What is Power Steering System: Types, Working & More

Power steering is no less than a game-changer in the automotive world. It revolutionised the driving experience. The system is designed to assist you in steering the wheels by using either hydraulic or electric mechanisms. Before the advent of this technology, you had to use greater physical effort to turn the steering wheels. It was challenging, especially when moving slowly or at a stop.

The power steering technology lightens the load on your arms and empowers smoother control. From hydraulic to electric, it comes in various forms, each with its magic. Let's read more about the power steering system in this detailed guide.

What is a Power Steering System?

A power steering system is like a helping hand for drivers. It's a mechanical gadget that makes turning the vehicle's wheels much easier. Imagine turning a large car without it – it would be quite a workout! Inside this steering system, there's a special pump called the power steering pump. This pump takes a special fluid and pushes it into the steering system, making it easier to turn the steering wheel.

There are two types of steering systems: electric and hydraulic. Both do the same job, but in slightly different ways. They provide extra muscle to help you steer, especially when driving at regular speeds or when your vehicle is stopped. Today, most cars you see on the road have power steering systems. They've become a must-have for all kinds of cars.

Now, let's take a trip back in time. As cars got heavier and tires changed, steering became harder. So, engineers added gears between the steering wheel and the turning wheels. These gears made steering easier but meant you had to turn the steering wheel more.

To solve this, power steering came onto the scene in the 1930s. Most power steering systems use hydraulic boosts that work on the steering linkage or the steering gear. Turning the steering wheel activates a valve, which sends pressurised oil (pumped by the engine) to push on a piston. This hydraulic boost helps only when the steering wheel is moving.

How Does Power Steering System Work

Your steering wheel takes the twirls you give it and turns them into short, snappy movements of your car's front wheels. But how does it do that? Well, it's due to the power steering system. Let's see how it works.

Hydraulic Steering System

The hydraulic power steering system (HPS) is all about fluid power. It acts as a superhero version of your car's steering. When you turn your steering wheel, a pump driven by your car's engine kicks into action. It pushes super-pressurized hydraulic oil through a series of tubes. This high-pressure oil heads into a cylinder with a piston inside. 

The oil boosts the piston and glides from one end to another. As the piston does its thing, it multiplies your steering force many times. All this piston oomph gets delivered to gears that help move your car's front wheels. It's a tag team effort to make your steering smooth and easy.

Electric Power Steering System (EPS)

If your car has an electric power steering system, it's a whole new ball game. Instead of hydraulic fluid, we've got an electric motor lending a hand. When you twist your steering wheel, a smart sensor on the steering column senses your moves. It then sends those signals to the car's brain, called the PCM (powertrain control module). The PCM does some quick thinking and sends electricity to an electric motor at the end of your steering column. 

These motor gears are always ready to roll. With the proper voltage signal, the electric motor springs to life. It gets power from your car's battery and flexes its muscles accordingly. Its gears stay connected with the steering system, and it dishes out just the right amount of extra force to steer your front wheels. So, as your pinion gears spin, they make your car's rack move just the right way to navigate those wheels where you want them to go.

Types of Power Steering System

Integral Power Steering

• Integral power steering is designed to provide power assistance when the steering wheel requires between two and five pounds of effort.

• It comprises a steering gear with a worm-and-ball bearing nut and a hydraulic rack piston along the worm shaft. Hydraulic pressure assists in moving the nut in any direction.

• A reaction contact valve connected to the worm shaft thrust bearing controls the oil flow between the valve body and the gear and pinion assembly.

When the vehicle moves straight ahead, oil flows from the pump through open centre valves and back to the reservoir. Oil also circulates the rack piston to cushion road shocks. When the vehicle turns right, the worm's movement causes the control valve to restrict fluid flow to the right turn cylinder, increasing pump pressure on the right side of the rack piston and causing the ball nut to move right. The fluid flow shifts to the left-turn power cylinder for left turns, moving the rack piston and ball nut leftward.

Linkage Power Steering

• Linkage power steering separates the power cylinder from the steering gear and connects it to the steering linkage. The power assistance directly affects the steering linkage.

• In the neutral position (straight-ahead motion), a centring spring holds the spool valve in the control valve assembly at the centre, allowing oil to flow to both sides of the power cylinder.

When the vehicle turns left with significant wheel force, Pitman's arm moves the spool control valve, removing centring spring pressure. It shifts the valve to the right side of the body, directing oil pressure to the right side of the power cylinder and turning the wheels left. When making a right turn, the process reverses, forcing the relay rod to turn the wheels right.

Hydraulic Power Steering

• Hydraulic power steering system, used from the 1950s to 2000s, relies on hydraulic assistance driven by a continuous pump. This system has drawbacks, including energy wastage when the vehicle requires no assistance.

• The hydraulic pump, powered by the engine, pressurises hydraulic fluid. This fluid increases the input force on the steering wheel, reducing the effort needed to turn the front wheels.

When the driver turns the wheel, the hydraulic pump pressurises the fluid, which acts on a piston, transferring the driver's input force to the front wheels through a rack and pinion mechanism.

Electric Power Steering (EPS)

• EPS is a modern power steering system that replaces hydraulic components with electric motors and sensors.

• Instead of hydraulic force, an electric motor powered by the vehicle's battery assists the steering gear. Sensors detect the steering column's position and control the motor's torque.

When the driver turns the wheel, electronic sensors transmit the input to the vehicle's electric control unit. The unit analyses these inputs and sends voltage signals to the electric motor, which engages with the pinion gear and provides the necessary torque to the rack. This rotation of the rack steers the front wheels.

Electro-hydraulic Power Steering

• Electro-hydraulic power steering is a hybrid system that combines hydraulic and electric power steering elements.

• Unlike traditional hydraulic systems, it uses an electric motor to drive the hydraulic pump, reducing energy waste. However, it does not offer all the features of full-electric power steering.

In this system, the hydraulic motor is powered by an electric motor instead of being run by the engine. It is employed in some heavy pickup trucks and a few other vehicles.

Power Steering vs. Manual Steering

Power Steering

• Power steering in cars makes it easier to steer by assisting, so the driver doesn't have to use as much physical strength.

• It makes steering quicker because it reduces the resistance felt in the steering wheel.

• It helps absorb shocks when driving on bumpy roads, making the ride smoother.

• Drivers can easily control the steering wheel with less effort.

Manual Steering

• Manual steering requires the driver to use their strength to steer the vehicle.

• It is slower than power steering because the steering wheel is harder to turn due to increased resistance.

• It is less effective at absorbing shocks on uneven roads, making the ride bumpier.

• Drivers find it more challenging to control the steering wheel because it takes more effort and strength than power steering.

Electric Steering vs Power Steering

Electric steering and power steering are two different technologies used to assist drivers in turning the steering wheel. Here's a simplified comparison of electric steering vs. power steering:

Electric Steering

Technology: Electric steering, often called Electric Power Steering (EPS), uses an electric motor that assists you with driving.

How it Works: When you turn the steering wheel, sensors detect the movement and send signals to the electric motor. The motor then provides the necessary assistance to turn the wheels.

Advantages:

• Energy-efficient because the electric motor only operates when needed.

• Allows for more precise control and adjustments, often used in modern vehicles with advanced driver-assistance systems.

• It can be fine-tuned for different driving conditions.

Disadvantages:

• It relies on electrical components, potentially failing and requiring more complex repairs.

• In the event of an electrical failure, steering assistance may be lost, requiring more effort from the driver.

Power Steering

Technology: Power steering is a broader term that includes various systems, including Hydraulic Power Steering (HPS) and Electro-hydraulic Power Steering (EHPS).

How it Works: In Hydraulic Power Steering, a hydraulic pump driven by the engine pressurizes hydraulic fluid, which assists in turning the wheels. Electro-hydraulic systems combine hydraulic components with electric controls.

Advantages:

• Offers consistent steering assistance regardless of electrical issues.

• Well-established technology with a history of reliability.

• Provides a familiar feel for many drivers.

Disadvantages:

• It is less energy-efficient as the hydraulic pump operates continuously, even when assistance is unnecessary.

• It may not provide the same level of precision and adjustability as electric steering in some modern vehicles.

Conclusion

While power steering started as an optional feature in the mid-1950s for American cars, it eventually became standard or available worldwide. This shift was driven by the rise of front-wheel-drive vehicles, larger car sizes, cost-efficient assembly line production, and wider tires, which increased the effort required for steering. Manoeuvring at low speeds without power assistance became challenging in some countries with heavier vehicles, while lighter vehicles didn't always need power steering.

A study conducted in 1999 on steering force feedback found that regular truck and car drivers naturally expected increased feedback torque as their speed increased. This preference led to early power steering systems without this effect receiving negative feedback from drivers. Today, Power steering systems have become an essential system that helps drivers steer in vehicles by reducing the force needed to turn the steering wheel, ensuring better vehicle comfort and stability.

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Frequently Asked Questions

Below are some of the frequently asked questions on What is Power Steering System | Types, Working & More

What is power steering and its types? 

Power steering is a technology used in vehicles to reduce the effort required for steering. There are various types of power steering systems, including Hydraulic Power Steering (HPS) using hydraulic fluid and a pump, Electric Power Steering (EPS) with an electric motor, Electro-hydraulic Power Steering (EHPS) combining hydraulic and electric components, Integral Power Steering with a hydraulic rack piston, and Linkage Power Steering connecting the power cylinder to the steering linkage.

Where is power steering used? 

Power steering is standard in various vehicles, including passenger cars, trucks, SUVs, and commercial vehicles. It is precious for urban driving, low-speed manoeuvres, and heavy loads or larger vehicles requiring efficient and comfortable steering control.

What are the five functions of a steering system? 

The steering system in a vehicle serves five critical functions: direction control, stability maintenance, manoeuvrability enhancement, feedback provision to the driver regarding road conditions, and ensuring safety by enabling obstacle avoidance and control maintenance in various driving conditions.

How often do we need to check the power steering fluid level?

Experts recommend checking the power steering fluid levels at least once a month or as per the vehicle’s manual. Regular checks help to identify and prevent potential leaks or low fluid levels that can affect the performance of the power steering system.