Breguet No. 28: Equal Segment Self-Winding Stop-Work
The following animations repeat indefinitely, but they cannot be reset. I suggest you use Firefox and install the following extension (or similar if others exist):
Firefox addon to toggle animated gifs
The two animations below show the mainspring being wound and wound from the perspective of the barrel.
The left animation shows that after the mainspring has been wound about one turn the crown on the arbor wheel butts agains the crown on the barrel wheel and further winding is impossible.
The animation on the right shown what happens if the crown of the arbor wheel is cut back (shown here as a simple notch). Now the mainspring can be fully wound and the weight locked. Note that at the end of this animation the boss on the barrel wheel has only just reached the annulus and the mainspring can probably be wound one more turn.
Winding Winding with a notch
Assuming, by an act of God, it is possible to fully wind the mainspring, then the following animation shows that the mainspring will unwind successfully.