air brake

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air brake:

see brakebrake,
in technology, device to slow or stop the motion of a mechanism or vehicle. Types
Friction Brakes

Friction brakes, the most common kind, operate on the principle that friction can be used to convert the mechanical energy of a moving object into
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air brake

[′er ‚brāk]
(mechanical engineering)
An energy-conversion mechanism activated by air pressure and used to retard, stop, or hold a vehicle or, generally, any moving element.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Air brake

A friction type of energy-conversion mechanism used to retard, stop, or hold a vehicle or other moving element. The activating force is applied by a difference in air pressure. With an air brake, a slight effort by the operator can quickly apply full braking force. See Friction

The air brake, operated by compressed air, is used in buses; heavy-duty trucks, tractors, and trailers; and off-road equipment. The air brake is required by law on locomotives and railroad cars. The wheel-brake mechanism is usually either a drum or a disk brake. The choice of an air brake instead of a mechanical, hydraulic, or electrical brake depends partly on the availability of an air supply and the method of brake control.

In a motor vehicle, the air-brake system consists of three subsystems: the air-supply, air-delivery, and parking/emergency systems. The air-supply system includes the compressor, reservoirs, governor, pressure gage, low-pressure indicator, and safety valve. The engine-driven compressor takes in air and compresses it for use by the brakes and other air-operated components. The compressor is controlled by a governor that maintains air compression within a preselected range. The compressed air is stored in reservoirs. The air-delivery system includes a foot-operated brake valve, one or more relay valves, the quick-release valve, and the brake chambers. The system delivers compressed air from the air reservoirs to the brake chambers, while controlling the pressure of the air. The amount of braking is thereby regulated. In the brake chambers, the air pressure is converted into a mechanical force to apply the brakes. As the pressure increases in each brake chamber, movement of the diaphragm pushrod forces the friction element against the rotating surface to provide braking. When the driver releases the brake valve, the quick-release valve and the relay valve release the compressed air from the brake chambers. The parking/emergency system includes a parking-brake control valve and spring brake chambers. These chambers contain a strong spring to mechanically apply the brakes (if the brakes are properly adjusted) when air pressure is not available. During normal vehicle operation, the spring is held compressed by system air pressure acting on a diaphragm. For emergency stopping, the air-brake system is split into a front brake system and a rear brake system. If air pressure is lost in the front brake system, the rear brake system will continue to operate. However, the supply air will be depleted after several brake applications. Loss of air pressure in the rear brake system makes the front brake system responsible for stopping the vehicle, until the supply air is depleted.

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.

air brake

1. a brake operated by compressed air, esp in heavy vehicles and trains
2. an articulated flap or small parachute for reducing the speed of an aircraft
3. a rotary fan or propeller connected to a shaft to reduce its speed
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
By carving notches into the rudder's trailing edge the noise-producing vortex can be broken and the loss of lift that occurs when ordinary air brakes are deployed, will be avoided.
Air brakes are fitted, which act on the wheels and the track-brakes.
Kavlico has introduced the P4050 pressure transducer for applications with air or inert gas media such as air brakes, air compressors, tire inflation systems, or vehicle air-ride systems.
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Typical applications for the molded seals include process controls, valve actuators, pressure regulators, valves, pumps, positioning actuators, pressure switches, flow meters, air brakes, and dispensing and metering equipment.
Summary: An air brakes joint venture between automotive equipment and electrical consumer goods manufacturer Robert Bosch GmbH and Knorr-Bremse AG, a fellow German supplier of braking and hydraulic systems for commercial, road and railway vehicles, has been cleared by the European Commission under EU merger control rules.
Air brakes are a type of brake system which use compressed air to stop vehicles.
By interlocking a trailer's air brakes with the dock door, the Salvo loading dock safety system prevents the accidental drive away of a vehicle during loading or unloading.
A missing dust cap on your vehicle's air brake chamber is an open invitation for sand, dust, and water to march in and mess up your air brakes.