Breguet Watch No. 28 Self-Winding Stop-Work



Three animations have been given at Animations-Breguet-No28.html; all three depict the design in the original photographs. And three animations at Animations-Breguet-No28-Equal-Segments.html show that the same design will work with equal segments (φ = 72°) if the arbor wheel crown is adjusted.


The first animation below uses the original values of Rb, C, φ and Ω , but Ra is reduced to 0.97Rb, 97% of Rb. As a consequence δ reduces from 20° to 16.6°. Again the design will work if the arbor wheel crown is adjusted; in this case the crown is tapered at the ends.

Animation-Breguet-No28-Winding-97.gif

Winding with a small arbor wheel


The next animation has exactly the same dimensions except it has equal segments with φ = 72°. As above, winding can continue if the arbor wheel crown is cut back appropriately. Note that δ reduces to 14.6°

Animation-Breguet-No28-Winding-Equal-97.gif

Winding with a small arbor wheel and equal segments


The third animation also has equal segments, but it reverts to Ra = Rb and keeps δ at the original 20°. To do this C must be reduced from 3.01 to 2.95. Again winding can continue if the arbor wheel crown is cut back appropriately.

The red circle on the barrel wheel is the size of the screw holding the wheel to the barrel. All the slots must be made deeper, because now the finger is closer, but only slot 1 has been deepened in the photograph. It is clear that this design would work, but the barrel wheel might be too fragile for it to be practical.

Animation-Breguet-No28-winding-equal-small-C.gif

Winding with small C and equal segments


The fourth animation uses the original values, but δ is set to 9° and consequently C increases by 0.25, from 3.01 to 3.26.

Animation-Breguet-No28-Winding-D9.gif

Winding with δ = 9


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