Swing Acceleration Performance Is Poor Or Swing Speed Is Slow In Only One Direction - Komatsu PC88MR-10 Shop Manual

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)
H-28 Swing acceleration performance is poor or swing speed is slow in
only one direction

Swing acceleration performance is poor or swing speed is slow in only one direction.

Failure
Related
Perform all troubleshooting with working mode set in power (P) mode.
information
No. Cause
Malfunction of swing
1
PPC valve
Malfunction of swing
2
control valve (spool)
Malfunction of swing
3
motor (safety valve)
Defective seating of
swing motor (suction
4
valve)
Defective seating of
swing motor (check
5
valve)
40-506
(PC88MR-L45-400-A-Z0-A)
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
PPC valve output
pressure
If no failure is found by check on cause (1) and upper structure does not
swing when swing control lever is operated with pump pressure at approx. 4
MPa, check whether spool is stuck near NEUTRAL position.
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
After troubleshooting, restore the machine to its original state.
Swing relief
pressure
(pump pressure)
Interchange suction valves on left and right swing sides of swing motor, and
check whether failure symptom changes to make judgment.
When removing valve, check it for sticking and defects.
Interchange check valves on left and right swing sides of swing motor, and
check whether failure symptom changes to make judgment.
When removing valve, check it for sticking and defects.
Swing control
At NEUTRAL
lever
Left swing and
Swing control
right swing
lever
Remove swing
parking brake Swing hydraulic
solenoid valve relief
connector.
0 MPa {0 kg/cm 2 }
Min. 2.65 MPa
{Min. 27 kg/cm }
2
20.5 ± 1.5 MPa
{210 ± 15kg/cm 2 }
PC88MR-10