1. Necessity of a connection between two shafts

The transmission of rotary motion from one shaft to another is necessary when a single shaft cannot fulfill the desired functions of the mechanism to be designed.

The cases described below require a discontinuous shaft line. Shafts are then connected by the transmission element: flexible coupling, hydrokinetic coupling, clutch, mechanical joint, etc. best suited to the operation of the assembly.

• Motion control: the transmission of rotary motion is not necessarily permanent. The non-simultaneity of the two rotational movements (one shaft at a standstill while the other is in motion) requires the shaft line to be interrupted by an element that may or may not allow the transmission of rotational movement.

• Two existing shafts: mechanical design is becoming increasingly...