Rack gear is a toothed bar into which a pinion meshes. Racks are gears
of infinite pitch radius. They are used to translate rotary motion to
linear motion or vice versa. They will mesh with pinions of the same
pitch. Materials of Construction
Racks are made of various materials. The commonly used materials for racks are stainless steel, brass, and plastic.
Applications of Rack Gears
They are widely used in automobiles. The steering wheel of a car rotates the gear that engages the rack. The rack slides right or left, when the gear turns, depending on the way we turn the wheel. Windshield wipers in cars are powered by a rack and pinion mechanism. They are also used in some scales to turn the dial that displays weight.