TM 10-3930-641-34-1
HYDRAULIC SYSTEM TROUBLESHOOTING (CONT)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
4. LIFT OR TILT CYLINDERS DO NOT HOLD POSITION WITH HYDRAULIC CONTROL LEVERS IN NEUTRAL POSITION
Step 1. Inspect lines and fittings for leaks.
Replace leaking lines and tighten fittings.
Step 2. Inspect cylinder piston seals.
Replace seals. (See page 7-54 or 7-66.)
Step 3. Inspect control valve.
a.
Check for worn valve spools.
Replace valve spools. (See page 7-44.)
b.
Check valve spool springs.
Replace springs. (See page 7-44.)
c.
Inspect control valve check valves.
Replace check valves. (See page 7-44.)
5. HYDRAULIC PUMP DOESN'T WORK
Step 1. Check oil level of hydraulic reservoir.
Add oil. (See page LO 10-3930-641-12.)
Step 2. Check viscosity of oil.
Drain system and add oil with correct viscosity. (See LO 10-3930-641-12.)
Step 3. Check for restriction in pump suction or discharge lines.
Clean lines.
Step 4. Check for air leaks in pump suction line.
Repair/replace. Tighten fittings.
Step 5. Inspect pump drive for damage.
Repair/replace. (See TM 10-3930-641-20.)
Step 6. Inspect pump for worn components. (See page 7-5.)
a.
Repair/replace. (See page 7-13.)
b.
Find and correct the cause of pump failure (cavitation, aeration, dirty oil).
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