TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test 11. Check primary air system relay valve (3) for proper pressure (forward-rear rear service
brake chambers (1) test low or nonexistent air pressure).
Step 1. Stop engine and open all drainvalves (2), in sequence shown, until brake system air
pressure is vented.
Step 2. Close drainvalves (2).
Step 3. Disconnect delivery line (4) from forward-rear rear service brake chambers (1) and
remove elbow (5) from delivery port (6) on relay valve (3).
Step 4. Connect test gauge to delivery port (6).
Step 5. Direct assistant to start engine and allow air system to build to normal operating
pressure.
Step 6. Direct assistant to fully apply and hold service brakes.
Step 7. Check reading on test gauge.
a. If pressure is below normal, stop engine, drain air, remove test gauge, connect air
line, and proceed to test 12.
b. If pressure is normal, inspect relay valve to service brake chamber delivery lines (4)
for blockage. Repair or replace as necessary (TM 9-243).
c. Stop engine, drain air, remove test gauge, and connect delivery lines (4).
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