OPERATOR'S MANUAL MAINTENANCE

Section E - Hydraulics
Fault Finding
Hydraulic Pump
E-240 E-240
9803/9880-3
Hydraulic Pump
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.
2 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.
3 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.
Table 6. Prime Mover Overload
Table 7. When pump flow is extremely low, delivery pressures does not increase
Table 8. Abnormal Sound and Vibration
Cause Treatment Note
Are the revolutions - pressure higher
than pre-determined values?
Set to pre-determined value.
Is the regulator torque setting too high? Re-inspect regulator. Refer to regulator instructions.
Seizure or damage of pumps internal
parts
Replace damaged parts. Check the filter or drain oil for signs of
abnormal wear.
Wrong regulator hose connection. Correct hose lines.
Cause Treatment Note
Regulator breakdown Repair the regulator Refer to regulator instructions
Seizure or damage of pump internal
parts.
Replace damaged parts. Check filter, drain oil.
Pump breakdown. Replace damaged parts. Remove pump and inspect shaft
coupling.
Attendant valve breakdown. Inspect attendant valve.
Incorrect regulator hose connection. Correct hose lines.
Cause Treatment Note
Cavitation. Prevent cavitation. Check to see if
hydraulic oil is white and cloudy.
Boost pressure is low. Pump is broken.
Air is sucked by suction pipe. Suction
resistance is high.
Damage of shoe caulking part. Replace piston, shoe, shoe plate.
Crack in cylinder. Replace cylinder
Bad installation of pump. Correct installation.
Relief valve bouncing. Repair relief valve. Refer to relief valve instructions.