User's Manual

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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 congurations

are offered, including both straight arm and

/8" yoke offset

models. The Versajust slack adjuster is offered in arm

lengths of 5, 5

/2 and 6 inches, and worm gear splines to

accommodate the standard 1

/4" and 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 deection, 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 specic 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 rst 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

YOKE

WORM

GEAR

Compatible with

Bendix

ASA-5

Automatic Slack

Adjusters

LUBE FITTING

Summary of content (8 pages)

PAGE 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.
PAGE 2
GENERAL SAFETY GUIDELINES WARNING! PLEASE READ AND FOLLOW T H E S E I N S T R U C T I O N S T O AV O I D PERSONAL INJURY OR DEATH: 5. When working on or around a vehicle, the following general precautions should be observed at all times. 6. 1. 7. 2. 3. 4. Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Always wear safety glasses. Stop the engine and remove ignition key when working under or around the vehicle.
PAGE 3
extended yoke adapter is also available as a separate service item. The extended adapter is 1/2 inch longer than the standard, and is primarily intended for use when the existing brake actuator push rod is too short. PUSH ROD 15 /16" A. With the brake chamber in the released position, place a square (or an equivalent object) so that one edge is parallel to the actuator push rod, while the other edge bisects the brake camshaft.
PAGE 4
environmental conditions, an application of anti-seize compound to both the camshaft and worm gear spline may facilitate later slack removal. INSTALLATION 1. Select the proper Bendix® Versajust™ slack adjuster. 2. Install the Versajust slack adjuster on the brake camshaft. 3. If the Versajust slack adjuster has the easy‑on yoke (see Figure 3), position the brake actuator push rod jam nut approximately 15/16 inches from the end of the brake actuator push rod.
PAGE 5
2. Lubricate the automatic slack adjuster through the lube fitting with a quality multipurpose chassis lubricant (N.L.G.I. Grade 2). Lubricate the slack adjuster until clean lubricant flows from the grease relief opening in the boot. 3. Perform the In Service Inspection described in this manual. IN SERVICE INSPECTION 1. Apply and release the vehicle brakes several times while observing the Bendix® Versajust™ slack adjuster.
PAGE 6
TESTING THE BENDIX® VERSAJUST™ ADJUSTER MECHANISM The following test can be made to determine if the Bendix Versajust™ adjuster mechanism is functioning properly. BRAKE MAINTENANCE INSPECTION ® 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.
PAGE 7
C. Rotate the manual adjustment hex counterclockwise until the Versajust slack adjuster is clear of the brake actuator push rod. Note: Considerably more torque is required to rotate the manual adjustment hex counterclockwise than is necessary to rotate it clockwise. The torque may be as high as 70 foot pounds. 2. If the Bendix® Versajust™ slack adjuster is equipped with the quick‑connect yoke assembly illustrated in Figure 3: A.
PAGE 8
The Bendix® Versajust™ Slack Adjuster Troubleshooting Chart Symptom 1. Brake Actuator stroke is too long. WARNING: Automatic slack adjusters should not be manually adjusted in an effort to correct excessive push rod stroke, because this condition indicates 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. 2. Brakes dragging — apparent over-adjustment of brakes. Cause Remedy A.