Troubleshooting guide

18
www.bendix.com 1-800-AIR-BRAKE (1-800-247-2725)
Slack Adjusters
Slack Adjusters
The slack adjuster is the link between a brake chamber or
actuator and the S-Cam brake camshaft. Its arm is fastened
to the push rod with a yoke and its spline is installed on
the foundation brake cam shaft. It transforms and multiplies
the force developed by the chamber into a torque which
applies the brakes via the brake camshaft.
Manual Slack Adjusters
To compensate for the gradual wear on the brake block
lining, slack adjusters are equipped with an adjusting
mechanism, which provides a means of adjusting for
brake lining wear. Slack adjuster models are designated
by a number which represents its maximum torque
rating (e.g. a type 20 unit is rated for a maximum of
20,000 inch-pounds of torque). Slack adjusters are
available in various arm configurations, lengths and
spline types.
The entire slack adjuster operates as a unit, rotating as
a lever with the brake cam shaft as the brakes are
applied or released. The most efficient braking action
is obtained when the slack adjuster arm travel is
approximately 90 degrees and in the recommended
range of the chamber. Therefore, it is important that
brake adjustments are made as often as necessary.
Automatic Slack Adjusters
Automatic slack adjusters perform the same function
as the standard unit, except that it automatically adjusts
for lining wear. The Bendix "sure stroke" unique design
monitors brake lining to brake drum clearance, thus
eliminating the possibility of over adjustment.
The automatic slack adjuster does not require periodic
manual adjustment, however, the unit does provide for
manual adjustment. All Bendix slack adjusters
incorporate a grease fitting and/or a tapped hole for a
lube fitting.
Ideal ASA-5
™
Slack Adjuster Installation
The brake chamber push rod and arm of the slack
adjuster should reach approximately 90 degrees at 1/2
the available stroke (mid-stroke) of the chamber. The
chart to the right shows the ASA-5
™
slack adjuster
installation tolerance.
Manual Slack
Adjuster
ASA-5
™
Automatic
Slack Adjuster
Off-set and
Straight Arm
Styles
Bendix offers the SureStroke
™
Indicator to help slack adjuster
inspection and maintenance.
Clamp Pin
Style
Clevis Pin
Style
X Inches
Arm Length
5.00" 0.75" to 2.00"
5.50" 0.75" to 2.00"
6.00" 0.00" to 2.00"
Slack
Arm
Length
X"
Adjustment
Mechanism
Lube
Fitting
ASA-5
™
Slack
Adjuster Installation
Tolerance
Spline
Yoke