Bidirectional clutch mechanism

Thread Starter


Joined Jan 17, 2007
I'm working on a design for a small rotary mechanism that needs to be actuated by a small motor, but must also be actuated manually when there's need. This means that it must be protected somehow, since manual operation could break its inner components if too much force is applied. Actuation of the mechanism is bidirectional, btw.

After some searching, I found this mechanism that looks promising. Basically, it's a clutch that will actuate a shaft (in both directions) when a force is applied to its outer ring, but will slip if the shaft is the one that rotates trying to drag the outer ring along. At least that's the way I understand it.


Here's a short youtube clip showing how it's supposed to work.

An detailed explanation of how it works is included in the video's description.

My main concern is that the outer ring will only actuate the shaft (which is labeled as a fork in the description) with a force equal to that of the springs. And after that it will also slip. But I'm not sure... I'd like to understand it a bit better before I venture into building it.

@shortbus, this is right up your alley. What do you think?
Last edited:


Joined Sep 30, 2009
Hi, not clear what your actually wanting to do. The thing described is something like what is called a sprag clutch or one way bearing. But never saw one that was capable of both directions before. A sprag clutch is used in the freewheel system in a 10 speed type bike or in all automatic transmissions that aren't a constant velocity type.

From the description that goes with the youtube this allows the center shaft to move the outer ring in either direction. But it won't allow the outer ring to move the shaft. I don't think it keeps anything protected from over force being applied.Quote from the youtube description, "The rotation of two directions can be transmitted from the outter disk to the fork. The inverse is impossible. "

If your uncomfortable talking about this (proprietary reasons) in open forum PM me. That would help me to know what you are trying to do.


Joined Sep 17, 2013
I think all you need is a slipping clutch.
Is the manual rotation allowed to rotate the motor shaft as well as rotate the mechanism?