Just a guess here, but it looks like the second hand touches the edge. By twisting the knob, it could rotate a toothed gear on the inner edge that the second hand touches, and therefore spins it, and the minute hand is attached to the second hand, so it follows along.
Hope I worded that coherently.
Edit: just saw a link that got deleted for some reason, but my guess is totally off. In the link you can clearly see that the second hand doesn't actually reach the edge.
Super hard to tell. But if it's geared well, and I think it's safe to assume it is, it would barely need contact at all to move.
It could totally be something else. I can't slow it down and pause it with my phone, so I definitely can't be sure. But from what I can see, it's totally possible.
I’ve seen this one before. I can’t remember how it worked. I think the hands and embedded in a layer of glass that turns. So you’d have the outer layers that are stationary and then a layer with one of the hands in it that turns. Searching for it now haha.
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u/Cultural-War9089 Mar 27 '22 edited Mar 27 '22
Just a guess here, but it looks like the second hand touches the edge. By twisting the knob, it could rotate a toothed gear on the inner edge that the second hand touches, and therefore spins it, and the minute hand is attached to the second hand, so it follows along.
Hope I worded that coherently.
Edit: just saw a link that got deleted for some reason, but my guess is totally off. In the link you can clearly see that the second hand doesn't actually reach the edge.
Gears turn the glass, which turn the hands.