While automatic brake adjusters don’t need a lot of attention, they are far from “set it and forget it.” Like their manual counterparts, periodic inspection and lubrication are critical to optimal performance.
When the brake is applied, a rod pushes out on the slack adjuster, which then turns the S-cam to force the brake shoes apart to apply the friction necessary to slow the truck. The automatic slack adjuster is designed to compensate for brake lining and drum wear to maintain a constant actuator stroke.
