Table 4-2. Unit Troubleshooting (cont'd)
TEST OR INSPECTION
Step 3. Check for weak or broken brake shoe return spring.
If return spring is not defective, proceed to step 4.
Step 4. Check for defective brake chamber.
If brake chamber is defective, replace brake chamber (para. 4-46).
If brake chamber is not defective, proceed to step 5.
Step 5. Check for low pressure.
Perform leakage test. Repair or replace leaking air lines, hoses or connections.
13. GRABBING BRAKES
Step 1. Check brake adjustment.
If brakes are out-of-adjustment, adjust brakes (para. 4-50 (XM1063) or 4-51 (M129A4)).
If brake adjustment is correct, proceed to step 2.
Step 2. Check for grease on brake lining.
If grease is present, replace oil seals (para. 4-52 (XM1063) or 4-53 (M129A4)) and brake
shoes (para. 4-55).
If grease is not present on brake lining, proceed to step 3.
Step 3. Check for loose or worn wheel bearings.
If wheel bearings cannot be adjusted, replace wheel bearings.
If wheel bearings are not loose or worn, proceed to step 4.
Step 4. Check for cracked, scored or deformed brake drum.
If brake drum is cracked, scored or deformed, replace brake drum.
If brake drum does not need replacement, proceed to step 5.
Step 5. Check for loose or worn brake lining.
Replace brake shoes.