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Railway air brake
A railway air brake is a railway brake power braking system with compressed air as the operating medium. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on April 13, 1869. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell Westinghouse's invention. In various forms, it has been nearly universally adopted.
The Westinghouse system uses air pressure to charge air reservoirs (tanks) on each car. Full air pressure causes each car to release the brakes. A subsequent reduction or loss of air pressure causes each car to apply its brakes, using the compressed air stored in its reservoirs.
In the air brake's simplest form, referred to as a straight air system, compressed air is directed to a brake cylinder, causing its piston to apply force to mechanical linkage, which linkage is conventionally referred to as the brake rigging (see illustration at right). The brake rigging, in turn, is connected to brake shoes that are pressed against the car's wheel treads (some types of passenger cars instead use disc brakes). The resulting friction slows the car by dissipating its kinetic energy as heat. The brake rigging is often quite elaborate, as it is designed to evenly distribute the brake cylinder's force to multiple wheels.
The source of high-pressure air needed to operate the system is an air compressor mounted in the locomotive, the compressor being driven by a Diesel locomotive's prime mover, or by a cross-compound steam engine on a steam locomotive. Compressors of electric locomotives are usually driven by their own electric motor. The output of the air compressor is stored in a tank, also mounted on the locomotive, this tank being referred to as the main reservoir. Air from the main reservoir is piped to a manually operated brake valve in the locomotive's cab. When the brake valve is opened to apply the brakes, air under pressure is conveyed to the brake mechanism.
A critical weakness of the straight air braking system is that any failure in the piping, such as a blown air hose. that results in a loss of pressure will render the brakes inoperative. For this reason, train brakes do not employ straight air for operation, as there is no redundancy in the event of such a failure. However, straight air is used to operate locomotive brakes, as redundancy is provided by the ability of a locomotive to come to a stop by reversing propulsion in an emergency, a procedure referred to as "plugging".
Locomotive brakes are controlled by an independent brake valve, so-named because the locomotive brakes may be applied or released independently from the train brakes.
In order to design a braking system without the shortcomings of the straight air system, Westinghouse invented an arrangement in which each piece of railroad rolling stock was equipped with a dual-compartment, compressed-air reservoir and a triple valve, also known as a control valve. A pipe referred to as the brake pipe was fitted to each car to act as a passage for the compressed air needed to make the system function. The brake pipes were fitted with hoses at each end of each car and locomotive for creating a continuous brake pipe connection throughout the train.
Unlike the previously described straight air system, the Westinghouse system uses a reduction in brake pipe air pressure to indirectly apply the brakes.
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Railway air brake AI simulator
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Railway air brake
A railway air brake is a railway brake power braking system with compressed air as the operating medium. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on April 13, 1869. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell Westinghouse's invention. In various forms, it has been nearly universally adopted.
The Westinghouse system uses air pressure to charge air reservoirs (tanks) on each car. Full air pressure causes each car to release the brakes. A subsequent reduction or loss of air pressure causes each car to apply its brakes, using the compressed air stored in its reservoirs.
In the air brake's simplest form, referred to as a straight air system, compressed air is directed to a brake cylinder, causing its piston to apply force to mechanical linkage, which linkage is conventionally referred to as the brake rigging (see illustration at right). The brake rigging, in turn, is connected to brake shoes that are pressed against the car's wheel treads (some types of passenger cars instead use disc brakes). The resulting friction slows the car by dissipating its kinetic energy as heat. The brake rigging is often quite elaborate, as it is designed to evenly distribute the brake cylinder's force to multiple wheels.
The source of high-pressure air needed to operate the system is an air compressor mounted in the locomotive, the compressor being driven by a Diesel locomotive's prime mover, or by a cross-compound steam engine on a steam locomotive. Compressors of electric locomotives are usually driven by their own electric motor. The output of the air compressor is stored in a tank, also mounted on the locomotive, this tank being referred to as the main reservoir. Air from the main reservoir is piped to a manually operated brake valve in the locomotive's cab. When the brake valve is opened to apply the brakes, air under pressure is conveyed to the brake mechanism.
A critical weakness of the straight air braking system is that any failure in the piping, such as a blown air hose. that results in a loss of pressure will render the brakes inoperative. For this reason, train brakes do not employ straight air for operation, as there is no redundancy in the event of such a failure. However, straight air is used to operate locomotive brakes, as redundancy is provided by the ability of a locomotive to come to a stop by reversing propulsion in an emergency, a procedure referred to as "plugging".
Locomotive brakes are controlled by an independent brake valve, so-named because the locomotive brakes may be applied or released independently from the train brakes.
In order to design a braking system without the shortcomings of the straight air system, Westinghouse invented an arrangement in which each piece of railroad rolling stock was equipped with a dual-compartment, compressed-air reservoir and a triple valve, also known as a control valve. A pipe referred to as the brake pipe was fitted to each car to act as a passage for the compressed air needed to make the system function. The brake pipes were fitted with hoses at each end of each car and locomotive for creating a continuous brake pipe connection throughout the train.
Unlike the previously described straight air system, the Westinghouse system uses a reduction in brake pipe air pressure to indirectly apply the brakes.