The drum brake system consists of a number of essential components, each of which has a distinct purpose. The components and their roles in a conventional drum brake system are described as follows:
Brake Drum: Mounted on the wheel hub, the brake drum is a cylindrical component with a drum form. Its main purpose is to give the brake shoes something to press on so they can generate friction and slow or stop the car.
Brake Shoes: The brake shoes are curved metal plates with an inner surface covered in friction material (brake lining or brake pads). They are a part of the brake system and are situated inside the brake drum. When the brakes are applied, hydraulic or mechanical pressure is exerted to pull the brake shoes outward and against the braking drum, causing friction and delaying the rotation of the wheel.
Wheel Cylinder: A hydraulic component positioned inside the brake drum, the wheel cylinder. It is made up of seals and a piston. The piston extends when hydraulic pressure is applied, pressing the brake shoes up against the drum. In order to activate the brake shoes, the wheel cylinder transforms hydraulic pressure from the master cylinder into mechanical force.
Brake Springs: When the braking power is released, brake springs are employed to retract the brake shoes. When the brakes are not applied, they assist in breaking the bond between the brake shoes and drum, enabling the wheel to spin freely.
Adjuster Mechanism: Drum brakes typically have an adjustment mechanism to account for wear and preserve the ideal brake shoe-to-drum clearance. As the brake shoes deteriorate, this device automatically modifies their location to maintain constant braking performance over time.
Brake Return Springs: After the brakes are disengaged, the brake return springs help retract the brake shoes. They assist in removing the brake shoes from the drum and returning them to their resting position so they are ready for the subsequent application.
Self-Adjuster Cable: To maintain the correct distance between the brake shoes and the drum, certain drum brake systems include a self-adjuster cable. The self-adjuster system activates when the brakes are applied, forcing the cable to rotate and change the position of the brake shoes to account for wear.
Brake Backing Plate: The wheel cylinder, the brake shoes, and other parts are joined to the brake backing plate, which is a rigid metal plate. It offers assistance and defence for the internal brake parts.
Dust Cover for Brake Drum: To shield the brake drum from dust, dirt, and debris, a dust cover or shield is frequently fitted over it. By preventing pollutants from entering the braking system, it promotes the longevity and effective operation of the brakes.
To provide the required friction and transform the given force into braking action, each component of the drum brake system is essential. Together, they contribute to the vehicle’s total braking performance by slowing or stopping the spinning of the wheels.