Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and also to let the synchronous rotation of several shafts generally industrial machinery. However, they are also used in steering systems to improve the direction of vehicles. The features of rack and pinion systems in steering are as follows: simple framework, high rigidity, small and lightweight, and superb responsiveness. With this system, the pinion, mounted to the steering shaft, is certainly meshed with a steering rack to transmit rotary movement laterlly (transforming it to linear motion) to ensure that you can control the wheel. Furthermore, rack and pinions are utilized for various other purposes, such as toys and lateral slide gates.
As a mechanical component to transfer rotary into linear Spur Gear Rack motion, gear racks are often in comparison to ball screws. There are benefits and drawbacks for using racks in place of ball screws. The benefits of a gear rack are its mechanical simplicity, large load carrying capacity, no limit to the distance, etc. One drawback though is the backlash. The benefits of a ball screw are the high precision and lower backlash while its shortcomings are 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 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 stock. If the application takes a long length requiring multiple equipment racks in series, we have racks with the tooth forms correctly configured at the ends. These are described as “equipment racks with machined ends”. When a equipment rack is created, the tooth cutting procedure and heat treatment process could cause it to try & walk out true. We can control this with unique presses & remedial processes.