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
Section 4-8.5, 4-9.5c.
4-9.5
Automatic Slack Adjuster
The semitrailer automatic slack adjusters pro-
vide the means for routine brake adjustment to
compensate for lining wear. Inspect slack adjusters
every 2,000 miles to assure correct operation.
CAUTION
THE INSTALLATION GUIDE MUST BE
USED WHEN INSTALLING OR REIN-
STALLING AUTOMATIC SLACK AD-
JUSTER. FAILURE TO DO SO MAY RE-
SULT IN IMPROPERLY ADJUSTED
BRAKES WHICH MAY CAUSE BRAKE
DAMAGE OR LEAD TO BRAKE FAIL-
URE.
a. Operational Check (See Figure 4-18)
1.
Block wheels to prevent vehicle from
rolling.
2.
Check that the push rod is fully retracted,
apply air to release spring brake.
3.
Turn adjustment hex counterclockwise to
create an excessive clearance condition.
(A ratcheting sound will occur.)
4.
Make a full service brake application. On
release, allow sufficient time for brake to
fully retract. During the brake release,
observe rotation of the adjustment hex
(attach a wrench on the hex to make this
movement easier to see). This rotation
indicates that an excessive clearance
condition has been determined by the slack
adjuster, and it is making an adjustment to
compensate. On each subsequent brake
release the amount of adjustment and push
rod travel will be reduced until the desired
clearance is achieved.
5.
The push rod stroke should be 1 1/2" to 2"
with an 100 to 105 PSI service brake
application.
6.
Measure the movement of the push rod
from the completely released position to
the applied position by marking the push
rod where it exits the air chamber before
and after application.
7.
If the brakes have been running tight, the
control arm location should be checked.
WARNING
IF THE ADJUSTER APPEARS NOT TO
BE OPERATING, CHECK THE OTHER
BRAKE COMPONENTS FOR PROPER
FUNCTION AND ELIMINATE ANY BIND-
ING. RECHECK THE AUTOMATIC
SLACK ADJUSTER. IF THE ADJUSTER
IS NOT FUNCTIONING, THE UNIT
MUST BE REPLACED BECAUSE FAIL-
U R E O F P R O P E R A D J U S T M E N T
FUNCTION WILL RESULT IN LOSS OF
BRAKES.
b. Replacing Slack Adjuster (See Figure
4-18)
1.
Chock wheels to prevent vehicle from
rolling. Release spring and service brake.
Air chamber push rod must be
fully
released.
2.
To maintain a fully released parking brake,
a minimum of 105 psi reservoir pressure
must be maintained. If air pressure is not
available the spring brake must be
manually caged.
3.
Remove the existing slack adjuster and
clevis - DO NOT REMOVE EXISTING JAM
NUT.
4.
Install the new clevis (with 1/2" pin) onto
the push rod up to the jam nut -DO NOT
TIGHTEN JAM NUT.
4-24
Summary of Contents for 325C
Page 2: ......
Page 8: ......
Page 12: ......
Page 36: ......
Page 44: ...4 8 Figure 4 3 Models 325 326 327 329C Wiring Diagram...
Page 54: ...4 18 Figure 4 13 Checking Axle Alignment Figure 4 14 Examples of Camber...
Page 59: ...4 23 Figure 4 17 Axle and Brake Assembly...
Page 68: ......
Page 78: ...NOTES 5 10...
Page 79: ......
