Power steering is a technology all drivers take for granted. Before the advent of this technology, the only thing helping you turn the steering wheel was your own strength. Power steering is now offered in a few different ways; hydraulic, electrical, and more recently, drive-by-wire. Continue reading to learn more about power steering, its history, reliability and repairs, and how each type impacts the driving dynamics of a car.
What is Power Steering?
On nearly all vehicles, there is a steering column connecting the steering wheel to the wheels themselves using a system called a rack and pinion. Rack and pinion steering transfers the driver input to the wheels. This system worked without any power assistance it did so on production cars until the early 1950s.
While the first commercial use of power steering was in the ‘50s, the technology was first patented 75 years before, in 1876.
Why was power steering invented if unassisted steering worked just fine then? While unassisted steering works, it’s not always easy. When your car is at a stop or moving slowly (think in a parking lot or turning at a stop light), you have to overcome a lot more friction than when they are turning. This can make the steering wheel very hard to turn. Power steering gives you a helping hand, making it easy to turn the wheel no matter what, where, or how fast you are driving.
Types of Power Steering
Power steering is either hydraulic, electronic, or electro-hydraulic. Drive-by-wire is a variation of electrical power steering.
Hydraulic Power Steering
Hydraulic, (which simply means a liquid moving under pressure in a confined space) power steering uses a compressed fluid to assist the driver when they turn the wheel. The fluid is pressurized by the power steering pump, which runs off the engine.
A rotary valve controls the flow of the pressurized power steering fluid to one side of a hydraulic piston, depending on which way the wheel is turned. The hydraulic fluid assists in the turning of the wheels, meaning the input required from the driver is kept to a minimum.
Pros and Cons Of Hydraulic Power Steering
Hydraulic power steering has been around for a long time. It’s a well-understood and engineered concept. If you ask an enthusiast, you may hear them say that hydraulic steering has a better “road feel”, or a more physical feeling connection to the road.
Hydraulic steering is not without flaws though. These systems are more complicated since they require the use of an engine-driven power steering pump. More components increase the likelihood of failures.
The hydraulic fluid pressurized by the pump can also become contaminated. On some vehicles, periodic fluid changes are needed. While the intervals between changes are usually much longer (50,000 miles or more), it’s still a maintenance item that electric power steering systems do not need.
Electric Power Steering
Electric power steering, or EPS, removes the power steering pump, fluid, and lines from the system. Instead, an electrical motor is fit to the steering column and provides the boost needed to make steering easier. This type of steering system communicates with the ECU (engine control unit) using sensors, allowing for the system to adjust the steering based on conditions like vehicle speed.
Pros and Cons of Electric Power Steering
Since electric power steering is not directly dependent on the engine (the motor gets power from the alternator, only when the wheel is turned), it can contribute to better gas mileage. EPS systems are also less complicated than their hydraulic counterparts, are less likely to have problems, and require less, if any maintenance.
When EPS was first introduced, many drivers complained about a lack of steering feel or feedback. Early EPS systems disconnected from the road, often described as “numb”. The feedback from EPS systems has improved significantly since then. Companies like Porsche now include electric power steering in their high-end sports cars like the 911.
Other Types of Power Steering
There are two other types of power steering employed in vehicles today.
Electro-Hydraulic Power Steering
A combination of the two aforementioned technologies, electro-hydraulic power steering uses an electric motor to drive the hydraulic pump. This allows the pressurization of the power steering fluid to not tie directly to the rotational speed of the engine, improving steering feel and fuel economy.
Drive by Wire Power Steering
Drive by wire, or steer by wire, is a relatively new technology that entirely removes the traditional steering rack from the car. Instead, steering input is sent to the wheels electronically. Relative to other power steering systems, steer-by-wire is used in very few vehicles.
Power Steering Service at Alex’s Autohaus
European vehicles often feature the latest and greatest technology, and power steering is no exception. If you are having steering issues with your BMW, Mercedes, Land Rover, Audi, or other European vehicle, give us a call or schedule an appointment online today!
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