Rack and pinions are used for lifting mechanisms (vertical movement), horizontal motion, positioning mechanisms, stoppers and also to permit the synchronous rotation of a number of shafts in general industrial machinery. However, they are also found in steering Spur Gear Rack 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 superb 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 movement) to ensure that you 
can control the wheel. In addition, rack and pinions are utilized for several other purposes, such as playthings and lateral slide gates.
As a mechanical component to transfer rotary into linear movement, gear racks are often in comparison to ball screws. There are pros and cons for using racks in place of ball screws. The benefits of a equipment rack are its mechanical simplicity, large load carrying capacity, and no limit to the length, etc. One disadvantage though is the backlash. The advantages 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 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 used 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 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 “gear racks with machined ends”. When a gear rack is created, the tooth cutting procedure and heat treatment process can cause it to try & go out of true. We can control this with unique presses & remedial processes.