Unveiled in 2006, the Tourbillon 24 Secondes Incliné (T24Si) is Greubel Forsey’s third fundamental invention and continues the exploration into minimising the effects of gravity on the regulating organ. This is achieved in the T24Si by means of an innovative tourbillon cage undergoing rapidly changing positions with a high angular velocity.
In 2007, Greubel Forsey launched the production model of the Tourbillon 24 Secondes Incliné watch. In that year, it won the Special Jury Prize at the prize-giving ceremony of the 14th “Watch of the Year” awards, , an annual competition organised by the Swiss “Montres Passion” magazine.
Immediately recognisable by its asymmetrical case, the Greubel Forsey Tourbillon 24 Secondes Incliné is distinguished by the fast rotation of a single inclined cage an original means of enhancing the performances of a single Tourbillon. This timepiece is presently available in red gold and white gold versions.
For Greubel Forsey, the Tourbillon is an inexhaustible field of research, as is powerfully confirmed by the Double Tourbillon 30° models already invented, as well as the projects still at the experimental watch stage in the EWT laboratories.
Not only do the various modern Tourbillon systems invented in the La Chaux-de-Fonds workshops bear extraordinary witness to the significant progress made in terms of micro technical research and development, but they also offer one of the finest aesthetic visions in Technical Haute Horlogerie.
With the Tourbillon 24 Secondes Incliné (Calibre GF01), Greubel Forsey capitalizes upon the speed of rotation and the inclination of the regulator to harness the influence of gravity on the regulating organ.
Enabling the moving parts to cover a major distance in a short space of time and to perform a complete rotation in just 24 seconds called for the implementation of innovative solutions including a specially constructed inclined gear profile.
The use of extremely low-density alloys stemming from the aeronautical and aerospace industries facilitated the creation of a unique and ultralight Tourbillon system inclined at a 25° angle, perfectly suited to the powerful stresses imposed by the speed and in particular by the cage advancing in steps which are two and a half times greater than in conventional tourbillon systems.
In comparison to the experimental model presented at its development stage in EWT, the definitive version of the Tourbillon 24 Secondes Incliné has an even lighter mechanism: the complete system composed of 88 parts weighs a mere 0.39 grams, which is 17% less than the laboratory version…
The construction of the Calibre GF01 has off-centred the Tourbillon 24 Secondes Incliné system, a technical option that provided scope to define an original case and dial architecture characterised by a well-balanced asymmetry. The latter serves to ensure ideal visual access to the mechanism and to the various items of information.
The matt-finished dial displays the 72-hour power reserve, while the seconds are read off by a double-tipped white gold hand moving across a dedicated sector.
A wide opening right through the dial and plate, complemented by a lateral window, facilitate visual access to the high-speed 25° inclined Tourbillon, which seems to enjoy complete liberty of movement free of any gear-trains.
Only the ultra-light Tourbillon cage with its titanium bridges and Avional pillars appear in the field of vision. One may also observe the rapid rotation of the cage on a 24-second subdial placed on a titanium and black PVD-coated platform.
The asymmetrical convex sapphire crystal case-back of the Greubel Forsey Tourbillon 24 Secondes Incliné provides ample views of the superlative finishing on the frosted nickel silver bridges and plates, as well as the olive-domed jewels placed on gold settings.
Model: Greubel Forsey Tourbillon 24 Secondes Incliné, in white gold or in 5N red gold
Mechanical hand-wound movement, GF Calibre 01
Diameter: 36.4 mm; Thickness: 9.65 mm
Number of parts
• Complete movement: 280 parts
• Tourbillon cage: 88 parts
• Weight of the cage: 0.39 g
Number of jewels: 36
Olive-domed jewels in gold chatons
Power reserve : 72 hours
Barrels: Rapid rotating twin barrels (1 Turn in 3.2 hours) one of which equipped with a slipping spring so as to avoid excess tension
Balance wheel: Free sprung balance with white gold mean-time screws (10 mm diameter)
Frequency: 21’600 vibrations/hour
Balance spring: Phillips terminal curve,Geneva-style stud
Main Plates: Spotted and snailed palladium-finished nickel silver
• Hand bevelled, frosted and spotted palladium-finished nickel silver “Greubel Forsey” gold nameplate, relief-engraved gold plate with the number of the timepiece
• Steel conical bevelled Tourbillon bridge
• Positioned on a black PVD-coated titanium platform with mirror-polished backdrop Gearing
• Involute circle profile
• Tangential inclined gear with profiled teeth, on fixed wheel and escape wheel pinion
• Inclined at a 25° angle, 24-second rotation
• Cage pillars in Avional
• Titanium cage bridges
• Gold counterweight.
Hours and minutes
Small second sector
72-hour power reserve on a sector
24-second Tourbillon rotation indicator at 8 o’clock
In white gold or in 5N red gold
Asymmetrical convex sapphire crystal
Diameter: 43.5 mm
Thickness: 15.76 mm
Transparent back with asymmetrical convex sapphire crystal
Lateral window with shaped sapphire crystal
Raised engraving of the name of the Invention on a hand-punched background
Gold security screws
Polished bezel and centre band with hand-finished straight graining
Hand-engraved individual number
Water resistance of the case: 3 ATM – 30 m – 100 ft
Crown: Gold with engraved and black lacquered GF logo
Multi-level in gold silvered or anthracite colour
Gold display sectors
Applied gold logo
Hours and minutes, small seconds and power-reserve in gold
24-second double-tipped hand, black anodised aluminium
Hand-sewn black alligator leather with gold folding clasp, hand-embossed with the Greubel Forsey initials