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Brake Assembly Maintenance
The brake assemblies should be inspected and adjusted
every 2,000 miles or monthly. Examine the brake linings
visually to locate the lining showing the greatest amount
of wear. The wheel and drum should be removed and the
linings replaced if the thinnest portion of the lining is 3/8
in. (9.5 mm) or less. Do not allow the linings to wear thin
enough that the lining rivet contacts the drum (See
Figure 4-14.) Lubricate brake assembly per Figure 4-1
and Table 4-2.
Do not allow grease to contact brake linings as
this could result in reduced braking performance.
Brake Adjustment
This semitrailer is equipped with automatic slack
adjusters which compensate for brake lining wear and
keep brakes adjusted. Brakes should not be adjusted
manually except when relining brakes.
Disassembly for 16-1/2" x 7" Brakes
1. Release brakes and back off slack adjuster (See
Figure 4-15.)
2. Remove slack adjuster lock ring and slack adjuster.
3. Remove drum assembly.
4. Disengage the roller retainers from the rollers.
5. Press down on the bottom brake shoe and remove
the lower cam roller. Lift the top shoe and take out
the top cam roller.
6. Lift out the shoe retractor spring, which is now free of
tension.
Figure 4-14: Brake Lining Wear
WARNING
MAINTENANCE AND LUBRICATION
7. Swing the lower shoe back approximately 180
relieve the tension on the shoe keeper springs.
Remove the springs and slip the shoes off the anchor
pins.
8. Remove camshaft lock ring, spacer washer(s) and
camshaft.
9. After removing the shoes, completely inspect all
brake components, servicing as necessary.
Reassembly for 16-1/2 x 7" Brakes
1. Install new anchor pin bushings, camshaft bushing
and camshaft seals into the spider (See
Figure 4-15.)
IMPORTANT
When installing camshaft seals, the seal on the slack
adjuster side is installed facing into spider. This
allows grease to purge outside the brake assembly
when greasing the camshaft bushing.
2. Install cam roller, retainer clip and retractor spring
retainers onto the camshaft.
3. Install 1/8" thick camshaft washer onto the camshaft.
4. Install the camshaft into the spider. Install spacer
washer and lock ring retainer on camshaft before
sliding the camshaft through the camshaft support
bracket. Install the slack adjuster, washer and lock
ring retainer.
5. Install the brake keeper onto the shoes. Install shoes
onto the spider by placing shoes in place on the
anchor pins, then "wrap" the two shoes into place
about the spider.
6. Install the shoe retractor spring onto the shoes.
7. Connect slack adjuster to brake chamber pushrod.
8. Adjust automatic slack adjuster as outlined in
"Adjusting Slack Adjuster" on page 4-24.
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