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double minute wheel


gary17

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Het

I'm just reassembling a sekonda and i am trying to put the train bridge into place.

When i do this and try the wheels they all turn and so does the escape. But when i start the balance it turns the wheels but then the minute wheel starts sticking or so i thought. A closer watch with a dental mirror shows the bottom wheel turns but not the top. (see pics to see what i mean) I apologise about my discription but only been at this 6 months.

Should i be able to turn  one train wheel anti clock wise and they all turn? and then clock wise and they all turn?

The second pic shows the double wheel.

Or do i have a completely different problem?

cheers

gary

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IMG_20200111_220201.jpg

IMG_20200111_220212.jpg

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Het
I'm just reassembling a sekonda and i am trying to put the train bridge into place.
When i do this and try the wheels they all turn and so does the escape. But when i start the balance it turns the wheels but then the minute wheel starts sticking or so i thought. A closer watch with a dental mirror shows the bottom wheel turns but not the top. (see pics to see what i mean) I apologise about my discription but only been at this 6 months.
Should i be able to turn  one train wheel anti clock wise and they all turn? and then clock wise and they all turn?
The second pic shows the double wheel.
Or do i have a completely different problem?
cheers
gary

Hi Gary,

A shot in the dark as I’m not familiar with Sekonda movements but possibly the friction fitting between the two wheels is loose/damaged. Maybe if you also quote the caliber someone else may have a better idea than me. Good luck with it.

Adam



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That's the 3rd wheel. It drives the 4th pinion, as well as a central pinion for the seconds. One wheel is free on the arbor, the other is tight; the free wheel engages the 4th wheel, the fixed wheel and free wheel engage the sweep seconds pinion. Sounds weird but it's a very elegant solution to keeping the sweep hand from fluttering without adding a friction spring.

 

The function is like this: the fixed 3rd wheel and free 3rd wheel are trying to move the sweep pinion but the free 3rd wheel is stopped by the escapement of the watch. The effect is that the fixed 3rd is pushing the sweep pinion while the free 3rd is resisting, effectively sandwiching a pinion leaf of the sweep wheel. It eats no power from the watch, but the seconds hand is totally stable. Felsa put the first watches out with this system on a commercial level, but the concept has been around for a long time. Not seen that often though.

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Ha crap didn't notice the whole movement photo. No sweep seconds? Probably the Russians copied the felsa design and just used the same wheel for versions with sweep or not. It's definitely a setup for sweep seconds. Or a part was swapped in in the past that works even if it's technically wrong.

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