This type of brake system is used on the rear wheels of most hatchback cars, entry-level sedans & MUVs. Drum brakes have more parts than disc brakes and are harder to service, but they are less expensive to manufacture, and they easily incorporate an emergency brake mechanism. Drum brakes work on the same principle as disc brakes: Shoes press against a spinning surface. 2. In this system, that surface is called a drum. First, the basics: Figure 5 shows only the parts that provide stopping power. Drum Brake Working Principle: Two-wheelers such as scooters, commuter bikes, three-wheelers including auto-rickshaws widely use the Drum Brake system for braking. When you hit the brake pedal, the piston pushes the brake shoes against the drum. When the driver presses the pedal, a piston inside the brake master cylinder pressurizes hydraulic fluid in the brake lines, which then pressurizes the wheel cylinder and pushes the shoes into the drum. As the brake shoe lining touches the inner surface of the drum, and due to the friction generated in between the brake shoe and drum, the motion of the wheel reduces and vehicle stops. 3. How drum brakes function The brakes should respond instantaneously. The outward motion of the piston of wheel cylinder forces the brake shoe outward against the brake drum. Many cars have drum brakes on the rear wheels and disc brakes on the front. But the drum brake also has an adjuster mechanism, an emergency brake mechanism and lots of springs. It is also widely used on both front & rear wheels of trucks, buses, and other commercial vehicles in combination with … 4. As the brake pedal is pressed, it compresses the fluid in the master cylinder and allows the piston of the wheel cylinder to expand outward. As the force is removed from the brake pedal, the retracting springs draw… 1. Like the disc brake, the drum brake has two brake shoes and a piston.