Upper Structure Overruns Excessively When It Stops Swinging - Komatsu Galeo PC800-8 Shop Manual

SEN00794-02
H-25 Upper structure overruns excessively when it stops swinging
Failure • Upper structure overruns excessively when it
phenomenon stops swinging
Relative
information
Wrong adjustment or mal-
1 function of swing motor
Possible causes
(safety valve)
and standard
value in normal
state
2 Leakage in swing motor
Failure • Upper structure overruns excessively when it
phenomenon stops swinging
Relative
information
Malfunction of left PPC
1
valve (swing circuit)
Malfunction of swing
2
control valve (spool)
Possible causes
and standard
value in normal
Malfunction of swing con-
3
state
trol valve (suction valve)
Malfunction of swing motor
4
(suction valve)
Malfunction of swing motor
5
(check valve)
36
Cause Standard value in normalcy and references for troubleshooting
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Left work equipment control lever
If the oil pressure is still abnormal after adjustment, the safety valve may
malfunction. Check the safety valve directly.
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Left work equipment control lever
Swing relief (in either direction)
Cause Standard value in normalcy and references for troubleshooting
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Left work equipment control lever
Swing RIGHT/LEFT stroke end
The spool of the swing control valve may malfunction. Check it directly.
The suction valve of the swing control valve may malfunction. Check it
directly.
(The suction valves of the right and left swing control valves can be
checked by exchanging them with each other and seeing the change of
the phenomenon.)
The suction valve of the swing motor may malfunction. Check it directly.
(The suction valves of the right and left swing motors can be checked by
exchanging them with each other and seeing the change of the phe-
nomenon.)
The check valve of the swing motor may malfunction. Check it directly.
(The check valves of the right and left swing motors can be checked by
exchanging them with each other and seeing the change of the phe-
nomenon.)
(1) The upper structure overruns excessively when it
stops swinging in both directions.
Swing relief
(in either direction)
(2) The upper structure overruns excessively when it
stops swinging in only 1 direction.
40 Troubleshooting
Swing relief pressure
+2.5
28.9 MPa
–0.5
+25
2
{295 kg/cm }
–5
Leakage from swing motor
Max. 10 l/min
PPC valve output pressure
+0.8
2.9 MPa
–0.2
+8
{30 kg/cm 2 }
–2
PC800, 850-8