Some cars have variable-ratio steering, which uses a rack-and-pinion gear set that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside.

For increased accuracy and repeatability, the unit can be supplied with an external anti-backlash POM (polymer) pinion gear which optimizes coupling to the wind turbine's large yaw bull gear.

The starter motor is a simple direct current (DC) motor which has a pinion gear attached to its shaft.