A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. This combination of Rack gears and Spur gears are generally called “Rack and Pinion”. Driving the pinion into rotation causes the rack to be driven linearly. Rack and pinion combinations are often used as part of a simple linear actuator, where the rotation of a shaft powered by hand or by a motor is converted to linear motion. The maximum force that can be transmitted in a rack and pinion mechanism is determined by the tooth pitch and the size of the pinion. The rack carries the full load of the actuator directly and so the driving pinion is usually small so that the gear ratio reduces the torque required.