Lifting equipment manufacturer, Demag Cranes & Components Ltd, has installed a crane system at Canterbury Cathedral’s new purpose built 400 sq m stone saw shop on the outskirts of the city.
The facility is operated by the Cathedral’s in house team of stonemasons, which is charged with an ongoing programme of restoration and conservation, replacing deteriorating stone at the Cathedral. Stone replacement activity is currently focused on the Corona Chapel at the eastern end of the building and the south east and south west transepts, which date back to the 12th century.
Much of the stone used in the restoration process is sourced from Caen, north western France, to provide an exact match to the material used in the original construction, with additional lepine stone imported from the area around Poitiers in south western France. The conservation programme currently involves the import of over 25 cubic metres of stone per year, weighing nearly 65 tonnes.
Raw stone scants are delivered to the stone saw shop and offloaded by the Demag crane. The crane is then used to load scants onto the saw, where they are cut into smaller block sizes to meet the requirements of the stone replacement programme. The blocks are transferred to the masonry workshop, within the Cathedral’s grounds, for precision cutting and carving by skilled technicians.
To meet the specific needs of the stone processing operation, Demag supplied an 18.25m span overhead travelling crane, rated at 10 t SWL. Mounted on the crane is a 10 t SWL Demag DR-COM electric wire rope hoist. The system has long travel speeds of 20/5 m/min, cross travel speeds of 5 to 20 m/min and lifting speeds of 4.0/0.7 m/min. The system is controlled by a mobile pendant, which allows the operator to position the stone accurately on the saw for precision cutting, maximising yield and reducing wastage of the expensive raw material. The smooth operation of the hoist also significantly reduces the possibility of damage to the stone blocks during movement.
Canterbury Cathedral’s Head of Stonemasonry and Stone Conservation, Heather Newton, reported that several options for the stone handling process had been investigated before the Demag system had been specified.
In addition to the use of state-of-the-art equipment, environmental sustainability has also been a driving factor in the development of the new saw shop. Heating for the building is provided by hot water, generated as a by-product at a neighbouring waste to energy facility, operated by waste management specialist, Viridor. Infrastructure and pipe work for the saw shop’s heating and hot water system were also provided by Viridor, in accordance with the renewable heat incentive initiative.