AIR COMPRESSOR TROUBLESHOOTING

TM 9-2320-285-24-2

3-21. TREADLE VALVE AND BRAKE CONTROLS TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

12. TRAILER SERVICE BRAKES DO NOT FUNCTION (REAR OF TRACTOR)

Relieve air system of all pressure (para 2-41h(1)).

Disconnect air hose connecting brake treadle valve to double check valve (located at bottom of tractor protection

valve).

Start tractor and allow air system to build to 100 psi pressure.

Install calibrated air pressure gage on hose.

Depress brake treadle valve fully.

Watch test gage.

Test gage shall indicate air system pressure (same as AIR PRESS gage indication).

If test gage indication differs by more than 10 psi from AIR PRESS gage indication, repair or replace

brake treadle valve (para 3-23).

3-22.

AIR COMPRESSOR TROUBLESHOOTING

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

1. PRESSURE TOO HIGH, OR AIR COMPRESSOR WON'T CUT OUT

Install replacement air compressor governor (para 2-52d).

Perform air compressor governor adjustment (para 2-52d).

a. If malfunction is corrected, repair or replace air compressor governor (para 2-52d).

b. If malfunction is not corrected, clean air compressor cylinder head (para 3-25b); replace stuck

inlet valves or leaking unloader grommets and back-up rings (para 3-25b), if necessary.

2. AIR COMPRESSOR KNOCKS

Remove air compressor (para 2-52e).

Check air compressor cylinder head for carbon deposits.

Check air compressor for worn or damaged front bearing.

a. If cylinder head contains carbon deposits, clean (para 3-25b).

b. If front bearing is worn or damaged, replace (para 3-25b).

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