2. Geometry: bisector plane theory

A theorem due to Myard can be stated as follows: two shafts can have a reciprocal and continuous rotational connection by means of two pivots linked to these shafts, these two pivots being constrained to remain in one plane.

A special case of this theorem: when the two shafts intersect and the two pivots are perpendicular to these shafts, or more generally inclined at the same angle, the speed of the output shaft is equal to the speed of the input shaft. This is the simplest diagram of a constant velocity joint. A fairly logical method for designing constant velocity joints of this first type is to start with the simple joint (figure