The Steering System
How steering systems work, types of steering systems and possible problems
In this discussion, we will take a deeper look at the steering. I think you may agree when we say that you hardly thought that this system was worth a discussion. I mean, it is after all just a round thing, turned to steer the vehicle. What can be so discussable about that? Indeed it is, but it is also so much more. Just as the brake pedal engage and disengage an entire intricate brake system, and the clutch a more complicated clutch system, so does the steering control an entire steering system that is much more than the sum of its parts – so to say!
During your reading experience, more information regarding the steering will be shared with you, in particular with regard to what it is and how the different types of steering systems work. This will culminate in the part where we look at the signs of any possible problems that you may experience with the steering system. Having knowledge about these aspects of the steering may empower you to identify problems with this system swiftly, and address them even swifter. By doing this, you may save both lives and costly aftercare. Let us then, without any further ado, dive right into this discussion.
Steering – a definition
Microsoft Encarta (2006) defines a steering wheel as the means of guiding a vehicle. It is the wheel in a vehicle that is connected by way of the steering column to the steering gear and is turned to change direction. When we refer to steering, the wheel is but a component making the steering as a system, possible. Within this system, called the steering system, there are other parts that have to work together to make this system function properly. In the following part, you will see how the different application of parts bring about different steering systems. Let us have a look at them.
Steering system types and how it works
There are primarily (and most commonly) two types of steering systems found in vehicles: the rack-and-pinion system and the recirculating-ball steering system. A third type is the hydraulic and electric power-steering system, which is merely a modified rack-and-pinion system, but more about this system later.
According to Karim Nice (2018) the rack-and-pinion system is a very popular type of steering on vehicles, small trucks and SUVs. This simple mechanism functions in the following way: a shaft that goes all the way down from the steering wheel, has a round gear at the end (called a pinion) that sits on a notched rod (called a rack). See Image 1 as an illustration of this. This rack extends the width of your vehicle and connects to both wheels. When you turn the steering wheel, the pinion rolls through the notches on the rack and pushes the rod to the right or the left, which in turn turns your vehicle’s wheels. That seems simple enough.
The recirculating-ball steering system follows on the heels of the rack-and-pinion system. Karim Nice (2018) points out that many trucks and SUVs use this system, which works in the following manner (Image 2). The recirculating-ball steering contains a worm gear. The worm gear consist of a block of metal with a threaded hole in it and gear teeth cut into the outside of it, which engage a gear that moves the pitman arm. The steering wheel connects to a threaded rod that sticks into the hole in the block. When the steering wheel turns, it turns the threaded bolt, which in turn moves the block, which moves the gear that turns the wheels. Instead of the bolt directly engaging the threads in the block, all of the threads – filled with ball bearings – recirculate through the gear as it turns, thereby creating its name. The ball bearings serves a dual purpose: they reduce friction and wear in the gear and they reduce slop in the gear. Slop is what you will feel when you change steering wheel direction – without the balls in the gear, the teeth would come out of contact with each other for a moment, making the steering wheel feel loose.
Power steering – Hydraulic and Electric
According to Wheelzine (2018), a typical power steering system utilizes the same mechanism as the normal rack and pinion system, with the addition of a hydraulic system that generates the needed power to assist in the steering effort (Image 3).
Part of the rack is modified to form a hydraulic piston and cylinder arrangement. Hydraulic fluid feeds the cylinder on two sides through openings to which two fluid lines are connected. The piston connects to the rack and moves between these two openings (bottom left side of the illustration). When pressurized fluid feeds into any one of the openings, the piston is pushed and it moves to the opposite direction, dragging the rack along with it. At the same time, the other opening vents the fluid out of the piston. A rotary vane pump, driven by the engine through a belt and pulley arrangement, pulls the low-pressure fluid from the reservoir, pressurizes it and then supplying it back to the cylinder in the hydraulic steering system. In this way, it provides power that significantly minimizes the effort needed to steer the vehicle. Thus, effectively, the fluid pressure does most of the steering work while the driver only controls the direction of the turn with the help of a very precise valve system. The hydraulic therefore only assist the steering – the steering wheel stay linked to the wheels in the usual way.
Power steering provides easier manoeuvrability and a better degree of control over the vehicle, which makes driving so much more effort-free. There is a downside to this form of steering. It is considered inefficient because the power steering pump on most vehicles today runs constantly, pumping fluid all the time, and this wastes horsepower. Wasted power translates into wasted fuel.
This was eradicated to a huge degree with the introduction of the electrically assisted power steering, also known as the EPS, as shown in Image 5. By replacing the hydraulic system with an electric motor, the load on the engine was reduced to only those occasions when the steering wheel is turned one way or the other, thereby producing better fuel economy.
In the EPS systems, the hydraulic part is replaced with a computer-controlled electric motor. The electric motor is mounted on either the steering column or the steering gear (usually a rack-and-pinion system); it applies torque to the steering column, thereby assisting the driver to turn the steering wheel. Sensors detect the steering wheel position and any input from the driver; if the driver holds the wheel steady, the system provides no assistance. The EPS improves steering feel and performance; it also offers the advantage of improving fuel economy and can be programmed by the computer for many different attributes.
Innovation – Steer-By-Wire
Technology evolves daily, and do not think that the steering system stagnated in this regard! Karim Nice (2018) draws our attention to the “steer-by-wire” or “drive-by-wire” system (Image 4). This system eliminates the mechanical connection between the steering wheel and the steering system, replacing it with a purely electronic control system (similar to those small steering wheel people buy to play computer games). This system holds sensors that tell the car what the driver is doing with the wheel; the output of these sensors control the motorized steering system. This frees up space in the engine compartment by eliminating the steering shaft; it also reduce vibration inside the car. Observe the connection to the steering system in Image 4. This system includes a clutch that, when the system is in normal use, disengages the mechanical link from the steering column to the steering rack. Whenever a fault is detected in the electronics, the clutch engage, which create a link between the steering wheel and the rack. One downside to this system thus far, is the possibility that the unit’s electronic control can be hacked. Yes, that is not impossible. It will be a while before this system (if ever) is in use in the majority of vehicles.
Steering – be aware of the following
If you are familiar with the content of a major service done by us at Steves Auto Clinic, then you will know that the steering is one of the many components and systems we check for functionality. Imagine for a second the following scenario: You drive at the top speed permitted on a road, and the steering system breaks down – you have NO control over the vehicle! Disaster. Checking your steering system and/or having it checked frequently, is a crucial part of vehicle maintenance and care.
As with any other component and system, the steering system is also prone to have its breakages and problems. Knowledge about the latter will enable you, no, empower you to identify and address any breakages and problems associated with the steering system. Vanessa Atwell (2014) highlights ten of these problems; let us look at them.
Vibration/Shimmying/Shaking While Driving
A vibration felt in the steering wheel are probably the most common problem. It should be noted that the steering system components are not always responsible for this type of behaviour. When vibration occurs during breaking, then it is highly likely that there is a problem with the braking system. Read our article regarding the breaking system here. If the vibration appears and disappears during low speed or during highway speeds, then the problem may be an out of balance wheel assembly, damaged rims, damaged tires or worn steering or suspension components. Because so many systems may be the cause of such a vibration, it is important to quickly determine the faulty system and have it remedied.
Electric Steering – Constantly Stiff
Problems with electric steering systems usually indicate a failure somewhere in the electric power steering system, and it takes a scan tool and service information to properly diagnose and repair the issue. You can do your own diagnosis by checking fuses, checking for binding or damage, checking that wiring is intact and correctly installed and checking that the battery voltage is fine. Attwell (2014), warns us against wiggling or disconnecting & reconnecting electric power steering components because the terminals inside the connectors lose their gripping ability after just a few times of disconnecting & reconnecting them. When this happens, erratic problems may rear their heads. Electric power steering components typically are not repairable – they need replacement.
Electric Steering – Stiff Steering on One Side Only
Whenever electric steering is stiff only in one direction, the usual cause is that the steering system is out of calibration and the usual fix is to recalibrate it.
Hydraulic Steering (Low Assist) – Constantly Stiff
The loss of power assist or low assist is often due to low power steering fluid, a lack of steering fluid pressure or actual steering/suspension components themselves malfunctioning. Start by checking the steering fluid level and condition. If the problem is because of low steering fluid, figure out where the fluid went. If the fluid and level is fine, check for binding components by raising the wheels off the ground (if you can) and moving them slowly from side to side to verify free movement. Moving the wheels too quickly can cause the fluid to shoot out through the pump and make a mess when the system is not running. Sometimes leaks hide themselves inside the dust bellows on the rack and can only be identified by removing the clamp. Ensure you have a new clamp available to install in case you are wrong. If you do not know how to do any of these, then please refrain from doing it and have it done by professionals, such as us. If the wheels move smoothly when lifted off the ground, then the problem is most likely in the steering assist system rather than in the binding components. Blockages and restricted passages do happen, but a faulty serpentine belt or the pump itself can also cause a lack of power steering fluid pressure. If the wheels cannot be moved when raised off the ground (with the steering column unlocked), then the problem is probably a bent, seized or damaged component that will need to be replaced.
Hydraulic Steering – Occasionally Stiff
This problem may arise due to aerated power steering fluid or binding steering components. Inspect the condition of the power steering fluid; if it smells funny or is a strange colour, it may be contaminated. While you are at it, check for tiny particles that may be present in the fluid. If any, flush and replace the contaminated fluid.
Hydraulic Steering – Not Returning to Centre after a Turn
A slight binding in steering or suspension components usually causes this problem, and unfortunately it often happens after an impact with something like a curb, or after a drastic change in alignment angles. The solution is to have it inspected for damaged or bent steering components and to correct the alignment angles accordingly.
Leaks – Visible on Driveway or Parking
Hydraulic leaks usually come from leaking seals, O-rings, crimps or from incorrectly topping up the fluid, (some people wrongly use transmission fluid as a substitute for steering fluid). Try to identify the origin of the leak and have it fixed. Hydraulic hoses deteriorate over time, and this is something that you should sporadically inspect. If you see a cracked and dry hose, have it replaced. Remember, if the pump runs out of fluid for whatever reason, it will burn out, so prevent unnecessary expenditure and problems by addressing any leakages.
Steering Wheel Off-Centre
If the vehicle travels straight down the road but the steering wheel is off-centre, the most common reason is a problem with alignment angles, possibly due to bent or damaged suspension or steering components. Identifying these bents is not easy, so have it checked by professionals and have it corrected.
Steering Pulls or Drifts
To fix this problem, you should consider performing a four-wheel alignment and correct the alignment angles, but uneven tire pressure and poor tire condition can also be the cause of this problem. It is also easy enough to check that the vehicle is the same height from side to side. If not, suspect suspension problems or a flat tire.
A squealing noise, whether it is irregular or constant, can be caused by a problem in the belt or pulleys, and not necessarily by the steering pump pulley itself. You can diagnose this problem by removing the belt (make sure to mark the direction of rotation first) and spinning all of the pulleys by hand, checking for problems, binding and free play in all of the pulleys. If you do not know how to do this, refrain from doing it, rather have professionals do it for you. The belt tensioner should also be inspected to ensure that it provides enough tension and that there is no cracks, glazing, missing chunks or contamination of the belt because they do tend to fail too.
One aspect that Vanessa Atwell (2014) did not include in her ten steering issues, is the one of uncontrollable steering, which may be caused by a damaged steering rack mount. If you experience steering of this nature, and if any of the abovementioned problems do not assist you in addressing this problem, then you may as well have the steering rack mount inspected. You can fix this (if it is the problem) on your own (if you know how), but you may also best be serviced by a certified mechanic, and we have plenty of them.
This brings us to the end of this article. It is said that your vehicle’s steering is the only system that you are quite literally always in touch with. Think about it, the steering wheel demands hands-on (or sometimes less advisable “knees-on”) control all of the time. Listen, feel and look at steering related issues as mentioned in this article. Never postpone any problem related with this system, for you can be sure that if you do, you may only regret it later. At Steves Auto Clinic, we do not deal in regrets but in precaution. We give advice on vehicle maintenance and care, we service vehicles and we inspect and repair that which is broken or dilapidated. Bring your vehicle to us for friendly and professional service.
Sources consulted during the writing of this article:
• Microsoft Encarta. 2006. Steering wheel. Definition. Microsoft Corporation.
• Nice, K. 2018. How Car Steering Works. Online available at: https://auto.howstuffworks.com/steering.htm Accessed on 31 July 2018.
• Wheezine. 2018. How does power steering work? Online available at: https://wheelzine.com/how-does-power-steering-work Accessed on 31 July 2018.
• Attwell, V. 2014. Top 10 Steering Problems and their Fixes. Online available at: https://www.searchautoparts.com/motorage/undercar-service-repair/top-10-steering-problems-and-their-fixes Accessed on 31 July 2018.
Images used in this article:
• Image 1. – Rack-and-pinion. Online available at: http://www.technologystudent.com/gears1/gears4.htm Accessed on 2 Aug 2018
• Image 2. – Worm and roller steering. (Amended). Online available at: https://www.indiamart.com/ohmpower/worm-and-roller-steering-gear-model.html Accessed on 2 Aug 2018
• Image 3. – Power steering. Online available at: http://www.ognibene.com/en/video/splash-page Accessed on 2 Aug 2018
• Image 4. – Electrically assisted power steering (EPS). (Amended). Online available at: http://www.radianceiitb.org/blog/power-steering/ Accessed on 2 Aug 2018
• Image 5. – Steer-by-wire. (Amended). Online available at: http://www.ognibene.com/en/video/splash-page Accessed on 2 Aug 2018