Steering System
In the past several years, the automotive industry has been getting closer to fully self-driving cars. Even so, we may have to wait quite some time until that becomes a reality and in the meantime, we will have to rely on vehicles with a steering system.
The way steering systems have been designed and implemented have evolved drastically over the years. Let’s take a look at all of the different kinds of steering systems and what they’re made up of, as well as the concept of power steering and how alignment works.
Steering system basics
At the most basic level, a steering system is designed to translate the rotational force of the steering wheel into the movement of your front wheels. Go-karts are a great example of a simple steering system. From the steering wheel, there is a shaft pointing downwards, which links up with a small arm on the bottom. The small arm has tie rod ends attached, one going out to each wheel. As you steer the steering wheel, the motion is transferred all the way down to the tie rod ends, which in turn move the wheels.
Your car’s steering system operates in the same way as the go-kart, only that it is slightly more sophisticated and complex. The steering wheel attaches to the steering column, which is connected to the steering gear. The steering gear moves a component known as the pitman arm, which connect to several tie rod ends. Just like in the go-kart, the tie rod ends are connected to each wheel and twist as you turn your steering wheel, transferring the motion into your front wheels.
Your wheels are mounted on metal components called spindles. These spindles are attached between the tie rod ends and the wheel. They move when they are pushed and pulled by the steering linkage, causing your wheels to turn as needed. They are secured by ball joints, which allows the spindles to move around without throwing off the alignment of the vehicle.
Steering system types
Rack-and-pinion steering
Your average car or truck likely utilizes a rack-and-pinion steering system. This simple system is made up of two main parts: the rack, a horizontal piece of metal with teeth along the top side, and the pinion gear, a round gear at the end of the steering shaft that interlocks with the teeth of the rack. This mechanical system is typically set inside of a tube. As you turn your steering wheel, the steering shaft and pinion gear turn with it. This will then shift the rack to one side or another, causing the tie rod ends to move the spindles and wheels in the desired direction.
The number of teeth on the pinion gear will have an impact on your steering as well. Fewer teeth will make it easier to turn the steering wheel, but will require more rotations to complete a sharp turn. More teeth will give you a quicker sharp turn but will require a bit more strength to complete. Most modern cars will pair this steering system with a power steering system to reduce the effort needed to complete turns.
Power-assisted rack-and-pinion steering
As mentioned, many modern vehicles that make use of rack-and-pinion steering will also be paired with a power steering system. This pairing is known as power-assisted rack-and-pinion steering. This system includes a cylinder and piston located on the rack. The piston is connected to power steering lines on both sides. The lines provide a pathway for power steering fluid to be delivered from a power steering pump, located outside of the rack. As you turn your steering wheel, a rotary valve on the power steering pump directs more power steering fluid to that particular side of the piston, which helps ease the steering. When driving in a straight line, the rotary valve will ensure equal amounts of pressure on both sides of the piston.
More advanced systems may vary the amount of fluid pressure based on additional factors, such as vehicle speed, turning force, or vehicle weight/load. As a result of the power-assist, you are able to turn easier when driving at low speeds (such as when parking) and have greater control when traveling at highway speeds.
Recirculating ball steering
Before the advent of power steering, recirculating ball steering was the steering system of choice. The recirculating ball system accomplishes the same tasks as the rack-and-pinion system with some key differences. Instead of teeth, the recirculating ball system utilizes a worm gear – a long spiral similar to that of a bolt. This system still has a steering shaft that turns as you rotate the steering wheel, only that the shaft now turns the worm gear instead of a pinion. The worm gear is inserted inside of a metal box with teeth in it. The teeth of the metal block then transfers the motion to a sector gear – a gear which has teeth on only one side.
The sector gear then turns a lever known as the pitman arm, which attaches itself to the steering linkage. This linkage is made up of inner and outer tie rods that are connected to the spindles, which complete the turning motion. Inside of the metal block exists many tiny ball bearings. The ball bearings reduce friction between the worm gear and the teeth, as well as eliminate the slack between the bolts and threads. This is where the name “recirculating ball” comes from.
Power steering components may also be combined with the recirculating ball system to add steering assistance. This operates in a similar way as the power-assisted rack-and-pinion system – where pressurized power steering fluid is applied to a certain side of the block to ease the steering in that direction.
Electric power steering
The most eco-friendly and fuel efficient steering system of them all, electric power steering systems utilize an electric motor that replaces the power steering pump from the traditional power steering system. This electric motor is attached either to the rack-and-pinion assembly or directly onto the steering shaft. By using a variety of sensors, an internal computer senses which direction the driver wants to turn and powers the motor to offer assistance in that direction. Since the power steering pump is replaced, power steering is available without any need of additional horsepower from the engine as in the standard power steering systems. The responsiveness of electric power steering systems can also be adjusted as you drive, providing the optimal amount of steering assistance whenever it is needed.
Alignment
No matter what steering system your vehicle utilizes, the alignment is crucial to the function of your steering. Poor alignment can cause a variety of issues, including but not limited to your vehicle pulling to one side, vehicle staying off center after completing a turn, and veering to one side after hitting a bump. There are three alignment angles in a steering system: the toe, the camber, and the caster. They are interconnected and impact your tire wear and affect your car’s handling.
Toe
The toe adjusts and controls the direction your tires are facing, relative to the center of the vehicle. This is the most common alignment angle that needs adjustment. If it is off, you will experience uneven wear on your tires. You may also notice your vehicle pulling to one side or a squealing noise coming from the tires or wheels.
Camber
The camber adjusts the vertical tilt of the tires. Negative camber means the tops of the tires are tilted inward, whereas positive camber refers to an outward tilt out of the top of the tires. Poor camber can wear out your tires, ball joints, bearings, and spindles.
Caster
You can view your car’s caster from the side – it is the angle of your steering axis. A good caster angle will promote stability when driving in a straight line. A bad caster angle will cause the vehicle to feel unstable. The caster of a car usually cannot be adjusted. It is set when the vehicle is manufactured and only needs to be reset after an accident or if the steering and suspension gets too worn.
Steering system maintenance
Thanks to advances in automotive technology, there is very little maintenance to keep up with as it pertains to your vehicle’s steering system. If your vehicle has power steering (as most modern vehicles do) having your power steering fluid inspected and replaced is a part of your regular preventative maintenance. Refer to your vehicle’s owner manual to note the interval that these services need to be done.
The most important steering system maintenance to keep up with is adjusting your alignment angles. Get your alignment checked out by a car care professional any time you replace your tires or feel a pull in one direction.
The best way to schedule an alignment is to book an appointment through CarAdvise. CarAdvise makes car care simple and guarantees that you will pay less than the shop price for all services!
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