Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and to let the synchronous rotation of several shafts in general industrial machinery. On the other hand, also, they are used in steering systems to change the direction of cars. The characteristics of rack and pinion systems in steering are the following: simple structure, high rigidity, little and lightweight, and excellent responsiveness. With this system, the pinion, installed to the steering shaft, is usually meshed with a steering rack to transmit rotary motion laterlly (switching it to linear motion) so that 
you can control the wheel. Furthermore, rack and pinions are utilized for various other purposes, such as playthings and lateral slide gates.
As a mechanical component to transfer rotary into linear movement, gear racks tend to be compared 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, no limit to the length, etc. One drawback though is the backlash. The advantages of a ball screw will be the high precision and lower backlash while its shortcomings are the limit in length due to deflection.
There are applications where the gear rack is stationary, as the pinion traverses and others where in fact the pinion rotates on a fixed axis while the gear rack moves. The previous is used widely in conveying systems while 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 gear racks in share. If the application takes a long length requiring multiple equipment racks in series, we’ve racks with the tooth forms correctly configured at the ends. These are described as “equipment racks with machined ends”. Whenever a equipment rack is produced, the tooth cutting procedure and the heat treatment process could cause it to try & walk out true. We are able to control this with particular Spur Gear Rack presses & remedial processes.