The Three Main Types of Power Steering Systems Explained

The three main types of power steering systems are Hydraulic Power Steering (HPS), Electro‑Hydraulic Power Steering (EHPS), and Electric Power Steering (EPS). In brief, HPS uses engine-driven hydraulic pressure, EHPS uses an electric motor to drive a hydraulic pump, and EPS uses an electric motor to assist steering without hydraulics. This article explains how each system works, where you’ll encounter them today, and the practical pros and cons for drivers and technicians.

The Three Categories at a Glance

Automakers and service manuals typically group power steering into three distinct categories. Below is a concise breakdown to frame the rest of the discussion.

• Hydraulic Power Steering (HPS): Traditional, fully hydraulic assist driven by an engine-mounted pump.
• Electro‑Hydraulic Power Steering (EHPS): A hybrid approach using an electric motor to power a hydraulic pump.
• Electric Power Steering (EPS): Fully electric assist with a motor on the steering column, pinion, or rack.

These categories reflect how assist is generated and controlled, which affects efficiency, maintenance, steering “feel,” and compatibility with driver-assistance features.

How Each System Works

Hydraulic Power Steering (HPS)

HPS relies on hydraulic fluid pressurized by a pump driven by the engine (via belt). Turning the steering wheel actuates a control valve that directs high‑pressure fluid to one side of a power piston in the steering gear, reducing the effort needed to turn the wheels.

Key components in a typical HPS system include:

• Engine-driven hydraulic pump and fluid reservoir
• High- and low-pressure hoses/lines
• Rotary control valve (often in the steering rack or gear)
• Steering gear (rack-and-pinion or recirculating ball) with a power piston
• Power steering fluid (and sometimes an in-line cooler)

Because the pump runs whenever the engine does, HPS provides consistent assist but consumes engine power and requires periodic fluid service.

Electro‑Hydraulic Power Steering (EHPS)

EHPS keeps the hydraulic steering gear but replaces the belt-driven pump with an electric motor driving the pump on demand. Sensors and an electronic control unit (ECU) modulate pump speed, improving efficiency over traditional HPS, especially at cruising speeds when little assist is needed.

Typical EHPS building blocks include:

• Electric motor-driven hydraulic pump assembly
• Reservoir, hoses, and hydraulic steering gear (as in HPS)
• ECU and inputs such as vehicle speed and steering torque/angle

EHPS offers a step toward electrification without redesigning the steering gear, making it a common bridge technology in the 2000s and early 2010s.

Electric Power Steering (EPS)

EPS eliminates hydraulics entirely. A brushless electric motor provides assist directly to the steering column, pinion, or rack, guided by an ECU using torque and angle sensors. EPS can vary assist with speed, integrate seamlessly with driver-assistance features, and reduces parasitic losses for better efficiency.

Common EPS actuator layouts include:

• Column-assist (C‑EPS): Motor on the steering column; compact and cost‑effective for smaller cars.
• Pinion-assist (P‑EPS): Motor assists at the pinion; balances packaging and steering feel.
• Rack-assist (R‑EPS): Motor mounted to the rack; preferred for larger vehicles and performance tuning.

Because assist is software-controlled, EPS allows fine-tuning of steering feel, variable ratios (with compatible hardware), and advanced features like lane-centering and automated parking.

Pros and Cons by Type

Each system offers a different balance of efficiency, steering feel, cost, and service complexity. The points below summarize practical trade-offs for owners and technicians.

• Hydraulic (HPS): Advantages — familiar steering feel, robust in heavy-duty use, straightforward diagnostics. Drawbacks — continuous engine load (reduced fuel economy), potential for leaks and hose/pump wear, regular fluid maintenance.
• Electro‑Hydraulic (EHPS): Advantages — efficiency gains vs. HPS, retains hydraulic gear feel, retrofit-friendly for manufacturers. Drawbacks — still has fluid/leak concerns, added electrical components, complexity versus pure EPS.
• Electric (EPS): Advantages — best efficiency (no pump drag), strong integration with ADAS/automation, fewer wear points (no fluid/hoses), tunable feel. Drawbacks — steering feel depends on calibration, potential for sensor/motor/ECU faults, thermal management under sustained heavy loads.

In everyday driving, EPS’s efficiency and software flexibility dominate, while HPS retains niche appeal for certain heavy-duty or legacy applications, and EHPS bridges the middle ground.

Where You’ll Find Them Today

Market adoption has shifted decisively toward EPS in the past decade, driven by fuel-economy standards and the rise of driver-assistance systems.

• EPS: Standard on most new passenger vehicles globally as of 2025; essential for features like lane keeping, lane centering, automated parking, and hands-free highway assist.
• EHPS: Seen on many 2000s–early 2010s European and Japanese models; still appears in some specialized or transitional designs where hydraulic architecture persists.
• HPS: Common on older vehicles, certain heavy-duty trucks, and some motorsport/off-road applications where hydraulic robustness or specific steering feel is prioritized.

The trajectory favors EPS for mainstream cars and light trucks, while HPS and EHPS persist where extreme loading, legacy platforms, or cost considerations apply.

Maintenance and Failure Signs

Hydraulic Power Steering (HPS)

HPS maintenance revolves around fluid integrity and leak prevention; the list below highlights what to watch and what to service.

• Common symptoms: whining pump, heavy steering at idle, fluid on hoses/rack, foamy or dark fluid, burning-fluid smell.
• Service items: periodic fluid inspection/flush (per manufacturer), hose and clamp checks, pump belt condition/tension, rack seal inspection, alignment checks after component replacement.

Address leaks early to prevent pump damage and contamination that can shorten rack-and-pinion life.

Electro‑Hydraulic Power Steering (EHPS)

EHPS adds electrical diagnostics to familiar hydraulic service items; consider both sides when troubleshooting.

• Common symptoms: intermittent heavy steering, warning lights, noisy electric pump, hydraulic leaks similar to HPS.
• Service items: scan for ECU codes, verify power/ground to pump, inspect fluid and hoses, ensure cooling airflow to pump module where applicable.

Because the pump runs on demand, electrical issues can mimic hydraulic failures—pull diagnostic codes first.

Electric Power Steering (EPS)

EPS eliminates fluid but relies on sensors, software, and high-current wiring; the bullets below outline typical issues and care.

• Common symptoms: steering warning light, inconsistent assist, pull or wander with no alignment cause, noise from column/rack motor, loss of lane-centering or park-assist functions.
• Service items: scan for DTCs, check torque/angle sensor calibration, inspect connectors and grounds, perform software updates/TSBs, verify 12V battery/charging system health.

Many EPS complaints trace to low system voltage or outdated calibrations—verify electrical health and software before replacing hardware.

Choosing the Right System

For buyers and builders, the “best” power steering depends on priorities like efficiency, feel, and feature compatibility.

• Daily commuters and ADAS users: EPS for efficiency and seamless integration with driver aids.
• Legacy builds or heavy-duty use with known hydraulic parts availability: HPS for durability and familiar service.
• Transitional platforms or retrofits needing hydraulic gear feel with some efficiency gain: EHPS as a compromise.

Most new-car shoppers will encounter EPS by default, while enthusiasts and specialty users may still prefer hydraulic solutions.

Summary

The three main types of power steering systems are Hydraulic (HPS), Electro‑Hydraulic (EHPS), and Electric (EPS). HPS uses engine-driven hydraulics and excels in robustness but costs efficiency; EHPS adds an electric pump for better economy while keeping hydraulic feel; EPS removes hydraulics entirely, delivering top efficiency and ADAS compatibility. As of 2025, EPS dominates new passenger vehicles, while HPS and EHPS continue to serve heavy-duty, legacy, and niche performance applications.

What is power steering type 3?

The three basic types:
A true hybrid of Type 1 and Type 2, EPHS sends energy to a hydraulic pump from an electric motor instead of an engine-driven belt. Type 3 — Electric Power Steering (EPS) The EPS replaces the hydraulic pump with an electric motor.

What are the three types of steering?

The three most common types of car steering systems are Rack and Pinion, Recirculating Ball, and Power Steering (with its variations like Hydraulic, Electro-Hydraulic, and Electric), which focuses on how assistance is provided to the steering. Rack and pinion is common in cars, recirculating ball in heavy-duty vehicles, and power steering reduces driver effort via hydraulic fluid or electric motors.
 
Rack and Pinion Steering 

• How it works: A steering wheel connects to a pinion gear, which moves a linear “rack” bar to turn the wheels. 
• Best for: Most modern passenger cars and light trucks due to its direct and precise feel. 

Recirculating Ball Steering

• How it works: A worm gear rotates, moving ball bearings within a nut, which turns a sector-shaft to direct the wheels. 
• Best for: Heavier vehicles like trucks and SUVs, providing robust and durable steering. 

Power Steering

• How it works: A system that provides assistance to the steering, reducing the physical effort needed by the driver. 
• Types of Power Steering:
  • Hydraulic Power Steering (HPS): Uses a pump driven by the engine to provide pressurized fluid to help move the steering. 
  • Electric Power Steering (EPS): Uses an electric motor to assist steering, drawing power only when needed, which improves fuel efficiency. 
  • Electro-Hydraulic Power Steering (EHPS): Combines features of both hydraulic and electric systems, using an electric motor to power the hydraulic pump. 

What are the three types of power steering systems?

There are three main types of power steering systems such as hydraulic power steering (HPS), electric power steering (EPS) and hydroelectric power steering (EPHS).

What is the 3 mode steering system?

Due to spur gear arrangement, the rear wheel steers in opposite direction to the front wheel. This results in third mode steering. Three steering modes can be changed as needed which assists in parking at heavy traffic conditions, when negotiating areas where short turning radius is needed and in off road Driving.