6
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 ASA-5
™
slack adjuster fails to
perform as described, it will be necessary to repair or
replace it.
4. Manually readjust the ASA-5
™
slack adjuster being
tested before returning the vehicle to service. (See sec-
tion Installation, Step 6)
Note: While it is possible to use the automatic adjustment
feature of the ASA-5
™
slack adjuster to bring the brake back
into adjustment, it will require numerous applications and
COMPLETE RELEASES (the number of applications de-
pends on how much the slack was de-adjusted).
BRAKE MAINTENANCE INSPECTION
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. Chock wheels to keep vehicle from moving.
2. Raise axle so wheel can be rotated.
3. Adjust slack adjuster to produce light brake drag with
wheel rotation.
4. Apply brake to 80-90 psi and measure stroke (See Item
3 of In Service Inspection for pressure tips).
5. If stroke significantly exceeds the values shown in the
chart, the brake may be out of the norm and brake main-
tenance may be required.
AL Factor 15"x4" 16.5"x7" 16.5"x7"
Front Tractor, Truck Trailer
Brake or Bus Brake 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"
FIGURE 6 - TESTING ADJUSTER MECHANISM
ADJUSTER HEX
ROTATES
CLOCKWISE
DURING
ADJUSTMENT
STRAIGHT
LINE SCRIBED
ACROSS HEX
AND BODY
If the actuator stroke exceeds those shown, inspection of
the foundation brake and/or the automatic slack should be
completed. Maintenance of the foundation brake may be a
factor in the long stroke conditions. Inspecting the founda-
tion brake per the Brake Maintenance Inspection presented
in this manual should determine how much of the long stroke
condition is caused by the condition of the foundation brake.
The ASA-5
™
slack adjuster can be tested using the instruc-
tions presented in this manual under Testing the ASA-5
™
Adjuster Mechanism.
TESTING THE ASA-5
™
ADJUSTER MECHANISM
The following test can be made to determine if the ASA-5
™
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).
3. Apply and COMPLETELY RELEASE the service brakes
several times while observing the manual adjustment
hex and the scribed line. The ASA-5
™
slack adjuster
manual adjustment hex should rotate clockwise during
(56 pages)
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