Posted to News on 29th Nov 2012, 00:00
Raising the stakes
An impressive raised floor automation project can now be seen at Lichfeld Cathedral, where the 32m2 floor surface can be raised 300mm in two stages to form a platform for Sunday services. At other times, especially when a concert is being staged, the area sits level with the surrounding floor.
>Building a floor that could be raised meant excavating the existing area to accommodate the lifting mechanism - an exciting opportunity for archaeologists as there has been a church on the site since the 7th century. The exposed archaeology was sealed in beneath sand and a concrete based brick-lined pit, that would support the lifting gear and steel platforms that the stone sits on. The stones on the perimeter of each section are 170mm thick to give a solid appearance when the platform is in the raised position. The rest of the stones are 20mm thick and are precisely cut to avoid gaps around the edges where the platforms rise.
>The mechanism for raising and lowering the eight tonne floor, uses precision screw jacks, specified and supplied by Drive Lines Technologies, and was designed by Hovair Systems, now a division of British Turntable Company. Screw jacks between 2.5 and 2000kN were chosen for their reliability and ease of use over hydraulics. The entire team is proud of the fact that the project was finished a week early and under budget. And the cathedral authorities are delighted with the result. "It's fantastic," says the chief executive of the cathedral. "It blends in so well, a lot of visitors are amazed to discover it's new."
>When the judges of the Natural Stone Awards saw the retractable alter platform, they commented: "Now every cathedral will want one." Sure enough Drive Lines has been working on similar systems for other UK cathedrals. Ripon Cathedral has also benefited from Drive Lines' expertise when updating and improving the frontage. Project Management Consultancy NCTS employed projects from Drive Lines Technologies on The Narthex Project to revamp the cathedral entrance.
>NCTS reports that the needs of this mechanical engineering project were that the pair of ancient oak doors, which are the Cathedral's main entrance, have to be closed in the windy conditions that Ripon is sometimes blessed with. The pair of gothic arched doors are almost 5.5m high, and with an area of 9m_ each they generate a significant wind load reaction. The system needed to have sufficient force to overcome this reaction but be gentle with the old doors and also comply with the relevant legislation to prevent personal injury. The system also needed to satisfy the aesthetic requirements of the Cathedral Architect.
>No standard system was available which satisfied these requirements, so NCTS was asked to design a solution. Drive Lines supplied geared motors consisting of a PGE 50/1 planetary gearbox coupled with a 3-phase 0.6kW motor for the outer oak door opening system. The outer doors can now be left open as the glass porch cures the problem of wind blast through the Nave. Commenting on the project, the Dean said: "This forms another part of the development of the Cathedral. We hope that these new doors will encourage more people to visit this historic church, which has stood here as a symbol of our Christian faith and heritage for over 1300 years."
