Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Safety of electric power steering

  1. Jul 18, 2015 #1
    Does anyone know if there's a backup linkage between the ball nut and the steering pinion so that the nut doesn't lock up the rack if the power goes out?

    Thanks.
     
  2. jcsd
  3. Jul 18, 2015 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Did you have a particular brand in mind?

    According to this article:

    http://www.caranddriver.com/feature...ering-a-comprehensive-comparison-test-feature

    there are still mixed feelings about EPS out there, including one scary comment which suggests that the EPS system locks the steering when the electric motor fails, unlike with a hydraulic system, where the car can still be steered, albeit with more effort applied to the steering wheel.

    IDK if this could be the Takata air bag fiasco or the GM steering/ignition lock fiasco of the future.
     
  4. Jul 19, 2015 #3
    No specific brand. I did see that BMW uses a ball screw, while some other manufacturers use a worm gear on the steering column. The lock-up behavior should be roughly the same for both.

    I hope not, but that's why I posted.
     
  5. Jul 19, 2015 #4

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    My advice is, you want to let someone else be the guinea pig to work out the bugs with any radical, new automotive technology.
     
  6. Jul 19, 2015 #5

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I have a 2003 Saturn Ion with electric power steering. At about 120,000 miles, the power steering went out but it was still drivable. It was just more difficult to turn. However, I'd say it was less difficult than some of the older, hydraulic power steering vehicles I've driven where the power went out. The power steering came back on after I turned the car off and re-started the car and it seemed fine for a while. Every once in a while it would lose power steering so I'd just continue on and it would work again the next time I drove it. At around the same time, GM decided to warrenty the power steering for the life of the car so I had it repaired for free.
     
  7. Jul 19, 2015 #6
    electric_steering_cobalt.gif
    I replaced a defective rack and pinion recently in an electric assisted system mounted to the steering column inside the car, and with the ignition off it had no assist but was not very difficult to turn sitting still on smooth cement or blacktop. The mechanical advantage of the pinion ratio makes the tires easier to turn but then you have to turn the steering wheel further to make the tires turn a given amount compared to many hydraulic units which provide a greater assist to a higher ratio pinion, and are therefore much harder to turn without the assist.
     
  8. Jul 19, 2015 #7
    Good to hear. So then I assume that there must be a safety release or backup linkage somewhere.

    Thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Safety of electric power steering
  1. Steering Mechanism (Replies: 8)

  2. Steering angle (Replies: 6)

Loading...