PISTON PUMP
Symptoms Major causes Remedies
Noise is too loud, unusual
sound is heard
• Suction hose is crushed or suction filter
is clogged
•
Joint in the suction side is loose and
sucking air
•
Cavitation is being produced due to too
high viscosity of the hydraulic oil
•
Pump and engine are not center
aligned
•
Frothing of hydraulic oil
• Engine RPM is too high
• Mechanical damage to the parts (e.g.,
bearing)
•
Remove the dirt and correct the crushing.
• Retighten each joint.
• Replace with hydraulic oil of proper viscosity.
• Center them again.
• Investigate the cause of frothing and correct it.
• Run at the rated RPM.
• Replace the damaged part(s) or the pump.
Discharge is insufficient • Engine RPM is too low
• Oil temperature is too high
• Viscosity of hydraulic oil is too high
• Pump volume efficiency becomes low
• Hydraulic oil tank level is too low
• Clogging in the suction piping or the
suction filter
• Leak volume of hydraulic devices other
than the pump is increased
• Run at the rated RPM.
• Stop running, and check the temperature again
after the oil cools down.
•
Replace with hydraulic oil of proper viscosity.
• Replace the pump.
• Add oil to the specified level.
• Clean the piping.
• Repair or replace the leaking hydraulic device.
Pressure is not increased • Set pressure for the relief valve drops
• Leak volume of hydraulic devices other
than the pump is increased
• Pump volume efficiency becomes low
• Set the relief valve pressure again.
• Repair or replace the leaking hydraulic device.
• Replace the pump.
Abnormal heat is gener-
ated
•
Leak volume from the pump is in-
cr
eased
• Mechanical damage to the parts (e.g.,
bearing)
•
Seizing on the sliding part
• Replace the pump.
• Replace the damaged part(s) or the pump.
• Replace the damaged part(s) or the pump.
Oil leak •
Seals are damaged
• Sliding part between the shaft and the
oil seal is worn out
• Plugs and bolts are loosened
• Replace the seal(s).
• Replace the shaft or the pump.
• Retighten the plugs and bolts, or replace the
seals.
PISTON PUMP
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