TCM FB30-8 - Troubleshooting Guide

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7.2.3 TROUBLESHOOTING GUIDE
If any problem occurs in the hydraulic system, locate the cause of the problem and take
necessary measures, referring to the tables given below.
(1) Control valve
Problem Cause Remedy
The control ow is not a specied
value.
Relief valve malfunctioning Readjust.
Noisy control valve Relief valve malfunctioning Readjust.
Oil leaks (external) “O”-ring deteriorated or damaged Replace “O”-ring.
Low pressure setting
Spring defective
Set surface defective
Replace spring.
Readjust.
Replace relief valve.
Oil leaks (internal) Seat surface damaged Correct seat surface.
Noisy control valve Sliding area too worn Replace relief valve.
Pressure setting rises Poppet stuck. Disassemble and clean.
(2) Main pump
Problem Cause Remedy
No oil discharged
from gear pump
Low oil level in oil tank Add oil to specied level.
Clogged suction tube or strainer Clean or change oil if necessary.
Gear pump pressure
won’t rise
Worn pressure plate
•
Worn bearing
•
Defective plate seal, bushing seal or back-
•
up
Replace with new one
Maladjusted relief valve
Adjust relief valve setting with a
pressure gauge.
Air being sucked
Retighten suction side piping
•
connections.
Add oil into oil tank.
•
Check pump oil seal.
•
Noisy gear pump
Collapsed suction hose or clogged strainer
causes cavitation
Check hose or service strainer.
Air being sucked due to a loose suction side
joint
Retighten a loose joint.
Too viscous oil causes cavitation
Change to oil of proper viscosity
Operate pump at proper temperature.
Air bubbles in oil
Find the cause of air bubbles and
take necessary measures.
Oil leaks from pump
Defective pump oil seal or plate seal Replace with new ones.
Defective pump Replace pump with a new one.
7. HYDRAULIC SYSTEM