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Trailer Installation ProceduresTrailer Installation Procedures

Automatic Brake AdjusterAutomatic Brake Adjuster

Why ABA’s?Why ABA’s?

Automatic Brake Adjusters are intended to provide efficient day-to-day service braking by maintaining optimum lining to drum clearance, which in turn ensures proper brake chamber stroke. However, different approaches by ABA manufacturers are sometimes used in accomplishing this goal.

The Haldex ABA is a “clearance-sensing” brake adjuster which maintains a nominal distance or clearance between the lining and drum under a variety of braking conditions.

Clearance-sensing adjusters are not subject to varying driver input or operational parameters. Clearance-sensing adjusters are not subject to varying driver input or operational parameters.

Trailer ApplicationsTrailer Applications

16 ½” Brake Assembly

Integral cam support anchor

bracket

12 ¼” & 16 ½” Brake Assemblies

12 1/4” Brake Assembly

Bolt-on cam support anchor

bracket

12 ¼” & 16 ½” Brake Assemblies

New InstallationNew Installation

1. Determine what axle the adjuster will be used on.

2. Determine the camshaft diameter & number of splines.

3. Determine the adjuster arm length.

4. Determine clevis pin diameter.

5. Ensure that chamber is installed in proper mounting position to match adjuster arm length.

6. Select the proper ABA kit.

P/N40910224

S/N33489

Installation Indicator and

Notch

Arm Lengt

h

Camshaft Diameter

Ask the right Questions!!Ask the right Questions!!

Installation ProceduresInstallation Procedures

Block wheels. Release spring and service brake. Air chamber push rod Must be Fully Released for proper adjuster installation and operation.

To maintain a fully released parking brake, a minimum of 80 psi reservoir pressure must be maintained. If air pressure is not available the spring brake must be manually caged. Push rod must be Fully Released during installation.

InstallationInstallation ProceduresProcedures

The slotted adjustment plate is mounted to the “S” cam support bracket. Adjustment plates for Rockwell/Meritor, Dana and Fruehauf axles require two bolts. Adjustment plates for Eaton axles require one bolt (see insert). Position plate on adjuster side of the “S” cam support bracket. Added plate thickness requires the use of longer mounting bolts.

Installation ProceduresInstallation Procedures

•Apply anti-seize type lubricant to splines and install adjuster on camshaft with adjustment hex pointed away from air chamber.

• Secure brake adjuster to camshaft with snap ring. Install enough washers (per TMC recommended practice) to reduce the end play to less than .060

Correct

(Brakes Released)

Incorrect

(Brakes Released)

Installation ProceduresInstallation Procedures

•Rotate adjustment hex clockwise until adjuster arm enters clevis and holes line up. Do not pull push rod out to meet adjuster.

•Coat the clevis pin with anti-seize type lubricant and install clevis pin, then secure with a cotter pin.

Installation ProceduresInstallation Procedures

Rotate the control arm away from the adjustment hex (towards the air chamber) until it comes to an internal stop.

Installation ProceduresInstallation Procedures

With brakes released and the control arm rotated properly to an internal stop, the “Installation Indicator” should fall within the slotted area as shown here.

Most Haldex adjusters are unhanded, and may be used on either side of the axle.

Note: Some steer axles utilize an offset casting which requires a left and right hand adjuster.

Note: Some steer axles utilize an offset casting which requires a left and right hand adjuster.

Installation ProceduresInstallation Procedures

Insert the flat end of the anchor stud through the control arm bushing. Push the threaded end of the stud into the anchor plate slot. The shoulder adjacent to the threaded end of the stud must engage the slot properly to prevent the stud from rotating. Install the 11/16” flange head nut loosely.

Installation ProceduresInstallation Procedures

Position adjuster control arm so the installation indicator falls within the control cover slot. Tighten the 11/16” flange head nut, 40-50 Ft. Lbs.. Check to make sure the control arm did not move out of position while tightening.

Installation ProceduresInstallation Procedures

After installation, the adjuster must be manually adjusted by rotating the adjuster hex clockwise until the lining lightly contacts the drum.

Once lining-to-drum contact is achieved, rotate adjusting hex counter-clockwise ½ of a turn (1/2 turn should include any free-play). A minimum of 13 Ft. Lbs. is necessary to overcome the clutch. Ratcheting sound will occur during back off.

Final InspectionFinal Inspection

• Ensure parking brake has remained fully released during installation. Check for proper installation of indicator (AA1 Adjuster only), snap ring and cotter pin.

•Check the application stroke of each brake assembly with the air supply system between 90-100 psi. If stroke is within operating range for chamber size, no action is necessary.

If stroke is too long or short, re-check adjuster for proper installation. Check for loose wheel bearings, binding camshafts, worn or missing shoe return springs, defective air chambers such as push rods binding or chambers inoperative. Check for cam bushing wear within the foundation brake and cam support wear or damage.

Continuous “manual” adjustment of an Automatic Brake Adjuster may cause internal clutch damage and shorter service life. Continuous “manual” adjustment of an Automatic Brake Adjuster may cause internal clutch damage and shorter service life.

Operational CheckOperational Check

2 Steps to Ensure Proper Adjuster Function2 Steps to Ensure Proper Adjuster Function

1. Rotate adjusting hex counterclockwise and check for minimum 13 ft.-lbs. torque (replace adjuster if less than 13 ft.-lbs. torque).

2. Rotate adjusting hex counterclockwise one full turn to create excessive clearance. Install 7/16” wrench on adjusting hex and make several service brake applications. If operating properly the wrench will rotate clockwise at the end of each “release” stroke. The Haldex adjuster is designed to take up approximately 10% of the excessive clearance with each release.

If the ABA is determined to be faulty, it should be replaced immediately. Do not operate as a manual brake adjuster.

If the ABA is determined to be faulty, it should be replaced immediately. Do not operate as a manual brake adjuster.

Measuring Measuring “Free”“Free” Stroke Stroke

Free stroke is the amount of movement of the adjuster arm required to move the brake shoes against the drum. With brakes released, measure from the face of the chamber to the center of the clevis pin “A”. Use a lever to move the adjuster until the shoes contact the drum “B”. The difference between the fully retracted, & drum contact measurement is the free stroke. Free stroke should fall between ⅜” & ¾”.

Free Stroke = Free Stroke = B minus AB minus A

Stroke Stroke measurements measurements taken from face taken from face of air chamber of air chamber to center of to center of clevis pinclevis pin

Measuring Measuring “Applied”“Applied” Stroke Stroke

NOTE: New brake assemblies require a burnish period. During this time you may experience a longer stroke than normal. Vehicle must be operated and brake assemblies allowed to reach normal operating temperatures in order to achieve full burnish.

1. Drain the air supply system to between 90-100 psi.

2. With spring brake released, and the service brake in the unapplied position, measure from the face of the brake chamber to the center of the clevis pin. Record this dimension.

3. Make a full service brake application and measure from the face of the brake chamber to the center of the clevis pin.

4. Record the difference between the two measurements. This is your “applied” stroke.

If the free stroke is good, but the applied stroke is too long, there is likely a problem within the foundation brake system.

If the free stroke is good, but the applied stroke is too long, there is likely a problem within the foundation brake system.

Applied Applied Stroke = C Stroke = C minus Aminus A

Applied Stroke Applied Stroke measurements measurements taken from face taken from face of air chamber to of air chamber to center of clevis center of clevis pinpin

NNorth AAmerican CCommercial VVehicle SSafety AAlliance

Type Adjustment Limit

9 1.375”

12 1.375”

16 1.750”

20 1.750”

24 1.750”

30 2”

36 2.250”

Type Adjustment Limit

16L 2”

20L 2”

24L (early Design) 2”

24L (Late Design) 2.50”

30L 2.50”

Standard Clamp Type Brake Chamber

Long Stroke Brake Chamber

*The applied stroke of the brake should be checked per CVSA guidelines at 90-100 psi reservoir pressure.

Service IntervalsService IntervalsAdjuster Type

Manufacture Date

Lubrication Interval

Type of Lubricant

Standard Adjuster Prior to June 199650,000 miles or every 3 months

Standard Chassis Grease

S-ABA After Jan. 2000 Once a yearStandard Chassis

Grease

Reduced Maintenance

AdjusterAfter June 1996 Once a year

Standard Chassis Grease

No-Lube ™ Adjuster After June 1996 None Sealed Unit

3+% Moly-disulfide & teflon grease should not be used or shortened service life may result.3+% Moly-disulfide & teflon grease should not be used or shortened service life may result.

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