What Powers the Steering System in Your Vehicle?

By Karen Johnston June 3, 2014

Quick facts

Power steering is power-assisted, meaning the vehicle can still be steered manually if the system fails.
The rack and pinion system is the most commonly used power steering design in modern passenger vehicles.
Power steering fluid should be flushed approximately every 50,000 miles to prevent component damage.
A low power steering fluid level can damage the pump as it relies on the fluid for both hydraulics and lubrication.

The power steering system in your vehicle enables you to steer your vehicle in the direction you would like it to proceed. Power steering is really "power-assisted" steering. Power-assisted steering will allow you to steer your vehicle manually when the engine is not running or if you have a failure in the power steering system which disables it.

Power steering utilizes a hydraulic pump running off a belt driven by the engine; this pump enables a small amount of fluid to be under pressure. This pressure, in turn, assists the steering mechanism in directing the tires as you turn the steering wheel. The power steering system typically includes a pump, power steering fluid, a pressure hose assembly, a control valve, and a return line.

There are two basic types of power steering systems used on vehicles. The rack and pinion steering system and the conventional/integral steering gear system, which is also known as a recirculating ball steering system. The rack and pinion steering system is the most commonly used power steering system in today's vehicles. The steering shaft turns a gear that moves the rack side to side, utilizing a power unit built directly onto the rack assembly. The steering gear system is generally used most often on trucks. It has a series of steel balls that act as rolling threads between the steering shaft and the rack piston. The steering wheel shaft connects to a gear assembly and a series of links and/or arms that turn the wheels to the left or right.

The best way to maintain the power steering system of your vehicle is to regularly check the power steering fluid level and condition. A low fluid level can cause damage to some of the components of the steering system. It is recommended to have leaks repaired if they arise, and to have the fluid flushed about every 50,000 miles to keep it clean from contaminants. This fluid is key to keeping the power steering pump, steering gear or rack and pinion assembly lubricated and is the hydraulic element of the power steering system.

If your vehicle starts to exhibit some of the following symptoms, we would recommend having your trusted repair facility perform an inspection of your steering and suspension system to identify the problem:

Hard steering
Heavy or unresponsive steering at low speeds or during parking lot maneuvers
Unusual noise when turning the steering wheel
A shimmy or shake in the steering wheel
A steering wheel that will not return to center properly
Fluid leaking from under the vehicle

Regular inspections and maintenance is the key to the longevity of your power steering system.

Frequently asked questions

Common questions

What is electronic power steering and how is it different from hydraulic power steering?

Electronic power steering (EPS) replaces the hydraulic pump with an electric motor that provides assist directly to the steering rack or column. Because there is no belt-driven pump running continuously, EPS improves fuel economy slightly and eliminates the hydraulic fluid maintenance requirement. The assist level can also be adjusted by software depending on vehicle speed and driving mode, giving manufacturers more control over steering feel. Most vehicles produced in the last decade use EPS rather than the traditional hydraulic system.

Why does power steering groan or whine when turning at low speeds?

Groaning during low-speed turns is the most common symptom of a hydraulic power steering system under stress, usually from low fluid level, a failing pump, or air in the system. At low speeds and full steering lock, the pump works hardest to maintain pressure. A pump that is wearing out or undersupplied with fluid cavitates, producing a distinctive whine or moan. Air enters the system through a leak and creates a foamy fluid condition that causes erratic assist and noise. Both situations require prompt attention to prevent pump failure.

Can worn tie rod ends affect steering feel the same way worn rack and pinion components do?

They can produce similar symptoms but in different situations. Tie rod end wear typically causes a loose or vague feeling when making minor steering corrections at highway speed. The vehicle wanders slightly and requires constant small corrections. Worn rack and pinion components tend to cause play in the center of the steering wheel or uneven effort across the range of motion. A technician can differentiate them by feeling for play at each component during a suspension inspection with the wheel lifted off the ground.

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