Feature: Records from Rosyth Royal Dockyard show machinery of 250 and 100 ton cantilever cranes

Rosyth Dockyard was constructed by Easton Gibb & Sons in 1909 in anticipation of a naval arms race with Germany and to provide an operational base and refitting facility for the Royal Navy's Grand Fleet. The first warships were docked in 1916.

The 250 and 100 ton cranes, with which this collection is primarily concerned, were constructed in 1918 by Sir William Arrol & Company of Glasgow, the same company responsible for the replacement Tay Rail Bridge in 1887 and the Forth Rail Bridge in 1890, the two largest bridges of their type in the world at that time.

250 ton cantilever crane, 1917

Details shown below from the general drawing for the 250 ton crane (NAS ref MW11/429) show some of the essential machinery parts:

The machinery house and the ballast box, which provide the counterweight for the cantilever arm

The resistance house and operator’s cabin, situated about halfway up the tower, with external stairs seen to the right continuing to the top platform

The main hoist hook with its winding mechanism

The cranes were located in the dockyard basin, the 250 ton crane in yard 29 on the west wall and the 100 ton crane in yard 21 on the north wall.

In 1971, due to overloading, the brake wheel on the 100 ton crane failed, sending its load crashing to the ground and seriously damaging the number 1 and number 2 main hoist units in the machinery house. Because of its age, it was felt that repairs could not guarantee the future reliability of the whole crane. From then on only the auxiliary lifting mechanism could be utilised, reducing the load-bearing capacity to 20 tons and therefore having an effect on the type of lifting work which could be done in yard 21. The drawing reproduced below shows the largest of three brake wheels documented in the collection.

'Detail of 30 inches diameter combined brake wheel and couplings, 1920

During the 1970s and 1980s, there were a number of discussions, documented in files MW11/502-504, about the future use of the cranes. For example, although the 250 ton crane was rarely used by that point to its full load-bearing capacity, it was always considered important to retain it for any necessary de-equipping of ships and, latterly, nuclear submarines.

Finally, a decision was taken to completely demolish the cranes. Presumably this was because the cost of maintaining them had simply become too great. Correspondence from the time shows that the cranes were in the process of being dismantled as this collection was being transferred in September 1991.

The collection is available for public viewing in the Historical Search Room.