JLG 600SC_660SJC Service Manual - Manual (Page 117)

SECTION 5 - CAT CHASSIS (S/N 0300128000 TO PRESENT)
3121157 – JLG Lift – 5-25
Troubleshooting for Low Pressure Relief Valve
TROUBLES (TYPE OF FAILURE) POSSIBLE CAUSES CORRECTIVE ACTIONS
1. Rise in circuit temperature Operation failure of relief valve;
Spring is broken. - Replace spring with new one. Then, remove foreign
articles thoroughly. Repair damaged parts, and reas-
semble 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.
2. Abnormal noises such as cavitation Lowered set pressure of relief valve;
1) Seat failure due to foreign substance jamming
2) Spring is broken.
3) Wear-out of spring
4) Lack of necessary parts - 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. Then, remove foreign
articles thoroughly. Repair damaged parts, and reas-
semble 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.
- Check the parts again.