Vehicle
Systems
Testing
and
Adjusting
45
Problem: The oil temperature is too high.
Probable Cause:
1.
The oil level is low.
2.
There is a restriction in an oil passage.
3.
The relief valve setting is too low.
4.
The oil is too thin.
5.
There is air leakage in the system.
6.
The pump has too much wear.
7.
The system operates at too high a pressure.
a.
Relief valve setting too high.
b.
Attachment components cause a restriction
during movement.
c.
Restrictions in flow regulator valve, load check
8.
Severe hydraulic usage.
Problem: Leakage on the shaft seal.
Probable Cause:
1.
The shaft seal is worn.
2.
There is a broken gasket behind the seal.
3.
The inner parts of the pump body are worn.
4.
Operation with too low oil level in tank causes
suction on the seal.
5.
Seal cut on shoulder of pump or keyway during
installation.
6.
Seal lips are dry and hardened from heat.
Problem: There is failure of the pump to deliver
the fluid.
Probable Cause:
1.
Low Level of the oil in the tank.
2.
There is a restriction in the pump inlet line.
3.
There is air leakage in the pump inlet line.
4.
The viscosity of the oil is wrong.
5.
The pump has too much wear.
6.
Failure of the pump shaft or coupling.
7.
The bolts of the pump do not have the correct
torque.
8.
Filter by-pass not working or installed backward.
Hydraulic Control Valve
Problem: The control spools do not move freely.
Probable Cause:
1.
The temperature of the oil too high.
2.
There is foreign material in the fluid.
3.
The fitting connections in the valve body are too
tight.
4.
The fastening bolts of the valve assembly do not
have the correct torque and have twisted the
body.
5.
Linkage of the lift and tilt levers does not operate
smoothly.
6.
Bent lift or tilt spools.
7.
Damage to the return springs of the spools.
8.
The valve is not at normal temperature for
operation.
Problem: Control valve spools have leakage
around the seals.
Probable Cause:
1.
There is foreign material under the seal.
2.
The valve spools are worn.
3.
The seal plates are loose.
4.
The seals have damage or are badly worn.
