The completely new and original titanium case, firmly positions this GMT in a "sports" league of its own. In their creation of this timepiece, Robert Greubel and Stephen Forsey have pushed back the limits of ergonomics and wrist comfort. They have invented a totally new case form, perfectly round from above, while revealing the accentuated arched and ovoid shape from other angles. The aerodynamics of this timepiece 4 patents are reinforced by its integrated lugs and strap resulting in distinct functional forms that perfectly fit any wrist. The display side of the GMT Sport presents classic Greubel Forsey architecture, an open, orchestrated theatre between suspended bridges, semi-apparent wheels and floating dials in three dimensions. In keeping with the sporting vocation of this timepiece, the focus is on legibility and efficiency. The hours and minutes are displayed by concentric openworked hands whose curved profile follows the curvature of the case and movement. The Tourbillon 24 Secondes is showcased at 1 o'clock secured by its distinctive and highly polished tourbillon bridge with black finished openings. This third Fundamental Invention by Greubel Forsey stands out with its cage inclined at 25 ° completing one full rotation in 24 seconds. The faster speed combined with the inventive cage inclination, significantly improves chronometric performance in a single-tourbillon system, with minimal movement height. Precision and reliability summarise Greubel Forsey’s ground-breaking GMT mechanism. In this double-patented mechanism, the second time zone indication on the auxiliary dial between 10 and 11 o’clock is combined with a universal time display to intuitively read the current time anywhere in the world.
Movement
Movement dimensions
- Diameter : 36.90 mm
- Tickness : 13.18 mm
Number of parts
- Movement : 435 parts
- Tourbillon cage : 88 parts
- Weight of the cage : 0.38 g
Number of jewels
- 63
- Olived-domed jewels in gold chatons
Chronometric Power Reserve
Barrels
- Two coaxial series-coupled fast rotating barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension
Balance wheel
- Variable-inertia with gold mean-time screws (10 mm diameter)
Frequency
Balance spring
- Phillips terminal curve
- Geneva-style stud
Main plates
- Titanium
- Frosted and spotted, polished bevelling and countersinks, straight-grained flanks, black treatment
Bridges
- Titanium
- Multi-level, suspended-arch bridge, polished with black treatment in relief, polished bevelling and countersinks, straight-grained flanks
- Flat black polished tourbillon bridge with black treatment in relief, spotted, polished bevelling and countersinks, straight-grained flanks
Tourbillon
- Inclined at a 25° angle, 24-seconds rotation
- Light alloy cage pillars
- Titanium cage bridges
- Gold counterweight
Gearing
- Involute circle profile
- Tangential inclined gear on fixed wheel and on escape wheel pinion
- Inclined gear and profiled teeth on intermediate wheels of the set-hands mechanism
Displays
- Hours and minutes, on suspended-arch bridge
- Small seconds on disc
- 72-hours power reserve on a sector
- 24-seconds tourbillon rotation
- Rotating titanium globe with universal time
- Day-and-night
- 2nd time zone GMT
Dial Displays
- 24 time zones universal time
- Summer time
Exterior
Case
- Titanium with curved synthetic sapphire crystal
- Three-dimensional, variable geometry-shaped bezel with raised engraved text
- Profiled lugs, screwed fixing
- Engraved pushers
- Transparent back with high domed synthetic sapphire crystal
- Titanium security screws
- Raised engraving “GMT Sport” and “Greubel Forsey”
Case dimensions
- Diameter : 42.00 mm
- Height : 15.70 mm
Water resistance of case
- Water-resistant 10 atm - 100 m - 328 ft
(Standard NIHS 92-20/SN ISO 22810:2010)
Crown
- Titanium and rubber with GF logo
- Colour-coded rubber capping, interchangeable
Hands
- Polished steel curved shape hours and minutes, with Super-LumiNova
- 2nd time zone GMT indicator, red triangle
- Small seconds, fixed red triangle
- Power-reserve indicator, in polished steel
- Aluminium 24-seconds double-tipped hand, black treatment
Strap and clasp
- Rubber with relief text
- Titanium folding clasp, engraved with the GF logo
Dial side
- Three-dimensional, variable geometry hour-ring, with luminescent hours and minutes indexes
- GMT indicator with raised engraving
- Power-reserve indicator, engraved and lacquered
- Tourbillon rotation indicator in gold
- Rotating globe with fixed day-and-night UTC indicator in synthetic sapphire, engraved and lacquered
Movement side
- Synthetic sapphire disc displaying city names surrounded by 2 rings (UTC engraved on the case / Summer time engraved on a gold movement plate, lacquered and hand matt-lapped)
- “Summer time” plate with limitation number, raised engraving, hand matt lapped
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