Noun
the axle of a self-propelled vehicle that provides the driving power
Source: WordNetA maximum traction truck has one driving axle with large wheels and one nondriving axle with smaller wheels. Source: Internet
In the process, it powers a piston that transmits power directly through a connecting rod (US: main rod) and a crankpin (US: wristpin) on the driving wheel (US main driver) or to a crank on a driving axle. Source: Internet
The pictures show a step drive by one sixth and one third rotation, respectively per full revolution of the driving axle. Source: Internet