Komatsu PC200-8M0, Shop Manual, Page: 916 / 1254

500 Troubleshooting of hydraulic and mechanical system (H-mode)
H-24 Upper structure overruns remarkably when it stops swinging
40-500
36
PC200, 200LC, 220, 220LC-8M0
SEN06139-00
H-24 Upper structure overruns remarkably when it stops swinging
Failure (1) Upper structure overruns excessively when stop swinging in both right and left directions.
Related infor-
mation
q
Perform all troubleshooting with working mode in power mode (P).
Probable
causes and cri-
teria
Cause Criteria and troubleshooting procedure
1
Improper adjustment or Mal-
function of swing motor
(safety valve)
a
Be ready with engine stopped, then troubleshoot with engine
high idle.
Swing lock
switch
Left work equipment
control lever
Swing relief pressure
ON
Swing to hydraulic
relief
28.9 to 3 2.9 MPa
{295 to 335 kg/cm
2
}
If normal oil pressure is not obtained by adjustment, swing motor
safety valve may malfunction or may internal defect. Check it.
2 Defective swing motor
a
Be ready with engine stopped, then troubleshoot with engine
high idle.
Swing lock
switch
Left work equipment
control lever
Leakage from swing
motor
ON
Swing to hydraulic
relief
Below 10
l
/min
Failure (2) Upper structure overruns excessively when stop swinging in only one direction.
Related infor-
mation
q
Perform all troubleshooting with working mode in power mode (P).
Probable
causes and cri-
teria
Cause Criteria and troubleshooting procedure
1
Malfunction of swing PPC
valve
a
Be ready with engine stopped, then troubleshoot with engine
high idle.
Left work equipment control
lever
PPC valve output pressure
Neutral
0 MPa
{0 kg/cm
2
}
Left swing
Right swing
2.84 to 3.43 MPa
{29 to 35 kg/cm
2
}
2
Clogged swing PPC slow
return valve
Swing PPC slow return valve may malfunction. Check it.
*
This failure can be checked by interchaning right and left swing
PPC slow return valve and watching how condition changes.
3
Malfunction of swing control
valve (spool)
Spool of swing control valve may malfunction. Check the spool.
4
Malfunction of swing motor
(suction valve)
Suction valve of swing motor may malfunction. Check the valve.
* This failure can be checked by interchaning right and left suc-
tion valves of swing motor and watching how condition
changes.
5
Malfunction of swing motor
(check valve)
Check valve of swing motor may malfunction. Check the valve.
* This failure can be checked by interchaning right and left suc-
tion valves of swing motor and watching how condition
changes.