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Thread: Comparison of Dual-Tube vs Mono-Tube Frame Deflection

  1. #31
    Senior Member TiLite's Avatar
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    Quote Originally Posted by sowseng View Post
    Comparing the color between frames (as in your screenshot) is not possible because it is relative to each frame individually. Because this is not intuitive, we will be removing the color from the frames in this video. Looking forward to future feedback as always!
    Here is a link to the corrected video: http://www.youtube.com/watch?v=ao6bI21QAAc

    In the end, matching the color representations to the same scale was achieved, and the video now accurately represents both frame deflections visually as well as through color relative to each other. I apologize for any confusion caused by the previous version of the video.
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  2. #32
    Senior Member lazierdog's Avatar
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    Quote Originally Posted by stephen212 View Post
    The graphics of the video are more than a little suspect. The deflection of the Aero Z is .635" but the graphic grossly exaggerates the degree of travel. Consider that the frame tube diameter is 1.25"; the deflection shown is greater than the 1.25".
    It's a scaling technique. FEA software allows the user to scale the results so it can seen better. If the scale was set to "true" (1:1), it maybe be more difficult to see how things are behaving, especially if the values are small relative to the part analyzed. Ultimately, there are too many unknowns in their analyses to come to a conclusion.

  3. #33
    Senior Member lazierdog's Avatar
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    Quote Originally Posted by tooley View Post
    My thinking is they are marketing their new AeroT as more rigid and rigid is better in an effort to make the majority of chair users currently in cantilevered frame chairs to consider replacing them - ie. to sell more chairs.
    Perhaps, but it's useless to make that claim unless you perform an FEA on their competitor's chairs.

  4. #34
    Quote Originally Posted by lazierdog View Post
    It's a scaling technique. FEA software allows the user to scale the results so it can seen better. If the scale was set to "true" (1:1), it maybe be more difficult to see how things are behaving, especially if the values are small relative to the part analyzed. Ultimately, there are too many unknowns in their analyses to come to a conclusion.
    TiLite adjusted the scaling in their revised video.

  5. #35
    Quote Originally Posted by TiLite View Post
    Here is a link to the corrected video: http://www.youtube.com/watch?v=ao6bI21QAAc

    In the end, matching the color representations to the same scale was achieved, and the video now accurately represents both frame deflections visually as well as through color relative to each other. I apologize for any confusion caused by the previous version of the video.

    So 100lbs aplicated to the fork arm and the maximum stress in the frame is in the footrest? i think this video is a joke.

    In the maximum deflection point there is less stress in the bend of the frame than in the straight down tube?, incredible.

    That deflection showed in the video is not reality, in a daily use any frame have stress in the footrest unless you hit something with it, the footrest will deflect with the frame, but dosen`t have any stress like showed in the video with the red colour, unless your test is done with a machine pushing the footplate.

    In a daily use, the deflection is transmitted to the frame through the front casters by the barrel housing and forks arms.

    A cantilever frame will have more deflection and will be more stressed using 3" casters than 5" for example, but nothing to do with the footrest.
    Last edited by totoL1; 04-20-2013 at 02:45 PM.

  6. #36
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    Mano a Mano ... Mono a Dual

    Aside from TiLite’s rather vague test of aluminum under stress – their apparently recent reclassification of wheelchair frames as ‘mono-tube’ and ‘dual tube’ is refreshingly clear compared to the confusing terms we commonly use:

    ‘Cantilever’ frame? A cantilevered structure is comprised of a substantial horizontal member projecting off a roughly-equal-sized vertical supporting member and its direct extensions. The horizontal portion is soley supported by the vertical portion. A giant weight-bearing wheel firmly attached to the unsupported end of a horizontal frame projecting off a vertical support frame kinda kills the cantilever part.

    ‘Box’ frame? Squarely-constructed Hospital and folding chairs, yes. Angular, thin upper frames supported by sweeping understructures, no boxes I’ve ever seen.

    ‘L’ shaped? I’m guilty on this one. A chair is only an L if you sit on its back, on the floor.

    Think I’ll simply call my ZR a mono-tube from now on.

    PS – Now put 4 casters on this baby, you've got a proper cantilevered wheelchair!
    Last edited by nofuss; 04-20-2013 at 07:23 PM.

  7. #37
    Quote Originally Posted by nofuss View Post
    Aside from TiLite’s rather vague test of aluminum under stress – their apparently recent reclassification of wheelchair frames as ‘mono-tube’ and ‘dual tube’ is refreshingly clear compared to the confusing terms we commonly use:

    ‘Cantilever’ frame? A cantilevered structure is comprised of a substantial horizontal member projecting off a roughly-equal-sized vertical supporting member and its direct extensions. The horizontal portion is soley supported by the vertical portion. A giant weight-bearing wheel firmly attached to the unsupported end of a horizontal frame projecting off a vertical support frame kinda kills the cantilever part.

    ‘Box’ frame? Squarely-constructed Hospital and folding chairs, yes. Angular, thin upper frames supported by sweeping understructures, no boxes I’ve ever seen.

    ‘L’ shaped? I’m guilty on this one. A chair is only an L if you sit on its back, on the floor.

    Think I’ll simply call my ZR a mono-tube from now on.

    PS – Now put 4 casters on this baby, you've got a proper cantilevered wheelchair!
    I am not sure about your moniker.
    C5-6 Complete - 8/13/1982

  8. #38
    Senior Member ~Lin's Avatar
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    Quote Originally Posted by Brianm View Post
    I am not sure about your moniker.
    Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

    I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

  9. #39
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    Quote Originally Posted by Brianm View Post
    I am not sure about your moniker.
    Yeah ... probably too fussy a thought.

  10. #40
    Senior Member lazierdog's Avatar
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    Quote Originally Posted by stephen212 View Post
    TiLite adjusted the scaling in their revised video.
    I interpreted your initial post as the value of the deflection not being in scale with the dimensions of the frame itself visually...if that made any sense.

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