2Why ABA’s?Automatic Brake Adjusters are intended to provide efficient day-to-day service braking by maintaining optimum 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 that maintains a nominal distance or clearance between the lining and drum under a variety of braking conditions.
4New Installation Determine what axle the adjuster will be used on. Available in 5/8” or 1 ½” OffsetsDetermine what axle the adjuster will be used on.Determine the camshaft diameter & number of splines.Determine the adjuster arm length.Determine if offset adjuster is required.Select the proper ABA kit.Arm LengthP/NS/N33489Camshaft DiameterInstallation Indicator
5Installation Procedures Step 1Anchor BracketNote: Block wheels to prevent vehicle from rolling. Ensure system tank pressure is above 100 psi.Check that the push rod is fully retracted; apply air to release spring brake. If air is not available, spring brake must be manually caged.Install anchor bracket loosely as illustrated (fig. 1).Some strap brackets have two mounting holes. Proper mounting location is determined by the length of adjuster arm. 5” & 5.5” adjuster arm lengths utilize the shorter hole while 6” & 6.5” length adjusters utilize the longer hole.Do not tighten anchor bracket fasteners at this time.Apply anti-seize type lubricant to camshaft splines.Fig. 1Note: Configuration of anchor bracket & brake adjuster housing may vary, depending upon axle.
6Installation Procedures Step 2Install the brake adjuster onto the camshaft with the adjusting hex pointing away from the brake chamber (fig. 2).Secure the brake adjuster on the camshaft. Use at least one inner washer & enough outer washers to allow no more than .060” movement of adjuster on camshaft. (Per TMC recommended practice RP609-A).DO NOT pull push rod out to meet the brake adjuster.Rotate the 7/16” adjusting hex nut CLOCKWISE until the clevis hole lines up with the brake adjuster arm hole.Apply anti-seize type lubricant to clevis pin, install & secure with cotter pin.Fig. 2
7Installation Procedures Step 3Fig. 3Rotate the control arm away from the adjusting hex toward the air chamber, until it comes to a definite internal stop (fig. 3).Most adjusters will be equipped with an installation indicator. The indicator must fall within the slot for proper installation with brakes fully released (fig. 4). If the control arm position is wrong, tight brakes will occur (fig. 5).Tighten all anchor bracket fasteners (make sure the control arm does not move from its position while tightening fasteners).Fig. 5Fig. 4Correct(Brakes Released)Incorrect(Brakes Released)
8Installation Procedures Step 4The adjuster must be manually adjusted at this time.Rotate the adjusting hex clockwise until the lining contacts the drum.Back-off the adjuster by turning the adjusting hex counter-clockwise ½ turn (fig. 6).A minimum of 13 ft. lbs. is necessary to overcome the internal clutch. A ratcheting sound will be present.Do NOT use an impact wrench or internal damage will occur!Fig. 6A mis-set control arm can cause a tight brake!FINAL INSPECTION: Make sure brakes are still fully released, & check that the installation indicator is within the slotted area. If out of position, repeat Step 3.
9Torque Specifications Round anchor stud pin with fabricated ring clamp ft. lbs.Flat anchor stud pin ft. lbs.U-Bolt style bracket ft. lbs.Round anchor stud pin with slide nut ft. lbs.Strap style bracket ft. lbs.Pic. #1Pic. #2Pic. #4Pic. #3Pic. #5
10Operational Check North American Commercial Vehicle Safety Alliance Standard Clamp Type Brake ChamberLong Stroke Brake Chamber2.250”362”301.750”2420161.375”129Adjustment LimitType2.50”30L24L (Late Design)2”24L (early Design)20L16LAdjustment LimitType*The applied stroke of the brake should be checked per CVSA guidelines at psi reservoir pressure.
11Operational CheckNew 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.
12Operational Check Measuring Free Stroke If the ABA is determined to be faulty, it should be replaced immediately. Do not operate as a manual brake adjuster.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” (fig. 19). Use a lever to move the adjuster until the shoes contact the drum “B” (fig. 19). The difference between the fully retracted & drum contact measurement “B” – “A” (fig. 19), is the free stroke. The free stroke should fall between 3/8” & 3/4”.If the free stroke is good, but the applied stroke is too long, there is likely a problem within the foundation brake system.
13Service Intervals Type of Lubricant Lubrication Interval *Sealed UnitNoneAfter 6/1/96No-Lube AdjusterStandard Chassis GreaseOnce a yearReduced Maintenance Adjuster50,000miles or every 3 monthsPrior to 6/1/96Standard AdjusterType of LubricantLubrication IntervalManufacture DateAdjuster TypeMoly-disulfide and teflon grease should not be used in Haldex ABA’s