Bendix Commercial Vehicle Systems ASA-5 AUTOMATIC SLACK ADJUSTER 2/11 - Manual (Page 6)

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that a problem exists with the automatic adjuster, with
the installation of the adjuster, or with related foundation
brake components, which manual adjustment will not fix.
Replacement of the automatic slack adjuster or other
foundation brake components may be necessary. Consult
with the manufacturer's troubleshooting guidelines to find
and fix the problem.
WARNING: Manual adjustment of automatic
slack adjusters is a dangerous practice that could
have serious consequences, because it can give
the operator a false sense of security about the
effectiveness of the brakes, which are likely to go
out of adjustment again soon. Do not make manual
adjustments of an automatic slack adjuster once it
can no longer automatically adjust the brakes. Manual
adjustment DOES NOT fix the underlying wheel end
adjustment again. As soon as possible, have the
vehicle inspected by a qualified technician or consult
the manufacturer's troubleshooting guidelines to find
and fix the problem.
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 7).
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
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
section 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
FIGURE 7 - TESTING ADJUSTER MECHANISM
ADJUSTER HEX
ROTATES
CLOCKWISE
DURING
ADJUSTMENT
STRAIGHT
LINE SCRIBED
ACROSS HEX
AND BODY
pressure for this test can be achieved as follows:
Build the system pressure up to 100 psi reading on the
vehicle gauge. Shut the engine off. Fan the brakes to
attain a 90‑95 psi reading. Make and hold a full brake
application while the strokes are checked.
4. The Bendix ® SureStroke ™ indicator is also available as
a visual stroke indicator. The SureStroke ™ indicator is
a metal bracketing system that bolts onto the brake
chamber and allows drivers to check the indicator for
operating stroke.
IF THE SLACK ADJUSTER DOES NOT
AUTOMATICALLY ADJUST THE BRAKES
If the actuator stroke exceeds those shown in the stroke
table, inspection of the foundation brake and/or the
automatic slack should be performed. Maintenance of the
foundation brake may be a factor in the excessive stroke
conditions. Inspecting the foundation 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 instructions presented in
this manual under Testing the ASA-5 ® Adjuster Mechanism.
The automatic slack adjuster is not designed to function as
a manual adjuster once it is unable to maintain adjustment
automatically. Manual adjustment should only be done as
a temporary measure to correct brake adjustment in an
emergency situation. The routine manual adjustment of
an automatic slack adjuster that is still within adjustment
limits may shorten its service life. Automatic slack adjusters
should not be manually adjusted in an effort to correct
excessive pushrod stroke, because this condition indicates