AskDefine | Define braking

User Contributed Dictionary



  1. present participle of brake

Extensive Definition

A brake is a device for slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again. The kinetic energy lost by the moving part is usually translated to heat by friction. Alternatively, in regenerative braking, much of the energy is recovered and stored in a flywheel, capacitor or turned into alternating current by an alternator, then rectified and stored in a battery for later use.
Note that kinetic energy increases with the square of the velocity (E = 1/2·m·v2 relationship). This means that if the speed of a vehicle doubles, it has four times as much energy. The brakes must therefore dissipate four times as much energy to stop it and consequently the braking distance is four times as long.
Brakes of some description are fitted to most wheeled vehicles, including automobiles of all kinds, trucks, trains, motorcycles, and bicycles. Baggage carts and shopping carts may have them for use on a moving ramp.
Some aeroplanes are fitted with wheel brakes on the undercarriage. Some aircraft also feature air brakes designed to slow them down in flight. Notable examples include gliders and some WWII-era fighter aircraft. These allow the aircraft to maintain a safe speed in a steep descent. The Saab B 17 dive bomber used the deployed undercarriage as an air brake.
Deceleration and avoiding acceleration when going downhill can also be achieved by using a low gear; see engine braking.
Friction brakes on cars store the heat in the rotating part (drum brake or disc brake) during the brake application and release it to the air gradually.

Effects on noise pollution

The action of braking for motor vehicles produces recognizable sound level emissions, varying with the specific tire types and with the roadway surface type produces considerable effect upon sound levels or noise pollution emanating from moving vehicles. There is a considerable range in acoustical intensities produced depending upon the specific tire tread design and the rapidity of deceleration required to slow the vehicle.
braking in Bulgarian: Спирачка
braking in Czech: Brzda
braking in German: Bremse
braking in Estonian: Pidur
braking in Spanish: Freno
braking in Esperanto: Bremsilo
braking in Persian: ترمز
braking in French: Frein
braking in Scottish Gaelic: Breig (càr)
braking in Croatian: Kočnice
braking in Indonesian: Rem
braking in Italian: Freno
braking in Hebrew: בלם (מכשיר)
braking in Hungarian: Fék
braking in Dutch: Rem
braking in Japanese: ブレーキ
braking in Polish: Hamulec
braking in Portuguese: Travão
braking in Russian: Тормоз
braking in Simple English: Brake
braking in Finnish: Jarru
braking in Swedish: Broms
braking in Tajik: Тормоз
braking in Turkish: Fren
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