The MoD contract consisted of the replacement of two ship-sets of gantry cranes and the supply of a bespoke anti-collision system, all for use in handling weapons, explosives and ammunition to and from landing craft/hovercraft in the vessels’ well docks (an area within the stern of the ship which lowers into the water to allow the landing craft to enter).

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As major contractor, marine design and engineering specialist, Houlder, chose SCX to provide lifting gear.

The cranes have utilised a number of extensively refurbished gantry cranes from the aircraft carrier HMS Ark Royal.

The two 4.5t SWL cranes meet the MoD Tri-Services JSP 467 standard for the safe handling of weapons, ammunition and explosives and are believed to be the first of their type to do so.

As the Landing Platform Docks (LPDs) are “docked down” for landing craft operations, the cranes tilt with the ship. To accommodate this movement, the existing gantry beams are built at an angle of 1 degree to the horizontal, providing constant headroom. The new gantry cranes have been designed to travel smoothly around this bend.

The cranes incorporate anti-tip brackets and a mechanical storm anchor interlocked with the crane movements so as to lock the cranes in position during adverse weather conditions.

Rack and pinion systems across both the long travel and cross travel directions prevent unwanted movement when the motion of the sea alters the orientation of the ship. In addition, sliding and pivoting bearings were used to accommodate any misalignment of the existing gantries and to allow travel across the change in angle.

Secondary brakes were incorporated on all motions to ensure optimum safety at all times. The crane hoists are fitted with load cells.

Access for maintenance is restricted, therefore, new access walkways and crawl-ways have been fitted to allow the cranes to be safely accessed at any point within the well dock.

Finally, the entire crane system has been painted in a special protective coating to protect it against the harsh marine environment and prolong service life. Parts that could not be painted, such as the wheels, were manufactured in stainless steel.