Cars usually have disk brakes on the front wheels and drum brakes on the rear wheels. Some automobiles also have an antilock-brake system to prevent sliding.
Hydraulic drum brakes use fluid pressure to slow a metal drum, which rotates with the wheel.
The fluid forces a pair of nonrotating brake shoes outward against the drum. An antilock-brake system is designed to prevent skidding on slippery roads. In normal braking, when the driver presses the brake pedal, a booster applies additional force to a hydraulic master cylinder. A piston inside the cylinder then applies pressure to a liquid called brake fluid. This pressure is transmitted through tubes called brake lines to apply the brakes.