Chevrolet 10 Series 1970 Service Manual page 307

FOOT
H O U S IN G
t
PISTON
SEAL
SET SNAP RING
SCREW HEX N UT -
SQUARE NUT
Caging and Uncaging Power Spring
On the Super F a il-S a fe
is exposed at a ll tim es.
The p ow er spring is caged by rotating the re le a se
bolt 18 to 21 fu ll turns clock w ise.
bolt beyond its norm al stop.
Both the caging and uncaging operation can be made
ea s ie r by applying a ir p ressu re (65 psi minimum) to the
F a il-S a fe . This w ill take the spring load o ff the re le a s e
bolt.
DISASSEMBLY OF SUPER FAIL-SAFE (Fig. 1 17)
NOTE: It w ill be n ecessa ry to hold the pow er
sprin g in com p ression fo r d isassem bly. A f ix ­
ture as illu strated in fig . 119 can be fabricated
fo r this operation.
1. Cage pow er spring by turning r e le a s e bolt 18 to 21
turns clock w ise.
2. R em ove F a il-S a fe fro m
clam p ring.
3. R elease foot set screw .
4. Unscrew foot fro m piston.
5. R em ove piston seal.
6. R em ove sealin g compound located at joint between
cap and housing.
7. R em ove lock ring fro m housing.
SERVICE RECOMMENDATIONS
HSG. LOCK G R O O V E
PISTON
" O " RING
BACK-UP
RINGS
F ig . 117—Super F a il Safe E xplode P osition
the head o f the re lea se bolt
Do not fo r c e the
non-pressu re housing at
O " R IN G
BACK-UP RING
(POSITIO NED IN
PISTON G R O O V E )
POWER SPRING
BEARING WASHER
RUBBER SEAL
8. Separate cap,
housing.
9. Rem ove back-up rin gs and " O "
in housing.
10. Rem ove hex nut and snap ring from re le a s e bolt.
11. Secure cap, spring and piston assem bly in fixtu re.
12. Turn rele a s e bolt until square nut fa lls fr e e .
13. R elease p re ssu re on fixtu re until spring is unloaded.
14. Rem ove assem bly fro m p ress o r fixtu re.
15. Separate cap fro m spring and piston assem bly.
16. Rem ove back-up ring and " O " ring fro m piston.
17. Rem ove the two spring bearing w ashers.
18. Rem ove c o tter pin o r snap ring fro m rele a se bolt.
19. Rem ove fla t w asher fro m relea se bolt.
20. Rem ove re le a s e bolt fro m cap.
21. Rem ove " O " ring fro m rele a s e bolt.
22. Rem ove second fla t w asher from relea se bolt.
23. Do not rem ove b rea th er assem bly fro m cap.
ASSEMBLY OF SUPER FAIL-SAFE
B efo re assem bly, clean and inspect a ll parts.
cate with recom m ended grea se. Do not lu bricate cap in
the a rea o f the b rea th er assem bly.
on back-up o r " O "
clean.
It is n ecessary to use a s e a le r on the foot set screw
and c o v e r the head of it with plastic tape until the s e a le r
sets.
BRAKES 5-69
LOCK R IN G (POSITIO NED
OVER CAP LIP A N D IN
CAP
H SG. LOCK G R O O V E )
" E" R IN G
INNER
WASHER — W ASHER
" O " R IN G
spring and piston assem bly
ring fro m gro o ve
Do not use solvent
rings. Use hot soapy w ater and wipe
CHEVROLET TRUCK SERVICE MANUAL
RELEASE
BOLT
OUTER
fro m
L u b ri­