Handling problem overcome at the British Museum
When the contract was let to reface the imposing stonework of the British Museum in London, few could have foreseen the national headlines in which the project was to feature.
The Times amongst others was to bring the Museum re-facing to national prominence, when it transpired that the British Museum was being covered in French stone. However, beef crisis or no, it transpired that the contract had allowed for this eventuality and the jingoism soon subsided.
The initial headache had appeared to be the handling of the large pieces of masonry to high level, but this was overcome via an ingenious arrangement involving two 10 tonne SWL ABUS overhead travelling cranes.
With space at a premium in Central London and hence the few site cranes in constant demand by the many on-site contractors involved with the project, Easton Masonry approached ABUS Crane Systems, one of the world’s leading crane manufacturers, for two overhead travelling cranes mounted to the top of a specially designed gantry scaffold on the face of the Museum.
As a project of this type has not been done for a hundred years, the lifting arrangement was in many ways a prototype. One crane has the role of feeding stones on to the loading gantry and the second crane was designed for accurate fixing of the fluted column nosing.
This specialist solution would then allow the masonry contractor an all-important independent lifting source, as the final positioning of the large stones could be a lengthy process due to the accuracy required. The joints between the massive stones are measured in fractions of millimetres.
Although ABUS Cranes are supplied as standard with a main speed and a much slower precision speed on all motions, it was decided that this operation required even more precise handling. The ABUS ABUliner variable speed controller was fitted to the hoist of one of the cranes to allow the extremely exact positioning of the very heavy and expensive pieces of masonry. The ABUliner not only allows the speed of the motor to be continuously variable, but it also boasts a very low minimum speed for sensitive operations and its smooth performance virtually eliminates load bounce or swing and extends the useful life of the cranes motors and support structures.
Against the changeable but generally dismal London weather, the ABUS Cranes were also weatherproofed and given a durable outdoor paint finish.
Given the prestige of the job in the capital and it’s tight deadlines, Easton Masonry needed reliable quality. Easton Masonry Director Geoff Smith commented that the industry-leading ABUS 4 year standard warranty and the performance of existing 16 tonne SWL double girder overhead travelling cranes at their factory in Portland, convinced them to use ABUS cranes.