Greubel Forsey’s 8th Fundamental Invention: the Tourbillon Cardan

November 2023

Greubel Forsey's 8th Fundamental Invention: the Tourbillon Cardan

After three years in development, a new type of tourbillon has evolved from concept to reality. The Tourbillon Cardan has achieved unprecedented chronometric precision through its three pillars: a rapid rotating tourbillon, a revolving 30° inclined plane, and two constantly tilting rings.


or 20 years, Greubel Forsey has been working from the standpoint that contemporary watchmaking is far from having exhausted all the technical possibilities of fine watchmaking. The Atelier has proven this on seven landmark occasions, developing Fundamental Inventions that rethink the basics of movement regulation and other major complications. This titanic undertaking, focused on chronometric performance, continues today with an 8th Invention: the Tourbillon Cardan.

The Tourbillon Cardan is designed to reach new heights of chronometric precision. It combines three principles. The first: the tourbillon. The mechanism patented by Abraham-Louis Breguet in 1801 was designed to compensate for the differences in rate, in vertical positions. For Greubel Forsey, this was not the end, but the very beginning.

While most tourbillons have a revolution of 60 seconds, that of the 8th Fundamental Invention is almost four times faster. Just 16 seconds. This is the fastest yet for a Greubel Forsey tourbillon. It moves through more positions in less time, and therefore offers much a higher average performance.

Greubel Forsey's 8th Fundamental Invention: the Tourbillon Cardan

What’s more, this tourbillon incorporates, for the very first time, the large balance wheel designed, developed and made in-house by Greubel Forsey. It benefits from the exemplary balance of its masses, its large size (12.6 mm) and its optimised oscillations. Its high inertia also makes it less sensitive to shocks and variations in speed.

Second principle: the 30° angle. The tourbillon, as it was conceived over two centuries ago, was designed for pocket watches worn vertically. For a wristwatch, its design needed to be totally rethought, optimised for the positions adopted in everyday 21st century life.

Third principle: this 30° high-speed tourbillon is guided by two mobile rings, linked by two 90° axes. In 48 seconds, they tilt backwards and forwards. This construction may seem reminiscent of gimbals, but is very different from a traditional gimbal where the two rings are free to move and their job is to keep the object they contain horizontal. In the Tourbillon Cardan, the tilt of the rings is controlled (+30° to -30° range), while the degree of inclination of the tourbillon is inclined (also 30°) and never varies, offering a better ratio of angular velocity to chronometric performance.

The Tourbillon Cardan has four barrels. This is a remarkable construction at Greubel Forsey (occurring just once in 20 years). They are coaxially stacked, with a slipping mainspring to prevent excess tension during winding. They offer 80 hours of chronometric power reserve. Beyond that point, the timepiece still runs very well, but maybe outside the rigorous Greubel Forsey precision tolerances.

As the tourbillon cannot be held in place by a fixed upper bridge, this function is performed by the two arched cardan rings. Without adopting the traditional construction, Greubel Forsey’s 8th Fundamental Invention creates a new type of tourbillon with a flying appearance, which is both original and patented. A seemingly complex construction but with a very small number of components, it offers an open, airy aesthetic that leaves the eye free to admire its kinematics.

Greubel Forsey's 8th Fundamental Invention: the Tourbillon Cardan

Some components of the Tourbillon Cardan require up to three days for hand finishing alone. A number of unique finishes have been developed specifically for this timepiece. Among them, the movement plates are in frosted nickel silver, with polished bevels and straight grained flanks while a titanium mainplate presents a large polished flank as a backdrop to the cardan. Even more particular: the upper bridge of the tourbillon cage is made of frosted titanium with straight grained flanks and polished bevels, above and below. Finally, the arch is barrel-polished. It takes more than 30 hours to finish this single component.

The cardan’s rings are matt finished, with polished bevels and straight grained flanks, while the lower plate is frosted by hand, a task that requires a particularly special expertise from the Atelier Manufacture. Finally, there are two dials (hours & minutes and seconds), one circular grained with polished flanks and a very large mirror finish angle, the other with a polished exterior flank. Greubel Forsey has also developed a high domed sapphire crystal for this piece. It houses the full height of the tourbillon and cardan system, offering a highly architectural technical vision. The view is completely unobstructed over the balance wheel measuring 12.6 mm in diameter. You can admire the majestic swaying of the two cardan rings into which it fits.

The Tourbillon Cardan will be available in a 45.5 mm titanium case. This metal was chosen for its modernity and lightness, in keeping with the airy aesthetic of the Cardan tourbillon. Greubel Forsey plans to build just 55 pieces of the calibre over the next 5 years.

Greubel Forsey's 8th Fundamental Invention: the Tourbillon Cardan


• Hand-wound movement with patented cardan tourbillon
• Overall diameter: 39.60 mm
• Thickness: 13.53 mm Number of parts
• Components: 389 parts
• Cardan tourbillon cages: 98 parts
• Weight of the cage: 0.92 g
• Number of jewels: 49
• Olived-domed jewels in gold chatons

Chronometric power reserve
• 80 hours

• Four coaxial series-coupled fast-rotating barrels (1 turn in 2.7 hours), one of which is equipped with a slipping spring to avoid excess tension
• Relief-engraved text, circular-grained, black treatment, polished chamfer

Balance wheel
• In-house variable-inertia with 6 gold mean-time screws (12.60 mm diameter)

• 21’600 vibrations/hour

Balance spring
• Phillips terminal curve
• Geneva-style stud

Bridges and main plates
• Titanium and nickel silver, frosted and spotted, polished bevelling and countersinks, straight-grained flanks
• Hand-bevelled and openworked cage pillars

Movement side
• Flat black polished steel tourbillon bridge, polished bevelling and countersinks
• Gold plate engraved with the individual number, circular-grained, polished bevelling, straight-grained flanks

Cardan Tourbillon
• Ultra-fast inner tourbillon cage (1 rotation in 16 seconds) in titanium, barrel-polished and hand-bevelled, inclined at a 30° angle with gold counterweight
• Outer flying cardan cages, 48-seconds cycle, double variable tilt at 30°, polished and hand-bevelled, straight-grained flanks

• Involute circle profile
• Conical gearing with profiled teeth

• Hours and minutes
• Small seconds
• Power reserve on a sector

• Titanium with high domed synthetic sapphire crystal
• Transparent back with high domed synthetic sapphire crystal
• Hand-polished bezel, caseband with hand-finished straight graining
• Titanium security screws
• Raised polished engraving “Tourbillon Cardan” and “Greubel Forsey” on a hand-punched background

Case dimensions
• Caseband diameter: 45.50 mm
• Bezel diameter: 46.00 mm
• Case height: 13.81 mm
• Height on synthetic sapphire crystals: 18.15 mm

Water resistance of the case
• Water-resistant 3 atm - 30 m - 100 ft (standard NIHS 92-20/SN ISO 22810:2010)

• Titanium, polished, with GF logo

Dial side
• Multi-level gold dial with openworked pillars, circular-grained with engraved and lacquered minute- circle, polished flanks
• Gold hour markers
• Small seconds and power-reserve indicators in gold, engraved and lacquered
• Engraved and lacquered GF logo

• Hours and minutes in polished steel, with Super-LumiNova
• Small seconds and power-reserve in polished steel, hand-polished countersink, flat black polished head

Strap and clasp
• Non-animal material, hand-sewn
• Titanium folding clasp, engraved GF logo

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