Fairbairn steam crane

The crane's innovation was in the use of a curved jib, made of riveted wrought iron platework to form a square-section box girder.

This curved jib could reach further into the hold of a ship, clear of the deep gunwales alongside the quay.

[1] Designing a strong curved jib required Fairbairn's advanced theoretical understanding of the mechanics of a box girder.

The tension forces were carried by the outer, convex surface of the girder which was made of back plates being chain-riveted together.

[1] The size of the crane jibs was determined by ships of the period, and their lifting capacity by men's ability to raise the load.

William Fairbairn & Sons of Manchester built a number of these cranes and also licensed the design to other makers.

After the expiry of the patent in 1875, other companies, notably Cowans Sheldon & Co of Carlisle, built many others as late as 1910, often powered by steam, water hydraulics or electricity.

The only surviving Fairbairn steam crane is in Bristol, on the quayside at Wapping Wharf in the Floating Harbour.

Iron-hulled ships were becoming larger, cargoes heavier, and there had already been investment in building a railway line along the harbour quay.

Accordingly, a more powerful steam crane was ordered, to be capable of lifting 35 tons and loading it directly onto a railway wagon.

A vertical boiler inside the cab operates at 100 psi and supplies two twin-cylinder steam engines: one for slewing (turning) the crane, a larger one for winding the lifting chain.

[5] Ships had increased in size by this time and the jib could no longer reach far enough to remove engines or boilers for repair work.

In 1972 it was grade II* listed[4] and it is also a scheduled monument,[6] as the last surviving Fairbairn steam crane.