FIFTH WHEEL DOESN'T LIFT (Cont) - TM-9-2320-285-24-10886

TM 9-2320-285-24-1

2-76. FIFTH WHEEL HYDRAULIC SYSTEM TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

1. FIFTH WHEEL DOESN'T LIFT (Cont)

Step 5.

Check hydraulic pump suction hose for restrictions (blockage, sharp bends).

Remove hose if necessary (para 2-78b(2)).

WARNING

Compressed air must not exceed 30 psi. Wear safety glasses when

using compressed air. Failure to do so could cause serious injury to eyes

and possible blindness. If you hurt your eyes or if a foreign object is

blown into your eyes, seek medical aid immediately.

a. If hose is blocked, use compressed air (30 psi maximum) to remove blockage; if hose remains

blocked, replace (para 2-78b(2)).

b. If hose is not blocked, go to step 6 below.

Step 6.

Check all fifth wheel lines, hydraulic control valve, and hydraulic cylinders for visible signs of large oil

leaks.

a. If large oil leaks are seen, repair as necessary.

b. If no large oil leaks are seen or if fifth wheel hydraulic cylinders or hydraulic control valve require

repair, notify direct support maintenance.

2. FIFTH WHEEL LIFTS SLOWLY

Step 1.

With vehicle engine idling, raise fifth wheel boom; clock lifting speed.

Then lower fifth wheel,

accelerate engine to 2000 rpm, and clock lifting speed.

a. If lifting speed increases with increase in engine speed, operation is normal.

b. If lifting speed does not increase, increases only slightly, or remains slow with increase in engine

speed, go to step 2 below.

WARNING

Do not remove filler cap when hydraulic oil is hot. Hot oil can cause

severe injury.

2-863