1. A brief reminder of the need for transmission

An automotive gearbox is a mechanical device which adapts engine power to the power required by the axle, depending on the driving conditions encountered (starting, acceleration, hill climbing, etc.).

The torque delivered by the internal combustion engine is variable over its speed range, and often too limited to propel the vehicle autonomously.

The gearbox multiplies the torque available to the drive axle and, more generally, adjusts power to the drive wheels according to the forces resisting the vehicle's forward motion, which in turn depend on the vehicle's driving configurations. Articles [BM 2 582]...