Vehicle System Testing and Adjusting 34
Probable Mechanical Cause:
1. The mast is not in alignment with the other lifting
components and does not slide freely.
2. Not enough lubricant on the parts of the mast that
move.
3. The carriage or mast rollers and bearings are
worn and do not move (seized).
4. Mast shimmed too tight.
Problem: Mast does not move smoothly.
Probable Hydraulic Cause:
1. Air in the hydraulic system.
2. Relief valve sticks or defective.
3. Damaged cylinders.
Probable Mechanical Cause:
1. Not enough lubricant on the parts of the mast that
move.
2. Load rollers defective or not adjusted correctly.
3. Mast rollers not shimmed correctly.
4. Mast assembly is damaged or not in alignment.
Problem: The mast does not tilt correctly or
moves too slowly.
Probable Hydraulic Cause:
1. There is a restriction in the hydraulic tilt lines.
2. There is an air leak, which lets air into the
hydraulic system on the inlet side of the hydraulic
pump.
3. The relief valve opens at low oil pressure.
4. The hydraulic pump has too much wear.
5. The internal valve of the tilt spool is stuck.
6. Control valve tilt spool has a restriction.
7. The priority valve does not work correctly.
8. Seals in tilt cylinder worn or damaged.
9. Unload function doesn’t work correctly.
Probable Mechanical Cause:
1. Damage or failure of the tilt cylinders.
2. Mast mounting pins seized.
Problem: The carriage will not lower correctly.
Probable Cause:
1. There are restrictions in the lift line.
2. The lift spool in the control valve has a restriction
caused by foreign material and does not operate
freely.
3. The lift cylinder flow control valve has a restriction.
4. Air in the hydraulic system.
Probable Mechanical Cause:
1. The mast is not in alignment with the other lifting
components and does not move freely.
2. Carriage chains need an adjustment.
3. Not enough lubricant on the part of the mast that
move.
4. The carriage or mast rollers (bearings) are worn
and do not move (seized) or shimmed too tight.
Problem: Unload function doesn’t work
The probable Electric Cause:
1. The electric switch (on-off) below a seat is
damaged.
2. The electric parts (relay and controller) related to
a unload solenoid is in trouble.
Unload function: Once the operator leaves a seat
more than 3 seconds, liftin
and tiltin
don’t work
even thou
h each spool is shifted in or out. Once
the operaton sits on seat, each function will
normall
work immediatel
.
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