Rack and pinion
（重定向自Rack gear）
![](/Images/godic/202502/05/Rack_and_pinion_animation1012.gif")
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A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. A circular gear called "the pinion" engages teeth on a linear "gear" bar called "the rack"; rotational motion applied to the pinion causes the rack to move relative to the pinion, thereby translating the rotational motion of the pinion into linear motion.