Synthesis of a four bar linkage with a ternary couplar

AI Thread Summary
The discussion focuses on designing a four-bar linkage for a bicycle rear shock, specifically a virtual pivot point mechanism. The goal is to create a coupler curve that traces an S-shaped path while ensuring the instantaneous center of rotation for the rear triangle is positioned correctly above the rear axle during compression and below it during extension. The user considers using the Freudenstein equation for synthesis but acknowledges the complexity of the problem. Additional input is requested regarding dimensions and limits of movement. The conversation emphasizes the need for clarity in the design parameters to facilitate effective assistance.
MechE
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Hi there!
Currently i am trying to design a four bar linkage for a bicycle rear shock.
You can find this linkage at here
http://ffden-2.phys.uaf.edu/211_fall2010.web.dir/Michael_Stanfill/VirtualPivot.html
This linkage is called virtual pivot point.
Critical part of this design is to achieve a coupler curve for rear axle in a way that it traces an S shaped path but also the instantenous centre of rotation for rear triangle(ternary coupler-which is the intersection of lines passing through two small linkages) must be above the rear axle for compression and below the rear axle for extension (this way suspension mechanism corrects itself)
I thought i can use freudenstein equation for synthesis but the problem is more complicated.
Thank you for your help!
(There is another explanation of this virtual pivot point mechanism at here http://www.lapierrebikes.com.au/technologies/fps)
 
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You have not given any dimensions or limits of movement.
What exactly is your question ?
 

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