Chevrolet 10 Series 1970 Service Manual page 239

Standard H ydraulic B r a k e s ...........
Bendix Pow er B rak es......................
Vacuum B ooster Pow er Brake Unit
A ir B r a k e s ........................................
General D e s c rip tio n .............................................................................. ..... 5-1
Main C y lin d e r .................................................................................... ..... 5-1
S e lf-A d ju s tin g D u o -S e rv o B ra k es................................................. ..... 5-1
Manually Adjusted Brakes - W a g n e r .................................................... 5-2
Wheel C y lin d e r s ................................................................................ ..... 5-5
Brake L in in g s .................................................................................... ..... 5-5
Parking B r a k e ........... ......................................................................... ..... 5-5
Brake Pipe Distribution and Sw itch A s s e m b ly ............................. ..... 5-5
Brake Pedal Travel Switch .............................................................. ..... 5-5
Maintenance and A d ju stm e n ts............................................................ ..... 5-6
Brake Shoe A d ju s t m e n t ........................................................................ 5-6
Bleeding Brakes ................................................................................ ..... 5-7
Parking Brake L u b r ic a tio n .............................................................. ..... 5-9
Brake Pedal A d ju s tm e n t........................................................................ 5-9
Brake Pedal and Push R od Travel A d ju s t m e n t ............................. ..... 5-10
Parking Brake Adjustm ents ............................................................ ..... 5-10
Hydraulic Brake Lines ..................................................................... ..... 5-11
M A IN CYLINDER
A ll 1970 10 through 30 s e r ie s m odels (except CA30 and
PA30/14,000 lb. GVW ) are equipped with a new dual
brake system . If a wheel cylin d er o r brake line should
fa il at eith er the fron t end o r re a r end of the veh icle,
the o p erator can s till b rin g the ve h ic le to a controlled
stop. The system is designed with separate hydraulic
system s fo r the fron t and r e a r brake using a dual main
cylin d er (fig . 1). The main cylin d er has two en tirely
separate r e s e r v o ir s and outlets in a common body cast­
ing. The fron t r e s e r v o ir and outlet is connected to the
fron t wheel brakes, and the r e a r r e s e r v o ir and outlet is
connected to the r e a r w heel brakes.
the main cylin d er r e c e iv e m echanical pressu re fro m the
brake pedal push rod and transm it it through the brake-
lin es as hydraulic p ressu re to the w heel cylinders. Main
cylin d ers fo r CA30, PA30 (14,000 lb. and o v e r GVW),
and a ll 40 through 60 s e r ie s m odels are of the single
hydraulic system (sin gle main cylin d er r e s e r v o ir ) type.
A dual system is standard on school bus m odels and
optional on other m odels.
SECTION 5
BRAKES
CONTENTS OF THIS SECTION
Page
5-1
5-43
5-44
5-53
STANDARD HYDRAULIC BRAKES
Page
GENERAL DESCRIPTION
Tw o pistons within
Trailer E q u ip m e n t................................................................................. ..... -WU
Em ergency and Parking B r a k e s ........................................................... ..... 5-78
Special T o o l s .......................................................................................... ..... 5-84
INDEX
Service O p e ra tio n s................................................................................ ......5-13
Main Cylinder - Dual System
Main Cylinder - Single System
Brake Com ponents - S e lf-A d ju s tin g
Front and Rear B r a k e s ...........................................................................5-19
Rear Brakes 40 and 50 S e r ie s ................................................................5-23
Brake Com ponents - Manually Adjusted (W a g n e r ).................................5-26
Brake Com ponents - S elf Adjusted (W a g n e r )......................................... 5-28
Wheel C y lin d e rs.................................................................................... ..... 5-32
Brake D r u m s ......................................................................................... ..... 5-35
Brake Pedal (E x cep t T ilt C a b ) ............................................................ ..... 5-36
Brake Pedal - T ilt C a b ......................................................................... ..... 5-37
Parking Brake - Rear Wheel T y p e
Parking Brake - Propeller Shaft (Band T y p e ) ................................... ..... 5-38
Parking Brake - Propeller Shaft Internal Expanding T y p e ............. ..... 5-40
Hydraulic Brake Lines and Tubing
SELF-ADJUSTING DUO-SERVO BRAKES
NOTE:
A ll m odels,
self-a d ju stin g du o-servo brakes, fron t and re a r.
40 and 50 s e r ie s m odels a re equipped with s e lf-
adjusting du o-servo brakes fron t and Tw inplex
two cylin der, self-ad ju stin g re a r brakes.
B rake shoe adjustment takes place when brakes are
applied with a fir m pedal e ffo r t while the veh icle is back­
ing. Applying the brake m oves an actuator which turns
the star w heel and lengthens the adjusting s cre w a ssem ­
bly (fig . 2). This action adjusts the shoes until clearan ce
between the lin in g and drum is within p ro p er lim its.
F ifty s e r ie s m odels with 15,000 lb. sin gle o r tw o-speed
re a r axle a re equipped with 15 x 4 o r 15 x 5 inch re a r
Tw inplex brakes (fig .
re a r brake is s e lf-c e n te rin g in operation, u tilizin g the
momentum of the ve h icle to assist in the brake applica­
tion. This s e lf-e n e r g iz in g
applied to both brake shoes at each wheel in both fo rw a rd
and r e v e r s e motion.
................................................................5-13
....................................................... ..... 5-17
............................................ ..... 5-19
..................................................... ..... 5-38
................................................... ..... 5-42
10 thru 30 s e r ie s , have
3). The Twinplex, self-a d ju stin g
or s e lf actuating fo r c e
CHEVROLET TRUCK SERVICE MANUAL
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