Specifications

65
7.9 Troubleshoot
If the hydraulic system occurs trouble, find out the possible cause according to
the following tables and repair it.
(1) Control valve
Problem
Possible cause
Remedy
Lower oil pressure and
lower oil amount of the
steering oil circuit
Spool is held up
Disassemble and clean,
renew oil
Slide surface broke down
Replace spool
Spring is broken
Replace spring
Oil hole is blocked
Disassemble and clean
Misadjusted relief valve
Adjust relief valve
Lower oil pressure of
the lifting oil circuit
Spool is held up
Disassemble and clean
Oil hole is blocked
Disassemble and clean
Vibrate and the oil
pressure rises too
slowly
Spool is held up
Disassemble and clean
Exhaust is inadequate
Exhaust fully
The oil pressure of the
steering oil circuit is
more than the specified
value
Spool is held up
Disassemble and clean
Oil hole is blocked
Disassemble and clean
Lower oil amount
Misadjusted relief valve
Adjust
Noisy control valve
Misadjusted relief valve
Adjust
Slide surface worn
Replace relief valve
Oil leakage (outside)
O-ring seal broken down
Replace O-ring seal
Lower adjusting
pressure
Spring is worsen
Replace spring
Valve seat surface is worsen
Adjust or replace relief valve
Oil leakage (inside)
Valve seat surface is worsen
Correct valve seat surface
Higher adjusting
pressure
Valve is held up
Disassemble and clean