Shaft Coupling

The standard type of coupling on railways following the British tradition is the buffer and chain coupling used on the pioneering Liverpool and Manchester Railway of 1830. These couplings followed earlier tramway practice but were made more regular. The vehicles are coupled by hand using a hook and links with a turnbuckle-like device that draws the vehicles together. In Britain, this is called a screw coupling. Vehicles have buffers, one at each corner on the ends, which are pulled together and compressed by the coupling device. This arrangement limits the slack in trains and lessens shocks. In contrast, Janney couplers encourage comparatively violent encounters in order to engage the coupling fully. The earliest buffers were fixed extensions of the wagon frames, but later spring buffers were introduced.