Rack and Spur Gear Rack pinions are used for lifting mechanisms (vertical movement), horizontal motion, positioning mechanisms, stoppers and to permit the synchronous rotation of a number of shafts in general industrial machinery. On the other hand, they are also found 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 exceptional responsiveness. With this system, the pinion, installed to the steering shaft, is meshed with a steering rack to transmit rotary movement laterlly (transforming it to linear movement) 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 motion, gear racks tend to be in comparison to ball screws. There are pros and cons for using racks in place of ball screws. The advantages of a equipment rack are its mechanical simplicity, large load carrying capacity, and no limit to the space, etc. One disadvantage though is the backlash. The benefits 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 on a fixed axis as the gear rack moves. The previous is used broadly 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 equipment racks in stock. If the application requires a long length requiring multiple gear racks in series, we have racks with the 
tooth forms correctly configured at the ends. These are described as “equipment racks with machined ends”. Whenever a gear rack is created, the tooth cutting procedure and the heat treatment process could cause it to try & go out of true. We are able to control this with particular presses & remedial processes.