Rack and pinions are used for lifting mechanisms (vertical movement), horizontal motion, positioning mechanisms, stoppers and to permit the synchronous rotation of a number of shafts generally industrial machinery. On the other hand, they are also used in steering systems to improve the direction of cars. The characteristics 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, mounted to 
the steering shaft, is certainly meshed with a steering rack to transmit rotary Spur Gear Rack movement laterlly (transforming it to linear motion) to ensure that you can control the wheel. Furthermore, rack and pinions are used for several other purposes, such as playthings and lateral slide gates.
As a mechanical element to transfer rotary into linear motion, gear racks tend to be 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, huge load carrying capacity, and no limit to the length, etc. One drawback though is the backlash. The benefits of a ball screw will be the high precision and lower backlash while its shortcomings include the limit in duration due to deflection.
There are applications where the gear rack is stationary, as 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 as the latter can be utilized in extrusion systems and lifting/lowering applications.
To provide many variants of rack and pinion, KHK has many types of equipment racks in share. If the application requires a long duration requiring multiple equipment racks in series, we have racks with the tooth forms properly configured at the ends. These are described as “gear racks with machined ends”. When a equipment rack is produced, the tooth cutting procedure and heat treatment process can cause it to try & go out of true. We are able to control this with special presses & remedial processes.