Chevrolet Light Duty Truck 1973 Service Manual page 281

Fig. 27 Override Component Operation
necessity of preventing star wheel "back-off" during the
maximum self-energizing condition. To do this, a "stop
tang" extends down from the under side of the actuating
lever to contact the secondary shoe (fig. 28). This limits
the actuating lever travel to a maximum of three notches
per stroke, which has the effect of maintaining pawl
engagement to the star wheel while braking to a stop.
Again, as in the case of a bound adjusting screw, any
additional shoe motion is absorbed by the over-ride
pivot plate and spring.
NOTE: The actuating lever stop is also the
mount and guide for the lever return spring.
The actuating lever is held against the secondary shoe by
the hold-down spring and cups. The pawl is connected to
the actuating lever and held in position by the pawl
return spring.
BRAKE INSPECTION
Every 12 months or 12,000 miles-whichever occurs first:
Inspect drum brake linings or disc brake pads, as well as
the other internal brake components at each wheel
(drums, rotors, wheel cylinders, etc.). For convenience, it
is recommended that disc brake pads be checked
whenever tires are rotated (at 6000 mile intervals). More
frequent checks should be made if driving conditions
and habits result in frequent brake application. Parking
brake adjustment should also be checked whenever brake
linings are checked.
NOTE: During any inspection period, the
remaining lining life expectancy should be
determined. This determination should dic­
tate the next inspection period.
M A IN TEN A N C E A N D ADJUSTMENTS
STOP TANG
SEATED ON
SHOE
Fig. 28-Actuating Lever Stop Tang
Parking Brake Activating Mechanism
The activating mechanism for the parking brake consists
of an operating lever located in back of the secondary
shoe, and attached to the shoe by a pivot at the upper
end. A strut rod located a few inches below the pivot
point, extends forward from this lever to the primary
shoe.
The parking brake cable is connected to the lower end of
the operating lever. When the parking brake is applied,
the cable pulls the lower end of the operating lever
forward, causing the strut rod to push the primary shoe
forward. At the same time, the upper end of the lever
pushes the secondary shoe rearward. The combined
action of the lever and the strut rod drives the primary
and secondary shoes apart and into contact with the
drums.
Lining Inspection
Drum Brake
Replace whenever the thickness of any part of any lining
is worn to within 1/32" of the shoe table or rivet head
whichever is applicable.
Another important point to remember, always replace
brake shoes in axle sets (right and left side).
Disc Brakes
Check both ends of the outboard shoe by looking in at
each end of the caliper. These are the points at which the
highest rate of wear normally occurs. However, at the
same time, check the lining thickness on the inboard
shoe to make sure that it. has not worn prematurely.
Replace whenever the thickness of any part of any lining
BRAKES 5-15
LIGHT DUTY TRUCK SERVICE MANUAL