air brakes as in aerodynamics most commonly used in airplanes and now recently in high end sports cars work on the principle of aerodynamic drag.
a large and very flat surface has a high drag coefficient. when it is moving, air has a hard time getting out of its way. by not being able to get out of the moving objects' way, air pushes back against the air brake and be extension, the vehicle.
in order to be more efficient, these vehicles can extend and retract the air brakes. this means that when not required, the surfaces are tucked away into a position where they don't generate a lot of drag. when the driver/pilot wants to slow down, the air brakes can be deployed.
in high end sports cars, air brakes (when present) are integrated with the wing of the car. the same surface that is slightly angled up and designed to force the car into the ground for more speed will be raised more to provide air resistance.
some of the cars I know that have active air braking are Bugatti Veyron, Mclaren MP4-12C, Mclaren 650S, Mclaren P1, Ferrari LaFerrari, Koenigsegg One:1, Pagani Huayra.
as for planes, most commercial and many non commercial planes have them. there's too many to list.
Hi the air brake system works in the opposite way to conventional brakes the compressed air keeps the brake off. so release of air from the chamber allows the brakes to come on.
The DR nailed it. Its found on semitrucks and trains. The advantage is, if pressure is lost, the brakes apply. A locomotive will build up air pressure to release the brakes. Should an air coupling come loose between boxcars, the complete system will lock up the brakes. Same on a semi-truck.
As such there is no air brake systems in the field. Wheels are fitted with mechanical linkage. Only the force required to stop the wheel are done by compressed air. Earlier in mechanical brakes , when driver applies the brakes through linkage, the movement is transferred to the wheels and brake cames stops the rotating wheels. Now in heavier vehicles dri ver pedal force is not sufficient to stop the wheels. Hence present air brake system is MECHANICAL BRAKES WITH AIR ASSISTED.
air supply releases the brakes. that is the big idea.
pushing the brake pedal, causes air to expand the brake shoes against the drum/disk, causing the vehicle to stop
