4-5
4.8 MAIN PUMP
Problem
Probable cause
Remedy
1. Insufficient oil discharge
from pump
Low oil level in tank
Add oil.
Air mixed in suction line
Retighten pipe connections.
Clogged suction line or strainer
Clean hydraulic line and
change oil.
Bushing, gear or pump body damaged due to
foreign matter
Clean hydraulic line and
replace pump assembly.
2. Noisy pump
Cavitation due to clogged strainer
Clean strainer or replace filter
element.
Bushing and gear worn or seized
Replace bushing and gear.
Pump body worn or seized
Replace pump assembly.
Improper centering of pump
Adjust.
3. Oil leakage from pump
“O”-ring or oil seal damaged
Replace.
End cover loose
Check bolts and retighten
evenly.
4.9 CONTROL VALVE
Problem
Probable cause
Remedy
1. Plunger fails to operate
normally
Foreign matter in valve
Clean hydraulic line and
change oil.
Lever or linkage bent
Repair.
Plunger bent
Replace valve assembly.
Return spring damaged
Replace.
2. Oil leakage from oil seal
Seal contaminated with paint
Replace seal and clean control
valve.
Foreign matter caught in seal
Replace seal and clean control
valve.
Plunger damaged
Replace valve assembly or
plunger section.
Seal plate loose
Clean and retighten.
Seal damaged
Replace seal.
3. No pressure builds up
Relief valve defective
Replace relief valve assembly.
Relief valve pressure setting improper
Adjust relief valve pressure
setting.
4.10 LIFT CYLINDER
Problem
Probable cause
Remedy
1. Oil leakage
Cap “O”-ring damaged
Replace.
Cap oil seal defective
Replace.
Piston rod damaged or bent
Repair or replace.
2. Cylinder jolts
Piston rod bent
Repair or replace.
Low hydraulic oil level
Add oil to specified level.
Defective pump
See “4.8 MAIN PUMP.”
3. Natural drop of piston
Piston packing damaged or worn
Replace.
Cylinder inner surface damaged or worn
Repair or replace.
Control valve defective
See “4.9 CONTROL VALVE.”
Содержание FD35C9
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Страница 112: ...2 68 Fig 2 182 Connect the hoses 2 to the lift cylinders 1 2...
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