Simple mechanism to translate linear to rotational motion?

[Syne]

I am looking for a simple (fewest moving parts) mechanism to translate a linear input force to a 180 degree rotation. Does a scotch yoke like mechanism provide much lever advantage, or is it really only efficient at translating rotational motion to linear?

 

[spidergoat]

http://www.mekanizmalar.com/

 

[Syne]

Nice resource, but doesn't answer my question. I know I can use a scotch yoke like mechanism, but only if the linear input force has enough lever advantage on the rotational motion.

I plan to build a mockup to test...since I'm not finding any answers.

 

[Syne]

Won't work as originally designed. It seems it only has enough lever advantage over about 45 degrees of rotation.

Something like this might have worked:

Except I only have from the rotation pivot up to work with for the linear engagement, instead of being able to engage all sides of the pivot.

I also debated using a rack and pinion, but again, I'm not sure if it offers enough lever advantage.

 

[iceaura]

By adjusting the lengths, you can get almost 180 (in the central rod) out of this: https://en.wikipedia.org/wiki/Peaucellier–Lipkin_linkage

This is in spidergoat's link under "Peaucellier's Cell"

In that Wiki link there is a hyperlink to this, which does give you 180 with what looks like good leverage - but it's 3D: https://en.wikipedia.org/wiki/Sarrus_linkage

Not simple enough, probably, but I've long wanted a reason to post that.

 

[Syne]

Thanks for the links...maybe they will inspire other solutions.

But yeah, too many moving parts in the first, and my pivot needs to keep a constant distance from my linear plane, so the second will not work either.

Well...maybe if I use the pivot on the Sarrus linkage's translating member I can almost get 180 degrees.

Thanks.

 

[Watcher]

I am looking for a simple (fewest moving parts) mechanism to translate a linear input force to a 180 degree rotation. Does a scotch yoke like mechanism provide much lever advantage, or is it really only efficient at translating rotational motion to linear?

Sounds like you have quite a few limits on you design space. I think we'll need your spec or requirements to be able to respond in a useful way.

 

[Syne]

I've already designed a custom scotch yoke that should work. The slot just had to be sort of hockey stick shaped to provide the needed mechanical advantage.