MERITOR-TP-9853
MERITOR WEDGE BRAKES
MAINTENANCE MANUAL NO. 4R
FEBRUARY 1995
MERITOR-TP-9853 - Page 29 of 32
Section 6
Diagnostics
25
Automatic
adjusters not
working.
1. Damaged shoe retainer/detent clip on
head of adjusting bolt.
2. Adjusting bolt threads extend through
bottom of actuator.
3. Adjusting bolt threaded too tightly.
4. Brake shoes installed backwards.
5. Foreign material on threads of adjusting
bolt or actuator.
6. Lack of lubrication, contamination,
corrosion, damaged seals.
7. Damaged teeth on pawl or actuator.
8. Damaged pawl spring.
9. Weak/damaged shoe return springs.
10. Pawl seized in its bore.
11. Anchor plungers installed in wrong
locations.
1. Replace adjusting bolt.
2. Install adjusting bolt so threads do
not extend past bottom of
actuator.
3. Make sure bolt turns freely.
4. Install brake shoes correctly.
5. Clean or replace adjusting bolt and
actuator. Replace seals as needed.
6. Replace adjuster parts and seals
as needed. Lubricate at scheduled
intervals.
7. Replace pawl and plunger
assembly.
8. Replace pawl assembly.
9. Replace return springs.
10. Clean and replace pawl or housing
as needed.
11. Install plungers in correct locations
as shown in
Figure 4.1
.
Spring brake
does not hold.
1. Broken power spring.
2. Power spring unable to expand
completely (spring still caged).
3. Hold-off air not being exhausted.
4. Air chamber assembly not threaded
completely into plunger housing.
5. Brakes not adjusted correctly.
6. Grease or dirt on linings.
1. Repair or replace assembly as
described by manufacturer.
2. Determine cause and repair or
replace as described by
manufacturer.
3. Determine cause and repair or
replace as described by
manufacturer.
4. Correctly thread air chamber into
housing. Tighten collet nut to
prevent loosening.
5. Adjust brakes correctly.
6. Clean or replace linings. Check
wheel seals for leaks.
Condition
Possible Causes
Correction
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