Baoli CPD10 - Page 112

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4. Trial run
After installing the gear pump in the truck, check it reassembled for specified
performance and do the trial run for it. If the pump’s gears are seized or internal parts
worn excessively, you should renew the hydraulic oil and filters or clean them. The trial
run procedures are as follows:
(a) Install the gear pump in the truck. Then install a pressure gauge in pressure
inspection port of the control valve.
(b) Loose the adjustment screw of the relief valve and run the pump at 500 to 1000
rpm for ten minutes. The oil pressure should be lower than 10 kg/cm
2
.
(c) Increase the speed of the pump to 1500 to 2000 rpm for ten minutes.
(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
Spool is held up
Disassembly and clean