A double tourbillon is a watch movement that holds two tourbillons rather than one. The two can work independently, each regulating its own gear train. Or they can be joined by a differential that averages the difference in rate between them. Breguet and Greubel Forsey have each built their own version.
What is the difference between independent and synchronised double tourbillons?
In the independent kind, each tourbillon works on its own. Each one regulates its own gear train, so the movement in effect has two separate regulating systems. In the synchronised kind, a differential links the two tourbillons mechanically. The differential takes the rates of both and averages the difference between them. The movement is then governed by an average of the two, rather than by either one alone.
How does the Breguet Classique Double Tourbillon 5347 work?
Breguet’s Classique Double Tourbillon 5347 has two tourbillons that run fully independently of each other. Both turn on the hour axis. Each tourbillon makes one turn a minute. At the same time, the whole mechanism carrying them makes one turn every 12 hours. A bridge joins the two tourbillons, and that bridge also serves as the hour hand. The hour is read from the turning tourbillon assembly itself.
How does the Greubel Forsey Double Tourbillon 30° work?
Greubel Forsey’s Double Tourbillon 30° takes a different approach. One tourbillon cage sits inside a second cage. The inner cage is tilted at 30° and turns once a minute. The outer cage turns once every four minutes. Greubel Forsey says the aim is to average out errors caused by gravity in all the usual positions of a wristwatch. The brand calls the mechanism its first invention and made the model between 2004 and 2010. Several international patents protect it. Greubel Forsey later built a quadruple tourbillon from two double tourbillons running independently.
Not to be confused with
The double-axis tourbillon is a related but separate idea. It does not have two tourbillons. Instead, a single tourbillon turns around two axes, and each axis makes one turn per minute. Anthony Randall invented it in January 1977 and patented it. Richard Good made the first working example in 1978. A double tourbillon, by contrast, has two tourbillons in one movement.
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