Does electric power steering have a steering pump?
Electric power steering (EPS) generally does not use a traditional engine-driven steering pump. Instead, an electric motor provides the assist directly to the steering mechanism. There are exceptions, notably electro-hydraulic power steering (EHPS), which uses an electrically driven hydraulic pump to generate steering pressure. This article explains how EPS works, whether a steering pump is involved, and what that means for maintenance and safety.
What is electric power steering?
Electric power steering uses a sensor to measure driver input and a controller to decide how much assist to apply. An electric motor mounted on the steering rack or column provides the assist torque, reducing engine load and improving efficiency. EPS also enables features like variable assist with vehicle speed and integration with advanced driver-assistance systems.
How EPS works
The system monitors steering wheel angle and torque, vehicle speed, yaw rate, and other data. The EPS controller commands the motor to apply the appropriate assist torque to the steering mechanism. If a fault occurs, the system may reduce or cancel assist, allowing manual steering with extra effort. Battery health and electrical reliability are therefore critical to EPS performance.
Is there a steering pump in EPS?
In the typical EPS arrangement, there is no hydraulic steering pump because the system does not rely on hydraulic pressure. Instead, the electric motor provides all the assist. There is an exception in electro-hydraulic power steering (EHPS), where an electric motor drives a hydraulic pump to pressurize the steering system.
EPS vs Electro-Hydraulic Power Steering
Below are the key contrasts between EPS and EHPS:
- EPS (pure electric): No hydraulic pump; assist torque is generated by an electric motor; typically lighter, more energy-efficient, and easily integrated with electronics.
- EHPS (electric motor-driven hydraulic): An electric motor powers a hydraulic pump to create hydraulic pressure for steering assist; can feel similar to traditional hydraulic PS but with electronic control; adds hydraulic fluid system and maintenance needs.
- Traditional hydraulic PS: Engine-driven pump pressurizes fluid to provide steering assist; heavier and less efficient; gradually being replaced by EPS or EHPS in many vehicles.
In practice, most modern passenger cars use EPS with no pump; EHPS is found in some models that want hydraulic feel with electric control, while traditional hydraulic systems are being phased out in favor of EPS or EHPS variants.
What this means for drivers
For drivers, EPS offers lighter steering at low speeds and stable weight at higher speeds, along with better fuel efficiency due to reduced engine load. If the vehicle's battery or electrical system is weak, EPS performance may degrade or fail gracefully. In EHPS-equipped vehicles, the hydraulic pump requires maintenance like any hydraulic system, including fluid checks and potential leaks.
Summary
Most electric power steering systems do not include a traditional steering pump. They rely on an electric motor for assist. The main exception is electro-hydraulic power steering (EHPS), which uses a motor-driven hydraulic pump to supply pressure. Understanding which system your vehicle uses helps anticipate maintenance needs and driving feel.
