B
66
Repair and Service Manual
BRAKES
Read all of SAFETY and this section before attempting any procedure. Pay particular attention to Notices, Cautions, Warnings and Dangers.
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cables. Each brake cable pulls a brake lever which
pushes the rear brake shoe against the brake drum.
When the rear shoe contacts the brake drum, it can no
longer move rearward. Additional pedal (and cable) travel
causes the actuator bracket (moving anchor) to move and
applies force to the front shoe, pushing it against the
brake drum. The force applied to the front and rear shoes
is approximately equal. As the shoes contact the moving
brake drum, the shoes try to move in the direction of drum
rotation. This movement results in the typical brake shoe
wear patterns.
Equalizer Link
The equalizer link balances braking between the driver
and passenger sides of the vehicle. Variations in wheel
brake adjustment, cable friction and manufacturing toler-
ances may cause the equalizer to be slightly misaligned.
This misalignment is normal.
Automatic Adjuster Mechanism
Never manually adjust the brakes at the star wheel.
Doing so will cause permanent damage to the
adjuster assembly and result in a gradual loss of
brakes.
The wheel brakes are equipped with an automatic
adjuster mechanism that is designed to compensate for
brake shoe wear and eliminate the need for manual brake
shoe adjustment. The brake adjuster is activated by
movement of the lever attached to the brake cable.
How the Park Brake Works
The park brake is operated by a smaller pedal which
extends across the top of the service brake pedal. It is
spring loaded and attached to the service brake pedal
with a hinge pin (Ref. Fig. 2).
Pressing the park brake pedal moves the latch arm
against the catch bracket attached to the chassis. As the
park brake is pressed, the service brake is applied until
the notch in the latch arm engages with the catch bracket.
The service brake pedal is held in the applied (down)
position by the catch bracket.
The latch arm is held in position by tension in the brake
linkage. The park brake can be released by two methods:
1.
Pressing the service brake, which permits the spring
loaded park brake pedal to return to its original posi-
tion, disengages the latch arm from the catch
bracket. This is the preferred method because it min-
imizes wear on components.
2.
Pressing the accelerator pedal rotates the kick-off
cam and forces the pedal latch arm to move away
from the catch bracket. The spring loaded park brake
pedal returns to its original position, releasing brake.
Fig. 2 Park Brake and Kick-Off Mechanism
Kick-Off Actuating Linkage
The kick-off actuating linkage may require periodic adjust-
ment to compensate for the normal wear. Replacement of
any linkage components will also require an adjustment.
Compensator Assembly
The compensator assembly contains a spring, which is
compressed until the stop tube within the spring is
engaged and the linkage becomes solid (Ref. Fig. 3). The
brake compensator assembly applies a spring load to the
park brake system and insures that the park brake
remains under tension whenever it is engaged.
Fig. 3 Compensator Assembly
Accelerator
Pedal
Pedal Latch Arm
Kick-Off Cam
Pedal Bumper
Catch Bracket
Pedal Latch Arm
Spring
Stop Tube