Chevrolet 30 Series 1967 Service Manual page 217

Standard Hydraulic Brakes
Bendix Power B r a k e s ......................................................
Vacuum Booster Power Brake U n it.................................
General D e s c r ip tio n ............... '......................................... ... 5"].
Main Cylinder......................................................................5-1
Self Adjusting Duo-Servo B r a k e s ................................. ...5-1
Manually Adjusted Brakes - W a g n e r ........................... ... 5-1
Wheel C y lin d e r s ............................................................ ... 5-4
Brake Linings ............................................................... ... 5-5
Parking B r a k e ............................................................... ... 5-5
Brake Pipe Distribution and Switch A s s e m b ly ............ ... 5-5
Maintenance and A dju stm en ts.......................................... ...5-5
Brake Shoe Adjustment ................................................ ... 5-5
Bleeding B r a k e s ............................................................ ...5-6
Parking Brake Lubrication
Brake Pedal to Floor C le a r a n c e ................................. ...5-8
Brake Pedal Adjustment - G 1 0 -2 0 .............................. ... 5-8
Brake Pedal and Push Rod Travel Adjustment............ 5-9
Parking Brake A dju stm en ts.......................................... ... 5-9
Hydraulic Brake L in e s ................................................... ...5-11
Service Operations ......................................................... ...5-13
Main Cylinder - Dual S y ste m ....................................... ... 5-13
MAIN CYLINDER
All 1967 10 through 30 series models (except CA30 and
PA30/14,000 lb. GVW) are equipped with a new dual
brake system as a safety feature. If a wheel cylinder or
brake line should fail at either the front end or rear end
of the vehicle, the operator can still bring the vehicle to a
controlled stop. The system is designed with separate
hydraulic systems for the front and rear brake using a
dual main cylinder (Fig. 1). The main cylinder has two
entirely separate reservoirs and outlets in a common
body pasting. The front reservoir and outlet is connected
to the front wheel brakes, and the rear reservoir and
outlet is connected to the rear wheel brakes. Two pistons
within the main cylinder receive mechanical pressure
from the brake pedal push rod and transmit it through the
brakelines as hydraulic pressure to the wheel cylinders.
Main cylinders for CA30, PA30 (14,000 lb. and over
GVW), and all 40 through 60 series models are of the
single hydraulic system (single main cylinder reservoir)
type.
SELF-ADJUSTING DUO-SERVO BRAKES
NOTE: All models, 10 thru 40 series, have
self-adjusting duo-servo brakes, front and rear.
Fifty series models are equipped with self-
adjusting duo-servo brakes front and rear, ex­
cept those with 15,000 lb. single or two speed
SECTION 5
BRAKES
CONTENTS OF THIS SECTION
.............................................
STANDARD HYDRAULIC BRAKES
.......................................... ...5-8
GENERAL DESCRIPTION
5-1
INDEX
Page
Main Cylinder - Single Reservoir T y p e ..................... 5-16
Brake Components - Self Adjusting
Front and Rear B r a k e s ................................................ 5-18
Rear Brakes 40 and 50 S e r i e s .................................... 5-22
Brake Components - Manually Adjusted (Wagner) . . . .
Wheel C y lin d e r s ............................................................... 5-28
Brake D r u m s ..................................................................... 5-30
Brake Pedal (Except Tilt Cab and Chevy V an)............... 5-30
Brake Pedal - Tilt C a b ................................................... 5-30
Brake Pedal - Chevy V a n ................................................ 5-33
Parking Brake - Rear Wheel T y p e ................................. 5-33
Parking Brake - Propeller Shaft (Single Shoe Type)
Parking Brake - Propeller Shaft (Band T y p e )............... 5-39
Parking Brake Cable L ubrication .................................... 5-40
Anchor Pin Replacement - Chevy V a n ........................... 5-40
Hydraulic Brake Lines and T u b in g ................................. 5-40
Brake Pipe Distribution and Switch A s s e m b ly ............... 5-41
rear axle which are equipped with Twinplex two
cylinder, self-adjusting rear brakes.
series are equipped with Wagner, two-cylinder,
manually adjusted brakes, front and rear.
Brake shoe adjustment takes place when brakes are
applied with a firm pedal effort while the vehicle is back­
ing. Applying the brake moves an actuator which turns
the star wheel and lengthens the adjusting screw assem­
bly (Fig. 2). This action adjusts the shoes until clearance
between the lining and drum is within proper limits.
Fifty series models with 15,000 lb. single or two-speed
rear axle are equipped with 15 x 4 o r l 5 x 5 inch rear
Twinplex brakes (Fig. 3). The Twinplex, self-adjusting
rear brake is self-centering in operation, utilizing the
momentum of the vehicle to assist in the brake applica­
tion. This self-energizing or self-actuating force is
applied to both brake shoes at each wheel in both forward
and reverse motion.
MANUALLY ADJUSTED BRAKES (WAGNER)
NOTE: All 60 series models are equipped with
Wagner, two-cylinder, manually adjusted brakes,
front and rear.
The Wagner manually adjusted brakes are of two dif­
ferent types: the Type
(Fig. 5). The " F " has two identical brake shoes mounted
on the backing plate so that their toes are diagonally
Page
A ir B r a k e s
T railer Equipm ent
Special T o o ls
........................... 5-18
(Fig. 4), and the " F R -3"
" F "
CHEVROLET TRUCK SERVICE M ANUAL
Page
Page
5-25
. . 5-35
All 60