Railway coupling

Key design considerations include strength, reliability, easy and efficient handling, and operator safety.

Dimensions and ratings noted in these articles are usually of nominal or typical components and systems, though standards and practices also vary widely with railway, region, and era.

The simple chain could not be tensioned, and this loose coupling allowed a great deal of back and forth movement and bumping between cars, as well as jarring when trains started.

This coupling is still widespread in Western and Central Europe and in parts of Northern Africa, the Middle East and South Asia.

Once the cars were joined, the employee inserted a pin into a hole a few inches from the end of the tube to hold the link in place.

This procedure was exceptionally dangerous and many brakemen lost fingers or entire hands when they did not get them out of the way of the coupler pockets in time.

[11][12] Likewise, in 1889, when the first locomotives were obtained by the newly established Netherlands-South African Railway Company in the Zuid-Afrikaansche Republiek, they were fitted with Johnston couplers.

[9][13] Unlike the 2 ft (610 mm) narrow gauge railways of the CGR, those of the NGR also made use of Johnston couplers.

The first of these narrow gauge lines came into operation in 1906, when the first NGR Class N 4-6-2T locomotives entered service on the Weenen branch out of Estcourt.

Johnston couplers gradually began to be replaced on the South African Railways from 1927, but not on narrow gauge rolling stock.

[7] Bell-and-hook couplers began to be replaced on the Avontuur Railway upon the introduction of Class 91-000 diesel-electric locomotives on the narrow gauge system in 1973.

Janney was a dry goods clerk and former Confederate Army officer from Alexandria, Virginia, who used his lunch hours to whittle from wood an alternative to the link and pin coupler.

[21][22] In 1893, satisfied that an automatic coupler could meet the demands of commercial railroad operations and, at the same time, be manipulated safely, the United States Congress passed the Safety Appliance Act.

The Janney coupler generally provides only mechanical coupling, only Type H adds automatic connections of pneumatic and electrical lines.

As of 2020[update] Construcciones y Auxiliar de Ferrocarriles is working on an automatic coupler based on SA3, a possible replacement of the buffers and chain coupling on European railways.

[36] As of 2020[update] it has found limited use: it has been adopted by the Iranian Railways[37] and is also used in Germany on trains transporting iron ore between Hamburg and Salzgitter.

[36] As of 2020[update] its use is limited to trains transporting ore between Rotterdam and Dillingen steelworks and lignite between Wählitz and Buna in Germany.

Uncoupling is done by turning the coupling pin against the spring force with an actuating arm operated by a shunting pole or by a fixed rod with handles that can be reached from a position next to the train away from the third rail.

The model N-2 used lightweight draft gear slung below the center sill, to allow for the wide swings required to go around sharp curves.

The Tomlinson coupler was developed by the Ohio Brass Company[21][22] for mass transit applications, but eventually found use in some mainline railroad vehicles as well.

For applications outside of rapid transit the coupler had to be significantly enlarged to meet the increased strength requirements first appearing in this capacity on the Budd Metroliner and later on the Illinois Central Highliner fleet.

Rail equipment manufacturers such as Bombardier offer the Schaku coupler as an option on their mass transit systems and their passenger cars and locomotives.

In North America all the trains of the Montreal Metro are equipped with it, as are new light rail systems in Denver, Baltimore and New Jersey.

[54] The Swedish-made Dellner coupling,[55] is a proprietary version of the Scharfenberg coupler, connecting vehicle, pneumatics and electronics at the same time.

The type was first introduced 1965 with the so called Gold Coast Express used as the first mass transit trains in the Greater Zurich area.

A barrier vehicle / wagon in Britain and "transition car" in North America) has different kinds of couplings at each end.

British Rail therefore decided to adopt a Janney variant for its passenger carriages, with the coupler able to swing out of the way for coupling to engines with the traditional buffer and chain system.

Early model trains were coupled using various hook-and-loop arrangements, which were frequently asymmetrical, requiring all cars to be pointing in the same direction.

Similarly, for many years, a "lift-hook" coupler known as the Rapido and developed by Arnold, a German manufacturer of N-scale model trains, was commonly used in that scale.

A recent development is an interchangeable coupling which plugs into a standardised socket, known as NEM 362 and which can be easily unplugged as required.