Henri Perregaux movement?

[Yoda]

It has a Maltese cross on the main spring barrel… I’m not sure exactly how it works but it’s suppose to produce a more even main spring tension. That’s very cool to see

The Maltese cross is sadly often missing in many old watches, because people were not aware of the function, it prevents someone from winding the movement too hard and will slip like a clutch if you try.

That's not exactly correct. What the Maltese cross (or stopworks) really does is try to use just the "best" part of the mainspring to run the watch. If you'll notice there are several edges with circular cutouts and one that is flat. The circular ones can get by the guard finger. The flat one cannot. So in practice you would assemble the watch and figure out the midpoint of the mainspring by counting how many turns to fully wound and then letting it back down. Then you would figure out how many turns there are with the Maltese cross installed. Split the difference for the maximum use of the "midpoint" of the mainspring. So once it's all assembled you cannot break the mainspring by winding it too tight since the stopworks prevents you from ever winding that far and the mainspring also never runs completely down because again the stopworks limits it's travel.

It will not slip like a clutch, once wound it will just stop dead and prevent any further winding.

I knew that you would chime in and teach me something new to me, thanks. I was told that it was like what I wrote and I didn't know better.

[Denis]

Great movement:)

[Tanukjaju]

It has a Maltese cross on the main spring barrel… I’m not sure exactly how it works but it’s suppose to produce a more even main spring tension. That’s very cool to see

The Maltese cross is sadly often missing in many old watches, because people were not aware of the function, it prevents someone from winding the movement too hard and will slip like a clutch if you try.

That's not exactly correct. What the Maltese cross (or stopworks) really does is try to use just the "best" part of the mainspring to run the watch. If you'll notice there are several edges with circular cutouts and one that is flat. The circular ones can get by the guard finger. The flat one cannot. So in practice you would assemble the watch and figure out the midpoint of the mainspring by counting how many turns to fully wound and then letting it back down. Then you would figure out how many turns there are with the Maltese cross installed. Split the difference for the maximum use of the "midpoint" of the mainspring. So once it's all assembled you cannot break the mainspring by winding it too tight since the stopworks prevents you from ever winding that far and the mainspring also never runs completely down because again the stopworks limits it's travel.

It will not slip like a clutch, once wound it will just stop dead and prevent any further winding.

So if we use 100% of a spring in a 6497 (for example). The Maltese cross would prevent us from using the top 10 and bottom 10% (for example), excluding the highest tension and lowest tension of the spring?

[sazabi2001]

It has a Maltese cross on the main spring barrel… I’m not sure exactly how it works but it’s suppose to produce a more even main spring tension. That’s very cool to see

The Maltese cross is sadly often missing in many old watches, because people were not aware of the function, it prevents someone from winding the movement too hard and will slip like a clutch if you try.

That's not exactly correct. What the Maltese cross (or stopworks) really does is try to use just the "best" part of the mainspring to run the watch. If you'll notice there are several edges with circular cutouts and one that is flat. The circular ones can get by the guard finger. The flat one cannot. So in practice you would assemble the watch and figure out the midpoint of the mainspring by counting how many turns to fully wound and then letting it back down. Then you would figure out how many turns there are with the Maltese cross installed. Split the difference for the maximum use of the "midpoint" of the mainspring. So once it's all assembled you cannot break the mainspring by winding it too tight since the stopworks prevents you from ever winding that far and the mainspring also never runs completely down because again the stopworks limits it's travel.

It will not slip like a clutch, once wound it will just stop dead and prevent any further winding.

So basically it’s a mechanical counter limiter that only allows the main barrel turn 4 turns in this case. So ifI install the main spring I need to adjust the spring location to ensure the 4-turn rang spread evenly from the middle point.

I think I made the right decision not opening the main barrel. I guess it will need special tool or at least some experience to set it right once disassembled.

Also, is this mechanism always comes with wolf-teeth. I saw a few wolf-teeth movement has this too.


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[unreformed66]

The Maltese cross is sadly often missing in many old watches, because people were not aware of the function, it prevents someone from winding the movement too hard and will slip like a clutch if you try.

That's not exactly correct. What the Maltese cross (or stopworks) really does is try to use just the "best" part of the mainspring to run the watch. If you'll notice there are several edges with circular cutouts and one that is flat. The circular ones can get by the guard finger. The flat one cannot. So in practice you would assemble the watch and figure out the midpoint of the mainspring by counting how many turns to fully wound and then letting it back down. Then you would figure out how many turns there are with the Maltese cross installed. Split the difference for the maximum use of the "midpoint" of the mainspring. So once it's all assembled you cannot break the mainspring by winding it too tight since the stopworks prevents you from ever winding that far and the mainspring also never runs completely down because again the stopworks limits it's travel.

It will not slip like a clutch, once wound it will just stop dead and prevent any further winding.

So if we use 100% of a spring in a 6497 (for example). The Maltese cross would prevent us from using the top 10 and bottom 10% (for example), excluding the highest tension and lowest tension of the spring?

That's the idea. The thought was that by excluding the last few turns of the mainspring where the motive force is the strongest and the bottom few turns of the mainspring where the motive force is weakest one could regulate the watch more closely over a 24 hour run. Also remember that mainsprings weren't as good as they later became as in not as consistent over their length.

[sazabi2001]

Geneva Stopwork