How can I design a linear to rotational crank mechanism without using gears?

[D9 XTC]

I'm looking for a crank that can give me linear movement to rotation (not the other way around).

There is a component that I'm aware of called a uni-directional drive that turns rotation movement in either direction into movement in only on direction... stick a rack in the mix and there is linear movement to rotational. The only thing is is that I don't want to have to deal with gears.

Anyone have any ideas?

 

[Unrest]

I'm looking for a crank that can give me linear movement to rotation (not the other way around).

There is a component that I'm aware of called a uni-directional drive that turns rotation movement in either direction into movement in only on direction... stick a rack in the mix and there is linear movement to rotational. The only thing is is that I don't want to have to deal with gears.

Anyone have any ideas?

Isn't clear what you want that makes a conventional crank unsuitable. Do you want to prevent the rotating part from driving the linear part? Is the linear movement in one direction or reciprocating? Do you need it to be self-starting in any position? A more linear force-torque relationship?

 

[D9 XTC]

My bad

For my application the linear part will drive rotational part. There's no need to prevent the rotational part from driving the linear part but it would be interesting to see if you have ideas for that. The linear movement has to be reciprocating for the crank to work. Not sure what you mean by self starting in any position and linear forve-torque relationship.

The reason why I think a crank with the usual config won't work is because the speeds I'm running are relatively low. Seems like the crank may not be able to rotate the shaft it's connected to the same direction all of the time.

 

[Unrest]

The reason why I think a crank with the usual config won't work is because the speeds I'm running are relatively low. Seems like the crank may not be able to rotate the shaft it's connected to the same direction all of the time.

Ah, gotcha. That's what I meant by "self starting", which is a term I just made up :P

How about the uni-directional drive, driven by a crank that has such a long stroke that it never completes a full revolution, so it never hits TDC or BDC where it might get stuck.

I suppose you have some arbitrary input force that can't be synchronized with the shaft's angle the way it is in an engine.