Slack Adjuster Does't Automatically Adjust Brakes; Testing Asa-5 Adjuster Mechanism - BENDIX ASA-5 AUTOMATIC SLACK ADJUSTER Manual

STRAIGHT
LINE SCRIBED
ACROSS HEX
AND BODY
FIGURE 7 - TESTING ADJUSTER MECHANISM
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
a visual stroke indicator. The SureStroke
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
adjuster can be tested using the instructions presented in
this manual under Testing the ASA-5
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 that a problem exists with the automatic adjuster,
with the installation of the adjuster, or with related foundation
6
ADJUSTER HEX
ROTATES
CLOCKWISE
DURING
ADJUSTMENT
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indicator is also available as
™ indicator is
™
™ Adjuster
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
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
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
slack
adjustment. If the ASA-5
perform as described, it will be necessary to repair or
replace it.
4. Manually readjust the ASA-5
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
into adjustment, it will require numerous applications and
COMPLETE RELEASES (the number of applications
depends on how much the slack was de-adjusted).
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ADJUSTER MECHANISM
™
slack adjuster
™ slack adjuster fails to
™
slack adjuster being tested
™ slack adjuster to bring the brake back
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