Hydraulic Drift Of Swing Is Large - Komatsu Galeo PC138US-8 Shop Manual

40 Troubleshooting
H-25 Hydraulic drift of swing is large
Trouble

• Hydraulic drift of swing is large.

• If the swing lock switch is turned ON or the swing holding brake release switch is in the normal posi-
Related
tion, the swing holding brake operates and the disc brake holds the upper structure.
information
• Conduct the troubleshooting in working mode P.
Possible causes Malfunction of swing holding
1
and standard brake solenoid valve
value in normal
state
Malfunction or internal defect
2 of swing motor (holding
brake)
Trouble • Hydraulic drift of swing is large.
• If the swing holding brake release is in the emergency position, the swing holding brake is released
Related
and the upper structure is held with only hydraulic pressure.
information
• Conduct the troubleshooting in working mode P.
Defective sealing of swing
1
control valve (spool)
Defective sealing of swing
Possible causes 2
motor (safety valve)
and standard
value in normal
Defective sealing of swing
state
3
motor (suction valve)
Malfunction or defective
4 sealing of swing motor
(reverse prevention valve)
PC138US, USLC-8
Cause Standard value in normal state/Remarks on troubleshooting
a
Right work equipment control
The holding brake of the swing motor may have a malfunction or
an internal defect. Check it directly.
Cause Standard value in normal state/Remarks on troubleshooting
Sealing of the spool of the swing control valve may have a mal-
function. Check it directly.
The safety valves of the swing motor may have a malfunction.
Check them directly. (They may be checked by exchanging with
each other and checking change of the phenomenon.)
The suction valves of the swing motor may have a malfunction.
Check them directly. (They may be checked by exchanging with
each other and checking change of the phenomenon.)
The reverse prevention valve of the swing motor may have a mal-
function or its sealing may be defective. Check it directly.
(1) When swing holding brake is operated
Keep the engine stopped for the preparations, and keep it
running at high idle during the troubleshooting.
lever
In NEUTRAL
Operated for swing
(2) When swing holding brake is released
SEN02468-01
Solenoid valve output pressure
0 MPa {0 kg/cm }
2
2.84 – 3.43 MPa
{29 – 35 kg/cm }
2
1
25