A draft gear is an apparatus which connects the coupler to the car sills or underframe of the car. Its function is to receive the shocks transmitted by the coupler and to dis sipate them without damage to the rolling stock. The friction type of draft gear is gradually superseding the spring type on American railways. Draft gear yokes, arms and various attach ments are necessary to connect the draft gear to the coupler, and then to the car. The constant increase in the length of the trains and in the size and weight of rolling stock in America has made it extremely difficult for draft gear development to keep pace with these conditions.
No standard design of draft gear has been established except for certain limitations of space in the car underframe into which the draft gear must be assembled.
Couplers are the mechatlisms by which cars are connected together. The standard American Railway Association (Master Car Builders) "D" coupler is in general use on American and Canadian railroads and also a few foreign railroads.
Before the advent of the M.C.B. type coupler in the United States the connec tion between the cars of a train and loco motive were made with the "link and pin." This was a very hazardous practice and resulted in many injuries and automatic Master Car Builders Association couplers were subsequently developed, and are now required by law.
Buffers are applied to the ends of passenger train equipment to pro vide smoothness of handling. This additional cushioning is ob tained by the use of buffers in addition to the ordinary draft gear. Buffers are of both the spring type and friction type design.
All American railway rolling stock is equipped with safety appliances in accordance with instructions and specifications from the Interstate Commerce Commission of the United States Gov ernment.
The air brake is a brake operated by com pressed air which was invented in its first form by George Westinghouse in 1869. In an air brake, the air is compressed by some form of a pump on the steam locomotive or by a motor compressor on electric or internal combustion locomotives or cars, and is conveyed by pipes and flexible hose between the cars to cylinders and pistons under each car, by which the pressure is transmitted by brake levers and thence to the brake shoes against the wheels. The adhesion of the wheels to the rails governs the amount of pressure that may be applied by the brake shoes.
A combination of straight air and automatic air brake has also come into use and is known as the automatic straight air brake. Other types of brakes are: the quick action automatic air brake, high speed brake, empty and load brake, vacuum brake, electro-pneumatic brake and the traction air brake. The auto matic air brake is in general service under American rolling stock. This system is designed so that the brakes will be applied automatically in case air escapes from the system or the train breaks in two.
Industrial cars are used in almost every branch of industrial activity; in manufacturing plants, mines, lumber operations, sugar cane plantations, and in construc tion work. They are also used in quarries, sand and gravel plants, brick and clay works, steel mills, smelters, foundries, machine shops and in many other places for handling all classes of loose or package materials. (See LOCOMOTIVE ELECTRIC TRACTION.)