A coupling is a mechanism typically placed at each end of a railway vehicle that connects them together to form a train. A variety of coupler types have been developed over the course of railway history. Key issues in their design include strength, reliability, ease of making connections and operator safety.
A buffer is a part of the buffers-and-chain coupling system used on the railway systems of many countries, among them most of those in Europe, for attaching railway vehicles to one another.
Type H Tightlock couplers are a variety of Janney coupler, typically used on North American mainline passenger rail cars. They are designed with mechanical features which reduce slack in normal operation and prevent telescoping in derailments, yet remain compatible with other Janney types used by North American freight railroads.
The Scharfenberg coupler is a commonly used type of fully automatic railway coupling.
SA3 couplers or Willison coupler and Russian coupler are railway couplings used primarily in Russia and states influenced or not influenced by the former Soviet Union, such as Finland, Iran, Poland and Mongolia.
In railroading, slack action is the amount of free movement of one car before it transmits its motion to an adjoining coupled car. This free movement results from the fact that in railroad practice cars are loosely coupled, and the coupling is often combined with a shock-absorbing device, a "draft gear", which, under stress, substantially increases the free movement as the train is started or stopped. Loose coupling is necessary to enable the train to bend around curves and is an aid in starting heavy trains, since the application of the locomotive power to the train operates on each car in the train successively, and the power is thus utilized to start only one car at a time.
The railcar couplers or couplings listed, described, and depicted below are used worldwide on legacy and modern railways. Compatible and similar designs are frequently referred to using widely differing make, brand, regional or nick names, which can make describing standard or typical designs confusing. 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. Transition between incompatible coupler types may be accomplished using dual couplings, a coupling adapter or a barrier wagon.
A barrier vehicle (BV), barrier wagon, match wagon or translator coach is used to convert between non-matching railway coupler types. This allows locomotives to pull railway vehicles or parts of a train with a different type of coupler. A match wagon has an identical dual coupling at both ends.
The C-AKv is a fully automatic coupler design, also known as the Faiveley Transpact; it is a hybrid compatible with both buffers and chain couplers and Russian SA3 couplers, intended as an option for the long delayed EU transition to center buffer couplers. C-AKv is an abbreviation of Compact Automatische Kupplung vereinfacht in German, translating to Compact Automatic Coupler simplified in English.
Janney couplers are a semi-automatic form of railway coupling that allow rail cars and locomotives to be securely linked together without rail workers having to get between the vehicles. They are also known as American, AAR, APT, ARA, MCB, knuckle, Buckeye, tightlock, Henricot or Centre Buffer Couplers.
A Norwegian coupling or claw hammer coupling or pickaxe coupling is a manual coupling consisting of a central buffer with a mechanical hook that drops into a slot in the central buffer. The system is only found on narrow gauge railways of 1,067 mm or less, such as Western Australian Government Railways, the Ffestiniog Railway and the Welsh Highland Railway, where low speeds and reduced train loads allow a simpler system. Norwegian couplings are not particularly strong, and may be supplemented by auxiliary chains. Not all Norwegian couplings are compatible with one another as they vary in height and width, and may or may not be limited to one hook at a time.
The South African Railways Class 18 2-10-2 of 1927 was a steam locomotive.
The South African Railways Class HF 2-8-2+2-8-2 of 1927 was an articulated steam locomotive.
The South African Railways Class U 2-6-2+2-6-2 of 1927 was an articulated steam locomotive.
The South African Railways Class GCA 2-6-2+2-6-2 of 1927 was an articulated steam locomotive.
The South African Railways Class GE 2-8-2+2-8-2 of 1925 was an articulated steam locomotive.
The South African Railways Class GF 4-6-2+2-6-4 of 1927 was an articulated steam locomotive.
From time to time, a railway decides that it needs to upgrade its coupling system from one that is proving unsatisfactory, to another that meets future requirements. This can be done gradually, which can create many problems with transitional incompatibilities, or overnight, which requires much planning.
Buffers and chain couplers are the de facto International Union of Railways (UIC) standard railway coupling used in the EU and UK, and on some surviving former colonial railways, such as in South America and India, on older rolling stock. Buffers and chain couplers are an assembly of several devices: buffers, hooks and links, or turnbuckle screws.
The balance lever coupling, also known as rocking lever coupling or compensating coupling, is a type of central buffer coupling that has found widespread use, especially in narrow-gauge railways. In Switzerland this type of coupling is called a central buffer with two screw couplings, abbreviated to Zp2, or referred to as a central buffer coupling with coupling hooks on the side
