Every watchmaker is fighting a series of physical laws when creating a watch. A great problem on precision is caused by the gravity since the positions of the tourbillon are limited.
Since 2002, the team from JLC (Magali Metrailler as responsible for the aesthetic aspects and Eric Coudray for the technical background) start thinking on a multiple-axis tourbillon for the new collections. The idea was not quite new, coming from the 90’s when the watches were still to small for such a thing – the fashion was not prepared for such big watches. A second issue was the design itself – such a complexity was hard to handle on the drawing board. Luckily, the advances of the 3D CAD (Computer Aided Desing) software and the general tendency on the bigger housing offer the possibility for Jaeger LeCoultre of giving to the market the gyrotourbillon in 2004.
Nevertheless, the size and the 3D design were not the only obstacles – also the materials used should have been light enough and rough enough for such a complexity. They just didn’t take an existing tourbillon and added a second axes, they designed the new tourbillon from “0” and managed to create a two axes tourbillon in two aluminium cages – a 3 dimensional tourbillon which compensates the gravitational forces not only on a vertical plan but on all planes and has a precision of maximum -1/+1seconds per day (for instance COSC – Contrôle Officiel Suisse des Chronomètres, the Official Swiss Chronometer Testing Institute, which is the institute responsible for certifying the accuracy and precision of wristwatches in Switzerland considers a -4/+6seconds deviation as good).
And this has not stopped here. Since the space available in the cage was enough, the team decided for a cylindrical (helical) balance spring – first used in a wristwatch (before used only in marine chronometer). This type of spring has the movement more symmetric and has an improved chronometry (better precision). The basic springs are supplied by Lange & Söhne Uhren (both companies are Richemont SA subsidiaries)
Torque limitation system mounted directly on the barrel
(Two gears with a different number of teeth: – one used when the barrel is driving the calibre and the second one is driving at the wound. Both have on the upper side a locking tooth and when they meet the device is stopped, either stopping the winding or the main train when torque is too high, respectively to low)
The calibre 174 has 371 components, the front features time in hours and minutes and 24h indication, the back side features the power reserve. It was revealed at SIHH 2008.
At SIHH 2013, Jaeger-LeCoultre presented the Caliber 176 – Gyrotourbillon 3: The Master Grande Tradition Gyrotourbillon 3 Jubilee. The Gyrotourbillon 3 no longer has a bridge on top becoming a flying tourbillon fixed with ball bearing on the movement. This design was created using KEYSHOT, a software used also for the creation of the AVATAR movie. This helped the team simulating and studying the complete assembly and the mutual effects of the components.
Another novelty is the 14k gold spherical spring, thermally blued.
Manufacturing the spheroid-spiral is not an easy task: the spring is wounded around a sphere and then the sphere is removed without damaging the new shape.
The only way to check the precision is the classic way – set the time and verify after 24h and again after 48h.
The cage is done using a five-axis CNC (Computer Numerical Control) machine (a specialized milling machine) from an aluminium rod.
The speed of the tourbillon was slowed: the inner cage rotates once in one minute and the outer cage once in 2.5 minutes and the frequency has been reduced to the original 3Hz or 21,600 vib/hour. It is claimed as the most precise tourbillon with a deviation of maximum 0.5 seconds per day.
All the information, images and movies are from (and I would like to thank for):
– Jaeger-LeCoultre site
– Jaeger-LeCoultre Youtube page
– Foundation de la Haute Horlogerie
– A Blog to Watch
– The Watches TV
– Revolution Press – celebrating the machine with a heartbeat