A crown wheel and pinion are a pair of gears found in a drive wheel of a vehicle
in which the pinion is at the end of the propeller shaft driving the crown wheel. The setup works when the pinion sets on top of the crown wheel. The pinion is substantially smaller than the crown wheel, and the teeth turn very quickly to produce forward motion.
In rear-wheel drive vehicles, the crown wheel and pinion is mounted on the differential of the back axle.
Crown wheel and pinion gears are not found on wheels without a drive train attached. The heights of the gears must be set correctly or the vehicle will not move forward correctly.
Crown Wheel and Pinion