d. Disassembly for 16-1/2" x 7" Brakes (See
Figure 4-10).
1.
Release brakes and back off slack
adjuster.
2.
Remove slack adjuster lock ring and slack
adjuster.
3.
Remove drum assembly
(See Figure
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.
7.
Swing the lower shoe back approximately
180
o
to 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.
e. Reassembly for 16-1/2 x 7" Brakes (See
Figure 4-10).
1.
Install new anchor pin bushings, camshaft
bushing and camshaft seals into the spider.
IMPORTANT
When installing camshaft seals, the seal on the
slack adjuster side is installed facing into spi-
der. 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
Section 4-8.6b.
4-8.6
Automatic Slack Adjusters
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.
a. Operational Check (See Figure 4-11)
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-
URE OF PROPER ADJUSTMENT
FUNCTION WILL RESULT IN LOSS OF
BRAKES.
4-20
Summary of Contents for 317B
Page 3: ...MODELS 317B 318 319 TRAILER OPERATOR S MANUAL PURCHASED FROM DATE ADDRESS PHONE NO SERIAL NO...
Page 8: ......
Page 14: ...3 2 Figure 3 1 Front Trailer Terminology Figure 3 2 Rear Trailer Terminology...
Page 18: ...3 6 Figure 3 4 Hydraulic Controls...
Page 24: ...3 12 Figure 3 5 Steps for Loading and Unloading...
Page 30: ...3 18 Figure 3 10 Dock Leveler Operation...
Page 34: ...3 22 Figure 3 12 Front Extension Bulkhead...
Page 36: ...3 24 Figure 3 13 Rear Impact Guard and Antilock Brake System...
Page 40: ...4 2 Figure 4 1 Lubrication Points...
Page 45: ...4 7 Figure 4 2 317B 318 319 Wiring Diagram...
Page 46: ...4 8 Figure 4 3 Remote Wiring Diagram...
Page 52: ...4 14 Figure 4 6 Checking Axle Alignment CURBSIDE DRIVER SIDE Figure 4 7 Examples of Camber...
Page 56: ...4 18 Figure 4 10 Axle and Brake Assembly...
Page 62: ...4 24 Figure 4 13 Inboard Mount Hub and Drum Figure 4 14 Three Spoke Wheel and Drum...
Page 66: ...4 28 Figure 4 18 Mounting Tires and Wheels Figure 4 19 Stud Tightening Sequence...
Page 69: ...4 31 Figure 4 20 Dock Leveler Leg Assembly...
Page 80: ...5 10 NOTES...