This is a nonplanar mechanism. Imagine the four bar linkage on the surface of a sphere with all the rotary axes intersecting at the center of the sphere. In this model, (similar to C1), the linkage can be demounted and each of the four links can be fixed using the pedestal H2. In this way Reuleaux wanted the instructor to demonstrate four inversions of the linkage. The making of the four circular shaped links is a remarkable feat of 19th century machining. Reuleaux called this linkage a 'conic quadric crank chain'. He describes in his book Kinematics of Machinery, 24 variations of conic crank chains.

Francis Moon 2001-00-00