When a brake pedal is pressed and the S-cam is turned, the S-cam: Question When a brake pedal is pressed and the S-cam is turned, the S-cam: Answers Presses the brake shoes against the inside of the brake drum. Tightens the brake drum onto the axle. Presses the brake lining against the wheel. Explanation When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow. This questions appears in the following tests: California Air Brakes