A comparison of hydraulic power steering and electric power steering (EPS): how each works, their strengths and their weak points.
An MSG Equipment article compares the two systems that make steering light. Hydraulic power steering is a closed circuit of a pump, fluid reservoir, power cylinder and high-pressure hoses. Electric power steering (EPS) uses a torque sensor, an electronic unit and an electric motor to provide assistance.
- Hydraulic: proven, robust and suitable for heavy vehicles, but the fluid needs monitoring and the constantly running pump increases fuel consumption
- EPS: compact, active only when the wheel is turned and well integrated with vehicle electronics, but its limited power keeps it out of heavy vehicles
The author recommends changing hydraulic fluid roughly every 50,000 km and diagnosing EPS units periodically. There is no single winner; the choice depends on the vehicle and its use.