A weighty matter

Alongside the old and the overweight, the young and fit can suffer spinal injuries that require them to be handled very carefully indeed, if they are not to become permanently disabled. Nurses are expensive and increasingly scarce, even in hospitals. A normal staffing ratio is now one nurse to 15 patients, with perhaps only one nurse on duty in a ward at night. Since up to four nurses may be required to lift a heavy patient, this poses a problem. Additionally, there are around nine million people in Europe and the US who need help getting in and out of bed, most of whom are not in hospital. There is an increasing desire on the part of both the state and the elderly, that they be able to live as long as possible in their own homes, rather than become institutionalised. Mechanical aids to allow them to stay at home are therefore highly desirable. The Challenge Our challenge this month is how to design a machine controlled by one person that can lift someone out of bed and place them in a chair or vice versa, without either alarming or damaging the patient, or risking the back of the operator. It should be capable of lifting fat people and thin people, frail people and those with possible back injuries, without causing further damage. Patient hoists do exist – Stoke Mandeville Hospital has 65 – but they all involve placing some kind of sling under the patient which bends under load, bending the patient. An ideal machine should be capable of lifting somebody without bending them or bend them by a properly controlled amount to place them in a chair. The solution offered in the Coffee Time Challenge area of the Eureka website solves the problem elegantly and could be adapted to lifting and handling large, delicate non human objects. Although electronically controlled, its operating principle is based on simple mechanics. A full sized working prototype of the solution will be described fully in Eureka's September edition. Solution to last month's Coffee Time Challenge The solution to last month's Coffee Time Challenge to find a good, low cost and totally reliable way of absorbing the shock of somebody falling off a roof, exists in the form of the 'Constant Force' post, which has been developed by the Devizes, Wiltshire based company, Latchways. Insides its 150mm long containment is a coiled steel rod. When a shock load is applied, this is pulled out, reducing maximum force to 10kN over several hundred mm during a time period of more than 150ms. It is tested with loads of 300kg, which is three times greater than that required in EN 795, which is the standard governing the testing of anchor devices. Its design is protected by patent. The testing programme includes installations on 6m x 6m sections of complete roofing systems.