What is power steering? All of us enjoy a smooth ride. The ease of the steering wheel, the rhythmic hum of the motor. If you’ve ever experienced driving without power steering, you know how crucial it is to an enjoyable trip.
The first power steering system was introduced in 1900 by Robert. E Twyford from Pittsburgh, however, it wasn’t until Cadillac released the Chrysler Imperial in 1951 that power steering became an American standard.
What is Power Steering?
Power steering is a mechanical device installed on a vehicle that reduces the effort needed to turn the steering wheel, making it easier for the vehicle to turn or maneuver at low speeds. There are three main types of power steering systems such as hydraulic power steering (HPS), electric power steering (EPS) and hydroelectric power steering (EPHS).
The most common power steering systems used today are HPS and EPS.
Power steering systems assist drivers by reducing the physical exertion needed to turn the steering wheel. Initial development happened in the early 1900s, and the technology for power steering entered the mainstream in the 1950s. Power steering is a convenience feature at its core, even though it’s standard on every mass-production model today because of customer demand.
The first power-steering system fitted to a production car debuted in the 1951 Chrysler Imperial, and the competition quickly followed suit.
Not only did power steering do the obvious—allow the driver to steer a heavy vehicle with much less effort and greater comfort—but it also allowed engineers to improve steering response, which is how quickly the car changes direction when the driver turns the wheel.
Before power assist became available, cars’ steering systems had been geared so that it took many turns of the wheel to negotiate tight turns or to park. This slow gearing gave drivers more leverage against the high effort required steer the front wheels.
But the advent of power steering allowed engineers to quicken the steering ratio—how much the steering wheel has to be turned relative to how much the angle of the front wheels changes—because the additional steering effort could now be offset by the new system. In fact, it was more than just offset; steering a car became nearly effortless.
However, some of the best-steering vehicles—purebred, lightweight sports cars—have had no power-steering assist, such as the Acura NSX from the early 1990s, the Lotus Elise and Exige, and the Alfa Romeo 4C, which is the last remaining new car that forgoes power steering.
But these cars got away without it due to their light weight and relatively narrow tires. And, still, it could be quite a chore to turn the wheel in these cars while stopped.
How Power Steering Works?
Now that we’ve covered the different types, let’s discuss how the two most common systems work.
Hydraulic Power Steering System
Using hydraulic pressure supplied by an engine-driven pump, or power steering pump, this pressure assists the motion of turning the steering wheel. The power steering pump is turned by a serpentine belt, or accessory drive, providing pressurized power steering fluid to the power steering hose and ultimately delivering it to the power steering control valve at the steering gear.
Power steering fluid is kept in a fluid reservoir that’s maintained by the low side power steering hose that returns fluid at low pressure.
HPS does have its drawbacks. Because the power-steering pump equipped on most vehicles runs constantly and pumps fluid all the time, it wastes horsepower. This wasted power translates into wasted fuel and higher emissions. Hydraulic power steering systems are also prone to leaks and noises and commonly result in failure due to a broken serpentine belt.
Electric Power Steering System
In this system, an electric motor replaces the components that make up an HPS. The motor, which is separate from the vehicle engine, is installed on the steering rack or steering column. An electric power steering system is often the preferred system because of its efficient fuel economy and lower emissions.
Additionally, EPS is customizable by vehicle type, road speed, and even driver preference and it eliminates environmental hazards of leakage and disposal of hydraulic power steering fluid.
Finally, if the engine fails or stalls, electrical assistance continues to function.
Electric Power Steering
Electric power steering (EPS) has become the norm for new vehicles. Instead of using a hydraulic pump to send fluid to the steering gear, the gear connects to an electric motor and a control module.
The control module collects data from sensors. It determines how much assistive torque the motor will apply by calculating vehicle speed, turning speed, and the steering wheel’s position. The amount of current used by the motor on the steering gear or steering column affects the assistance from the power steering system.
The benefits of providing assist electrically are multifold: it improves fuel economy by a few percent, as the electric motor only draws power when needed; it eliminates the hydraulic fluid maintenance mentioned above; and it also enables a variety of features.
Any driver-assist or convenience feature that involves turning the wheels without steering input from the driver is enabled by electric power steering. Features such as lane-keep assist, automated parking and lane changes, and the ability to guide the car around obstacles all utilize EPS’s ability to steer itself when necessary.
Electric power steering is also more tolerant of out-of-spec alignment settings, using software to recognize and compensate the steering pulling to one side. It can also automatically adjust to a crosswind or a crowned road surface that would otherwise require constant steering correction from the driver.
What’s more, tomorrow’s autonomous, self-driving cars will rely on electric power steering, because it allows the car to be steered by an onboard computer system when on automatic pilot. Several systems, such as Cadillac’s Super Cruise, are already capable of steering themselves down the highway under certain conditions.
Electric Power Steering vs. Hydraulic Power Steering
Modern vehicles offer one of two distinct systems: electric power steering or hydraulic power steering. Both work to provide easier, more responsive steering control. However, the way they work is completely different.
Electric power steering relies on an electric motor to assist drivers in turning the steering wheel. This system is highly efficient, only consuming power whenever assistance is needed. It provides improved fuel economy since the electric motor draws power from the vehicle’s electrical system, helping to reduce the engine load.
Electric power steering systems are generally lighter and more compact, making the overall vehicle weight lighter. The system also offers greater flexibility and adjustability, easily integrating with other vehicle systems and features, including advanced driver-assistance systems.
Electric systems also allow for various steering modes to create a customizable steerig feel and responsiveness based on preferences or driving conditions.
Hydraulic power steering uses hydraulic pressure that is generated by a pump to assist steering. These are usually more robust and capable of handling heavier loads than electric systems, which is why it’s more commonly used in larger vehicles, trucks, and SUVs, to offer more stability and control.
Hydraulic systems maintain steering assistance even if the engine is off so the vehicle can still be maneuvered in an emergency. While these do offer some advantages, they are less efficient than electric systems because of the continuous power consumption required to operate they hydraulic pump.
They, unfortunately, are prone to leaks and require periodic maintenance to check and refill the fluid. Hydraulic components are also more complex, meaning higher manufacturing costs and potentially higher repairs costs required if they fail.
Which power steering system is better will ultimately depend on your vehicle’s size, intended use, fuel efficiency needs, and desired driving experience. However, most standard vehicles will include electric power steering unless you are purchasing a heavy-duty vehicle with high towing or load capacity.
Between the hydraulic and electric types of power steering, there’s a hybrid of the two systems called electrohydraulic. It functions like a hydraulic-assist system, only that the hydraulic pressure is created by an electric motor, rather than driving the pump off the engine.
This gets rid of the wasted-energy complaint noted earlier but doesn’t enable all of the features possible with electric power steering. Only a few vehicles, including some heavy-duty pickup trucks, currently use this system.
Power Steering Fluid
Power steering fluid is the hydraulic fluid that transmits the power in a power steering system. The pressurized fluid decreases the effort required to turn the steering wheel. It also keeps the moving parts in the system lubricated and ensures the hoses, pistons, valves, and power steering pump work as intended.
Types of Power Steering Fluids
Depending what type of power steering system your vehicle has will determine the type of power steering fluid it requires. There are three main types of power steering fluids available:
- Automatic Transmission Fluid (ATF)
- Synthetic-Based Hydraulic Fluid
- Universal Powering Steering Fluid
Each of these fluids has different specification standards and is designed to work with specific systems. It’s important to understand that using the incorrect power steering fluid for your vehicle’s power steering system can cause damage to your steering system.
How to Check Power Steering Fluid
If you hear a whining sound coming from under your hood when you make a turn, or it’s becoming harder to turn the steering wheel, your car might be running low on power steering fluid.
Check your car’s power steering fluid in a few simple steps. First, warm the engine to a normal operating temperature. Get the fluid up to temperature by turning the steering wheel in one direction until it stops. Then crank it all the way in the opposite direction. Repeat this back-and-forth process several times. Follow the below steps next.
- Turn off the engine.
- Locate the power steering fluid reservoir (typically yellow or white with a black cap) under the hood. Wipe it and the cap clean with a cloth.
- Check the fluid level by viewing the dipstick attached to the cap. Remove, wipe clean, and reinsert the dipstick.
- Remove the dipstick again and observe where the level reaches. If it is below the MIN line, add new fluid not exceeding the MAX line.
- Examine the quality of the fluid. Suitable fluid will have a clear appearance and not show any debris. Contaminated fluid will appear dark, cloudy, or foamy.
When to Change Power Steering Fluid
In general, power steering fluid needs changing every five years or 50,000 miles. Always follow the guidelines in the owner’s manual, which may indicate a different schedule. Changing the fluid or flushing the steering system can help prolong the life of other steering components that cost much more to replace.
In addition to scheduled maintenance, replace the power steering fluid if it appears dark or if any dirt, debris, sludge, or other contaminants are visible. Uncontaminated fluid will have some color and appear clean.
Power Steering Fluid Color
Good power steering fluid is relatively clear and has a red, pink, or amber color. Power steering fluid that is dark brown, black, or foamy is contaminated. Replace the fluid or flush the steering system as needed. According to Kelley Blue Book data, a power steering fluid flush typically costs less than $200 at a dealership.
Power Steering Fluid Standards
Power steering fluid meets requirements for viscosity, detergents, additives, and other components. Meeting these standards ensures the power steering fluid is safe to use in specific vehicles. Because requirements vary among car makes and models, always use the fluid recommended in your owner’s manual.
How Often Does Power Steering Need Maintenance?
Your vehicle’s power steering system, although imperative to its performance, is a delicate system that requires a professional’s service to maintain correctly. You should perform a fluid check regularly to ensure it’s properly filled and your filter should be changed annually. When necessary, your steering system fluid will need to be flushed and replaced.
If your power steering system is in need of service, there are some symptoms to look out for. These include:
- Whining noises when turning the wheel
- Difficulty or resistance turning the steering wheel
- Leaking red liquid underneath the car
What happens if you run out of power steering?
When driving without power steering fluid is prolonged, damage to the steering pump is inevitable. As a result, the pump vanes that produce heat is left with no lubrication, fuses down, and increases the risk of damaging the drive belt. With no power steering fluid, the shaft and rack seal will also break down.
What is the difference between power steering and normal steering?
Power steering in cars offers assistance to decrease the manual strength necessary for steering. A manual steering system requires the driver to provide the entire force alone for steering. Power steering doesn’t allow the wheel resistance to reach the steering wheel, making steering quicker.
How often do you need to change power steering fluid?
On average, vehicles need a power steering fluid flush every 40,000-80,000 miles. In some cases, manufacturer recommendations can go even higher or lower than this range. Your recommended flush routine depends heavily on your type of vehicle—as the steering system and fluid needs can vary.
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