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 service brake chambers (2) and (3) for proper pressure.
NOTE
Air pressure to service brake chambers must be compared with
reading on primary air pressure gauge. Air pressure to spring and
service brake chambers must be compared with reading on
secondary air pressure gauge.
Step 1. Install test gauge on service brake chambers (2) and (3) and check for proper pressure as
outlined in test 3, steps 1 through 7.
Step 2. Check test gauge reading and compare with reading on instrument panel primary air
pressure gauge.
a. If reading on all four service brake chambers (2) and (3) are the same as reading
from primary air pressure gauge, stop engine, drain air, remove test gauge, connect
lines, and proceed to test 5.
b. If reading from two forward-rear rear service brake chambers (2) are not the same, stop
engine, drain air, remove test gauge, connect lines, and perform test 11.
c. If reading from two rear-rear forward service brake chambers (3) are not the same, stop
engine, drain air, remove test gauge, connect lines and perform test 12.
d. If reading from all service brake chambers (2) and (3) are not the same, stop engine,
drain air, remove test gauge, connect lines, and perform test 13.
Test 5. Check spring and service brake chambers (1) and (4) for proper pressure.
Step 1. Install test gauge on spring and service brake chambers (1) and (4) and check for proper
pressure as outlined in test 3, steps 1 through 7.
Step 2. Check test gauge reading and compare with reading on instrument panel secondary air
pressure gauge.
a. If reading on all four spring and service brake chambers (1) and (4) are the same as
reading on secondary air pressure gauge, stop engine, drain air, remove test gauge,
connect lines, and proceed to test 17.
b. If reading from two forward-rear forward spring and service brake chambers (1) are
not the same, stop engine, drain air, remove test gauge, connect lines, and perform
test 14.
c. If reading from only two rear-rear rear spring and service brake chambers (4) are not
the same, stop engine, drain air, remove test gauge, connect lines, and perform
test 15.
d. If reading from all four spring and service brake chambers (1) and (4) are not the
same, stop engine, drain air, remove test gauge, connect lines, and perform test 16.
Test 6. Check limiting valve (7) for venting (front service brake chambers test low or nonexistent
air pressure).
WARNING
Do not look into limiting valve vent port when performing test.
Injury to personnel may result.
Step 1. Direct assistant to apply and hold service brake pedal.
Step 2. Disconnect vent line (5) from limiting valve vent port (6).
Step 3. Feel for escaping air at limiting valve vent port (6).
a. If air is felt, replace limiting valve (7) (para. 3-190).
b. If no air is felt, reconnect vent line (5) and proceed to test 7.
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