What does a slack adjuster do in an S-cam air brake?

• A.It stores compressed air for the brake chamber
• B.It cools the brake drum between applications
• C.It is the lever between the chamber pushrod and the brake camshaft, and its adjustment controls how far the pushrod must travel to apply the brake
• D.It replaces the service brake chamber

Why

The pushrod pushes on the slack adjuster arm, which turns the camshaft and spreads the brake shoes into the drum. As linings wear, the adjuster setting determines whether that motion still happens within the chamber's available travel.

Manual topic: Air Brakes - Slack Adjusters · From the Air Brakes practice bank (AB-156).

Practice this subject as a full test

More Slack Adjusters & Pushrod Stroke questions

• How do you measure pushrod stroke (applied stroke) when checking brake adjustment?
• For many common brake chambers with a manual slack adjuster, about what pushrod stroke is the commonly cited maximum limit?
• What happens when pushrod stroke becomes excessive?
• When checking slack by hand, how much free movement at the slack adjuster suggests the brake needs adjustment attention?
• With the service brakes fully applied, what angle relationship should the pushrod and slack adjuster arm show?