cardanThe universal joint can connect two rotating shafts that change of place or are not (continuously) in a line. It's a double universal joint. The ends of the axles have a U-shape which is pushed into one another. They can be secured with a pin. In practice, both hinge pins are in a slice in the same plane, at right angles to each other. Then, not to the U- shape, but the disc is the connection.
Robert Hooke (1635-1703) was an English scientist who invented the universal joint.