What is "air brake"

Air brake \Air" brake`\ (Mach.) A railway brake powered by compressed air.
--Knight.

Syn: airbrake.

Brake \Brake\ (br[=a]k), n. [OE. brake; cf. LG. brake an instrument for breaking flax, G. breche, fr. the root of E. break. See Break, v. t., and cf. Breach.]

1. An instrument or machine to break or bruise the woody part of flax or hemp so that it may be separated from the fiber.

2. An extended handle by means of which a number of men can unite in working a pump, as in a fire engine.

3. A baker's kneading though.
   --Johnson.

4. A sharp bit or snaffle.

   Pampered jades . . . which need nor break nor bit.
   --Gascoigne.

5. A frame for confining a refractory horse while the smith is shoeing him; also, an inclosure to restrain cattle, horses, etc.

   A horse . . . which Philip had bought . . . and because of his fierceness kept him within a brake of iron bars.
   --J. Brende.

6. That part of a carriage, as of a movable battery, or engine, which enables it to turn.

7. (Mil.) An ancient engine of war analogous to the crossbow and ballista.

8. (Agric.) A large, heavy harrow for breaking clods after plowing; a drag.

9. A piece of mechanism for retarding or stopping motion by friction, as of a carriage or railway car, by the pressure of rubbers against the wheels, or of clogs or ratchets against the track or roadway, or of a pivoted lever against a wheel or drum in a machine.

10. (Engin.) An apparatus for testing the power of a steam engine, or other motor, by weighing the amount of friction that the motor will overcome; a friction brake.

11. A cart or carriage without a body, used in breaking in horses.

12. An ancient instrument of torture. --Holinshed. Air brake. See Air brake, in the Vocabulary. Brake beam or Brake bar, the beam that connects the brake blocks of opposite wheels. Brake block.

    1. The part of a brake holding the brake shoe.

    2. A brake shoe.

       Brake shoe or Brake rubber, the part of a brake against which the wheel rubs.

       Brake wheel, a wheel on the platform or top of a car by which brakes are operated.

       Continuous brake . See under Continuous.

n. (alternative spelling of airbrake English)

Air brake may refer to:

• Air brake (aeronautics), in aeronautics, a type of flight control system used on aircraft to reduce speed
• Air brake (road vehicle), a type of brake used on large vehicles in place of hydraulic brakes, using compressed air
• Railway air brake, a type of brake operated by compressed air and used on locomotives and railroad cars .

In aeronautics, air brakes or speedbrakes are a type of flight control surfaces used on an aircraft to increase drag or increase the angle of approach during landing. Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift, whereas spoilers reduce the lift-to-drag ratio and require a higher angle of attack to maintain lift, resulting in a higher stall speed.

The earliest known air brake was developed in 1931 and deployed on the wing support struts. Not long after, air brakes located on the bottom of the wing's trailing edge were developed and became the standard type of aircraft air brake for decades.

In 1936, Hans Jacobs developed self-operating dive brakes, on the upper and lower surface of each wing, for gliders.Most early gliders were equipped with spoilers on the wings in order to adjust their angle of descent during approach to landing. More modern gliders use airbrakes which may spoil lift as well as increase drag, dependent on where they are positioned.

Often, characteristics of both spoilers and air brakes are desirable and are combined - most modern airliner jets feature combined spoiler and air brake controls. On landing, the deployment of these spoilers ('lift dumpers') causes a dramatic loss of lift and hence the weight of the aircraft is transferred from the wings to the undercarriage, allowing the wheels to be mechanically braked with much less chance of skidding. In addition, the form drag created by the spoilers directly assists the braking effect. Reverse thrust is also used to help slow the aircraft after landing.

Virtually all jet powered aircraft have an air brake or, in the case of most airliners, lift spoilers that also act as air brakes. Propeller driven aircraft benefit from the natural braking effect of the propeller when the engine is throttled back, but jet powered aircraft have no such innate braking effect and must utilise air brakes to control descent speed. Many early jets used parachutes as air brakes on approach ( Boeing B-47) or after landing ( English Electric Lightning).

The Blackburn Buccaneer naval strike aircraft designed in the 1950s had a tail cone that was split and could be hydraulically opened to the sides to act as a variable air brake. It also helped to reduce the length of the aircraft in the confined space on an aircraft carrier.

The F-15 Eagle, Sukhoi Su-27 and other fighters have an air brake just behind the cockpit.

An air brake or, more formally, a compressed air brake system, is a type of friction brake for vehicles in which compressed air pressing on a piston is used to apply the pressure to the brake pad needed to stop the vehicle. Air brakes are used in large heavy vehicles, particularly those having multiple trailers which must be linked into the brake system, such as trucks, buses, trailers, and semi-trailers in addition to their use in railroad trains. George Westinghouse first developed air brakes for use in railway service. He patented a safer air brake on March 5, 1872. Westinghouse made numerous alterations to improve his air pressured brake invention, which led to various forms of the automatic brake. In the early 20th century, after its advantages were proven in railway use, it was adopted by manufacturers of trucks and heavy road vehicles.