ORGANIZATIONAL TROUBLESHOOTING - CONTINUED
TEST OR INSPECTION
AIR SYSTEM AND BRAKES - CONTINUED
PARKING BRAKE WILL NOT HOLD
When performing parking brake maintenance, follow this procedure exactly. The release of trapped air
inside chamber can cause brakes to apply suddenly under extremely high spring tension causing
Before removing brake hose, if air is trapped, unscrew one to two turns only and allow air to escape. Air is
under pressure and can cause the hose and fitting to break apart causing personnel injury.
Step 1. Check air control valve (1) for proper operation.
a. Start engine (TM 9-2320-269-10), let air pressure build up, and shut off engine (TM 9-
b. Pull air control valve (1) to the APPLY position, push to the RELEASE position, and
If air control valve (1) does not exhaust, remove (page 2-526). Clean exhaust port (2),
or replace valve (1) as needed (page 2-526), or notify Direct Support Maintenance.
Step 2. Check inversion valve (3) for proper operation.
a. Have assistant pull air control valve (1) to the APPLY position, then push to the
RELEASE position, and listen for exhaust.
b. If inversion valve (3) does not exhaust, remove (page 2-535). Clean exhaust port (4) or
replace valve (3) as needed (page 2-535), or notify Direct Support Maintenance.
Step 3. Inspect brake hoses (5) for damage.
b. If hoses (5) are bent or pinched between vehicle components, remove and reroute, or
If hoses (5) are damaged or collapsed, replace as needed (page 2-567).