JLG 600SC_660SJC Service Manual - Manual (Page 115)

SECTION 5 - CAT CHASSIS (S/N 0300128000 TO PRESENT)
3121157 – JLG Lift – 5-23
Troubleshooting for Low Pressure Shuttle Valve
TROUBLES (TYPE OF FAILURE) POSSIBLE CAUSES CORRECTIVE ACTIONS
Motor rotates slowly. Operation failure of plunger;
1) Foreign substances are jammed between plunger
and body.
2) Spring is broken. - Remove foreign articles thoroughly. Repair dam-
aged parts, and reassemble the parts after cleanup. If
deep scratches or more than normal wear are found
on the parts, the parts should be replaced with new
ones.
- Replace spring with new one.
Motor does not stop or stops slowly. Plunger does not return;
1) Foreign substances are jammed.
2) Spring is broken.
3) Spring is not assembled. - Remove foreign articles thoroughly. Repair dam-
aged parts, and reassemble the parts after cleanup. If
deep scratches or more than normal wear are found
on the parts, the parts should be replaced with new
ones.
- Replace spring with new one.
- Install spring in proper position.
Rise in oil temperature of circuit Operation failure of plunger
1) Foreign substances are jammed.
2) Orifice is clogged. - Remove foreign articles thoroughly. Repair dam-
aged parts, and reassemble the parts after cleanup. If
deep scratches or more than normal wear are found
on the parts, the parts should be replaced with new
ones.
- Wash the orifice before reassembly.