Page M-11
Repair and Service Manual
B
B
MECHANICAL BRAKES
Read all of Section B and this section before attempting any procedure. Pay particular attention to Notices, Cautions, Warnings and Dangers.
Fig. 14 Adjuster Mechanism
If the adjuster arm
engages and turns
the star
wheel, proceed. If the arm
fails to engage
the star
wheel, it has been damaged and both wheel brake
assemblies must be replaced.
If adjuster arm engages star wheel but
fails to
rotate it
, the adjuster assemblies must be replaced
with new color-coded adjusters. Note the location of
the two Teflon coated washers (Ref. Fig. 15).
7. Check the condition and operation of the moving
anchor assembly.
Operate the brake lever to check for free motion. The
adjuster assembly and brake lever should move
smoothly from front to back on the backing plate. If
the moving anchor assembly is damaged or binds
against the backing plate, replace both of the wheel
brake assemblies.
A backing plate assembly that shows any indi-
cation of galling or gouging is not repairable
and must be replaced with a new wheel brake
assembly. Always replace wheel brake assem-
blies in pairs.
8. Inspect the backing plate.
Inspect for gouges, galling or other damage, particu-
larly where the backing plate is contacted by the brake
shoes and by the moving anchor assembly. Replace
both backing plates if any gouges or galling is found.
9. Measure the brake shoe thickness.
Measure at the most worn area. Brake shoe thickness
must never be less than .060" (1.5 mm) at any point
on the shoe. It is normal for the shoes to show more
wear at the leading and trailing edges (Ref. Fig. 15). If
the brake shoe thickness is approaching .060" (1.5
mm), it is recommended that the shoes be replaced. It
is recommended that the brake shoe springs and
brake adjusters be replaced when installing new brake
shoes.
10. Inspect the brake shoe springs.
Be sure that they are not broken or damaged and are
correctly installed. The hooked end of the adjuster
spring is inserted through the front of the front shoe
and the opposite end hooked to the adjuster with the
hook end facing out. The brake shoe springs must be
installed with the light spring closest to the adjuster
mechanism with the hook installed down through the
rear brake shoe and up through the front brake shoe.
The heavy top spring is installed with both spring
hooks installed down through the brake shoes (Ref.
Fig. 16).
.
Fig. 15 Brake Shoe Wear
Brake Adjuster
Arm
Star
Wheel
Adjusting
Screw
Front of Vehicle
Wheel Brake
Lever
Forward
Forward
A
A
B
B
C
C
D
D
Drum Rotation
Drum Rotation
Driver side
Passenger Side
The pattern of normal brake shoe wear is
shown in quadrant ‘A’, ‘B’, ‘C’ & ‘D’ with
quadrant ‘A’ showing the most wear.
Quadrant ‘B’ will show the second most wear.
Summary of Contents for EXPRESS L4
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