(Updated on April 21, 2020)
A rack and pinion can exist in vehicles with or without power steering systems. Since most modern cars have power steering, then you can assume that racks and pinions are in them too. Any SUV, car, or small truck that you see on the road probably has rack and pinion steering in it. These two components make turning the steering wheel much easier because it takes that rotational motion energy and converts it into linear motion energy. This is how the wheels underneath the body can turn so easily.
Common Parts and Their Functions
Basically, a rack and pinion are two gears which make up a gear set. These gears are positioned within a metal tube. On each side of the tube, you can see the rack coming out. There is also a component called a tie rod which ties off the ends of the rack and connects the steering arm and spindle together. The function of the tie rod is to relay the force of the rack gear (or steering center link) to the steering knuckle. This is done as the tie rod connects with the steering arm. As a result, the steering wheel can turn as you try to rotate it with your hands.
The pinion is a component which also contributes to this process. You’ll find the pinion connected to both the steering shaft and rack. The connection is made on each end of the pinion. So basically, the pinion kind of links the steering shaft and rack together. When you go to rotate the steering wheel. Those rotational movements are received by the steering shaft and then passed along to the pinion that is connected to it. As the pinion rotates, it then rotates the rack which is also connected to it. Therefore, the steering wheel rotations move the pinion and then the rack in that order.
In a power steering system, the design of the rack is a little different. You’ll find a cylinder and piston on the rack too. The piston and rack are connected to one another, and each side of the piston has a fluid port. The high-pressure power steering fluid enters the piston from one side, causing it to move forcibly. This causes the rack to move afterward, creating the power assistance feature of the system.
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The rack and pinion are the two main components, but what are the other components worth mentioning in this steering system? Well, you can’t forget about the power steering fluid, vane pump, and hoses. The vane pump is what creates the hydraulic pressure needed for the power steering fluid to work its magic with the piston and rack. The hoses are obviously what carry the steering fluid from one component to the next in the steering system. And, of course, the steering fluid is what allows the rotational energy to transform into linear energy.
The rack and pinion are responsible for the number of revolutions it takes to get from the far-left lock of the steering wheel to the far-right lock. In most cases, you can complete 3 to 4 revolutions to get from one lock to the other lock. The number of teeth on the gears are really what make the difference here. Also, if the rack is positioned toward the center more, it reduces the effort needed to turn the wheel. You’ll often find this in sports cars or luxury cars. But for all other cars, it will just be the standard number of teeth per inch on the rack. If you ever need to replace these components, your mechanic will likely replace them with a new rack and pinion that are the equivalent of the old ones.