FIFTH WHEEL DOESN'T LOWER (Cont)

TM 9-2320-285-24-2

3-40. FIFTH WHEEL HYDRAULIC SYSTEM TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

4. FIFTH WHEEL DOESN'T LOWER (Cont)

WARNING

Keep clear of fifth wheel boom moving parts to prevent serious injury or death.

Step 2. Check movement of fifth wheel hydraulic control valve metering spool.

Have assistant push 5th WHEEL control lever fully forward; watch movement of hydraulic control valve

metering spool.

a. If metering spool does not move to the fully "down" position, repair or replace 5th WHEEL control

lever or cable (para 2-78a).

b. If metering spool moves to the fully "down" position, proceed to step 3 below.

Step 3. Rotate handle of bleed valve to fully open (horizontal) position.

a. If fifth wheel lowers, close bleed valve and proceed to step 5 below.

b. If fifth wheel does not lower, proceed to step 4 below.

Step 4. Support fifth wheel boom.

Check hose assemblies between bleed valve and hydraulic cylinders for restrictions (sharp bends,

blockage).

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 attention immediately.

a. If hoses are blocked, use compressed air (30 psi maximum) to remove blockage; if hoses remain

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

b. If hoses are not blocked, replace bleed valve (para 2-78b(2)). If malfunction is not corrected, proceed

to step 5 below.

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