TM-9-2320-361-20

2-1/2-TON, 6x6, M44A2 SERIES TRUCKS (MULTIFUEL)

TECHNICAL MANUAL; UNIT MAINTENANCE

OCTOBER 1991
TM-9-2320-361-20

  TM-9-2320-361-20 - Page 151 of 1207

TM 9-2320-361-20
Table 2-3. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
9. NO AIR PRESSURE OR COMPRESSED AIR READS BELOW 60 PSI (LOW AIR PRESSURE WARNING
BUZZER SOUNDING, INDICATING AIR PRESSURE NOT BUILDING UP TO NORMAL OPERATING RANGE
AS INDICATED BY GAGE)
Step 1. Check for missing or loose air compressor drivebelt (3).
If air compressor drivebelt (3) is missing or loose, replace or adjust drivebelt (3) (para. 8-28).
Step 2. Check for leaking compressed air lines and fittings.
If leakage is found, repair or replace compressed air lines or fittings (TM 9-243).
Step 3. Start engine (TM 9-2320-361-10) and feel compressor outlet line (5).
a. If compressor outlet line (5) is hot, proceed to test 1.
b. If compressor outlet line (5) is cool or warm, proceed to test 2.
Test 1. Check air reservoirs (1) for air pressure.
WARNIN G
Eyeshields must be worn when working with compressed air system.
Failure to wear eyeshields may result in injury to personnel.
Step 1. Start engine (TM 9-2320-361-10) and allow air pressure to build to normal operating
pressure.
Step 2. Loosen air reservoir draincocks (2).
a. If a low volume of air pressure is released, perform step 3.
b. If a high volume of air pressure is released, proceed to test 2.
Step 3. Check compressor outlet line (5) for restrictions.
a. If compressor outlet line (5) is restricted, repair or replace (TM 9-243).
b. If compressor outlet line (5) is not restricted, proceed to test 2.
Test 2. Check for air pressure at air horn supply line (7).
Step 1. Stop engine and open all draincocks (2) (TM 9-2320-361-10) until brake system air
pressure is vented.
Step 2. Disconnect air horn supply line (7) from air horn elbow (9).
Step 3. Connect air horn supply line (7) to test gage (8).
Step 4. Direct assistant to start engine (TM 9-2320-361-10) and allow sufficient time for pressure
to build.
Step 5. Compare test gage (8) reading with gage reading on instrument panel.
NOTE
Air pressure gage on instrument panel has a maximum pressure
scale of 120 psi. If old governor has been replaced with new
governor, air pressure may exceed maximum pressure reading on
instrument panel gage.
a. If low or no air pressure is indicated on test gage (8), check air horn supply line (7) for
restrictions or leaks. Repair or replace damaged compressed air lines (TM 9-243).
b.
c.
If air compressor (4) is continuously unloading, not allowing air compressor to build air
pressure, adjust air governor (6) (para. 8-29).
If air governor (6) adjustment will not increase pressure and/or compressor outlet line (5)
is warm or cool, replace air compressor (para. 8-26).
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