Final Drive
On orthodox vehicles, the final stage in the transmission of engine torque to the driving wheels in which the direction of drive line turns from longitudinal to transverse, a permanent torque multiplication is applied, by crown wheel and pinion, and the differential gear is included. Also refers to the gear reduction in a differential or other last
transmission unit in a drive train. A reduction of 3:1 refers to the input shaft turning three times faster than the output shaft.
Also see: How it Works - The Final Drive Unit 
