I am looking for the following mechanism:

A pair of gears initially in side-by-side arrangement.

The shaft of the first gear is fixed to a first plate. The shaft of the second gear is fixed to a second plate.

The first and second plate are connected by a hinge. The plates are initially in a flat side-by-side configuration. The shafts are initially parallel.

The first plate is held stationary. The second plate moves freely on the hinge.

As the first gear is rotated it rotates the second gear. It also pushes on the second gear causing the second plate to pivot on the hinge.

As the first gear rotates through a partial turn (e.g. from 0 to 120°) the second gear also rotates through an equivalent partial turn (e.g. from 0 to -120°). As the gears rotate the second plate pivots a small angle (e.g. from 0 to 40°). Thus the shafts of the gears are parallel in the initial position and tilted relative to each other in the final position.

Is such a mechanism known or possible?

Here a rough illustration of the idea:

[Initial position [Final position

  • $\begingroup$ A drawing or photo would help. $\endgroup$ – Eric S Feb 13 at 21:15
  • $\begingroup$ It sounds like continuous rotation is not required, - or else you'll get in to trouble when the angle of the plate hits the limits of the hinge - therefore, what you are describing is effectively a complex 'rack and pinion' mechanism. If you assume the gear on the moving plate is circular, and track its desired rotation and path through 3D space, then you can plot the location of the teeth that would be required to mesh with it. $\endgroup$ – Jonathan R Swift Feb 13 at 21:50
  • $\begingroup$ The fact that you want the stationary shaft to also be driven, and by an equal angular displacement to the moving shaft complicates things further, however... The more important question is not whether the mechanism you describe is possible, but what you are actually trying to achieve? What are the design constraints? There is very likely a more elegant solution that we cannot suggest without more context. $\endgroup$ – Jonathan R Swift Feb 13 at 21:51
  • $\begingroup$ interesting. As drawn the gears would disengage as the bend angle increases. First thing that comes to mind is to put the contact point in the line of the hinge, or to put a gear with axis on that line, as an intermediate gear, whose distance to the input and output gears remains fixed. maybe possible with beveled gears? $\endgroup$ – Pete W Feb 13 at 23:37
  • $\begingroup$ @PeteW I was thinking the angle of the gear face would vary along its length. $\endgroup$ – Xavier Feb 14 at 0:16

I do not see any problems with your gears.

If you need continuous rotation you need to complete your ellipse shape of the gears, if it will be a partial rotation back and forth it is fine as you designed it.

The gears should always align with an axis from a hypothetical point of the intersection of the two shafts extensions, except at the vertical position they are vertical. This is basically like a double cam mechanism with a tilting axis.


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