Description

Steel pin used to secure the suspended trusses to the Forth Bridge cantilevers (c.1889). Eight pins are used on the bridge and are  placed vertically in the joints between the ends of cantilevers and the suspended trusses (two at each joint).

This pin was made and kept as a spare.

The overall length of the pin is 1,610 mm. The diameter progressively decreases in steps along its length. Starting at the wider end the diameter progressively decreases along its length. At the wider end for a length of 213 mm the diameter is 229 mm and the outer end of this section is threaded for 140 mm. The longest middle section is 1,115 mm long with a diameter of 226 mm. The narrower end is in two sections. The first of these is 219 mm in length with a diameter of 216 mm and is threaded for 150 mm towards its outer end. The end section is 63 mm in length and has a diameter of 191 mm. There is a single right-angled groove running the full length of the pin which is 12 mm deep and 14 mm in width. There are eight (8) threaded holes located in the narrowest section of diameter 26 mm and is 50 mm in depth. There is also a single unthreaded hole whose centre is located 233 mm from the narrow end – this hole has a diameter of 35 mm and is 68 mm in depth.

It is reported that the pin was designed with a safety factor of 28.

This item is related to the nut and washers – see items 2013/021 and 2013/022 respectively.

This item is on loan from the National Railway Museum, York.