Mar 222019

Power steering is quite possibly the best thing to happen to vehicles, since the installation of the steering wheel. Why? Because you no longer need guns of steel to drive your car; turning the steering wheel is augmented by a power steering device. So in actual fact, power steering should really be called ‘power assisted steering’.

In an automobile, there are two types of power steering systems:

  1. The rack and pinion steering system.

Image credit: HowStuffWorks

This is the most common type of power steering system in use in modern cars. It is a relatively simple concept: the steering shaft moves the rack from one side to the other.

2. The conventional/integral steering gear system.

Image credit: How Stuff Works

This type of power steering is most commonly found in trucks and has a series of steel balls that act as rollers between the steering shaft and the rack piston.

Advantages of power steering

There are numerous advantages to having power steering, most notably:

  • Ease of operation – the driver need only exert minimal effort to comfortably turn the wheels when driving at speed.
  • The force needed to turn the wheels when the car is stopping or travelling slowly is greatly reduced, when you’re parking, for example.
  • The power steering system itself can be manipulated to provide artificial feedback to the driver, depending on the terrain (because typically the power steering overpowers the road feedback).
  • Increases fuel efficiency.

How electric power steering works

For hydraulically-assisted rack and pinion power steering, the frontrunner to electric power steering, the car’s own engine powered the hydraulic pump that gave the requisite pressure to aid steering.

In electric power steering there is no need for an hydraulic pump. Instead an electric motor connected to the steering shaft provides all the power assist.

Difference between electric and hydraulic power steering

  • Where hydraulic power steering relies on pressurised fluid in the steering gear cavity to provide assistance to the steering, electric power steering uses an electronic control unit attached to the steering rack.
  • Electric power steering provides a better fuel efficiency as their minimal set up significantly reduces their weight. Plus, it only utilises energy when it’s in use.
  • Electric power steering doesn’t draw its power from the engine unlike hydraulic power steering.
  • Electric power steering requires less maintenance as it doesn’t need fluid to operate.
  • Hydraulic power steering provides a better road feel than standard electric power steering, however electric power steering can be modified to give the driver artificial feedback.
  • With electric power steering, if the engine stalls you will still have power assist, unlike with the hydraulic power steering.

Cars with electric power steering

The first production car to have electric power steering was the 1988 Suzuki Cervo, however at present unless your car is a rally car or built pre-1988, you will more than likely have an electric power steering system.

Put aside for a moment the fact that cars with electric power steering are lighter and therefore more fuel efficient to drive than hydraulic power steered ones. One of the other key reasons for modern car builders to prefer using electric power steering over hydraulic power steering (which some petrolheads prefer), is that electric power steering is necessary for cars of the future and high end cars to operate.

Why? Because technology is advancing so quickly, that new cars can now have radar guided parking and semi-autonomous driving modes, and for that, the car’s computer has to be able to operate all aspects of the car, and that includes the steering.

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