A lower platform and an upper platform are connected first and second levers having different lengths, each lever being articulated about a first axis on said lower platform and a second axis on said upper platform. The upper platform can be swiveled from a rest position to a position of maximum excursion relative to the lower platform so that the distance between platforms is immediately reduced upon swiveling from the rest position. At least one axis is provided with a brake which slows down rotational movement.
展开▼
