Railway coupling
![Traditional buffer-and-chain coupler](/Images/godic/202502/09/Mh_eisenbahn_schraubenkupplung2641.jpeg")
![Albert Coupler](/Images/godic/202502/09/Strassenbahn_Albertkupplung2641.jpeg")
![Norwegian coupling in Uganda](/Images/godic/202502/09/URCengines2641.jpg")
![Syracuse Malleable Iron Works – 1894. The gap in the knuckle accommodates the link of a link and pin coupler and the vertical hole in the knuckle accommodates the pin. This design was used in the transition period](/Images/godic/202502/09/Syracuse-malleable_18992641.jpg")
A coupling (or a coupler) is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the track gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.