brake

A brake is a device that slows or stops motion by extracting kinetic energy, usually by converting it to heat. The most common type uses friction between a pad or shoe and a rotating surface. Brakes are used on vehicles, bicycles, trains, and various machines, and must provide reliable control and heat dissipation.

In motor vehicles, most friction brakes are hydraulic. A master cylinder pressurizes brake fluid that transfers force to calipers or wheel cylinders. Pads press on discs, or shoes on drums, converting motion to heat. Standard components include rotors or drums, pads or shoes, calipers or wheel cylinders, lines, a hydraulic reservoir, and fluid. Some systems use rear brake drums only, while others employ discs at one or more axles.

Other braking methods include regenerative braking, which uses electric motors to slow the vehicle and recover energy, and air brakes used on many heavy trucks. Anti-lock braking systems prevent wheel lock by rapidly modulating brake pressure. Performance depends on pad or shoe condition, rotor or drum wear, fluid quality, and the absence of leaks; temperature management is also important to avoid brake fade.

Maintenance and safety: regular inspection of pad wear, rotor thickness, and lining condition; checking fluid for contamination and proper levels; bleeding lines to remove air; and ensuring seals and hoses are intact. History: brakes evolved from early mechanical devices to hydraulic systems in the early 20th century, with anti-lock braking systems becoming common in the late 20th century. Standards and testing vary by region and application.