Air Brake Manual Adjustment – Pry Bar Method

Using the pry bar method, confirm that the brake is in fact out of adjustment.

After confirming that the brake is out-of-adjustment and it is equipped with a manual slack adjuster, complete the following steps to bring the brake back into adjustment.

If one brake is out, you must adjust the brake on the other side of the axle for even braking.


air brake adjustment

      • Confirm brake is fully released; to check rear push rod stroke with springs brakes system pressure must be above 90psi.
      • Using pry bar, check push rod stroke and direction of “S” cam shaft rotation.
      • Using 9/16” wrench, depress locking collar (may need a hammer to tap on the box end of the wrench).
      • Tighten the adjusting nut, ensuring that the “S” cam is rotating in the same direction as a brake application.
      • Turn wrench until snug.
      • Using bar, confirm that slack adjuster is tight.
      • Turn nut in opposite direction 1/3 – ½ turn.
      • Recheck push rod travel, which should now be between ½” & ¾”.
      • Re-engage locking sleeve by either tapping with hammer or turning “every so slightly” with wrench.

If the adjusting nut does not go snug after 1-2 full turns, it is most likely that the nut is being turned in the wrong direction to make the brake manually apply.

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