The brake camshaft is a part of the brake linkage for heavy duty truck air brakes. The camshaft is the component responsible for spreading the brake shoes apart. In air brake systems, the brake chamber expands and the operating rod pushes on the (brake) slack adjuster. As the operating rod pushes on the slack adjuster, it rotates around the shaft of the S-Cam. When the camshaft is rotated the eccentric shape of the cam head pushes the brake shoes apart. The brake shoes separate and cause friction between the brake lining and the brake drum. It is this friction that slows and stops the vehicle.
When replacing the camshaft of your brakes on your truck, tractor or trailer, it is very important to replace the bushings, washers, seals and lock rings. These components should be replaced to avoid uneven wear between these items. Such uneven wear can lead to excessive camshaft deflection, causing your brakes to function improperly or even fail.