IV-39
HYDRAULIC UNITSGEAR PUMP
Symptom Probable Causes Remedy
Pump won·t discharge. • Direction of rotation is reversed.
• Oil level in the tank is low.
• Suction side pipe or suction filter is
clogged.
• Hydraulic oil·s viscosity is too high.
• Speed is low.
• Run the pump in the specified direc-
tion.
• Replenish the oil to the specified level.
• Clean the pipes.
• Replace the hydraulic oil with oil of the
proper viscosity.
• Run the pump at the specified speed.
Noise level is high.
Abnormal noise is
generated.
• Suction side hose is crushed, the suction
filter is clogged or cavitation is occur-
ring.
• Suction side joint is loose and air is be
-
ing sucked in.
• Hydraulic oil·s viscosity is too high, and
cavitation is occurring.
• Pump and engine are out of center with
respect to each other.
• There are bubbles in the hydraulic oil.
• Remove the dirt or eliminate the
crushed condition of the hose.
• Tighten all the joint.
• Replace the hydraulic oil with oil of the
proper viscosity.
• Correct the centering between the
pump and engine.
• Investigate the cause of the bubbles and
correct it.
Oil leaks from oil
seals.
• Oil seal is worn, damaged or deformed. • Replace the oil seal.
Oil leaks from mat-
ing surfaces between
housing and flange and
between housing and
cover.
• Body seal is damaged or worn by rub-
bing.
• Replace with a new part.
Discharge volume is
low.
• Bushing seal is damaged.
• Cavitation is occurring.
• Aeration is occurring.
• Viscosity of the hydraulic oil is too
low.
• Replace the bushing.
• Clean the suction filter and suction side
piping.
• Check for insufficient tightening of
pipes, etc. and repair.
• Replace the hydraulic oil with oil of the
proper viscosity.
TROUBLESHOOTING
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