Greubel & Forsey - Tourbillon 24 Secondes Incliné

Greubel & Forsey - Tourbillon 24 Secondes Incliné

A beautiful and interesting meeting, the one with Robert Forsey, which took place last week in Milan. The technical in-depth analysis of the inventions of the brand, specialised in prestigious tourbillons, will be published in one of the next issues of L'Orologio. Here, however, I want to anticipate the suggestive images of the new Tourbillon 24 Secondes Incliné, presented at BaselWorld 2007.

This is the description given by the House:

"The Tourbillon is limitless research territory for Greubel Forsey. Both the first Double Tourbillons 30° that have already been produced and the watch projects that are still in the experimental phase in the EWT (eXperimental Watch Technology) laboratories prove this: the various modern Tourbillon systems invented in the laboratories in La Chaux-de-Fonds are not only extraordinary proof of the significant progress made in the research and development of microtechnology, but also offer one of the most beautiful spectacles of Haute Horlogerie Technique.

With the Tourbillon 24 Secondes Incliné (Calibre GF01), Greubel Forsey uses the rotation speed and inclination of the regulator to neutralise the influence of the earth's gravity on the regulating organ. To make the cage travel a long way in a very short time and perform a complete rotation in 24 seconds, new solutions were found, in particular an innovative inclined gear profile.

The use of low-density alloys, used in the aeronautical and aerospace industries, has enabled the creation of a unique Tourbillon system, inclined at 25° and ultra-light, which is perfectly suited to the stress caused by speed, in particular the cage jump, which is two and a half times greater than in conventional systems.

Compared to the experimental project presented during development at the EWT, the final version of the Tourbillon 24 Secondes Incliné features an even lighter mechanism: composed of 88 elements, the complete system weighs only 0.39 grams, which means a relative weight loss of 17% compared to the laboratory version...

The construction of the calibre GF01 features a decentralisation of the Tourbillon 24 Secondes Incliné system, a technical option that made it possible to define an original architecture for the case and dial, characterised by a balanced asymmetry, ideal for admiring the mechanism and the various information.

The dial in satin-finished gold in different shades according to zone, allows the 72-hour power reserve to be monitored, while the seconds display is indicated on a semi-circle by a white gold double-headed hand.

A large opening on the dial and the mainplate, complemented by a side porthole, facilitates observation of the "Tourbillon à grande vitesse incliné à 25°", which seems to evolve in absolute freedom, freed from all gearing. Only the Tourbillon bridge in steel, the Titanium cage and the Avional columns appear in the field of view. One can also follow the rotation of the cage on a 24-second graduated circle set on a titanium platform with a black PVD finish.

The back of the case allows one to appreciate the high level of finishing of the bridges, the silver granite plates and the flat rubies set in gold."

Technical characteristics:

Tourbillon 24 Secondes Incliné

Hand-wound movement, Calibre GF 01

Tourbillon 24 Secondes Incliné, 24-second Tourbillon rotation indication, seconds display and remaining power reserve indication. Mechanism T24Si Patent pending


Movement size

- Diameter: 36.4 mm

- Height: 9.65 mm

Number of components

- Complete movement: 280 components

- Tourbillon cage: 88 components

- Cage weight: 0.39 g

Number of rubies 36

Flat rubies in gold bezels

Power reserve 72 hours


Fast-rotating double barrel in series (1 revolution in 3.2 hours), equipped with a sliding hairspring to prevent over-tensioning


Variable inertia with gold adjustment screws (10 mm diameter)

Frequency of 21,600 vibrations per hour


- Phillips curve

- Python made to Geneva Hallmark standards

Silver-plated palladium-plated perlé silver platelets, snailed


- In perlé and grené silver, palladium-coated, hand-chamfered, screwed gold 'Greubel Forsey' plate, asymmetrical gold sector, screwed gold plate with individual watch number

- Tourbillon bridge in steel

- Mounted on black PVD-treated titanium platform and mirror-polished walls


- Evolvent profile

- Tangential bevel gear with shaped toothing, on fixed wheel and escapement pinion

Tourbillon Cage

- Inclined at 25°, 1 rotation in 24 seconds

- Avional cage column

- Titanium bridges

- Gold Balancing Mass


- Hours and minutes

- Small sectoral seconds

- 72-hour power reserve display with sectorial counter

- Tourbillon rotation indication in 24 seconds at 8 o'clock



- In gold with asymmetrical sapphire crystal

- Transparent back with asymmetric sapphire crystal

- Side window with sapphire glass in shape

- Relief engraving of the name of the Invention on a hand-hammered background

- Gold security screws

- Polished bezel and hand-finished satin-finished case middle

- Individual hand-engraved watch number

Case dimensions

- Diameter: 43.5 mm

- Height: 15.76 mm

Water resistance of the case

3 ATM - 30m - 100FT

Crown Gold with engraved GF logo, black lacquered


- Gold dials

- Gold applications

- Gold Indication Sectors

- Applied gold logo


Hours and minutes in gold, Small seconds and Power Reserve in gold

24-second hand in black anodised aluminium


Black alligator, hand-stitched with gold folding clasp, hand-engraved Greubel Forsey