Greubel Forsey Double Tourbillon Technique
Written by James Matthews
Greubel Forsey has pioneered a frontier in the world of horology the Double Tourbillon Technique. The Tourbillon which was invented in 1795 by French watchmaker Abraham-Louis Breguet, a tourbillon counters the effects of gravity by mounting the escapement and balance wheel in a rotating cage, ostensibly in order to negate the effect of gravity when the timepiece (and thus the escapement) is rotated. Originally an attempt to improve accuracy, tourbillons are still included in some expensive modern watches as a novelty and demonstration of watchmaking virtuosity.
The mechanism is usually exposed on the watch’s face to show it off. In this uniqe watch Double Tourbillon 30°, Hours and minutes display, Outer Tourbillon 4-minute rotation indicator, Inner Tourbillon 60 Second rotation indicator, power-reserve indicator.
Patented Movement
Movement dimensions
• Diameter : 38.40 mm
• Thickness : 12.15 mm
Number of parts
• Complete movement : 385 parts
• 2 Tourbillon cages : 128 parts
• Weight of the two cages : 1.17 g
Number of jewels
• 43
• Olive-domed jewels in gold chatons
Power reserve 120 hours
Barrels
• Four coaxial series-coupled fast-rotating barrels (1 turn in 3.2 hours), equipped with a slipping spring to avoid excess tension
• Gold nickel-palladium finished cover with relief engraving Balance wheel Variable-inertia with white gold mean-time screws (10.70 mm diameter)
Frequency 21,600 vibrations/hour
Balance spring
• Phillips terminal curve
• Geneva-style stud
Main Plates Frosted nickel silver, polished bevelling, black chromed finish
Bridges Frosted nickel silver, polished bevelling, nickel-palladium finish, gold nameplate
bearing the watch number
Gearing
• Involute circle profile
• Conical gearing with corrected profile
Inner Tourbillon Inclined at a 30° angle, 1 rotation per minute
Outer Tourbillon
• 1 rotation in 4 minutes
• Hand-bevelled and openworked cage pillars
• Solid gold counterweight
Displays
• Hours and minutes
• Small seconds
• 4-minute Outer Tourbillon rotation indicator
• 120-hour power reserve on a sector
Exterior
Case material and finishes
• In 5N red gold, white gold or platinum with convex sapphire crystal
• Transparent back with convex sapphire crystal
• Raised polished engraving of the name of the Invention on a hand-punched background
• Gold security screws
• Nameplates with text screwed to the sides
• Three-dimensional lugs secured with screws
• Hand-engraved individual number
Case dimensions
• Diameter : 47.50 mm
• Thickness : 16.84 mm
Water resistance of the case 3 ATM – 30 M – 100 FT
Crown Gold with engraved and black lacquered GF logo
Dial
• Sapphire hour markers
• Small seconds and power-reserve indicators in gold
Hands
• Hours and minutes in gold
• Small seconds, Power reserve (red triangles)
• Sapphire 4-minute indicator
Strap Hand-sewn black, brown, dark blue, grey or burgundy alligator leather with gold folding clasp, engraved with the Greubel Forsey logo
This post was written by James Matthews. If you have any questions or comments you may contact him at james@jewelerslounge.com
