July 23rd, 2012, 11:23
Cantilever ( bellcrank )
I have been toying aroung with this idea for a while. After reading the "searched" posts on cantilever and bellcranks, I found it was mostly theory and little useful numbers and angles. I still learned alot reading them, so don't think I'm tring to be a dick.
I attached a hand drawing that is 1/6 scale. So my numbers are not exact but close enough.
The black lines are the shock compressed (full bump) and extended (full droop)
The shock is a fox 2.5"x 14".
At full bump the shock is 90* to the bellcrank (drawn in red)
At full droop the shock rotates or pivots 11* (the bellcrank is blue)
The bellcranks pivot points; the shock side is 16", the axle side is 28", and the 3rd side is aprox. 24.75".
Inside angle of the bellcrank is 62* and it rotates 55* (full bump to full droop)
Total movement at axle end is 26" yeilding an "overall" 2:1 ratio. (I know it changes through the movement)
I was surprised that the shock only pivots 11* total. So a ride height the angle correction factor would only be about 5.5*.
This is the same as an A arm set up with the shock mounted at 84.5* to the lower arm pivots at ride height.
Also if the shock side of the bellcrank equal to the shock stroke the total was only 13* (not shown)
Now the questions. I am having trouble with the axle side and understanding how it REALLY WORKS!
Mainly with the bellcrank to axle "link". At first I reasoned that the force placed on it would be the same throught the travel regardless of the angles it operated at (obviously talking about operation in a narrow range that would not cause failure or binding) but now I am thinking that the force will change slightly because the leverage between the liks mounts will change as the link angle changes thoughout is travel.
Is this correct? Will the angle of the link change the force transfured though it? Or will it be the same?
or is it even worth thinking about or worring about?
Any help in understanding this would be great. Joel.
July 23rd, 2012 11:23
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