Here is the location of the disc brakes in a car:
The main components of a disc brake are:
- The brake pads
- The caliper, which contains a piston
- The rotor, which is mounted to the hub
The disc brake is a lot like the brakes on a bicycle. Bicycle brakes have a caliper, which squeezes the brake pads against the wheel. In a disc brake, the brake pads squeeze the rotor instead of the wheel, and the force is transmitted hydraulically instead of through a cable. Friction between the pads and the disc slows the disc down.
A moving car has a certain amount of kinetic energy, and the brakes have to remove this energy from the car in order to stop it. How do the brakes do this? Each time you stop your car, your brakes convert the kinetic energy to heat generated by the friction between the pads and the disc. Most car disc brakes are vented.
Vented disc brakes have a set of vanes, between the two sides of the disc, that pumps air through the disc to provide cooling.