A rack and pinion mechanism is used to transform rotary motion into linear motion and vice versa. A circular spur gear, the pinion, meshes with a spur gear which has teeth set in a straight collection, the rack. Rack and pinion gears are used to convert rotation into linear motion. An ideal example of this is the steering program on many vehicles. The tyre rotates a gear which engages the rack. As the apparatus turns, it slides the rack either to the proper or left, depending on which way you switch the wheel.
A rack and pinion program gives the ability to transfer rotary to linear motion, with all the accuracy expected of a geared program.
The racks are produced from ground, hardened stainless steel or ground stainless steel and available with a choice of accuracies, pitches, and lengths, in addition to the facility to provide modifications such as for example flats, journals or custom ends. Hobbed stainless steel and brass racks are also obtainable. The rack pinions are plain or anti-backlash, also with a choice of accuracies, pitches, bore sizes, alternative components and coatings.
Surface rack can be utilized for both measurement and actuation. Generally the smaller pitches (1 mm) match measurement as small pinion diameter provides higher linear resolutions. The larger pitches (2 mm and 2.5 mm) enable an increased load capacity. For some applications the rack can be used for both the opinions and the actuation; however in very precise applications it is advisable to us a non-drive section of the rack for opinions, alternatively a separate rack may be used. Hobbed rack are more suited to 
light actuation applications where price is an integral consideration.
You can expect three types of rack – rectangular, solid round and tubular rack. Rectangular rack are utilized when the application needs the rack to become stationary and the rack pinion provides the element of motion. Our rectangular racks are used with a motor, slide and carriage for example in the printing industry for the actuation of paper reducing knives in a printing press. Round rack are a more flexible alternative, with regard to mounting, used for example in XY levels. The tubular racks allow for the passage of liquids, fibre-optics, gasses etc, producing them perfect for Spur Gear Rack medical and scientific applications, such as laboratory automation choose and place mechanisms.
Round racks are perfect for linear actuators in accurate automation applications . Tubular racks are especially useful for medical and scientific applications, where in fact the hollow shaft permits the passage of fluids, fibre optics and gases.