and elsewhere. The Janney coupler generally provides only mechanical coupling, only Type H adds automatic connections of pneumatic and electrical lines. Changes since 1873 Bazeley coupler Henricot coupler The Henricot coupler is a variation on the Janney coupler, introduced by Belgian engineer and entrepreneur of Court-Saint-Étienne. It is used on certain EMUs of the National Railway Company of Belgium, including the ). Willison/SA3 coupler The Willison coupler was developed in the US in 1916 to address issues present in the Janney coupling. The Russian SA3 coupler works according to the same principles as the AAR coupler but the two types are incompatible. It was introduced in the Soviet Union in 1932 based on a British patent and has since been used on the whole network, including Mongolia. Finnish locomotives have Unilink couplers that can couple to UIC couplers used in Finnish stock and SA3 couplers used in Russian stock. It is also used on the networks of Iran and on Malmbanan in Sweden for ore trains. Some gauge cane tramway vehicles in Queensland have been fitted with miniature Willison couplers. It was introduced on the narrow gauge Avontuur Railway of the South African Railways in 1973. Russian trains are rarely longer than about and rarely exceed a maximum tonnage of about . The heaviest trains using these couplers are on Malmbanan where they are up to . Maximum force the SA3 coupler is able to carry, both tensile and compressive, is about . The maximum allowed tractive effort to the SA-3 is limited to () by Russian white papers. The proposed European automatic coupler is compatible with the Russian coupler but with automatic air, control and power connections. Implementation is permanently delayed except for a few users. See Europe below. The SA3 resembles a left-handed fist. The SA3 coupler is one of the strongest couplers in the world – maximum tonnage of a train that uses this type of coupler is about 8000 t – but provides only mechanical coupling. Adding automatic electrical and pneumatic connectivity is a complex challenge. There are many variations and brand names for these couplers. CAF is working on an automatic coupler based on SA3, a possible replacement of the buffers and chain coupling on European railways. Unicoupler/Intermat Unicoupler has been developed by Knorr from West Germany in the 1970s, in parallel with a compatible counterpart, the Intermat coupler, by VEB Waggonbau Bautzen from East