No Motion Of Hydraulic Cylinders

UPRIGHTS

TROUBLESHOOTING

CAUSE

REMEDY

1. No oil or insufficient oil being supplied to cylinder

1. Check the hydraulic system for: defective pump or

pump drive; vacuum or pressure leak in lines; low relief

setting; relief valve stuck open; low reserve oil level;

disconnected control valve linkage. Repair defective unit.

Cold oil or unspecified oil in system: allow oil to warm

before working truck; drain system and fill with specified

oil.

2. Load too heavy

2. Reduce load.

Slow Motion

1. Insufficient oil being supplied to cylinder

1. Refer to "No motion of hydraulic cylinders," Remedy 1.

2. Worn cylinder-piston packing

2. Replace packing.

3. Linkage between handlever and plunger worn or

3. Repair or replace linkage.

broken

4. Structural warpage, clearance too close, lack of

4. Check upright alignment, repair, adjust and lubricate

lubricant

uprights as necessary.

Spongy Or Jerky Action

1. Air in system

1. Check reserve oil level, fill tank as necessary. Check

inlet side of pump for vacuum leaks. Tighten connections;

repair or replace connection or hose as necessary.

2. Sticky relief valve

2. Remove and check the relief valve in the manual

control valve. Repair or replace parts as necessary. If

foreign particles were the cause of malfunction, check

reserve oil for contamination. Whenever reserve oil is

contaminated it should be replaced, the filters serviced,

making sure the sealing surfaces are mating properly and

the filter elements are not ruptured.

3. Bent or deformed cylinder-piston rod or plunger.

3. Disassemble, check and repair cylinder assembly.

B-191