Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and to let the synchronous rotation of several shafts generally industrial machinery. However, they are also used in steering systems to improve the direction of cars. The characteristics of rack and pinion systems in steering are the following: simple framework, high rigidity, small and lightweight, and superb responsiveness. With this mechanism, the pinion, mounted to the steering shaft, is definitely meshed with a steering rack to transmit rotary movement laterlly (switching it to linear motion) so that you can control the wheel. In addition, rack and pinions are used for various other purposes, such as playthings and lateral slide gates.
As a mechanical component to transfer 
rotary into linear motion, gear racks are often in comparison to ball screws. There are advantages and disadvantages for using racks in place of ball screws. The benefits of a equipment rack are its mechanical simplicity, large load carrying capacity, and no limit to the distance, etc. One drawback though may be the backlash. The benefits of a ball screw are the high precision and lower backlash while its shortcomings include the limit in size due to deflection.
There are applications where in fact the gear rack is stationary, while the pinion traverses and others where the pinion rotates upon a fixed axis as the gear rack moves. The previous is used widely in conveying systems while the latter can be used in extrusion systems and lifting/lowering applications.
To provide many variants of rack and pinion, KHK has various kinds of equipment racks in stock. If the application requires a long size requiring multiple gear racks in series, we have racks with the tooth forms Spur Gear Rack correctly configured at the ends. They are described as “equipment racks with machined ends”. When a equipment rack is created, the tooth cutting procedure and the heat treatment process can cause it to try & go out of true. We can control this with unique presses & remedial processes.