A drum brake chamber is a component in a drum brake system that helps to apply the brakes on a vehicle. It consists of a cylinder that houses a piston, which is connected to the brake shoe. When the brakes are applied, hydraulic pressure from the brake fluid pushes the piston outward, which in turn pushes the brake shoes against the inner surface of the brake drum. The friction between the brake shoes and the drum slows the rotation of the drum, which helps to stop the vehicle. Drum brake chambers are typically found on the rear wheels of a vehicle, although they may also be used on the front wheels in some cases.