In January of 2017, Greubel Forsey replica watches announced that it had been experimenting with nanomechanical wristwatch technology – that is, the use of micro-scale components, in order to make new display systems possible and also to dramatically increase the performance of mechanical watches. (True nano-scale structures are atomic scale, so the term “nano” is perhaps a bit of poetic license; however as you’ll see, the components in the Nano Foudroyante EWT are much smaller than those ordinarily seen in watchmaking.) The original announcement teased a watch that would have a regulating system so compact, and so efficient, that it could theoretically have a 180 day power reserve, which would obviously be unprecedented. Greubel Forsey has just released the latest news on the evolution of the concept: a watch with a foudroyante seconds hand complication that uses only 1/1800 the energy of a traditional foudroyante seconds hand, and which is 96% smaller than the usual mechanism. This is the third basic invention in Greubel Forsey’s Experimental Watch Technology program – the others are the synthetic diamond Binomial escapement of 2009, and the Différentiel d’Egalité (a spherical differential remontoire d’egalité, patented in 2006).
A foudroyante seconds hand is one that jumps in fraction-of-a-second intervals, making one full 360º revolution per second. Usually the foudroyante is found as an addition to a chronograph complication; in modern watchmaking it’s an extremely rare complication. The Lange & Söhne Grand Complication has a foudroyante seconds hand (you can see it doing its thing in our 2013 video in-depth review) and the F. P. Journe Centigraphe is essentially a chronograph with a foudroyante seconds hand you can stop somewhere in mid-jump. The word “foudroyante” means “lightning” and the complication is also sometimes called a diablotine (“little devil”). You generally do not see a watch with a foudroyante seconds hand apart from a chronograph, as in its traditional form, it uses a lot of extra energy (relatively speaking). However, the EWT version makes use of micromechanical manufacturing methods to produce components for a foudroyante so small that it can be driven directly by the escape wheel, continuously, while producing virtually no additional drag on the going train with Greubel Forsey fake watches .
The patent for this invention is somewhat general in its language but does specifically mention LIGA fabrication as a way of producing the components. In the images above you can see roughly how it works. It’s really simplicity itself; you have a double driving wheel mounted on the axis of the escape wheel, which gears to two crown wheels on the shaft of the foudroyante hand. As far as I can tell, every time the escape wheel unlocks and advances a tooth, the seconds hand jumps forward. The foudroyante dial is marked off in 1/8 second increments, which would indicate a 28,800 vph base movement.