Buccleuch Dock Swing Bridge, Barrow
1880 Briefly described in Engineering[1]. The bridge crossed an opening 80ft. wide, and was divided into two leaves, each of which weighed 116 tons. The total width of the bridge was 31ft., and arranged for railway, vehicle, and foot traffic. Each leaf was suspended on a pivot by means of spring girders (long leaf springs), which lifted the structure from its bearings when unloaded, greatly facilitating the work of turning. When a load passed on to the bridge the spring girders yielded, and the structure came down to its bearings. The two parts of tho bridge were locked at the centre by means of a key working in a groove. Designed by Francis Croughton Stileman.
The swing bridge is long gone, and various moving bridges were subsequently installed in the docks, the most interesting being a 'lifting drawbridge' which survived into the 1960s. See here for information and photos[2]