Baoli CPDS15 - Page 75

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(d) Without the change of the speed in step, increase the pressure to 20 to 30 kg/cm
2
at a time and run the pump for five minutes. Then increase the pressure to 175 kg/cm
2
.
Each circuit works for five minutes and then renews the return filter.
During the increase of the pressure, observe the change of oil temperature and pump
body surface temperature and working voice. If the oil temperature or pump body surface
temperature is excessively high, decrease the load to reduce the oil temperature, then go
on doing the test.
(e) After the trial run, measure the flow amount through lift speed with the pressure of
175 kg/cm
2
of the relief valve.
7.2.2 Troubleshoot
If the hydraulic system has a fault, find out the possible cause according to the
following tables and repair it.
1. Control valve
Problem
Possible cause
Remedy
Lower oil pressure of the lifting oil
circuit
Spool is held up
Disassembly and clean
Oil hole is blocked
Disassembly and clean
Vibrate and the oil pressure rising
slowly
Spool is held up
Disassembly and clean
Exhaust not fully
Exhaust fully
The oil pressure of the steering oil
circuit is more than the specified
value
Spool is held up
Disassembly and clean
Oil hole is blocked
Disassembly 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 aging or
broken down
Replace O-ring seal
Lower setting 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 setting pressure
Valve is held up
Disassembly and clean