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Q&A of Prius Brakes

Discussion in 'Gen 2 Prius Main Forum' started by DanMan32, Feb 21, 2005.

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  1. jayman

    jayman Senior Member

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    The steering is absolutely NOT "by wire" no car is. The steering has a direct mechanical linkage from the steering wheel to the rack. The power assist is electric, which some folks have complained about due to the lack of feedback.

    If worse comes to worse, you can steer your Prius although it will take more effort. Just like if the belt breaks for the power steering pump on a conventional car or pickup, the steering is heavy but still works.

    I had new a 1980 Toyota 4x4 pickup with manual steering and didn't see anything wrong with it. And I'm a scrawny guy.
     
    #41 jayman, Mar 22, 2005
  2. Frank Hudon

    Frank Hudon Senior Member

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    the steering has a mechanical link thru the torque sensor bridge/strain gauge. It's a metal rod from wheel to rack and pinion.
     
    #42 Frank Hudon, Mar 22, 2005
  3. hdrygas

    hdrygas New Member

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    Yes there is a mechanical linkage for steering, but the car does have the capability to steer itself. First US and other cars with VSC will "modify" your steering request for direction control by adding or subtracting boost. The car is second guessing you just like the ASB and Traction control do. Also item two the auto park feature of the Japanese Prius that totally steers itself. Autodrive is coming!
     
    #43 hdrygas, Mar 22, 2005
  4. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(hdrygas\";p=\"74865)</div>
    I was under the impression that VSC works by applying an individual front or rear brake (Depending on model of car) to "Correct" the anticipated path. It uses yaw sensors to figure this out.
     
    #44 jayman, Mar 23, 2005
  5. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    That is also true. VSC compares the yaw sensors with the steering angle to determine if the car is going in the direction the driver is intending. It can then counteract any error with brake pressures in addition to increased or reduced steering effort to assist the driver in correction by preventing under or over correction.
     
    #45 HTMLSpinnr, Mar 23, 2005
  6. Ray Moore

    Ray Moore Active Member

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    bump
     
    #46 Ray Moore, May 7, 2005
  7. mr5150

    mr5150 New Member

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    Great info....thanks.
     
    #47 mr5150, May 7, 2005
  8. DanMan32

    DanMan32 Senior Member

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    I've gotten a comment that the JPG diagram of the brake hydraulics is of a poor resolution. The uploaded image is actually quite good, but the image may be shrunk to fit how it is displayed by your browser, esp when viewing inline with the thread. Click on the image, and be sure the browser is showing the image in full size, and not shrunk to fit the screen. I really hate that browser feature.
     
    #48 DanMan32, May 7, 2005
  9. greencanuck

    greencanuck New Member

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    A related question...without getting too technical on me pleeease. Does the braking scheme originally only use regenerative braking , then switch to hydraulic at slow speeds and/or high demand, or are the rear brakes utilized in conjunction with regen mode as well? Just wondering if there are any safety/handling concerns with 'braking' force only being applied to the front wheels.

    Perry
     
    #49 greencanuck, May 8, 2005
  10. hdrygas

    hdrygas New Member

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    At high demand the front and rear friction brakes kick in to slow the car. The sensor not only determines how hard you are pressing on the brake but how fast you did it. I have had to do one panic stop to avoid a SUV (of course) who blew thorough a red light while talking on the phone and eating and I am here to tell you the brakes work very well indeed as does the skid control and the ABS!
     
    #50 hdrygas, May 8, 2005
  11. DanMan32

    DanMan32 Senior Member

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    I don't believe the rear brakes are used during regen braking, unless it needs to be suplemented with hydraulic braking, but I can't say for sure. But to have the rear brakes engaged for low brake demand would be counter productive to the intent of regen, as one can safely brake gently with only front wheels.
     
    #51 DanMan32, May 9, 2005
  12. greencanuck

    greencanuck New Member

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    I was kinda hoping that would be the response. Both to take full advantage of the regen, and to save brakes.

    Perry
     
    #52 greencanuck, May 10, 2005
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