Steering Systems Explained: Hydraulic vs Electric Power Steering (EPS)
Modern vehicles are designed not just for speed and safety, but also for comfort and ease of control. One of the most essential features that makes driving smoother is the steering system. Over time, steering systems have evolved from fully mechanical setups to more advanced power-assisted systems like Hydraulic Steering and Electric Power Steering (EPS).
In this article, we’ll explore both these systems, how they work, their components, and the advantages they offer.
What is Hydraulic Steering?
Hydraulic steering, also known as Hydraulic Power Steering (HPS), is an upgraded version of the traditional mechanical system. It uses hydraulic fluid pressure to assist the steering operation, making it easier for the driver to turn the wheels—especially at low speeds or when the vehicle is stationary.
How Hydraulic Steering Works
Here’s a step-by-step breakdown of how hydraulic steering operates:
Turning the Steering Wheel
The driver turns the steering wheel. A control valve detects the direction of this turn and sends hydraulic fluid to one side of the steering cylinder.
Pump Pressurizes the Fluid
A hydraulic pump, driven by the engine, pressurizes the fluid and sends it to the cylinder.
Cylinder Assists the Movement
The pressurized fluid pushes a piston in the hydraulic cylinder, which moves the steering rack. This reduces the driver’s effort significantly.
Return Flow
The fluid from the opposite side of the cylinder flows back into the reservoir.
Key Components of Hydraulic Steering
Hydraulic Pump: Generates pressure using engine power.
Hydraulic Fluid: Transmits pressure and lubricates components.
Control Valve: Directs fluid flow based on steering input.
Hydraulic Cylinder: Converts fluid pressure into mechanical motion.
Reservoir: Stores hydraulic fluid for continuous operation.
Real-Life Experience
If you try turning the steering wheel when the engine is off, it becomes very hard to move. That’s because the hydraulic pump isn’t working, and the system loses its assistance. In a running vehicle, 90% of the steering force is provided by hydraulic power—only 10% comes from the driver.
Why Hydraulic Power Is Effective
Hydraulic systems are powerful and efficient. They are commonly used in heavy machines like JCBs, cranes, tractors, and more. Even a small hydraulic pump can produce massive force, making steering much easier under load.
What is Electric Power Steering (EPS)?
As vehicle technology evolved, manufacturers started replacing hydraulic systems with Electric Power Steering (EPS). EPS uses an electric motor instead of hydraulic fluid to assist steering. It is now common in most modern cars due to its simplicity, precision, and energy efficiency.
How Electric Power Steering Works
Steering Input
When the driver turns the steering wheel, sensors detect the direction and torque (force) applied.
Electronic Control Unit (ECU)
The ECU processes sensor data and decides how much assistance is needed and in which direction.
Electric Motor Activation
Based on ECU commands, the motor provides the needed torque to assist in turning the wheels. The motor can be mounted on the steering column, rack, or pinion.
Reduction Gear
A gear system ensures the motor’s speed is reduced and torque is increased for smoother control.
Components of EPS
Steering Angle Sensor: Detects direction and rotation.
Torque Sensor: Measures force applied by driver.
ECU (Control Unit): Processes input and controls motor.
Electric Motor: Provides steering assistance.
Reduction Gear: Increases torque and reduces speed.
Battery System: Powers the entire EPS unit.
Advantages of EPS over Hydraulic Steering
Feature Hydraulic Steering Electric Power Steering
Power Source Engine-driven pump Electric motor
Fuel Efficiency Lower Higher (power used only when needed)
Maintenance Requires fluid and pump care Low maintenance
Integration Limited Easily integrates with ADAS features
Steering Feel Smooth but less precise Highly responsive and adjustable
Conclusion
Both hydraulic and electric steering systems serve the same purpose—to make driving easier—but they do it in different ways.
Hydraulic steering uses fluid pressure and is widely used in heavy-duty and older vehicles.
Electric Power Steering (EPS) uses electronic sensors and a motor, making it ideal for modern cars that demand precision, efficiency, and advanced features.
As technology advances, EPS has become the preferred choice due to its fuel efficiency, low maintenance, and compatibility with smart driving systems. However, hydraulic systems still hold their ground in heavy vehicles where raw power is needed.