SPECIFICATIONS

Vehicle Systems Testing And Adjusting
4. Seal cut on shoulder of pump or keyway during
installation.
5. Seal lips are dry and hardened from heat.
Problem: There is failure of the pump to deliver
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.
a. Loose bolts.
b. Defects in suction line.
4. The viscosity of the oil is wrong.
5. The pump has too much wear.
6. Failure of the pump shaft.
7. The bolts of the pump do not have the correct
torque.
Hydraulic Control Valve
Problem: The control spools do not move freely.
Probable Cause:
1. The temperature of the oil is 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 hydraulic oil 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.
Problem: The load lowers when the lift spool is
moved from the NEUTRAL position to the RAISE
position.
Probable Cause:
1. There is foreign material in the check valve area.
2. The check valve poppet and seat show wear.
3. Sudden loss of pump oil pressure.
4. Damage to the relief valve which causes low oil
pressure.
Problem: Spools do not return to neutral.
Probable Cause:
1. The springs are broken.
2. The spool is bent.
3. The system or valve has foreign particles in it.
4. The control linkage is not in alignment.
5. The fastening bolts of the valve have too much
torque.
Problem: No motion or slow, then a too sudden
action of the hydraulic system.
Probable Cause:
1. The relief valve is not correctly set, or will not
move in base and/or is worn.
2. There is air in the system.
3. Dirt or foreign particles between relief valve control
poppet and its seat.
4. Valve body has a crack inside.
5. Spool not moved to a full stroke.
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