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Thread: Axle & suspension design help

  1. #1
    dergerch
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    Post Axle & suspension design help

    Hi there,

    can somone of the 'vehicle builders' teach me how to do a "simple yet sturdy" axle & suspension design? I tried to tear existing vehicles apart in order to understand how it's done, but without luck… So I tried it on my own (also without luck). My basic problem is, that I can't stop the 'axle' beams from rotating, so my steering doesn't really want to stay in its designated plane (ie, my steering doesn't necessarily work left-right but more up-down, because the 'axle construction' rotates (with suspension at least - no problems with a rigid frame-axle connection). I used the attached image (posted somwhere else in this forum) as a base for my axle design… I think my problem is, that I can't get the axle 'fixed in place' and at the same time allow the 'sideways shearing' for steering movement…

    Don't misunderstand that: I don't want someone to actually build me a working chassis, but more of an explanation (maybe as an addition to the attached pic or a 'new' drawing…)

    PS: sorry, if that all sounds a bit complicated, but I really don't know how to explain it in an easier-to-read fashion :

    Regards, Gerch
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  2. #2
    Bonehead
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    Post Re: Axle & suspension design help

    Well uhrm. Axle1 showing the axle itself, the thinner beams being reinforcements, then axle2 showing the attachment I usually make to the orange chassi nodes, it's not the most effective for steering axle but can take a real beating.

    Axle3 is same as axle2 but from another angle. Axle4.jpg showing the full thing in higher res..

  3. #3
    dergerch
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    Post Re: Axle & suspension design help

    Wow… that's exactly what I needed. Thanks a lot, Bonehead!
    Well, lets see, if I can actually weld together something driveable w/o going completely nuts (again…).

    Btw: how did you create those pics? It seems, like they're rendered?

    Regards, Gerch

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    Aperion
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    Post Re: Axle & suspension design help

    Bonehead, do those axles articulate very well? I don't mean to be critical but from looking at those pictures it looks to be cross braced a little too much. Such that movement is restricted to only up and down motion and not allow one side to go up and the other side to move down without taxing some of the beams.

    yeah and what do you use to do those models?

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    dergerch
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    Post Re: Axle & suspension design help

    Another question: what's the white beams in your pics? Are the 'normal' beams or are they shocks yet? (sorry for asking but it seems I have a major problem understanding 'basic engineering'…)

    Regards, Gerch

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    Bonehead
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    Post Re: Axle & suspension design help

    Quote Originally Posted by Aperion
    Bonehead, do those axles articulate very well? I don't mean to be critical but from looking at those pictures it looks to be cross braced a little too much. Such that movement is restricted to only up and down motion and not allow one side to go up and the other side to move down without taxing some of the beams.

    yeah and what do you use to do those models?
    I use these axles for the trail masher, and I'd say that one articulates pretty durn good I used 3dsmax9 for making those.
    You could also place the chassi attachment nodes closer to eachother(sideway wise..) and/or remove the lower crossbrace to get more flex.

    Quote Originally Posted by dergerch
    Another question: what's the white beams in your pics? Are the 'normal' beams or are they shocks yet? (sorry for asking but it seems I have a major problem understanding 'basic engineering'…)

    Regards, Gerch
    The light grey beams are just reinforcement beams.

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    Aperion
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    Post Re: Axle & suspension design help

    oh, it should be pointed out that the above design is only needed for axles that steer. if the axles isn't steerable you only need 4 nodes on the axle and 2 on the body, then define the axle rigidity in the wheels section.

    Quote Originally Posted by Bonehead
    I use these axles for the trail masher, and I'd say that one articulates pretty durn good I used 3dsmax9 for making those.
    yeah it articulated but how easily and smoothly? and how far? do any of the suspension beams turn red when articulating?

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    Bonehead
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    Post Re: Axle & suspension design help

    Quote Originally Posted by Aperion
    oh, it should be pointed out that the above design is only needed for axles that steer. if the axles isn't steerable you only need 4 nodes on the axle and 2 on the body, then define the axle rigidity in the wheels section.
    yeah it articulated but how easily and smoothly? and how far? do any of the suspension beams turn red when articulating?
    Smothly, yes
    Easily, yes
    And probably 1 meter travel per wheel up and down.
    And only thing that turns red is the crossbeam suspension behind the axle, but that's due to the settings(You might notice they keep flashing green/red).

    The thing that is a major thing about how much it'll articulate is how wide the chassi attachment points are, if they're equal width as the axle then it's not going to articulate so much, but if the chassi attachment is less wide than the axle then it's going to articulate more, but this is of course not the ultimate articulation axle, just a simple and sturdy one.

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    dergerch
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    Post Re: Axle & suspension design help

    I don't want to start a new thread on this, so I post it here (it's related to the same vehicle, so it's at least not completely OT…)

    Can someone tell me, what's happening here? The truck just lays on its side, no further action (KB input, …) involved.
    BTW: that's my first attempt at building a truck for RoR, I just wanted to learn it myself rather than starting a vehicle request ;D

    haha, there we are, back on topic: You can see a bit of my actual suspension layout; I set it up with some kind of 'arm' (reminds me I should put it into the wheels section :-[) holding the axle in place from the front-side, and the actual 'spring' holding the axle (at a steeper angle) from the back. Is that a setup, you could recommend, or would it be adviseable to replace the arm with 'springs', too?

    Regards and thanks again for the help!

    [Edit: added caption to screenshot]
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  10. #10
    Bonehead
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    Post Re: Axle & suspension design help

    Mind uploading the .truck file? It'd be easier to find the problem, if I understood it right it won't steer ? >_>

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    dergerch
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    Post Re: Axle & suspension design help

    little misunderstanding there: it does steer (quite good, thats why it lays on its side *g*). No, I wanted to know,

    1) whats happening with the beam in the middle of the pic? (it grows thicker and longer - kinda 'flickers'…). I'm quite sure, that's a rendering / graphics issue only
    2) is my suspension built the way you meant it to be? (OK, it needs a lot of tuning, since the vehicle is quite light and the springs way too strong atm…

    I'll attach the .truck file anyways, even if i wouldn't even call it WIP yet… it's really more of a MIA-project
    Attached Files Attached Files

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    Aperion
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    Post Re: Axle & suspension design help

    [quote=dergerch]
    little misunderstanding there: it does steer (quite good, thats why it lays on its side *g*). No, I wanted to know,

    1) whats happening with the beam in the middle of the pic? (it grows thicker and longer - kinda 'flickers'…). I'm quite sure, that's a rendering / graphics issue only
    2) is my suspension built the way you meant it to be? (OK, it needs a lot of tuning, since the vehicle is quite light and the springs way too strong atm…

    I'll attach the .truck file anyways, even if i wouldn't even call it WIP yet… it's really more of a MIA-project

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    Bonehead
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    Post Re: Axle & suspension design help

    I've had that flickering before, never really found out why it occurs.

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    dergerch
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    Post Re: Axle & suspension design help

    @ Aperion: My suspension isn't triangulated at all; I've used the arm öike in Bonehead's pics (the one with the orange nodes which attach to the chassis) and a spring (well two, avctually, maybe I should kick one of them out) which attach directly to the chassis on one end, and to the nodes 'over' and 'under' the actual 'axle' (the turning point of the wheel).
    I think they're just way to strong for the relatively light vehicle (maybe I should check what these things weigh in RL… I have no idea) - so atm it's like stuffing a truck's suspension system into a family car *g*
    As I said, it's my first truck, and therefore things are a bit 'unbalanced' atm.

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    Aperion
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    Post Re: Axle & suspension design help

    Quote Originally Posted by dergerch
    @ Aperion: My suspension isn't triangulated at all; I've used the arm öike in Bonehead's pics (the one with the orange nodes which attach to the chassis) and a spring (well two, avctually, maybe I should kick one of them out) which attach directly to the chassis on one end, and to the nodes 'over' and 'under' the actual 'axle' (the turning point of the wheel).
    I think they're just way to strong for the relatively light vehicle (maybe I should check what these things weigh in RL… I have no idea) - so atm it's like stuffing a truck's suspension system into a family car *g*
    As I said, it's my first truck, and therefore things are a bit 'unbalanced' atm.
    I doubt you'd need two shocks per wheel, I know the Baja Renault only has one per wheel and it is enough and you can jump abuse it quite a bit.

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    dergerch
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    Post Re: Axle & suspension design help

    soooo… a little update here:
    Aperion, I followed your advice and removed one of the springs (and 'centered' the remaining one on the axle); also, I made the err… 'hub-mesh' (ie. the part that 'defines' the wheel and allows steering actuators to be connected (what's the name of that stuff anyway?) bigger, which results in better stability on the road as the wheels don't fold over so often.
    And then, for some eye-candy, I positioned that §$%&/ dashboard (who'd have thought positioning a dashboard can take about half a lifetime :P) - besides, from the outside it still looks a bit like a golf-kart…
    so there's the updated .truck file, if anyone's interested…
    Attached Files Attached Files

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    Steve Ror Fan
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    Post Re: Axle & suspension design help

    Quote Originally Posted by dergerch
    I positioned that §$%&/ dashboard (who'd have thought positioning a dashboard can take about half a lifetime :P)
    You won't like me then cause the last prop I added (drivers seat) was sited perfectly first time. ;D
    "I see your point, and you are 100% right" - khadner http://theoatmeal.com/comics/religion

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    dergerch
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    Post Re: Axle & suspension design help

    Quote Originally Posted by Steve Ror Fan
    You won't like me then cause the last prop I added (drivers seat) was sited perfectly first time. ;D
    hmm… with me, we're talking "First. Prop. Ever." Don't tell me, your first prop was also positioned perfectly on your first try… please?!

  19. #19
    Steve Ror Fan
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    Post Re: Axle & suspension design help

    Quote Originally Posted by dergerch
    hmm… with me, we're talking "First. Prop. Ever." Don't tell me, your first prop was also positioned perfectly on your first try… please?!
    No, it wasn't my first prop ever, and I kinda cheated cause it's location was 0,0,0.
    "I see your point, and you are 100% right" - khadner http://theoatmeal.com/comics/religion

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    dergerch
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    Post Re: Axle & suspension design help

    Quote Originally Posted by Steve Ror Fan
    But I had taken the trouble to place the camera right, which controls relative direction.
    Just a moment. Does that men if I decide to change the camera, my props 'follow' that change? If so…well there's always zhe other half of the lifetime… :P

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