Chevrolet 10 Series 1970, Service Manual

Page: 299 / 671

BRAKES 5-61
F ig . 103—Q u ic k Release V a lv e
C o v e r: Inspect condition o f exhaust p ort seat on co v e r
fo r signs o f pitting. The seat must be smooth and flat.
If the exhaust p ort seat shows deep scratch es o r pitting,
it must be replaced.
Spring Seat: If the spring seat is worn o r damaged,
rep la ce with new spring seat.
Repairs
If the exhaust p o rt seat on c o v e r shows scratch es o r
pitting, it can som etim es be rep a ired by ca refu lly la p ­
ping the seat, using a fine em e ry cloth on a fla t su rface.
Fig . 104—S la ck A d ju s te r—C u ta w a y V ie w
1. Lo ck S leeve
2 . S pring
3. D ow el
4. Le ver
5. Plug
6. Worm
7. W orm S haft
8. G e a r
9. C o v e r P late
Assembly
1. In sert diaphragm into spring seat.
2. P osition diaphragm and spring seat in body with
spring in place, in stall and tighten c o v e r secu rely.
Testing Rebuilt Unit
If fa c ilitie s are availab le, the rebu ilt quick re le a s e
v a lv e can be tested on a suitable test rack. If such fa c il­
itie s a re not availab le, the va lv e can be tested on the
v e h icle.
Both operating and leakage tests must be made in
eith er case to make certain the quick re le a s e va lve m eets
the tests outlined under S ervice Checks.
Installation
1. With attaching bolts, mount quick re le a s e va lv e in
place.
2. Connect a ir lin es to the v a lve.
3. Be certain exhaust p o rt is open.
SLACK ADJUSTERS (Fig. 1 0 4 )
The slack adjuster is used with the cam type brake to
com pensate fo r lining w ear. The com pensation fo r w ear
is not automatic, but must be accom plished by manual
adjustment.
Removal
1. Rem ove c le v is pin attaching brake cham ber push rod
yoke to slack adjuster.
2„ Rem ove lock rin g and sp acer securing slack adjuster
on cam shaft. Slide slack adjuster o ff end o f shaft.
Disassembly
1. Rem ove d irt and g rea se from outside o f unit by
washing in a suitable cleaning fluid.
2. Cut o ff riv e te d ends o f riv e ts attaching c o v e r plates
to body. D rive out r iv e ts and rem ove c o v e r plates.
3. Rem ove welch plug fro m end o f w orm shaft b ore.
In sert a fla t end punch into the w orm shaft b ore and
d riv e w orm shaft out o f body and w orm .
4. R em ove lock s le e v e and spring fro m w orm shaft.
Rem ove g e a r and w orm fro m slack adjuster body.
Inspection and Repair
1. Wash parts in cleaning fluid and wipe dry.
2. Inspect w orm and g e a r and rep lace with new parts if
chipped o r broken teeth a re evident.
3. Inspect w orm shaft fo r w ear. Make sure co rn ers on
hex end are not rounded.
4. Inspect bushing in le v e r arm . If worn, out-of-round,
o r oth erw ise dam aged, it must be replaced. To
rep lace bushing, p re s s o il bushing out and p re s s new
bushing into p lace. Bushing must be ream ed a fte r
installation to 0.503"-0.504".
5. Examine lock s le e v e fo r cracks o r other damage.
R eplace i f n ecessary.
6. Examine le v e r (body) fo r cracks o r distortion . If
le v e r is damaged in any way, a new body and bushing
assem bly must be used.
Assembly
1. P la ce w orm and g e a r assem bly in position in body.
2. P la c e lock s le e v e o v e r w orm shaft, with so c k e t-lik e
end o f s le e v e at hex end o f shaft. P la ce lock spring
in r e c e s s form ed by s le e v e and shaft.
3. E nter sm all end o f w orm shaft through hole in body
and w orm . P r e s s w orm shaft into w orm and body,
PUSH LO C K SLEEVE IN TO
D IS E N G A G E HEAD O F W O RM
] 2
SHAFT TO MAKE ADJUSTMENT
LO C K SLEEVE MUST COM E OUT
AN D E N G A G E HEAD O F W O RM
SHAFT TO LO C K ADJUSTM ENT
CHEVROLET TRUCK SERVICE MANUAL