Chevrolet 10 Series 1970 Service Manual page 306

BRAKES 5-68
The Stopm aster " Super F a il-S a fe "
actuation feature fo r pow er brakes and is tw o-fold in
purpose. It is used as an a ir-re le a s e d , sp rin g-applied
F ig . 114— Super F a il Safe
F ig . 115—Super F a il Safe in N o rm a l P osition
The Super F a il-S a fe is a spring pow ered brake actua­
to r that mounts " p iggy back" on the a ir cham ber non­
p ressu re housing o f the S TO P M A S T E R B RAKE (F ig . 114).
BRAKE CHAMBERS
SUPER FAIL-SAFE
GENERAL
is a m echanical
DESCRIPTION AND OPERATION
parking brake, as w ell as a safety feature in the event o f
a ir brake failu re,
POWER SPRING IN " O N " POSITION
F ig . 116—Super F a il Safe A p p lie d P osition
When 65 psi o r m ore o f a ir pressu re is applied against
the piston, the pow er
p ressed position (F ig . 115). When a ir pressu re is r e ­
moved, the pow er spring w ill push the piston against the
diaphragm plate. The wedge head w ill be pushed deeper
between the r o lle r s spreading the plungers apart and
applying the brake (F ig . 116).
The unit is equipped with a manual re le a s e bolt to
p erm it safe handling fo r s e r v ic e .
sealed by an " O " ring on the relea se bolt.
An internal venting system
with a one way breathing arrangem ent, and a foam air
filte r , on the cap allow s system a ir to f ill the vacuum
behind the piston when the F a il-S a fe is actuated and keeps
the unit sealed from d irect atm ospheric contamination.
NOTE: When brakes are
F a il-S a fe units, cage the pow er spring b efore
starting any disassem bly o r rem oval o f wheels
o r drums to avoid possible injury.
When a veh icle is disabled, due to low o r lost
a ir p ressu re, block the wheels and cage the
pow er spring b efore
veh icle.
BREATHER
ASSEMBLY
spring w ill be held in a com ­
The cap cavity is
working in conjunction
equipped with Super
attem pting to m ove the
CHEVROLET TRUCK SERVICE MANUAL