Dumping Air Bags on the Scale

Discussion in 'Experienced Truckers' Advice' started by albert l, Sep 5, 2017.

  1. albert l

    albert l Road Train Member

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    This was a test to see what happens when air bags are deflated

    In the first image i am scaling the truck normally by setting the tractor brakes (air bags remain inflated) and leaving the trailer released

    Second image is remaining in the same position on the scale with tractor brakes set and setting the trailer brakes which in turn dumps air out of the trailer.
    The end result is by setting my trailer brakes i have severely altered my steer weight.
    You can see in the second image with my trailer deflated it took the weight off my drives and added it to the steers.

    First image is with all inflated
    12040
    30840
    32000
    74880

    Second image is with trailer deflated
    13440
    28820
    32260
    74520

    In my Cascadia when Tractor is set air remains


     
    Last edited: Sep 5, 2017
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  3. snowwy

    snowwy Road Train Member

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    Why did you slide your 5th wheel forward? You're too heavy now on the steers. I would have slid up 1 maybe 2 notches and left it at that forever.
     
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  4. albert l

    albert l Road Train Member

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    I have edited my original post as i did not explain it correctly.
    I did not slide my 5th wheel, the weight went from the drives to the steers when the trailer dumped it air
     
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  5. snowwy

    snowwy Road Train Member

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    Interesting how the weights worked differently and how some of it disappeared.
     
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  6. albert l

    albert l Road Train Member

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    I had been meaning to take these photos for ages
    Leaving the terminal today, i was able to do it and not hold anyone up
    Just wanted to show one instance of the weight variance when dumping your trailer air
    See too many guys pull onto a Cat Scale and dump their trailers
     
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  7. STexan

    STexan Road Train Member

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    That issue is also about the "bind" you created when you set both tractor AND trailer brakes. Holding the tractor in place as your trailer settles down and forward a few inches will mess with tractor weight configuration big time (since the trailer wheels are also locked, something has to give as it falls and settles into place) as your putting "forward forcing torque" on the tractor set

    If you would release the tractor brakes and let it settle into a "non-binding position", you'll get a whole new (more realistic) set of numbers
     
  8. albert l

    albert l Road Train Member

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    In my truck (LT Wt Cascadia) i can set my truck brakes and because it does not dump any air my drive weights stay the same regardless if i have my brakes set or released
    I have seen guys pull onto a Cat Scale in a Cascadia and set both brakes and have the trailer dumping air, hence not getting what i belive to be a correct scale ticket
     
  9. ZVar

    ZVar Road Train Member

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    What this shows me is you should never thrust that scale with a 360lb difference in gross. :)
     
  10. White Dog

    White Dog Road Train Member

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    Apparently @albert l didn't understand a word you said @STexan ....seems to have went right over her head. I on the other hand, completely understand (sense I deal with it daily loading hopper).
     
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  11. albert l

    albert l Road Train Member

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    Thank you
    Now that I am awake and have re-read @STexan post again, I understand what happened with the binding as I have read previously you guys talking about it.
    However when taking the photos for the purpose of showing what happens on a scale, the binding process was not calculating in that little old pea rattling around in my head.
    When I get a chance in the future, I will scale again and post the results.
     
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