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Lifter is safe and removes operator fatigue
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15/06/2004
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Problem: Designing equipment to lift a 200kg roof truss is not a difficult task for most design engineers, especially to a height of only 50mm. However, if the customer wants a system that fits into a table only 60mm thick, with no protruding cylinders and capable of withstanding a compressive point load of two tonnes, the solution becomes somewhat more complicated. The timber is cut to size and placed against mechanical stops, steel nail plates are then positioned over each joint and squeezed together using a mobile press. The truss is removed by the operator by lifting over the stops, which not only causes operator fatigue but has the potential for serious back problems.
Solution: Initially, engineers from Fluid Target Services based in ???? came up with the idea of using an inflatable tube under a 100mm x 50mm steel channel. The tube provided far more force than was required but could not reach the height needed to clear the stops. Bob Jackson, managing director of the company, told Eureka: "Using a lever mechanism connected by a steel plate fitted under the tube, our engineers were able to magnify the movement of the inflated tube. Although the lever ratio reduced the force to the beam, we still had plenty in hand to lift the truss. In fact, the lifting mechanism only requires a pressure of 3 to 4 bar."
Applications: According to Jackson, this is the first system of its type and has now been used in two installations. Although it is too early to evaluate its long term reliability, preliminary findings indicate that it will be a successful and cost effective solution to the problem. Eureka believes the idea could be extremely useful for applications where the ratio of closed and open height is critical. DP
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Author
Tom Shelley
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