Internet Horology Club 185
Interesting plate layout

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https://ihc185.infopop.cc/eve/forums/a/tpc/f/2291010082/m/8701081982

November 08, 2007, 20:41
Stephan Gaal
Interesting plate layout
This watch appears to have an extra shaft. Can anyone comment on this. No I have not played with the picture. aplina
November 08, 2007, 20:43
Stephan Gaal
Here is the movement picture from the posting in case it dissappears.


November 09, 2007, 00:50
Jerry Treiman
This is a Tavannes movement. I think this layout was used to allow a thinner watch. Attached is a picture of one with the barrel bridge removed so you can see the train layout a little better. You will note that the center arbor has a pinion only - no wheel - so the normally large center wheel does not have to lie over or under the balance wheel. The next wheel in the train is the steel wheel which is an idler wheel with no pinion - all it does is reverse the train and get the gear train out from over (or under) the balance wheel. There are then two standard wheels with pinions to gear it down to the wheel that has the seconds hand. The extra gear also reverses the direction again so that the seconds hand turns properly. What is normally the 4th wheel is the 6th in this watch.


November 09, 2007, 00:50
Cort Moore
Stephen,
That is an odd one. I count two extra wheels. The visible third wheel is much smaller than normal and, judging by the jewel spacing, the other wheels are of small diameter too. One of the main concepts of watch design is to reduce and extend the force of the mainspring through reduction gearing so that,at the end of the gear train, there is a little force that will last a long time.There are lots of combinations of gear and pinion ratios that can work but four is the norm before getting to the escapement. Manufacturers like Waterbury and Roskopf designed watches with three gears in order to cut costs. The extra cost is why it is odd to see a watch with six. Alpina is certainly a good company but I can't guess their motive here.

I've never seen a case marked "Niel" (for niello)before either. Interesting.
-Cort
November 09, 2007, 01:01
Cort Moore
Jerry,
I can't see the forest for the trees! I completely missed the second wheel, 'cause it ain't there!
-Cort