TM 5-3805-254-20-1
ORGANIZATIONAL TROUBLESHOOTING - CONTINUED
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
68.
REAR BRAKES DO NOT WORK - CONTINUED.
NOTE
Check AIR PRESSURE gage for air pressure between 90 and 130 psi. If specified air pressure is not
present, start engine and check that air pressure in air system is between 90 and 130 psi (TM 5-3805-254-
10). Shut down engine (TM 5-3805-254-10).
Step 8.
Check double check valve (1) for input air pressure as follows: using 314-inch and 5/8-inch open-
end wrenches, loosen input hose fitting (2) six turns. Have assistant press down brake pedal (3),
listen for hissing noise at input hose fitting (2), release brake pedal (3).
a. If hissing noise is heard at input hose fitting (2), tighten using 3/4inch and 5/8-inch
open-end wrenches, replace double check valve, notify Direct Support Maintenance.
b. If hissing noise is not heard at input hose fitting (2), tighten using 3/4-inch and 5/8-inch
open-end wrenches, and go to step 9.
Step 9.
Check treadle valve (4) rear brake output air line (5) for air pressure as follows: using 7/8-inch and
13/16-inch open-end wrenches, unscrew and loosen output air line fitting (6) at tee fitting (7) six
turns. Have assistant press down brake pedal (3), listen for hissing at output air line fitting (6),
release brake pedal (3).
a. If hissing noise is not heard at output air line fitting (6), tighten using 7/8-inch and
13/16-inch open-end wrenches. Replace treadle valve (4) (page 2-1052).
b. If hissing noise is heard at output air line fitting (6), tighten using 7/8-inch and 13/16-
inch open-end wrenches. Go to step 10.
WARNING
Ensure that vehicle is on level ground and that rear wheels are chocked to prevent vehicle from moving or
severe injury to personnel may result.
Step 10.
Chock rear wheels of truck. Check parking brake valve (8) for air pressure as follows: pull handle
(9) out to apply parking brakes, using 5/8-inch open-end wrench, loosen output hose fitting (10) six
turns, push in handle (9) and listen for hissing noise.
a. If hissing hoise is not heard at output hose fitting (10), tighten using 5/8-inch open-end
wrench. Replace parking brake hand valve (8), notify Direct Support Maintenance.
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