Large Unusual Noise Is Heard When Upper Structure Stops Swinging - Komatsu PC88MR-10 Shop Manual

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)
H-32 Large unusual noise is heard when upper structure stops
swinging
(PC88MR-BAB-400-A-Z0-A)

Large unusual noise is heard when upper structure stops swinging.

Failure
Related
Perform all troubleshooting with working mode set in power (P) mode.
information
No. Cause
Malfunction of back
1
pressure valve
Malfunction of swing
2
motor (safety valve)
Defective seating of
swing motor (suction
3
valve)
Defective swing
4
machinery
40-510
Procedure, measuring location, criteria, and remarks
Back pressure valve of control valve may malfunction.
Check for stuck valve, defects of valve, and fatigue of spring.
Safety valve of swing motor may malfunction.
If normal pressure is not obtained after adjustment, safety valve may have
internal failure.
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.
Swing machinery may have internal failure.
a Check for unusual noise, unusual heat, and metallic powders in drained oil
to make judgment.
PC88MR-10