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Thread: The steps for design the bell cranks

  1. #1

    The steps for design the bell cranks

    Hi sir,I am xiao age22, I am now design the spring &damper system for our car. But I dont know how to design the bell cranks. How to design the bell cranks arms the dimensions?Which software and books should I read?Plz help me give me some clue!
    Last edited by xiaolu; 11-26-2014 at 01:07 PM. Reason: suspension

  2. #2
    Quote Originally Posted by xiaolu View Post
    Hi sir,I am xiao age22, I am now design the spring &damper system for our car. But I dont know how to design the bell cranks. How to design the bell cranks arms the dimensions?Which software and books should I read?Plz help me give me some clue!

    What motion ratio do you need? Is it possible to use a direct-acting setup instead?


    What geometry is needed?


    Connect the dots. I would probably design a bell crank as a sketch in CAD, followed by the design of a solid body which resembles the geometry in the sketch.
    Andrew Palardy
    Kettering University - Computer Engineering, FSAE, Clean Snowmobile Challenge
    Williams International - Commercial Turbofan Controls and Accessories

    "Sometimes, the elegant implementation is a function. Not a method. Not a class. Not a framework. Just a function." ~ John Carmack

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  3. #3
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    bell-end

    If you make the bell-cranks out of cast iron and/or make them very big then they will act as an inerta which must be an advantage because F1 use them.

    No wait... I though bellcranks REDUCE the unsprung mass....

  4. #4
    The motion ratio we want is 1:1, I just dont know how to calculate the dimensions of the bell cranks such as the length of the bell cranks arm

  5. #5
    Use angles, with the lines and points. Their lengths will bring truth to your question.
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  6. #6
    Use mechanism analysis to solve for motion ratio. All that is needed is simple position analysis. Draw out the mechanism. Label your vectors. Determine number of knowns and unknowns. Each suspension link will be known in length and unknown in angle. The spring/damper will be unknown in length and angle. The height of the tire print location will be your input. Write vector loop equations (r1+r2+...=0). Write components of vector loop equations (cosines and sines for 2D analysis). You should have X number of unknowns and X number of equations. Program in matlab - using fsolve to solve. Approach the analysis with the intention of making it as general as possible in order to be able to quickly change the geometry of your suspension so you can easily run different geometries in the matlab program until you are satisfied with the resulting motion ratio.
    Fitz Matush
    Auto Seat Tester

  7. #7
    Quote Originally Posted by Simactive View Post
    Use angles, with the lines and points. Their lengths will bring truth to your question.
    Probably the most poetic thing ever to grace the forums.

    Also trig.
    Dalhousie University
    Halifax, NS, Canada
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