Greubel Forsey
Greubel Forsey Launches GMT Quadruple Tourbillon
A dream timepiece for the jetsetter, the GMT displays three timezones as well as a universal time function. As complications go, this is as useful as can be in the modern era of international flight as a common occurrence. But the company’s speciality, whatever other complications or devices it may master, is the tourbillon, conceived by Abraham-Louis Breguet over 200 years ago as a means of eliminating the effects of gravity on a watch’s timekeeping.
His answer to the problem was to house the regulating organ of a watch – its hairspring, balance wheel and escapement – within a rotating cage. With this assembly turning around on its own axis, usually completing the revolution in one minute, the elements subject to the pull of gravity would experience constantly changing positioning, thereby averaging out timing variations.
For Robert Greubel and Stephen Forsey, their life work has been to “re-imagine the tourbillon principle”, leading to their first three Fundamental Inventions: the Double Tourbillon 30° (2004), the Quadruple Tourbillon (2005) and the Tourbillon 24 Secondes (2006). Now, in the GMT Quadruple Tourbillon, they have chosen to combine their second invention with a multiple timezone display.
To facilitate this need for compactness, and to save space in all three dimensions, they cleverly constructed the tourbillons in pairs, devising a unique system of compact cages. As the Greubel Forsey Inventions complement each other, the pair modelled their solution on the Double Tourbillon 30°, its first cage rotating in one minute and angled at 30°, fitted inside a second upright cage which completes its full rotation in four minutes. When combined, the inclination of the inner cage and the different rotational speeds of the two cages cancel out the timing variations due to the earth’s gravitational attraction, exploiting all the positions a wristwatch can adopt.