The lower ratio gives the steering a quicker response -- you don't have to turn the steering wheel as much to get the wheels to turn a given distance -- which is a desirable trait in sports cars. These smaller cars are light enough that even with the lower ratio, the effort required to turn the steering wheel is not excessive.
Some cars have variable-ratio steering , which uses a rack-and-pinion gearset that has a different tooth pitch number of teeth per inch in the center than it has on the outside. This makes the car respond quickly when starting a turn the rack is near the center , and also reduces effort near the wheel's turning limits.
When the rack-and-pinion is in a power-steering system, the rack has a slightly different design. Part of the rack contains a cylinder with a piston in the middle. The piston is connected to the rack.
There are two fluid ports, one on either side of the piston. Supplying higher-pressure fluid to one side of the piston forces the piston to move, which in turn moves the rack, providing the power assist. We'll check out the components that provide the high-pressure fluid, as well as decide which side of the rack to supply it to, later in the article.
In a similar vein, racks and pinions are used with paired pneumatic cylinders to produce limited rotational motion in high-torque motion control operations.
They are used for elevators and gates. Rack-and-pinion drives are used in machine tools, pick-and-place mechanisms, and so forth to provide linear motion of slides, gantries, etc. Sometimes a lead- or ball-screw is preferred, especially for shorter motions, but racks and pinions provide an economical way of achieving long runs.
One drawback is accuracy, as the pinion and rack need a certain amount of clearance to mesh properly, resulting in backlash.
Depending on the diametral pitch of the gear, the recommended backlash can range from as little as 0. For something as crude as a CNC plasma cutter, backlash would play no role in the quality of the cut product but would certainly be a factor in the work produced on precision equipment.
Rack-and-pinion manufacturers do offer zero-backlash designs for these purposes which use technologies such as dual- or split-pinions. In addition, fairly new roller-pinion systems are making inroads into some of these markets. In the automotive market, rack-and-pinion steering pretty much dominates cars and small trucks and SUVs, while recirculating-ball systems are used for larger vehicles. Variable-ratio steering varies the teeth out near the ends of the rack to produce quicker wheel turning in low-speed maneuvers while maintaining lower sensitivity for high-speed course corrections.
Just how this is managed is left for the reader to pursue. Washington cog railway is a prime example. Full of interesting videos, useful tips and clear instructions, MOOG TV is the ideal place to learn more about your car.
Want to diagnose your steering and suspension car problems? Take a look at our diagnostic centre. Visit Diagnostic Centre. The content contained in this article is for entertainment and informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein.
Under no circumstances will we be liable for any loss or damage caused by your reliance on any content. What can cause a rack and pinion system to leak? Read more. Easy car guide: How a steering system works.
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