Table 2-2. Unit Troubleshooting -continued
TEST OR INSPECTION
AIRBRAKE SYSTEM (Model WPES-1) - continued
Step 4. Remove hub and drum assembly for each wheel (refer to paragraph 2-100). Inspect brakeshoe linings for
wear. Using 6-inch scale, measure brakeshoe lining thickness.
a. If brakeshoe linings are greater than 1/8 inch (3.2 mm) thick, adjust service brakes. Refer to paragraph 2-
b. If brakeshoe linings are less than 1/8 inch (3.2 mm) thick, notify Direct Support Maintenance.
2. ONE BRAKE DRAGS.
Step 1. Tell assistant to pump towing vehicle brake pedal several times while you are watching air chamber action
on wheel that drags.
a. If air chamber assembly pushrod moves out and returns quickly as brakes are engaged and released, go
to step 2.
b. If air chamber assembly pushrod on any wheel returns slowly, go to step 4.
Step 2. Check brakeshoe adjustment on wheel that drags. Refer to paragraph 2-101.
a. If brakeshoe adjustment is good, go to step 3.
b. If brakeshoe adjustment is too tight, adjust brakeshoes Refer to paragraph 2-101.
Step 3. Remove hub and drum assembly for wheel that drags (refer to paragraph 2-100) and check for rusted or
damaged brake parts or weak return spring.
Notify Direct Support Maintenance if parts are damaged/or corroded.
Step 4. Tell assistant to hold down towing vehicle brake pedal. Loosen uppermost hose fitting on slow returning
a. If air chamber assembly pushrod returns slowly, go to step 5.
b. If air chamber assembly pushrod returns quickly, tighten hose fitting and replace airbrake relay valve. Refer to