The Bendix® Foundation Drum Brake (FDB) camshafts - commonly referred to as s-cams - are forged steel shafts that act as the mechanical link between the air brake actuator and the brake shoes. Their core function is to convert the rotary torque provided by the slack adjuster into a linear force that spreads the brake shoes apart, pressing them against the inner surface of the brake drum to create friction and slow the vehicle. The specialized "S" shaped head geometry at one end of the shaft acts as a cam that lifts the brake shoe rollers. The opposite end features a precision-machined spline teeth that mate directly to the gear of the slack adjuster.