BEAUTIFUL VIEW

BEHAVIOR

When teaching your children to drive a car, your feet keep reaching for the pedal to activate these. Brakes sap kinetic energy from the moving wheels and convert it into heat. Most would say they slow and stop a car.

HABITAT

Brakes are found either riding above the disc (as in disc brakes) or

inside the wheel (drum brakes).

HOW IT WORKS

Disc brakes pinch the disc to slow its motion. Hydraulic fluid is forced

from the brake cylinder when you push on the brake pedal. The increased pressure in the brake line forces brake pads on both sides of the disc to squeeze toward each other. The friction of the pads on the discs converts rotary motion into heat. The brake is exposed to air so the heat can dissipate, keeping the brake relatively cool. The pads and  cylinders are held above the wheel by the caliper. As the pads wear,

they expose a thin piece of metal that rubs against the disc, making that squealing sound that warns you to have them checked.

With drum brakes, often used for the rear wheels, the friction is applied inside the brake drum. Two hydraulic cylinders push the brake lining outward to rub against the drum, which is attached to the wheel. Springs pull the lining away from the drum when you release the brake. Since drum brakes are surrounded by the rest of the wheel, the heat they generate can build up and make the brakes less effective.

INTERESTING FACTS

Both disc and drum brakes were invented in 1902. Louis Renault, the engineering brother of the trio who founded the Renault car company, invented drum brakes, hydraulic shock absorbers, and the turbocharger.

Englishman Frederick Lanchester, a giant in car engineering and inventing, invented disc brakes.

A field guide to automotive technology

Ed Sobey

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