Hydraulic Drift Of Work Equipment Is Large - Komatsu Galeo PC800-8 Shop Manual

40 Troubleshooting
H-11 Hydraulic drift of work equipment is large
Failure

• Hydraulic drift of work equipment is large

phenomenon
Relative
information
Defective seal of boom
1
control valve (spool)
Malfunction of boom con-
Possible causes
2 trol valve (safety & suction
and standard
valve)
value in normal
state
Defective seal of boom cyl-
3
inder
Failure
• Hydraulic drift of work equipment is large
phenomenon
Relative
information
Defective seal of arm con-
1
trol valve (spool)
Malfunction of arm
Possible causes
2 control valve
and standard
(safety & suction valve)
value in normal
state
Defective seal of arm
3
cylinder
PC800, 850-8
Cause Standard value in normalcy and references for troubleshooting
Since the spool of the boom control valve (Lo) may have a malfunction,
check it directly.
Since the safety & suction valve (bottom side) of the boom control valve
(Lo) may have a malfunction, check it directly. (The safety & suction
valve may be checked by replacing it with one of another work equip-
ment circuit. After checking, however, be sure to return the safety & suc-
tion valve since its set pressure and structure are different from the
others.)
aPrepare with the engine stopped, then carry out troubleshooting with
the engine at high idle.
R.H. work equipment control lever
Relieved in boom RAISE position
Cause Standard value in normalcy and references for troubleshooting
Since the spool of the arm control valve (Lo) may have a malfunction,
check it directly.
Since the safety & suction valve (head side) of the arm control valve
(Lo) may have a malfunction, check it directly. (The safety & suction
valve may be checked by replacing it with one of another work equip-
ment circuit. After checking, however, be sure to return the safety & suc-
tion valve since its set pressure and structure are different from the
others.)
aPrepare with the engine stopped, then carry out troubleshooting with
the engine at high idle.
L.H. work equipment control lever
Relieved in arm IN position
(1) Hydraulic drift of boom is large
(2) Hydraulic drift of arm is large
SEN00794-02
Leakage from cylinder
Max. 20 cc/min
Leakage from cylinder
Max. 20 cc/min
19