TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test 4.
Check secondary reservoir air pressure.
1. Stop engine and drain secondary air reservoir at drainvalve (4).
Step
2. Remove drainvalve (4) from secondary drain line (6).
Step
3. Connect test gauge to secondary drain line (6).
Step
4. Direct assistant to start engine and allow air system to build to normal operating
Step
pressure.
Step 6. Check test gauge reading.
a. If test gauge reads normal operating pressure, perform test 5.
b. If test gauge reads no pressure, low pressure, or pressure is building slowly,
perform test 6.
c. Stop engine, drain air, remove test gauge, and install drainvalve (4).
Test 6. Check supply line (1) from secondary air reservoir to brake pedal valve.
Step 1. Stop engine and open all drainvalves (3), (4), and (5), in sequence shown, until brake
system air pressure is vented.
Step 2. Disconnect secondary air system supply line (1) from brake pedal valve fitting (2) and
connect test gauge to supply line (1).
Step 3. Direct assistant to start engine and allow air system to build to normal operating
pressure.
Step 4. Check test gauge reading.
a. If test gauge reads normal operating pressure, replace brake pedal valve
(para. 3-197 or 3-198).
b. If test gauge reads no pressure, low pressure, or pressure is building slowly, repeat
steps 1 and 2, install secondary air system supply line (1), and proceed to
test 6.
Test 6. Check one-way check valve.
Step 1. Stop engine and open all drainvalves (3), (4), and (5) in sequence shown, until brake
system air pressure is vented.
Step 2. Remove one-way check valve (para. 3-186).
Step 3. Inspect check valve for clogging and damage.
a. If clogging or damage is indicated, replace defective one-way check valve
b. If no clogging or damage is present, repair or replace clogged secondary air supply line (1).
END OF TESTING!
15. PRIMARY AIR SYSTEM FAILS TO MAINTAIN PRESSURE (NO MAJOR LEAKS, AIR CAN BE HEARD ESCAPING
INTO AIR INTAKE STACK, PARKING BRAKE APPLIED)
Perform malfunction 3, test 2.
END OF TESTING!
16. SECONDARY AIR SYSTEM FAILS TO MAINTAIN PRESSURE (NO MAJOR LEAKS, AIR CAN BE HEARD
ESCAPING INTO AIR INTAKE STACK, PARKING BRAKE APPLIED)
Test 1. Check secondary relay valve. Perform malfunction 3, tests 14 and 15.
Test 2. Check brake pedal valve. Perform malfunction 14, test 3.
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