Railway coupling

A mechanical device that joins railway vehicles and transmits pulling and pushing forces between them. Coupling designs also determine how vehicles connect, separate, and accommodate movement on the track.

Draft gear: A shock-absorbing assembly between a railway coupler and the vehicle frame that cushions buff and draft forces. It moderates the shocks transmitted through a coupling during starting, stopping, and impacts.
Janney coupler: A knuckle-type railway coupler that locks automatically when two compatible couplers meet. Its widespread adoption made it the dominant coupling design on North American freight railways.
John H. Janney: An American inventor who patented a knuckle-type railway coupler in the nineteenth century. His design became the basis of the Janney coupler used across North American railways.
Freight train: A train that carries goods rather than passengers. Freight couplers must endure heavy loads and repeated impacts during switching and operation.
Railway worker safety: Practices, equipment, and regulations intended to prevent injury to people working on railways. Automatic couplers reduced the need for workers to place hands between moving vehicles.
Slack action: Longitudinal movement between coupled railway vehicles caused by clearance in couplers and draft gear. Clearance at successive couplings lets forces travel through a train as waves of motion.
Buffers and chain coupling: A railway coupling system using chains for connection and buffers to absorb compression between vehicles. It contrasts with central couplers by separating tensile connection from compressive cushioning.
Eli H. Janney: The name sometimes mistakenly given to John H. Janney, the inventor associated with the Janney coupler. Distinguishing the inventor's correct name prevents a persistent error in accounts of the coupler.
Passenger train: A train designed to carry people between locations. Passenger operations often favor rapid coupling and integrated air, electrical, or control connections.
Railway interoperability: The ability of railway systems, vehicles, and equipment to operate together across technical boundaries. Incompatible couplers can prevent direct interchange even when track and vehicle dimensions match.

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