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GM COACH MAINTENANCE MANUAL
Sec. 21
Page 207
bearings,
differential
gears
or
bearings, or by insufficient lu-
bricant in the differential,
Add
lubricant, adjust wheel bearings,
ad just,
repair, or replace axle
differential assembly
AXLE NOISE ON DRIVE OR
ON COAST ONLY
l. Differential pinion and ring
gear out of adjustment or worn
excessively,
Adjust,
repair, or
replace differential assembly.
TROUBLE SHOOTING
EXCESSIVE BACKLASH
IN AXLE
1. Loose axle shaft flange cap
screws or stud nuts; worn holes
in flanges;
worn shaft splines,
2, Differential pinion and ring
gear out of adjustment or worn,
BRAKE
TROUBLE
SHOOTING
SLOW BRAKE APPLICATION
1, Low line pressure, Adjust
application valve.
2, Broken
brake
chamber
diaphragm
or leaking chamber.
3. Restriction in brake lines,
4, Excessive chamber push-
rod travel.
5, Worn brake shoe linings,
6, Quick
release
or
relay
valve corroded,
SLOW BRAKE RELEASE
l. Quick
release, relay, or
application
valve
exhaust
port
restricted.
2, Quick
release, relay, or
application valve corroded.
3, Restricted
lines
prevent
quick
release
of air pres sure,
4. Intake valve in application
valve improperly seated,
5, Brake
camshaft
binding.
6. Brake shoe rollers stick-
ing or shoe frozen at anchor pin,
7. Lack of lubrication,
LOW AIR PRESSURE
1, Leak
in
fittings
or
air
lines,
2, Leak at application valve
intake valve.
3. Governor is defective or
improperly adjusted,
4, Defective compressor un-
loading valve operation,
5. Defective compressor dis-
charge valve operation.
6. Compressor discharge line
choked with carbon,
SLOW PRESSURE BUILD-UP
1, Check all items previously
listed under "Low Air Pressure,"
2. Worn
compressor
parts
necessitating
complete overhaul
of compressor,
RAPID LOSS OF PRESSURE
WHEN ENGINE IS STOPPED
1, Air leaks in system,
2, Defective compressor dis-
charge valve operation.
EXCESSI.VE AIR PRESSURE
1. Unloading
diaphragm
is
defective,
2, Excessive unloading valv,e
clearance,
3. Governor improperly ad-
justed or defective.
4. Restriction in air line from
unloading chamber to governor.
NOISY BRAKES
1, Dirty, worn, or loose brake
lining, or distorted brake shoes.
2, Scored or damaged brake
drums,
ONE BRAKE DRAGS
l, Improper adjustment,
2. Corroded
or
bent brake
mechanism,
Weak
or
broken
brake shoe return spring.
3, Restricted brake line.
4. Inoperative
chamber
due
to bent push rod,
5, Wheel
bearings
out
of
adjustment.
CLUTCH
TROUBLE
SHOOTING
The
clutch
is designed for
maximum efficiency and long life,
and
with
reasonable
care,
no
operating
difficulty
should
be
encountered.
Natural wear will
occur,
however,
and
must
be
compensated for by adjustment.
CLUTCH SLIPPING
1. Improper
adjustment (no
pedal free-travel).
2. Worn facings,
grease on
facings, clutch disc hub binding
on
clutch shaft, or insufficient
spring tension.
3. Pressure
plate
sticking.
Clearance
between
the
driving
block and the pressure plate lugs
is excessive.
CLUTCH GRABBING AND
CHATTERING
1. Improper operation due to
poor driving practices.
2. Improper pedal free-travel
adjustment.
3. Mounting bolts in engine
loose.
4. Grease on facings, worn
splines on clutch shaft or in disc
hub,
facing
loose
on
disc, or
pressure plate scored or rough.
Replace defective parts or com-
plete
clutch assembly.
Inspect
for worn splines on clutch shaft
and replace if this condition is
found.
IMPROPER RELEASE
1. Improper adjustment.
2. Pressure plate or driven
disc worn, warped, or distorted.
3. Weak
or
broken
return
springs.
4. Worn release bearing.
5. Controls binding.
SPRING
TROUBLE
SHOOTING
HARD RIDING
1, Vehicle overloaded or load
unevenly distributed,
2, Shackle pins and bracket
bolts
"frozen"
or
broken due
to insufficient lubrication,
3, Axle
shifted
on springs.
OVER FLEXIBLE
1, Excessive
lubrication
of
spring leaves,
2, Spring leaf rebound clips
broken,
3, Shock absorbers defective,
Lack
of
fluid, worn or broken
parts,
Keep filled to level plug
or disassemble and inspect for
parts failure.
EXCESSIVE NOISE
l. Worn
spring
eye
shackle
bolts
and
bolts
or
bushings,
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