MECHANICAL BRAKES
Read all of Section B and this section before attempting any procedure. Pay particular attention to all Notes, Cautions and Warnings
the system and still apply the shoes to the drums, the
braking effort at the wheel brake will not be adequate.
The self adjusting mechanism in the wheel brakes
requires enough cable travel at the wheel brake to work
reliably. When the brake is released, there must be slack
in the system so the brakes will release fully and the
adjusters will function. Free pedal travel, pedal force,
shoe to drum clearance and braking capability are
closely related. It is very important to maintain the proper
relationships to assure braking performance and the best
wheel brake adjustment.
How the Service Brake Works
Depressing the service brake pedal pulls the compensa
tor assembly and equalizer link, which are connected to
the brake cables (Ref Fig. 1 on page M-1). The first part
of the pedal travel removes slack from the system. Con
tinued motion of the brake pedal pulls both the left and
right brake 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
CAUTION
Never manually adjust the brakes at the
star wheel. Doing so will cause perma
nent 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. Do not manually adjust the
brakes by prying back the adjuster arm and turning the
star wheel.
Adjustment takes place only when the brake is fully
applied and released
while the vehicle is moving
(Ref
Fig. 2 on page M-2). It is very important that the brake
�Bcake Adjuste, A,m
Star Wheel
Adjusting Screw
Brakes adjust only while the vehicle is moving.
When the brake pedal is depressed, the brake lever moves
toward the front of the vehicle
(A).
The other end of the brake lever moves to the rear of the
vehicle (B) where it contacts the brake adjuster arm,
causing it to move.
The brake adjuster arm moves away from the star wheel
(C). The amount of adjuster travel is limited by the amount
of brake shoe travel required to contact the brake drum.
The amount of travel increases as the brake shoe lining
wears.
When the brake pedal is released, the adjuster spring
retracts the brake adjuster arm which contacts the star
wheel.
Note that adjustment only takes place when the
brake pedal is released while the vehicle is in motion.
If the brake shoes
have
worn far enough to permit the
brake adjuster arm to contact the next tooth of the star
wheel, the star wheel will be advanced by the tension
applied to the adjuster arm by the adjuster spring.
If the brake shoes
have not
worn enough to permit the
brake adjuster arm to contact the next tooth of the star
wheel, the brake adjuster arm will move on the flat of the
star wheel. The star wheel does not rotate and no
adjustment occurs.
Fig. 2 Wheel Brake Adjustment
cables permit the brake levers to release fully when the
brake pedal is in the released position.
How the Parking Brake Works
The parking brake is operated by a smaller pedal which
extends across the top of the service brake pedal. It is
attached to the service brake pedal with a hinge pin and
is spring loaded (Ref Fig. 3 on page M-3).
Depressing the parking brake pedal moves the latch arm
against the catch bracket attached to the chassis. As the
Page M-2
Repair and Service Manual
Summary of Contents for FLEET 1999
Page 6: ...TABLE OF CONTENTS Notes __________________________ _ Page iv Repair and Service Manual...
Page 10: ...SAFETY INFORMATION Notes _________________________ _ Page viii Repair and Service Manual...
Page 26: ...SAFETY Notes _ _ ___________________________ _ Page B ii Repair and Service Manual...
Page 48: ...BODY Notes _ _ ___________________________ _ Page C ii Repair and Service Manual...
Page 56: ...WHEELS AND TIRES Notes __________________________ _ Page D ii Repair and Service Manual...
Page 72: ...SPEED CONTROL Notes _ _ ________________________ _ Page F ii Repair and Service Manual...
Page 80: ...ENGINE Notes _ _ __________________________ _ Page G ii Repair and Service Manual...
Page 94: ...FUEL SYSTEM Notes _ _ _________________________ _ Page H ii Repair and Service Manual...
Page 110: ...ELECTRICAL Notes _ _ _________________________ _ Page K ii Repair and Service Manual...
Page 120: ...ACCESSORY WIRING Notes __________________________ _ Page L ii Repair and Service Manual...
Page 148: ...REAR SUSPENSION Notes __________________________ _ Page N ii Repair and Service Manual...
Page 154: ...REAR AXLE Notes _ _ ___________________________ _ Page P ii Repair and Service Manual...
Page 158: ...PAINT Notes _ _ ___________________________ _ Page Q ii Repair and Service Manual...
Page 162: ...TROUBLESHOOTING Notes _ _ ________________________ _ Page R ii Repair and Service Manual...
Page 170: ...LIMITED WARRANTY Notes __________________________ _ Page S ii Repair and Service Manual...
Page 176: ...LIMITED WARRANTY Notes __________________________ _ Page S 6 Repair and Service Manual...
Page 178: ...GENERAL SPECIFICATIONS Notes _________________________ _ Page T ii Repair and Service Manual...