# Converting Rotational Motion to Pendulum-Like Oscillation

• bobthebloh
In summary, the engineer is trying to provide a direction for the user to research some methods to create a mechanism that will rotate an output gear about an anchor point. The user may find it helpful to research a reciprocating motor or a free swinging pendulum that can be driven by a motor.

#### bobthebloh

Hello,

I am trying to create a mechanism that will allow for a motor to power a pendulum-like motion (but not an actual pendulum), back and forth. As shown in the picture, I need 180 degrees of rotation about the swinging part. I have researched escapement, but I need this design not to rely on gravity and to move much faster than I imagine the anchor escapement works. Ideally, such a mechanism would minimize the loss of torque on the output gear, so that I can use this oscillating motion to accomplish other tasks in my application.

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• Untitled drawing (1).png
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There are lots of ways to do this - you know how to turn back-and-forth motion into circular motion ... this is just going the other way.

Simon Bridge said:
There are lots of ways to do this - you know how to turn back-and-forth motion into circular motion ... this is just going the other way.
Could you please provide an example?

I'm not sure if it's clear in my drawing, but the green part is intended to rotate, not slide linearly. I could easily come up with mechanisms that convert linear to rotational or vice versa, but my problem is achieving a back-and-forth rotational motion to power another mechanism.

I would really appreciate an example name or reference site! Thank you!

A reciprocating motor turns back-and-forth motion into rotating motion.

Now: none of us are going to present you with a design - this is what you pay engineers for.
What we can do is attempt to match your existing knowledge with a direction for you to do your own research, maybe some trial and error.

Imagine your green wheel has a peg sticking out of it ... that peg can fit into a groove in a rod. If one end of the rod is fixed to a pivot, then, as the wheel turns, the rod is forces to swing back and forth.

This won't give you the full 180 ... but you can put a section of toothed gear on the swinging end and use that to drive another cog that your pendulum arm is fixed to.

This is not actually a pendulum - it is a motor that waves a rod back and forth.
If you prefer to have a free swinging pendulum that can be driven by a motor, that is a different design.