MERITOR-TP-9853
MERITOR WEDGE BRAKES
MAINTENANCE MANUAL NO. 4R
FEBRUARY 1995
MERITOR-TP-9853 - Page 28 of 32
Section 6
Diagnostics
24
Brakes grab or
vibrate during
application.
1. Low air pressure at air chamber.
2. Grease or dirt on linings.
3. Wedge and roller assembly not correctly
installed in plunger ramp.
4. Incorrect lining friction rating.
5. Linings worn below minimum thickness,
damaged or missing.
6. Shoes bind due to improper assembly
or weak, worn out shoes.
7. Weak/damaged shoe return springs.
1. Inspect and repair air delivery
system.
2. Clean or replace linings. Check
wheel seals for leaks.
3. Install correctly.
4. Replace with correct lining.
5. Replace linings.
6. Install shoes correctly or replace
as needed.
7. Replace return springs.
Brakes drag.
1. Spring brake not completely released.
2. Weak/damaged return springs.
3. Air lines connected to wrong ports.
4. Leaks in the air system.
5. Air trapped in air chamber when brakes
are released.
6. Brake drum out-of-round.
7. Loose wheel bearings.
8. Push rod not connected to wedge.
9. Plungers seized in housing.
10. Damaged return spring or cotter pin on
wedge assembly.
11. Grease or dirt on linings.
12. Loose, worn or missing shoe retaining
hardware.
13. Incorrect manual adjustment.
1. Inspect and repair air system and
spring chamber.
2. Replace return springs.
3. Connect air lines correctly.
4. Repair leaks.
5. Repair or replace release valves.
6. Replace drum.
7. Adjust wheel bearings correctly.
8. Inspect and correct as needed.
9. Inspect seals, lubricant and
plungers. Service as necessary.
10. Replace spring or cotter pin.
11. Clean or replace linings. Check
wheel seals for leaks.
12. Repair or replace retaining
hardware.
13. Adjust brake correctly.
Condition
Possible Causes
Correction
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