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Summary
  • Power steering is a driver-assistance feature that helps turn the wheels with minimal effort.
  • There are generally two types of power steering systems一electronic and hydraulic.
  • In an electronic power steering setup, an electric motor controls the steering gear and provides steering assistance. This setup has parts like the steering gear and motor, a control module, and sensors.
  • Meanwhile, a hydraulic power steering system uses an engine-driven pump and hydraulic fluid to turn the wheels. It has a steering gear, power steering pump, reservoir, and hoses.

Back in the day—before the invention of the cell phone, the personal computer, or even the color television—nearly all production cars had manual steering. The setup primarily relied on the driver’s muscles to turn the car’s front wheels back and forth via the steering wheel.

Fortunately, all modern cars have the convenience of power steering. The technology makes the steering system easier to operate, creating a more enjoyable (and far less taxing) driving experience for whoever is behind the wheel.

What is Power Steering?

All modern cars have power steering—a feature that assists the driver in turning the front wheels. The power steering system makes the steering wheel easier to turn by augmenting the force the driver exerts on the vehicle’s mechanical steering gear.

Most vehicles have either electric power steering (EPS) or hydraulic power steering. There are also a few models that use an electro-hydraulic system, which combines elements of both the EPS and hydraulic designs.

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Electronic Power Steering

electronic power steering system
A typical electronic power steering system diagram

EPS, which is found in nearly all new cars, uses an electric motor to act on the steering gear and provide steering assist. A typical EPS system includes the following power steering components:

Steering Gear (Rack and Pinion Assembly)

The steering gear contains a set of gears that transfer input from the steering column shaft (and the steering wheel) to the steering linkage. From there, the steering linkage connects to the steering knuckles, which, in turn, attach to the wheels and tires. All of the components working together cause the wheels to move in or out in response to the driver’s input.

electric steering rack isolated on whited background
The steering gear (Rack and Pinion Assembly) contains a set of gears that transfer input from the steering column shaft (and the steering wheel) to the steering linkage.

Steering Motor

An electric motor (mounted on either the steering column or steering rack) is the focal point of the EPS system. The motor applies the force needed to turn the steering gear and provide the driver with steering assist. Depending on the system design, the motor may operate on 12 volts (like most automotive electrical components) or 48 volts.

Control Module

A computer, which is often referred to as the EPS control module, operates the steering motor based on input from the steering system sensors. To retrieve additional information regarding vehicle operation, the EPS module also communicates with other onboard modules over a data network.

Sensors

The steering wheel sensor, which is usually an angle sensor and a torque sensor integrated into a single assembly, is the primary input to the EPS module. There’s also a sensor that relays the position of the motor back to the EPS module.

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The video below demonstrates electronic power steering system operation:

Hydraulic Power Steering 

hydraulic power steering system
An example of a hydraulic power steering pump diagram.

Many vehicles on the road today still have hydraulic power steering. The design uses an engine-driven pump and hydraulic fluid to provide steering assist. A typical hydraulic system includes the following power steering components:

Steering Gear (Rack and Pinion Assembly or Worm Gear Box)

Hydraulic power steering systems may use either a steering rack and pinion assembly or steering box, depending on the vehicle design. Both types of units contain a set of gears that transfer input from the steering column shaft (and the steering wheel) to the steering linkage.

car steering rack isolated on white background
Hydraulic power steering systems may use either a steering rack and pinion assembly or steering box, depending on the vehicle design.

From there, the steering linkage connects to the steering knuckles, which, in turn, attach to the wheels and tires. All of the components working together cause the wheels to move in or out in response to the driver’s input.

Power Steering Pump

The power steering pump, which is driven off of the engine by a belt, pressurizes the power steering fluid and sends that fluid to the power steering gear. When the pressurized fluid acts on the gear, it makes the steering wheel easier to turn for the driver.

car power steering pump
The power steering pump, which is driven off of the engine by a belt, pressurizes the power steering fluid and sends that fluid to the power steering gear.

Reservoir

Pressurized hydraulic power steering fluid acts as the medium that applies force to the steering gear. A reservoir—mounted either remotely or on top of the power steering pump—stores the fluid.

Power Steering Oil Fluid Reservoir
A reservoir—mounted either remotely or on top of the power steering pump—stores the fluid.

Hoses

A set of hoses (or lines) connect the steering gear to the power steering pump. The hose that carries pressurized fluid from the pump to the gear is called the pressure hose. Meanwhile, the hose that routes fluid from the gear back to the pump is called the return hose.

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The video below demonstrates hydraulic power steering system operation:

Where to Get Quality Replacement Parts for Your Power Steering System

Your vehicle’s power steering system is composed of many different parts, each one of them essential to the system’s ability to control your vehicle when you turn the wheel. Should any of these parts fail, it can cause maneuverability and control issues, which can be dangerous on the road. Thankfully, if you need any replacement parts for your power steering system, you can turn to CarParts.com.

CarParts.com offers a wide range of parts for different systems and vehicles, all of which are available to order from the comforts of your own home. Our easy-to-navigate website is designed to make the experience as easy as possible for online consumers. It takes only a few quick clicks to pick your parts and proceed through the convenient and secure checkout. We’ll deliver your power steering system parts in as few as two working days.

Don’t risk driving with a faulty power steering system. Order the parts you need for repairs, such as a new steering gear and other power steering system components, from CarParts.com today.

About The Author
Written By Automotive Subject Matter Expert at CarParts.com

Mia Bevacqua has over 14 years of experience in the auto industry and holds a bachelor’s degree in Advanced Automotive Systems. Certifications include ASE Master Automobile Technician, Master Medium/Heavy Truck Technician, L1, L2, L3, and L4 Advanced Level Specialist. Mia loves fixer-upper oddballs, like her 1987 Cavalier Z-24 and 1998 Astro Van AWD.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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