Chevrolet 70 Series 1970, Service Manual

Page: 353 / 841

BRAKES 5-62
1 Spanner Nut R etaining W asher
2 Spanner Nut
3 W edge Rod Guide
4 Tag Nut
5 Caution Tag
6 Nut
7 Lock W asher
8 C lam ping Ring
9 W asher
10 Bolt
11 N o n -P re ssu re Housing
12 Push Rod Boot
13 D iaphragm Plate Rod
14 Rubber D iaphragm
15 "F ail-S afe'' P re ssu r e Housing
16 Housing to Cap Rubber W asher
n
!2 21
17 Housing to Plunger "O" Ring
18 Air Chamber Piston Plunger
A ssem b ly
19 Air Cham ber Cap A ssem b ly
20 R e le a se Bolt Spring Lock
21 C apscrew
22 Lock W asher
Figure 38—“ Fail-Safe" Air Chamber Components
SERVICING STANDARD "FAIL-SAFE”
BRAKE CHAMBERS
B rake cham ber com ponents can be rem oved
from the v e h icle for in spection and rep lacem en t of
p a r ts without rem oving the n o n -p ressu re housing
and without disturbing the m echanical actuating
m echanism .
REMOVAL AND DISASSEMBLY
R efer to figu re 37 (also r e fe r to figu re 38 for
com ponents).
CAUTIO N: BEFORE A T T E M P T IN G
BRAKE CHAM BER R EM O VA L, BLOCK
W HEELS SECURELY, SINCE PARKING
BRAKE W IL L NOT BE A P P LIE D .
Figure 39—Compressing “Fail-Safe” Power Spring
1. With air p r e s s u r e in parking brake cham ­
b er (brake r e lea sed ), lo o sen r e le a s e bolt spring
lo ck and swing to one side; then turn r e le a s e bolt
clo ck w ise a s far a s it w ill go (approx. 18 turns)
to co m p ress the power sp rin g. R efer to figu re 39.
2. Exhaust a ir p r e ssu r e from parking brake
cham ber by pulling parking brake knob out.
3. D isconnect a ir lin e s from both cham bers.
4 . Mark p r e ssu r e housing and n o n -p ressu re
housing so that p a rts can be r e a ssem b led in the
sa m e rela tiv e position . L oosen clam ping ring by
unscrew ing bolt. Hang clam ping ring on n o n -p res­
su re plate tube.
5. R em ove en tire cap and spring a ssem b ly ,
p r e s s u r e housing, and rubber diaphragm (s e e fig .
40). Diaphragm p late rod and boot w ill rem ain in
the n o n -p r essu re housing.
6
. Mount p r e ssu r e housing in v is e .
NOTE: DO NOT tighten v is e jaws enough to
d istort p r e ssu r e housing. U sing a w rench on hex
end of cap, un screw cap and spring a ssem b ly from
housing; OR mount hex end of cap in v is e and, using
s p e c ia l "strap" type w rench to rem ove p r e s s u r e
housing from cap a ssem b ly . See fig u re s 41 and 42
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL