Hydraulic Pump - jcb JS300 Service Manual

Often the regulator and attendant valves or pump are
combined which makes it very difficult to discover the
reason for the trouble. Inspect the following categories
which will assist in discovering the abnormal point.
1 Filter and Drain Oil Inspection. Inspect the filter
element. Check to see whether there is an
abnormally large amount of foreign matter. There will
be a small amount of metallic powder due to wear of
the shoe or cylinder, but if there is a large amount of
metallic powder in the filter, it may be due to trouble
with the shoe. Also check the drain oil in the pump
casing.
Cause
Are the revolutions - pressure higher
than pre-determined values?
Is the regulator torque setting too high? Re-inspect regulator.
Seizure or damage of pumps internal
parts
Wrong regulator hose connection.
Table 8. When pump flow is extremely low, delivery pressures does not increase
Cause
Regulator breakdown
Seizure or damage of pump internal
parts.
Pump breakdown.
Attendant valve breakdown.
Incorrect regulator hose connection.
Cause
Cavitation.
Damage of shoe caulking part.
Crack in cylinder.
Bad installation of pump.
Relief valve bouncing.
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Hydraulic Pump

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Table 7. Prime Mover Overload
Treatment
Set to pre-determined value.
Replace damaged parts.
Correct hose lines.
Treatment
Repair the regulator
Replace damaged parts.
Replace damaged parts.
Inspect attendant valve.
Correct hose lines.
Table 9. Abnormal Sound and Vibration
Treatment
Prevent cavitation. Check to see if
hydraulic oil is white and cloudy.
Replace piston, shoe, shoe plate.
Replace cylinder
Correct installation.
Repair relief valve.
9813/5100-1
Section E - Hydraulics
Hydraulic System Fault Finding
Abnormal Vibration and Sound. Check to see if
there is any abnormal vibration or sound in the pump
main body. Check to see if it is like the regular
frequency sound of the regulator's working or
attendant valve relief working. If it is an abnormal
vibration or sound, it is possible that there is damage
or cavitation inside the pump.
Measure Pressure of Each Part. When it is a control
problem, do not unnecessarily open ports for
inspection purposes, measure the pressure for each
section and find the abnormal item.
Refer to regulator instructions.
Check the filter or drain oil for signs of
abnormal wear.
Refer to regulator instructions
Check filter, drain oil.
Remove pump and inspect shaft
coupling.
Boost pressure is low. Pump is broken.
Air is sucked by suction pipe. Suction
resistance is high.
Refer to relief valve instructions.
Hydraulic Pump
Note
Note
Note
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