Invalid chair hand drive mechanism - has adjustable lever on handle with ropes unwinding from drums

摘要

The hand-operated drive mechanism for an invalid chair comprises a thrust handle (11) with steering grip (12), coupled via an unwinding mechanism (3,4) and a freewheel to the driving wheel. A rocker lever (9) hinges at a point adjustable for position on the handle and has two ropes (5,6) with bars (7,8) unwinding from drums (3,4). These drums tighten or release a spring wound for more than half a turn round a driving drum coupled to the wheel, so as to drive the latter drum in one direction and release it in the other. The first drums can be non-round affecting the relationship between the hand pressure on the handle and the torque at the wheel.