Disc Brakes

Disc brakes are one of the greatest advances in braking technology. Before the 1970's drum style brakes were used on all cars and trucks. The push toward disc brakes came from auto racing. As racers achieved greater speeds, they need a better braking system. They quickly discovered that the disc brake design was superior and more efficient than drum brakes. Disc brakes are simpler in design, lighter, and more compact than drum brakes. Plus, they dissapate heat better. Eventually auto manufacturers realized their superiority and in the early 1970's began installing disc brakes on new cars and trucks. Disc brakes are now found on the front wheels of all cars and light trucks. On many new vehicles, they are used on all four wheels.

Operation:
Disc brakes are called "disc" brakes because a round metal disc is a key component of the braking mechanism. Disc brakes basically work like manual brakes on a bicycle. On a bicycle, as you pull the brake lever, rubber pads squeeze against the sides of the metal wheel rim. Disc brakes on a car work in much the same way. As you push on the brake pedal with your foot, brake pads are squeezed against a rotating disc which the wheel attaches to. The clamping action slows and stops the disc and wheel.

The illustration below shows the main parts of a disc brake setup: