skyeriding
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The Duometre works with two barrels thanks to one key component that's visible on the dial - the foudroyante
Oct 04, 2019,10:21 AM
One barrel powers the timekeeping train, just like any watch. But at the same time, there is an extra "escape wheel" of sorts, stacked on top of the regular escape wheel. This extra escape wheel regulates the power of a second geartrain (which powers the chronograph), through a six-pronged star wheel.
Thus by this mechanism, power is effectively isolated between the timekeeping train and the chronograph/complication train. There are some parallels of how it works compared to a star and flirt of a deadbeat or a foudroyante, in a way.
Among the three regular Duometres (excluding the tourbillon variants), the best use of the double barrels is the chronograph, because the chronograph is a complication that requires a sudden spike of power on the user's demand.
When the chronograph is stopped, a lever blocks the star wheel so that the teeth of the star wheel are moved out of the way of the second escape wheel, thus they are disconnected. This is at the 0s mark of the foudroyante dial.
When the chronograph is started, the lever is released, and the power of the chronograph mainspring barrel drives it forward until it engages the teeth of the second escapement.
In the video below, you will notice the foudroyante hand jump to the nearest half between the 1/6th numbered markings of the dial, rather than on the numbers themselves. This is because the half markings are when the star wheel engages the second escapement, while anything in between are the "dead zones" where the chronograph is disconnected from the second escape wheel. By having the lever stop the star wheel right on the dead zone at 0, the chronograph is effectively stopped and isolated.
Regards,
skyeriding