Chevrolet Light Duty Truck 1973, Service Manual

Page: 278 / 979

5 -1 2 BRAKES
there is not a condition of pedal travel increase with
respect to the front brake as the linings wear (fig.
21
).
As the driver releases the brake pedal, it is important
that the piston immediately release from the shoe and
lining. As pointed out earlier, the movement from no
application to full application is very slight, therefore it
should be easy to understand that as force is removed,
the piston and caliper merely relax into the released
position and braking effort is removed.
An important thing to remember about disc brakes is
that the lining is in constant contact with the disc (fig.
21
) giving the added advantages of improved brake
response, reduced pedal travel and faster generation of
line pressure. The shoe, being at zero clearance, also
"wipes" the disc free of any foreign matter. Disc brakes
also have good fade resistance with fast recovery.
The major components of the single piston sliding
caliper disc brake are the hub and disc assembly, the
shield, the support, the caliper assembly, and the shoe
and lining assemblies (fig. 22). The cast iron disc is of
the fully ventilated design. Note that between the
machined braking surfaces are cooling fins. This design
acts to cool the brakes by fanning the air and in addition
has many cooling surfaces.
Hub and Disc
The purpose of the disc is to provide the frictional
surfaces required to stop the vehicle.
Shield and Support
The disc is protected from cross vehicle splash by a
shield on the inboard side that is bolted to the steering
knuckle.
Brake Caliper
The caliper provides a means of applying the shoe and
lining assemblies to the disc. It is connected to the system
by a hydraulic line. It is mounted to the support plate by
two housing retainer bolts, two sleeves and four rubber
bushings. An inner caliper rubber bushing is installed
between each sleeve and groove in the housing, and an
outer caliper rubber bushing is installed between each
bolt and groove in the housing. Shoe and lining
assemblies are positioned on the caliper so they straddle
the disc.
REAR DRUM BRAKES (Fig. 2 3 )
The entire rear wheel brake mechanism is mounted on
the brake flange plate, which is bolted directly to the axle
housing (fig. 23).
Fig. 21- New and W orn Linings
Fig. 22- Disc and Caliper - Single Piston Fig. 23-Rear Drum Brake - Right Side Shown
NEW
WORN
FWD"*'
PULL BACK SPRINGS PRIMARY SHOE
SECONDARY
SHOE
ACTUATING LEVER
HOLD DO W N
SPRING
A N D PIN
LIGHT DUTY TRUCK SERVICE MANUAL