Once on site Summit quickly discovered the object in fact weighed 2.5 tons, more than twice the original estimate! They supported the set piece by static lines to a 10m by 4m box truss grid which in turn hangs by six electric chain hoists, rigged to spreader beams laid between the Theatre’s wooden beams. "The big problem is daily movement," explained Walker. "Due to the object being moved in and out for every show on a multiple point movement system, there’s always the possibility of any single point taking too much load due to minute variations in hoist speeds. These can build cumulatively into a big displacement. To avoid this we installed one of Summit Steel’s loadcell monitoring devices in line with each hoist to indicate such discrepancies."
Despite their tight schedule, Summit found time during the installation to train the theatre’s Master Carpenter, who has responsibility for moving the set piece each day, to use the hoist control and load monitoring system. "He has a daily check list much like that used by airline pilots with a list of operational checks, each of which has to be ticked off as he does them," said Walker. "That way there’s no excuse for errors, and the man responsible can feel confident and competent in the system operation." The show runs until 3 June.
