Bendix Commercial Vehicle Systems VERSAJUST AUTOMATIC SLACK ADJUSTER - Manual (Page 6)

6
BRAKE MAINTENANCE INSPECTION
Note: Make certain the vehicle has been prepared
according to the instructions under the heading GENERAL
SAFETY GUIDELINES in this manual.
The following test can be used to inspect the maintenance
condition of the foundation brake and to determine how
much of the chamber stroke is caused by the condition of
the foundation brake.
1. Always chock the wheels to keep the vehicle from
moving.
2. Raise the axle so the wheel can be rotated.
3. Adjust the slack adjuster to produce light brake drag
with wheel rotation.
4. Apply the brake to 80-90 psi and measure the stroke
(See Item 3 of In Service Inspection for pressure tips).
5. If the stroke significantly exceeds the values shown in
Chart 3 below, the brake may be out of the norm, and
brake maintenance may be required.
AL
Factor
15"x4"
Front
Brake
16.5"x7"
Tractor, Truck
or Bus Brake
16.5"x7"
Trailer
Brake
12 X 5.0" 1 /
2
" N/A N/A
12 X 5.5" 1 /
2
" N/A N/A
16 X 5.0" 5 /
8
" 1 /
2
" N/A
16 X 5.5" 3 /
4
" 1 /
2
" N/A
16 X 6.0" 7 /
8
" 5 /
8
" N/A
20 X 5.0" 5 /
8
" 1 /
2
" 3 /
8
"
20 X 5.5" 3 /
4
" 5 /
8
" 1 /
2
"
20 X 6.0" 7 /
8
" 3 /
4
" 5 /
8
"
24 X 5.0" N/A 5 /
8
" 1 /
2
"
24 X 5.5" N/A 5 /
8
" 5 /
8
"
24 X 6.0" N/A 3 /
4
" 5 /
8
"
30 X 5.0" N/A 3 /
4
" 5 /
8
"
30 X 5.5" N/A 7 /
8
" 3 /
4
"
30 X 6.0" N/A 1" 7 /
8
"
CHART 3 - AL FACTOR
BENDIX ® VERSAJUST ™ SLACK
ADJUSTER REMOVAL
Note: Make certain the vehicle has been prepared
according to the instructions under the heading GENERAL
SAFETY GUIDELINES in this manual.
1. If the Versajust slack adjuster is equipped with the
easy-on yoke assembly illustrated in Figure 2:
A. Loosen the brake actuator push rod jam nut
and run it back on the brake actuator push rod
approximately 5 /
8
inch.
B. Loosen the easy-on yoke adapter and run it back
on the brake actuator push rod until it is free of the
yoke.
TESTING THE BENDIX ® VERSAJUST ™
ADJUSTER MECHANISM
The following test can be made to determine if the Bendix ®
Versajust ™ adjuster mechanism is functioning properly.
1. With the brakes released and the vehicle wheels
blocked, de-adjust the brakes by rotating the manual
adjustment hex counterclockwise approximately 1 /
2
to
1 revolution.
Note: Considerable torque is required to rotate the
manual adjustment hex counterclockwise and should
be considered normal. The required torque may be as
high as 70 foot pounds.
2. Using a straight edge, scribe a line across the manual
adjustment hex head and slack adjuster body. (Refer
to Figure 6).
ADJUSTER HEX
ROTATES
CLOCKWISE
DURING
ADJUSTMENT
GREASE
FITTING
FIGURE 6 - TESTING ADJUSTER MECHANISM
3. Apply, and COMPLETELY RELEASE, the service
brakes several times while observing the manual
adjustment hex and the scribed line. The Bendix
Versajust slack adjuster manual adjustment hex
should rotate clockwise during the application and
remain stationary during release. No counterclockwise
rotation of the hex should be observed. The
amount of clockwise rotation (adjustment) will
decrease progressively as the brake nears proper
adjustment. If the Versajust slack adjuster fails to
perform as described, it will be necessary to repair or
replace it.
4. Manually re-adjust the Versajust slack adjuster being
tested before returning the vehicle to service. (See
section Installation, Step 6)
Note: While it is possible to use the automatic adjustment
feature of the Versajust slack adjuster to bring the brake back
into adjustment, this process will require numerous applications
and COMPLETE RELEASES (the number of applications
depends on how much the slack was de-adjusted).