25 - 2
Fault finding (cont’d)
Section E Hydraulics
9803/6020
Section E
25 - 2
Issue 1
Hydraulic Pump
Symptom
3 Pressure does not increase.
4 Overload at static load.
5 Rotation speed low in dynamic load.
6 Pump produces abnormal heat.
7 Oil leakage
Possible cause
a Relief valve is set low.
b Switching valve or actuator leakage.
c Inadequate pump displacement.
a Pump horsepower settings
b Fault on control devise.
c Component mechanically damaged,
Bearing etc.
a Peak pressure occurs due to
decrease in responsiveness of the
relief valve.
b Decrease in responsiveness of the
control device.
a Increase in pump leakage.
b Component mechanically damaged,
Bearing etc.
c Seizure or wear of pump internal
parts.
a Damage to o-rings or seals, confirm
the oil leakage points and measure
for abnormal pressure.
b Damage to oil seal, check for
damage due to foreign matter and
measure for abnormal pressure.
c Wear of seal due to contact with
input shaft.
d Loose plugs.
Remedy
Reset the relief valve.
Replace the switching valve actuator.
Replace the pump.
Reset the pump.
Fix damage caused by foreign matter or
replace the pump.
Replace the damaged parts
Reset the pressure.
Flush the circuit.
Change the hydraulic oil.
Check for abnormal vibration of the circuit
and measure pressure, if found replace the
relief valve.
Check for foreign matter clogging the
servo line. If found remove the foreign
matter.
Check for debris on each sliding part of
the control devices. Fix the damage
caused by the foreign matter.
Measure actuator speed, replace pump.
Replace the damaged parts
Reset the pressure.
Flush the circuit/change the hydraulic
oil.
Replace damaged parts or pump.
Replace damaged seals.
Replace damaged seals.
Replace input shaft or pump.
Tighten plugs or replace seals.
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