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, they are also used in steering systems to change the direction of vehicles. The characteristics of rack and pinion systems in steering are the following: simple framework, high Spur Gear Rack rigidity, small and lightweight, and excellent responsiveness. With this mechanism, the pinion, mounted to the steering shaft, is meshed with a steering rack to transmit rotary motion laterlly (transforming it to linear motion) so that you can control the wheel. Furthermore, rack and pinions are utilized 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 instead of ball screws. The advantages of a gear rack are its mechanical simplicity, large load carrying capacity, no limit to the space, etc. One drawback though is the backlash. The benefits 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, while the pinion traverses and others where 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 equipment racks in share. If the application takes a long length requiring multiple equipment racks in series, we’ve racks with the tooth forms properly configured at the ends. These are described as “equipment racks with machined ends”. When a gear rack is created, the tooth cutting process and heat treatment process could cause it to try & walk out true. We can control this with unique presses & remedial processes.