Pitch Transmissions
Since the first development of automobiles, pitch transmissions have been designed, manufactured, and tested over and over again, however, with no lasting success. The figure presents some basic forms of pitch body force transmission.
The continuously variable change of the transmission ratio takes place under load by varying the point of action of the force, meaning the effective pitch body radius. Apart from the friction coefficient, the pressure force of the pitch bodies determines the transferable force.
A renewed interest in pitch transmissions can be attributed to the development of new high-friction lubricants which enable nearly twice as large force transmission between the pitch bodies when compared to conventional lubricants.
For the application in motor vehicles, only those concepts which enable a firm position between input and output shaft can be used. This can be achieved by an intermediate link in the form of a rotationally symmetrical body.