-
place
•
Add hydraulic oil
•
Clean or replace
Insufficient power: front attachment
•
Failure or incorrect pressure set-
ting of main or pilot relief valve
•
Damaged hydraulic cylinder
packing
•
Damaged cylinder piston or cyl-
inder tube
•
Re-adjust pressure setting, or re-
place
•
Replace cylinder packing
•
Replace cylinder piston, cylinder
tube, or the cylinder
Machine does not travel smoothly.
•
Too tight track (sag)
•
Foreign matter, such as rocks,
stuck in the tracks
•
Counterbalance valve failure
•
Travel motor performance drop
•
Adjust track sag
•
Remove foreign matter
•
Replace
•
Replace
Machine mistracks
•
Track sag is not equal on both
sides
•
Hydraulic pump performance
drop
•
Oil leak inside control valve
•
Adjust track sag properly (and
equally on both sides)
•
Replace
•
Replace the control valve
Insufficient swing power or jerky
upperstructure swing
•
Hydraulic pump performance
drop
•
Low pressure valve setting
•
Swing motor performance drop
•
Swing bearing seizure
•
Foreign matter sticking in brake
valve
•
Oil leak inside control valve
•
Replace
•
Adjust pressure setting, or replace
•
Replace
•
Lubricate or replace swing bear-
ing
•
Clean the brake valve
•
Replace the control valve
NOTE: Contact your authorized dealer for any inspection, adjustment, repair, and/or replacement as required.