GREUBEL FORSEY GMT TOURBILLON WATCH

AMAZING COMPLICATION BY GREUBEL FORSEY

GREUBEL FORSEY GMT TOURBILLON

Like all timepieces made by Greubel Forsey this new one looks as impressive as everything they’ve done before and also different.

The main "act" on stage is the spherical earth that can be viewed from many angles because of it’s ingeniously secured at just one end of its rotational axis, the South Pole.

With the GMT Robert Greubel and Stephen Forsey have focused their attention on displaying both a second time zone and universal world time as intuitively as possible.

The second time zone is a highly practical complication and is greatly valued by connoisseurs, globetrotting businessmen, frequent leisure travellers and those with family and friends around the world.

The GMT offers an original method of visualising world time by means of a rotating three-dimensional globe in conjunction with a second time zone indication.

A 25° inclined Tourbillon 24 Secondes escapement regulates the timing of the movement.

The globe simultaneously permits the visualisation of the time as well as the position of day and night across different continents via the 24-hour ring around the equator and the caseband window, which symbolises the position of the sun on the earth.

SECOND TIME INDICATOR

The 12-hour second time zone dial at 10 o’clock indicates the time in a designated second time zone and is easily adjusted using the quick-set, dual-function pusher on the caseband.

HOURS, MINUTES, SECONDS AND POWER RESERVE

Cascading clockwise from 12 o’clock is the main hour-minute dial, on which is mounted a small seconds dial and a sectorial power reserve indicator at 4 o’clock.

Two coaxial mainspring barrels connected in series provide the GMT with an optimal 72 hours running time.

TOURBILLON 24 SECONDS

The GMT features a 25° inclined Tourbillon 24 Secondes cage

One of Greubel Forsey’s major patented inventions.

ROTATING GLOBE

A wonderful three-dimensional temporal representation

This rotating globe offers a truly original view of time all over the world and a new way of perceiving different time zones.

DUAL FUNCTION PUSHER

The quick-set, dual-function pusher at 10 o’clock on the caseband adjusts the 12-hour second time zone and is also used when reading the globe to indicate 24-hour worldtime.

THE WORLDTIME DISC

A worldtime disc connected to the globe bears the names of 24 cities, each representing one of 24 global time zones.

To facilitate setting, cities not using summertime are on a dark background and time is read on the outer chapter ring

THE SUN

When setting the worldtime disc a resplendent sun on a golden gear serves as a useful visual reference for midday and radiantly lights up the movement.

DIFFERENTIALS

The GMT is equipped with an efficient spherical differential.

This can be glimpsed through the display back and is used with the pusher for correcting the second time zone.

TECHNICAL DETAILS of the GREUBEL FORSEY GMT TOURBILLON Watch

MOVEMENT:
Mechanical hand-wound movement
Calibre GF05
2nd time zone GMT display
Tourbillon 24 Secondes
Rotating globe with universal time display
24 time zone worldtime display
Summer time indicator
Worldtime disc with summer time zones
Day and night indicator
Power reserve indicator
Hour and minute display
Small second indicator
GMT pusher
Equatorial sapphire crystal lateral window
2 patents pending
Movement with patented tourbillon

BARRELS:
Two coaxial series coupled fast rotating barrels with 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 meantime screws with 10mm diameter

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 finish

BRIDGES:
Nickel silver
Frosted and spotted
Nickel-palladium finish
Hand-bevelled
Straight grained flanks
Polished countersinks
Gold nameplates bearing the individual number of the timepiece
Flat black polished steel tourbillon bridge hand bevelled

GEARING:
Involute circle profile
Conical gearing with corrected profiles

TOURBILLON CAGE:
Inclined at a 25° angle
24 second rotation
Cage pillars in Avional
Titanium cage bridges
Gold counterweight

NUMBER OF PARTS:
Complete movement with 436 Individual components
Tourbillon cage with 87 Individual components
Weight of the cage with 0,36 g

MOVEMENT DIMENSIONS:
Diameter: 36,40 mm
Thickness: 12,46 mm

VIBRATIONS:
21,600 vph 3 (Hz)

JEWELS:
50 Jewels
Olived domed jewels in gold chatons

POWER RESERVE:
72 hours

FUNCTIONS:
Hour and minute
Small second
72-hour power reserve on a sector
2nd time zone GMT indicator
24 time zone worldtime display
Rotating globe with universal time display
Summer time indicator
Day-and-night indicator

CASE:
White gold
Three dimensional variable geometry shaped lugs
Polished bezel and centre band with hand-finished straight graining
Lateral window with shaped sapphire crystal
White gold pusher with raised polished engraving "GMT" on a hand-punched background
Raised polished engraving "Greubel Forsey" on a hand-punched background
Hand-engraved individual number
Gold security screws

CROWN:
white gold with engraved and black lacquered GF logo

HANDS:
Hour and minute in polished gold with Super- Luminova
Small second and power-reserve in blued steel
2nd time zone GMT indicator
Red triangle Strap and clasp

CASEBACK:
Asymmetrical convex sapphire crystal

DIMENSIONS:
Diameter: 43.50 mm
Thickness: 16.14 mm

DIAL:
Principal hour-minute dial in gold
Frosted and anthracite finish (NAC)
Hour indicator in white gold circular graining
Gold power reserve sector matt lapped
Gold small second indicator matt lapped
Gold GMT indicator matt lapped
Applied gold Greubel Forsey logo

GLASS:
Asymmetrical convex sapphire crystal
Lateral window with shaped sapphire crystal
Asymmetrical convex sapphire crystal on caseback

WATER RESISTANCE:
3 Bar = 30 meters

STRAP:
Hand-sewn blue or black alligator

CLASP:
White gold folding clasp
Hand-engraved with the Greubel Forsey logo

Published by José Sousa