<P> A disc brake is a type of brake that uses calipers to squeeze pairs of pads against a disc or "rotor" to create friction . This action retards the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hold it stationary . The energy of motion is converted into waste heat which must be dispersed . </P> <P> Hydraulically actuated disc brakes are the most commonly used form of brake for motor vehicles, but the principles of a disc brake are applicable to almost any rotating shaft . </P> <P> Development of disc - type brakes began in England in the 1890s . In 1902, the Lanchester Motor Company designed brakes that looked and operated in a similar way to a modern disc - brake system even though the disc was thin and a cable activated the brake pad . Other designs they were not practical or widely available in cars for another 60 years . Successful application began in airplanes before World War II, and even the German Tiger tank was fitted with discs in 1942 . After the war, technological progress began to arrive in the 1950s, leading to a critical demonstration of superiority at the 1953 24 Hours of Le Mans race, which required braking from high speeds several times per lap . The Jaguar racing team won, using disc brake equipped cars, with much of the credit being given to the brakes' superior performance over rivals equipped with drum brakes . Mass production began with the 1955 Citroën DS . </P>

Which type of break is most common in commercial vehicles