Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and to permit the synchronous rotation of several shafts in general industrial machinery. However, also, they are used in steering systems to improve the direction of vehicles. The features of rack and pinion systems in steering are as follows: simple structure, high rigidity, small and lightweight, and excellent responsiveness. With this system, the pinion, installed to the steering shaft, can be meshed with a steering rack to transmit rotary motion laterlly (converting it to linear motion) to ensure that you can control the wheel. In addition, rack and pinions are used for several other purposes, such as toys and lateral slide gates.
As a mechanical component to transfer rotary into linear movement, gear racks are often compared 
to ball screws. There are benefits and drawbacks for using racks instead of ball screws. The advantages of a gear rack are its mechanical simplicity, huge load carrying capacity, no limit to the space, etc. One disadvantage though may be the backlash. The benefits of a ball screw are the high precision and lower backlash while its shortcomings are the limit in duration due to deflection.
There are applications where the gear rack is stationary, as the pinion traverses and others where in fact the pinion rotates upon a fixed axis while the gear rack moves. The former is used widely in conveying systems as the latter can be used in extrusion systems and lifting/lowering applications.
To provide many variations of rack and pinion, KHK has various kinds of equipment racks in stock. If the application takes a long duration Spur Gear Rack requiring multiple equipment racks in series, we’ve racks with the tooth forms properly configured at the ends. They are described as “equipment racks with machined ends”. When a equipment rack is created, the tooth cutting process and the heat treatment process could cause it to try & go out of true. We can control this with unique presses & remedial processes.