TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
SERVICE BRAKES
3. INSUFFICIENT BRAKES (VEHICLE STOPPING DISTANCE TOO LONG, NO APPARENT AIR SYSTEM FAILURE WITH
GAUGES AT NORMAL OPERATING PRESSURE, WARNING BUZZER NOT SOUNDING)
NOTE
Assistant will help with this procedure.
Test 1. Check lines and hoses for leaks.
Direct assistant to fully apply service brakes.
a. If air leaks are found, repair as necessary.
b. If no air leaks in lines and hoses are found, perform test 2.
Test 2. Check service brake chambers (1) for leaks through vent lines (2).
WARNING
Do not look in service chamber vent port when performing test.
Injury to personnel may result.
Step
1. Disconnect vent line (2) from service brake chamber (1).
Step
2. Direct assistant to apply service brakes and feel for evidence of escaping air at vent
port (3).
a. If air is escaping, air is present. Notify DS maintenance.
b. If no air is escaping, install vent line (2) on service brake chamber (1).
c. Check all remaining vent lines (2) on service brake chambers (1) before proceeding to
test 3.
Test 3.
Check front service brake chambers (1) for proper pressure.
1. Stop engine and open all drainvalves (4), in sequence shown, until brake system air
Step
pressure is vented.
2. Close drainvalves (4).
Step
3. Disconnect delivery line (5) from service brake chamber (1).
Step
4. Remove adapter fitting (7) from service brake chamber (1).
Step
5. Connect tee (6) to service brake chamber (1) and connect test gauge and delivery
Step
line (5) to tee (6).
6. Direct assistant to start engine and build air supply to normal operating pressure.
Step
7. Direct assistant to fully apply and hold service brakes.
Step
8. Check test gauge reading and compare with reading on instrument panel primary air
Step
pressure gauge.
a. If readings from both front service brake chambers are the same as reading from
primary air pressure gauge, stop engine, drain air, remove test gauge, connect lines,
and proceed to test 4.
b. If test gauge readings are nonexistent or far less than primary air pressure gauge,
stop engine, drain air, remove test gauge, connect lines, and perform tests 6
through 10.
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