While automatic brake adjusters don’t need a lot of attention, castle are far from “set it and also forget it.” choose their hands-on counterparts, routine inspection and also lubrication are vital to optimal performance.

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When the brake is applied, a pole pushes out on the slack adjuster, i m sorry then transforms the S-cam to pressure the brake pair of shoes apart to apply the friction necessary to slow the truck. The automatic slack adjuster is designed to compensate for brake lining and also drum undertake to preserve a constant actuator stroke.

“Dimensions and also the geometry have to be maintained throughout the life the the pad in order to keep the performance and also efficiency of the brake up,” claimed Joe Kay, manager of brake engineering for Meritor. “That’s whereby the automatically slack adjuster comes into play.”

Inadequate stroke deserve to have an adverse implications on braking power, do the ASA a vital component.


Proper maintenance

Keith McComsey, director of marketing and also customer options for wheel ends at Bendix Spicer structure Brake, stated ASAs often are not greased regularly during scheduled maintenance and inspections.

“Slack adjusters that don’t carry out properly through absence of lubrication can have a direct impact on both safety and also regulatory compliance,” he said.

Properly lubricating the ASA purges old grease, water and also contaminants from the adjuster and also protects the internal gear sets, clutches and also other materials from wear.

McComsey stated lubrication through an NGLI grade-2 lubricant at the very least every 30,000 miles must take much less than a minute per adjuster. “You can additionally make points less complex by greasing the ASAs every time you perform a preventative maintenance inspection,”he said.


Mitch Forbes, senior technical organization representative for Haldex, recommends at the very least an yearly lubrication interval v a traditional chassis grease applied by hand. Program visual inspections and also operational checks, including brackets and also control arms, have to be performed in ~ each preventative maintenance business interval. Adjusters or anchor brackets that show damage or fail work checks must be changed immediately, Forbes said.

As part of pre- and post-trip inspections, vehicle drivers should inspect the slack adjuster for correct operation, shed or missing hardware, a missing cotter pin, bending or damaged materials such as the manage arm or it is registered anchor brackets, and also worn clevises, clevis pins and clevis pin bushings.


Fleets that operation lightly invited are much more susceptible to vibration, which Kay said can accelerate brake stroke issues.

“You desire to make sure the clevis pins room inspected, because the an ext vibration castle get, the more wear castle get,” the said. “Pins wearing inside the feet can include extra clearances, and those extra clearances can include up to extra stroke when applying the brake.”

McComsey additionally recommends check the brake shoe return springs come ensure a ideal return come the zero-stroke position.

“If the punch is as well long, the brake room would basically go come its maximum length, and the force of the brake drops,” Kay said. “ is one of the very first things the would indicate that something’s not right with this particular brake.”

Duty cycle additionally can affect a slack adjuster’s life, but Kay stated that in usual line-haul applications, it’s typical for ASAs to last for the life that the truck with basic maintenance.


However, segments that feature much more starting and stopping would require a maintenance cycle that includes ASA replacement. “Every ingredient on the brake is going through a exhaustion cycle,” that said.

No hand-operated adjustments

Proper maintain of automatically slack adjusters also method no hands-on adjustments. “The just times that an automatic brake adjuster requirements to be changed is throughout a structure brake fix or initial setup,” Forbes said. “Manually adjusting a brake adjuster reasons premature undertake on interior components and leads to the adjuster becoming inoperable.”

McComsey claimed there are many reasons one ASA may fall out of adjustment, but it is unlikely the a manual adjustment will correct the problem.

“Manual adjustment may seem to temporarily solve the out-of-adjustment issue, however there may be other factors at play that have to be addressed,” he said. “Otherwise, the condition will reoccur.”


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