Double lever comprising upper and lower angle levers - with gain in lifting effort without lowering of common centre of mass

摘要

An upper lever with its two arms roughly parallel is loaded at its centre and the ends of its arms are supported by a sharply angled lower-lever. The lower lever has one almost vertical arm and one almost horizontal arm. The fulcrums of the upper and lower levers are parallel to each other and normal to the same plane. The upper lever fulcrum is displaced sideways relative to that of the lower lever. There is a shortening effect on the load arm in the upper lever, and the lengths of the arms and design of the lever ensure that there is a resultant gain in lifting effort.