Disc brake definition
A type of brake that has two basic components : a flat rotor (disc) that turns with the wheel and a caliper that is stationary. When the brake pedal is depressed, linkage (mechanical or hydraulic ) causes the caliper to force its heat-resistant brake pads against both sides of the rotating disc thus slowing or stopping the wheel. Almost all new cars have disc brakes on the front wheels with drum brakes on the rear. More expensive cars have four wheel disc brakes. Because of the need for greater pressure to activate disc brakes, most cars so equipped also have a power booster . Wear takes place in the pads and the rotors. The pads are usually replaced while the rotors can sometimes be reground else they too must be replaced. If the rotors are not tightened correctly when installed, they can warp and cause a jerking motion when stopping. Also see brake, disc type .