Users' questions

Should you adjust automatic slack adjusters?

by Rhyley Bryan

Should you adjust automatic slack adjusters?

Because properly installed, operating, and lubricated automatic slack adjusters should never need adjusting after the initial setup, aside from brake relining, Bendix also emphasizes that an out-of-adjustment ASA should never simply be manually adjusted to correct an out-of adjustment brake stroke.

Are slack adjusters used to adjust brakes?

On an air-brake system, the slack adjuster is what is used to adjust the brakes. It is located on the axle housing on the air canister near the wheel.

What year are automatic slack adjusters required?

1994
Automatic slack adjusters, or ASAs, also called automatic brake adjusters, have been required for trucks and tractors since 1994 and trailers since 1995.

How often should the slack adjusters be adjusted?

In a “normal” U.S. highway environment a manual slack adjuster would probably need adjustment approximately every 10,000 miles. But since there are no such things as normal truck brakes, slack adjusters are designed to be adjusted.

What do you need to know about slack adjusters?

but a lot are found to be out of adjustment during roadside brake inspections.

  • Normally don’t require manual readjustment.
  • When they go out of adjustment something else is usually happening.

    • How can you check slack adjuster?

    Park the truck or trailer on level ground

  • Ensure the parking brake if OFF so can move the slack adjusters
  • Pull on the slack adjuster. If it moves more than 1 inch or 25mm where the pushrod is attached it most likely requires adjustments
  • Out-of-adjustment brakes is one of the most common problems found in roadside inspection.

    • What are the slack adjusters?

    On an air-brake system, the slack adjuster is what is used to adjust the brakes. It is located on the axle housing on the air canister near the wheel. On drum brakes, it’s between the pushrod and the S-cam. On disc brakes, it is between the pushrod and the power screw.