Bendix Commercial Vehicle Systems VERSAJUST AUTOMATIC SLACK ADJUSTER - Manual

1
®
SD-05-4630
Bendix ® Versajust ™ Automatic Slack Adjuster
DESCRIPTION
The Bendix ® Versajust ™ automatic slack adjuster is
designed for use on cam-actuated drum brakes, the
type in use on most highway vehicles. Like a manual
slack adjuster, the Versajust ™ slack adjuster multiplies
and transforms the linear force of the air actuator into
a rotational force, or torque, which is used to apply the
foundation brake. In addition, the Versajust slack adjuster
automatically adjusts the clearance between the brake
lining and drum to compensate for wear.
A variety of Bendix Versajust slack adjuster configurations
are offered, including both straight arm and 5 /
8
" yoke offset
models. The Versajust slack adjuster is offered in arm
lengths of 5, 5 1 /
2
and 6 inches, and worm gear splines to
accommodate the standard 1 1 /
4
" and 1 1 /
2
" SAE 10C-, 24-,
and 28-tooth splines.
Either of two yoke designs (easy-on and quick connect) in
combination with an external manual adjuster hex provides
for convenient installation and maintenance of the Bendix
Versajust slack adjuster. Note: The manual adjuster
hex is intended for use during installation. CAUTION:
Automatic slack adjusters should not be adjusted
manually to correct excessive push rod stroke.
OPERATION
GENERAL
The automatic adjustment provided by the Bendix Versajust
slack adjuster results in consistent brake-lining-to-drum-
clearance and brake actuator stroke. The key to its
operation is the ability to complete the brake adjustment
during the early part of each brake application and to cease
adjusting as resistance to brake cam rotation begins to
build. This aspect of the adjuster mechanism’s operation
prevents over-adjustment caused by lining compression,
actuator bracket deflection, drum and foundation brake
component distortion, or brake component wear.
The Versajust slack adjuster incorporates a clutch-type
adjuster mechanism that continuously adjusts – in very
small increments – as lining and drum wear occurs. The
adjustments made by the Versajust slack adjuster are,
therefore, not in specific increments relative to actuator
stroke.
FIGURE 1 - BENDIX ® VERSAJUST ™ AUTOMATIC SLACK
ADJUSTER
Note that the Versajust automatic slack adjuster is
compatible with Bendix ® ASA-5 ® automatic slack adjusters.
Therefore, it is acceptable to have a Versajust automatic
slack adjuster on one side of the axle and an ASA-5
automatic slack adjuster on the other side of the same axle.
BRAKE APPLICATION
When the brakes are applied, the linear travel of the brake
actuator’s push rod causes the Versajust slack adjuster to
rotate the foundation brake camshaft, which in turn begins
to force the brake shoes into contact with the drum. When
the Versajust slack adjuster rotates, the yoke assembly
pivots on the yoke pin, causing the link to be pulled upward.
The “teeth” on the link mesh with the adjuster mechanism
pinion. As the link is pulled, it travels first through its free
play and then causes the pinion to rotate. Rotation of the
pinion is transmitted through the clutch spring to the worm
MANUAL
ADJUSTMENT
HEX
BOOT
LINK
LINK
PIN
YOKE
PIN
YOKE
WORM
GEAR
Compatible with
Bendix ® ASA-5 ®
Automatic Slack
Adjusters
LUBE FITTING