How Car Brakes Work
Let us start with how they work: When you press the brake pedal, fluid is forced through the brake lines that run to each wheel. The pressure of the fluid forces brake pads against a brake rotor, causing friction that slows the wheel and consequently, the vehicle. On vehicles with rear drum brakes, the fluid forces shoes outward (instead of pads) against a drum (instead of a rotor), but the effect is the same -- friction slows the wheel.
Because friction is created whenever you step on the brake pedal, the parts involved with creating that stopping power wear over time. Ensuring your vehicle has adequate friction material is essential to safe braking performance.
Maintaining and replacing those parts cannot be ignored. Periodic brake checks are key. If you already notice signs of brake wear don't wait! Because the longer you wait, the worse the performance will get -- and it may prove more expensive when you finally take action.
Here are the standard vehicle brake system components:
Disc rotor: It is the circular part mounted behind a wheel that rotates with it. The brake pads rub against it to slow the rotation.
Disc pads: Generally about the size of your hand, pads are made of a special material that rub against the disc rotor to slow the rotation of the wheel. A pair of them acts on each rotor -- one on each side -- creating friction as the pads are "squeezed" against the rotor.
Caliper: With a disc-brake system, the caliper is mounted over the edge of the disc rotor and houses the brake pads. A brake line feeds hydraulic fluid to the caliper and when the brake pedal is pushed, the fluid pushes a piston outward that pushes the pads into the rotor to slow the wheel.
Drum: On vehicles with drum brakes (on the rear wheels only for most vehicles), the drum is located behind the wheel and rotates with it. When the brake pedal is pushed, the friction-creating shoes push against the drum to slow the wheel.
Shoes: They are the friction-creating pads used with a drum system. Rather than squeezing to create friction, as on a disc system, they push out against the inside surface of the drum.
Wheel cylinder: On a drum system, it receives the brake fluid from the brake line and distributes it to push the shoes out against the brake drum.
Master cylinder: It is a mechanical device that contains a piston that forces fluid through the brake lines when you step on the brakes.
Wear indicator/wear bar: It is a piece of metal inserted in a disc brake pad that creates a squealing/squeaking sound on the rotor when the pad is worn. It is the sign the pads are near the end of their life and should be inspected and likely replaced.
Bleeding: When brake work is performed, it is imperative that no air is tapped in the brake lines. Bleeding is a process that helps ensure air is removed.
For more information about the brake system, you can visit here.