Greubel Forsey QP à Équation (Equation of Time Perpetual Calendar) White Gold

The QP à Équation (Equation of Time Perpetual Calendar) watch was introduced in 2014 in coincide with the 10th anniversary of Greubel Forsey, the high end Swiss luxury watch atelier established by Robert Greubel and Stephen Forsey.

This timepiece was born after the brand has decided to revive the mechanical “computer”, integrating an equation of time function. To harmoniously integrate this complication, a mechanical computer was created. This mechanism comprises a stack of irregularly shaped cams with “fingers”. These are used to trigger changes in the displays: The dial side shows the 24 hours of the day and night, the day of the week, the large date, the month, and the hours and minutes; the bridge side shows the equation of time, the seasons and the year. This system, which required three patents to be filed, is more compact and perfectly integrates the equation of time within the mechanical computer. It can be adjusted in both directions more easily and safely.

All the adjustments are made without additional correctors. There is a single selector position via the crown; it is even easier to adjust than a simple “quantième” calendar watch, as the Greubel Forsey Equation of Time Perpetual Calendar watch is bidirectional. It is an ultra- complicated watch with its inclined tourbillon and its complete equation of time perpetual calendar function, but it is as easy to use and adjust as a watch with just three hands and the date.

The Equation of Time Perpetual Calendar watch measures the seconds, minutes, hours, days, months, season and years, according to the equation of time integrated in the mechanical computer.

Technical details
Model: QP à Équation
In white gold – Millésimé
Mechanical hand-wound movement with patented tourbillon 24’’ Calibre GF07
Bi-directionnal perpetual calendar, Equation of time, Tourbillon 24 Secondes • hours, minutes • small second • power-reserve indicator • day, date, month, calendar year, leap year indicator, day/night (24h with red zone) • function selector • with months, seasons, solstices and equinoxes indications.

Movement
Diameter: 36.40 mm
Thickness: 9.60 mm

Number of parts
• Complete movement: 624 parts
• Tourbillon cage: 86 parts
• Weight of the cage: 0.37 g
Number of jewels: 75; Olived-domed jewels in gold chatons

Power reserve: 72 hours
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: Free sprung variable-inertia balance with gold mean-time screws (10 mm diameter)
Frequency: 21’600 vibrations/hour
Balance spring: Phillips terminal curve; Geneva-style stud
Main plates: Nickel silver, frosted and spotted, with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment

Bridges
• Nickel silver, frosted and spotted, with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
• 4 engraved gold plates, one with the individual number
• Flat black polished steel tourbillon bridges, hand-bevelled
• Synthetic sapphire crystal mechanical computer bridge

Tourbillon cage
• Inclined at a 25° angle, 24-second rotation
• Cage pillars in Avional
• Titanium cage bridges
• Gold counterweight

Gearing
• Involute circle profile
• Tangential inclined gear with profiled teeth, on fixed wheel and escape wheel pinion

Functions
Dial displays
• Hours & minutes
• Small second
• 72-hours power reserve on a sector
• Day of the week, date and month indicators
• Leap year indicator
• Day-and-night indicator
• Function selector indicator

Back displays
• Year indicator disks
• Equation of time with seasons, solstices and equinoxes indicators

Case
In white gold with asymmetrical convex synthetic sapphire crystal
Diameter: 43.50 mm
Thickness: 16.00 mm
Transparent back with flat asymmetrical synthetic sapphire crystal
Polished bezel, centre band with hand-finished straight graining
Three-dimensional, variable geometry-shaped lugs
Raised polished engraving “QP à Équation” and “Greubel Forsey” on a hand-punched background
Hand-engraved individual number
Gold security screws
Water-resistant: 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown: In white gold with engraved and black lacquered GF logo

Dial
In anthracite gold, multi-level

Hands
Hours and minutes in polished gold, with Super-luminova
Small second in blued steel
Power reserve in blued steel
Leap year indicator hand in blued steel

Strap and clasp
Hand-sewn black alligator
White gold folding clasp, hand-engraved with the Greubel Forsey logo

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