Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and to permit the synchronous rotation of many shafts generally industrial machinery. On the other hand, they are 
also found in steering systems to improve the direction of cars. The characteristics of rack and pinion systems in steering are as follows: simple framework, high rigidity, little and lightweight, and exceptional responsiveness. With this system, the pinion, installed to the steering shaft, is definitely meshed with a steering rack to transmit rotary movement laterlly (switching it to linear motion) to ensure that you can control the wheel. Furthermore, rack and pinions are utilized for many other purposes, such as playthings and lateral slide gates.
As a mechanical element to transfer rotary into linear movement, gear racks tend to be in comparison to ball screws. There are pros and cons for using racks instead of ball screws. The benefits of a equipment rack are its mechanical simplicity, huge load carrying capacity, and no limit to the space, etc. One disadvantage though is the backlash. The advantages of a ball screw are the high precision and lower backlash while its shortcomings include the limit in length due to deflection.
There are applications where in fact the gear rack is stationary, as the pinion traverses and others where in fact 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 variations of rack and pinion, KHK has many types of gear racks in stock. If the application requires a long length requiring multiple equipment racks in series, we have racks with the tooth forms correctly configured at the ends. These are Spur Gear Rack described as “gear racks with machined ends”. When a gear rack is created, the tooth cutting process and heat treatment process could cause it to try & go out of true. We can control this with particular presses & remedial processes.