TM 5-3805-262-20
3-17. PARKING BRAKE SYSTEM TROUBLESHOOTING
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1. PARKING BRAKE DOES NOT APPLY (WILL NOT HOLD).
Step 1. Start and operate engine at 1000 rpm until AIR PRESS gage needle
indicates in green area.
Push in and momentarily hold in knob of parking brake valve.
Release parking brake valve knob.
Check that parking brake valve knob stays in and parking brake is
r e l e a s e d .
a. If parking brake valve knob does not stay in, parking brake
valve has leakage. Replace parking brake valve (page 7-12).
If parking brake does not release, adjust parking brake linkage
(page 7-17).
b. If parking brake valve knob stayed in and parking brake releas-
ed, go to step 2 below.
Step 2. Shut off engine.
Operate brake treadle and valve and declutch treadle and valve until
AIR PRESS gage needle is approximately 1/4 inch into red zone.
Check that parking brake valve knob comes out and parking brake en-
gages.
a. If parking brake valve knob does not come out, replace
brake valve (page 7-12).
If parking brake does not engage, adjust parking brake
(page 7-17).
If parking brake linkage is adjusted properly, replace
brake chamber (page 7-8).
b. If parking brake valve knob came out and parking brake
remove parking brake drum and check brake linings for wear or
contamination (page 7-2). Replace if necessary.
parking
1 inks ge
parking
engaged,
2. PARKING BRAKE WILL NOT RELEASE.
Check adjustment of parking brake linkage.
a. If parking brake linkage is not adjusted correctly, adjust (page
7 - 1 7 ) .
b. If parking brake linkage is adjusted properly, replace parking
brake chamber (page 7-8).
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