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GM COACH MAINTENANCE MANUAL
Sec. 4
Page 57
tion, the entire slack adjuster rotates bodily with
the camshaft.
As the brake chamber push rod
reaches its maximum travel due to normal lining
wear, turning worm shaft rotates lever back to
original setting.
SLACK ADJUSTER SERVICEABILITY TEST
Adjust brakes as previously directed under
"Brake Adjustment" in this section, then carefully
measure brake chamber push rod travel as brakes
are applied. Make several full brake applications
and again measure push rod travel.
Push rod
travel should be the same as it was immediately
after adjustment. If push rod travel increases, or
if difficulty is experienced in keeping the brakes
adjusted in service, the slack adjuster must be
overhauled or replaced.
SLACK ADJUSTER REPLACEMENT
Removal
1.
Remove clevis pin attaching slack adjuster
to brake chamber push rod.
2. Remove snap ring (front) or bolt and wash-
ers (rear) securing slack adjuster on camshaft.
Slide slack adjuster off end of shaft.
Installation
1.
If a new slack adjuster is being installed,
make sure it is the same size and type as the
one removed.
Slide slack adjuster onto camshaft
and attach with bolt and washers or with snap
ring.
2. Connect brake chamber push rod to slack
adjuster, using clevis pin and cotter pin.
3. Lubricate slack adjuster as directed in
LUBRICATION (SEC. 13).
4. Adjust brakes as previously directed under
"Brake Adjustments."
SLACK ADJUSTER DISASSEMBLY (Fig. 11)
1. Remove dirt and grease from outside of
unit by washing in a suitable cleaning fluid.
2. Cut off riveted ends of rivets attaching
cover plates to body.
Drive out rivets and re-
move cover plates.
3. Remove welch plug from end of worm shaft
bore. Insert a flat end punch into the worm shaft
bore and drive worm shaft out of body and worm.
4. Remove lock sleeve and spring from worm
shaft. Remove gear and worm from slack adjust-
er body. Remove lubrication fitting.
INSPECTION AND REPAIR
1.
Wash parts in cleaning fluid and wipe dry.
2. Inspect worm and gear and replace with
new parts if chipped or broken teeth are evident.
3. Inspect worm shaft for wear.
Make sure
corners on hex end are not rounded.
PUSH LOCK SLEEVE IN TO
DISENGAGE HEAD OF WORM
SHAFT TO MAKE ADJUSTMENT
LOCK SLEEVE MUST COME OUT
AND ENGAGE HEAD OF WORM
$HAFT TO LOCK ADJUSTMENT
1 Lock Sleeve
2 Spring
3
Dowel
4
Lever
5 Worm
A-See Text
AIR BRAKES
6
Worm Shaft
7
Gear
8
Lubrication
Fitting
9
Cover Plate
TP 5521
Figure 11-5/ack Adjuster
4. Inspect bushing in lever arm.
If worn, out-
of-round, or otherwise damaged, it must be re-
placed. To replace bushing, press old bushing out
and press new bushing into place. Bushing must
be reamed after installation to .501" - .503".
5. Examine lock sleeve for cracks or other
damage. Replace if necessary.
6.
Examine lever (body) for cracks or dis-
tortion.
If lever is damaged in any way, a new
body and bushing assembly must be used.
SLACK ADJUSTER ASSEMBLY (Fig. 11)
1.
Place worm and gear assembly in position
in body.
2.
Place lock sleeve over worm shaft, with
socket-like end of sleeve at hex end of shaft.
Place lock spring in recess formed by sleeve
and shaft.
3. Enter small end of worm shaft through
hole in body and worm.
Press worm shaft into
worm and body, making sure the groove in lock
sleeve is aligned with pin in body.
Press shaft
in until distance from small end of shaft to edge
of body (A, fig. 11) is as follows:
Front - 5/8";
Rear - 9 /16".
Install welch plug in worm shaft
bore.
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