The World’s Thinnest Automatic COSC & Geneva Seal Stop-Seconds Tourbillon

Why Is COSC Certification Important for a Tourbillon? This goes to the roots of the tourbillon’s raison d’être, which is to be a chronometric device. Back in the 18th century, gentlemen of substance and style wore pocket watches in their waistcoats. In the evening, they would often hang these pocket watches on small nightstands, meaning that these timepieces spent the majority of their time in the vertical position. But this caused a problem. It was discovered that gravity had an erosive effect on timekeeping because the hairspring powering the oscillations of the balance wheel would not breathe concentrically. Further, an uneven friction was placed on crucial pivots such as the balance staff and that belonging to the escape wheel. It was the genius Abraham-Louis Breguet who came up with the solution. He placed all the regulating organs consisting of the balance wheel, the hairspring, the escape wheel and the lever inside of a cage which rotated once on its own axis every minute (initially this was slower), thereby averaging the errors caused by gravity. He named this extraordinary device the tourbillon or “whirlwind,” for obvious reasons.

 

It was the genius Abraham-Louis Breguet who came up with the solution. He placed all the regulating organs consisting of the balance wheel, the hairspring, the escape wheel and the lever inside of a cage which rotated once on its own axis every minute (initially this was slower), thereby averaging the errors caused by gravity. He named this extraordinary device the tourbillon or “whirlwind,” for obvious reasons. In 1947, Omega made a series of 12 tourbillon wristwatch calibers for use in the famous chronometric trials. These movements designated caliber 30 I were never cased until 1987 when they were rediscovered in storage, then overhauled and placed in watches. The first commercially produced tourbillon in wristwatch format was created in 1986 when Audemars Piguet launched the exquisite, though technically flawed (the winding function wasn’t great), ultra-thin automatic wristwatch tourbillon designed by the incomparable Jacqueline Dimier.

But one question soon emerged, and that was, as a wristwatch spends its time in many different positions and not just in the vertical position, does a tourbillon still have any functional relevance? Well, leave it to Patek Philippe to respond to this in the way they knew best — by simply ending all debate and achieving COSC certification for their tourbillons as chronometers. For many years, and throughout the massive boom in tourbillons during the early 2000s, Patek Philippe remained the only brand with COSC certification for their tourbillons. That is despite the rise of many brands that added constant force mechanisms and chain and fusées to their tourbillons, all in the pursuit of improving chronometric performance. Some brands even went so far to say, “We cannot send our tourbillons for COSC certification because they have no seconds hands.” Which is absolute rubbish because you can stick a seconds hand to any point on the cage that rotates precisely once every minute. Patek Philippe remained alone in empirically proving the chronometric value of their tourbillons until Chopard L.U.C entered this realm with the Quattro Tourbillon, a tourbillon with a vibrational speed of 4Hz powered by four barrels and a power reserve of eight days, accompanied by the Geneva Seal and — drum roll please — yes, COSC certification.

Says Karl-Friedrich Scheufele, “When we approach any complication, we want to do so with the utmost respect and authenticity. For our tourbillon, this meant that it had to be COSC certified to prove it was genuinely chronometric.” Which is, of course, a typically polite statement from a true gentleman. However, I will go one step further to emphatically state that, to me, a tourbillon without COSC certification or the equivalent of one is a watch with a visually entertaining device but zero horological validity. This is why I have so much respect for Chopard L.U.C in that all of its watches but one (an ultra-thin watch with no seconds hand) has received both the Geneva Seal, as a testament to their refinement in finish, and COSC certification to validate their accuracy. Accordingly, the Chopard L.U.C 1860 Flying T, Special Revolution is a genuine COSC-certified chronometric masterpiece.

Why Are Stop-Seconds Tourbillons Superior to Other Tourbillons? This follows the logic that if a tourbillon was created to be a chronometric device, then in order for it to be set accurately, it had to have a stop-seconds or hacking seconds function. Think about it this way. Back in the day when the SAS (Special Air Service) were using their 5517 MilSubs to coordinate clandestine attacks, they set their watches to the same time down to the second. Which was why it was important that their watches had a hacking function. You couldn’t say to your commander, “Oh wait, hang on, sir, the seconds on my watch doesn’t hack, it keeps running. Can I be approximately synchronized with everyone else?” This would probably result in your being jettisoned from the cargo bay of the transport plane sans parachute. And you would deserve it, right? So then, how is it that while there are hundreds of tourbillons in existence, there have only been six wristwatch tourbillons  with a stop-seconds function? The answer is, they are difficult to make and a pain to set up perfectly. But once they have been set up, they are clearly superior to versions without stop seconds. Even Breguet saw the technical merit in the creating of a stop-seconds tourbillon as he made at least one example of this watch during his lifetime. This was No. 1176, the Garde Temps Four-Minute Tourbillon, dated to 1809. The first wristwatch tourbillon with a stop-seconds function dates to 2008 and was the A. Lange & Sohne Cabaret Tourbillon. This watch was discontinued in 2013 but it has been revived this year in a stunning Handwerkskunst limited edition. Lange’s innovation was to create a Y-shaped stop-lever to stop the balance wheel, even when one arm was potentially blocked by the pillar of the cage. This same solution was used for the 1815 Tourbillon, which ingeniously incorporates a heart-cam on the tourbillon pinion to make for a zero-reset seconds hand when the tourbillon is arrested.

Moritz Grossmann, another brand based in Glashütte, Germany, also has a stop-seconds tourbillon — leave it to the Germans to be obsessed with precision — and uses a tiny brush made from human hair that acts as a brake on the balance wheel. If the pillar of the cage gets in the way, the brush will split and still contact the balance wheel.

The Grönefeld Brothers make a watch called the Parallax Tourbillon, which features a massive seconds hand that in combination with the raised outer seconds track is meant to eliminate parallax error; hence, the watch’s name. When you push in the crown here to the setting mode in this watch, a stop lever comes into play, acting on the tourbillon cage and causes both the  seconds hand and tourbillon cage to stop at precisely 12 o’clock to allow for a pseudo “zero-reset” type of accurate time setting.

 

The Montblanc ExoTourbillon features a deconstructed tourbillon where the cage, hairspring and balance sit at different levels. As such, the stop-seconds lever can directly contact the balance.

IWC’s flying tourbillon also has a hacking function. When you pull out the crown, a pair of brake arms descend on the balance wheel. But what happens if the pillars of the cage get in the way? IWC have very cleverly mounted these brake arms on springs, so they are able to flex and move around the pillars should they be in the way — a typically ingenious solution from Schaffhausen.

It is not lost on me that of the other five brands that have incorporated the stop-seconds function into their tourbillon wristwatches, two are German, one is Dutch, and one is made in Switzerland but its parent company is based in Hamburg, Germany, and one sits at the very border between Switzerland and Germany. Perhaps the proximity to Germany and its culture for ultra-precision has something to do with the desire to make a better tourbillon.

But this is where Chopard L.U.C has again brought a game-changing level of innovation to the stop-seconds tourbillon. Because, here the brake function is not applied to the balance but instead to the cage, somewhat like that in the case of the Parallex Tourbillon. Further, because the cage of the tourbillon is exactly the same diameter as the tourbillon aperture on the dial, the brake function is hidden from view so that it is, in effect, a mysterious stop-seconds tourbillon. This is what happens when you pull the crown out on the Chopard L.U.C 1860 Flying T, Special Revolution. The tourbillon cage on which the seconds hand is mounted stops dead in its tracks. The balance wheel will power down by oscillating a few times then come to a standstill. But what is important to understand is that these oscillations have no effect on the timekeeping accuracy of the watch. Why? OK, let’s explain how this tourbillon works. The first wheel, which is powered by the barrel engages the center wheel, which turns the cannon pinion that drives the minute and hour wheel. The center wheel turns the third wheel, which engages the pinion of the tourbillon cage. The cage drives the escape wheel around a fixed fourth wheel, which powers the lever which causes the balance to oscillate.

When you stop the cage, you stop the entire motion works of the gear train, meaning the minute and hour hands cannot turn — time is frozen in place. When you lift the brake off the cage, it is the third wheel being driven by the barrel through the other wheels that starts the balance again. In fact, you could make an argument that stopping the cage rather than the balance is a much less aggressive way to create a stop-seconds tourbillon, because the balance wheel is delicately regulated and poised to oscillate uniformly. The rapidity with which the balance starts to oscillate again is based purely on the quality of torque coming from the mainspring and flowing through the gear wheels. And in this case, the L.U.C 1860 Flying T, Special Revolution wins again as it has the advantage of being powered by a pair of stacked twin barrels. Ultimately, not only is this Chopard watch a remarkable feat of technical innovation, but it is also extraordinary in terms of how wearable it is. The IWC tourbillon watch with hacking function is 16.9mm in height. Compare this with the L.U.C 1860 Flying T, Special Revolution’s incredible 8.2mm in height. The fact that this watch is an automatic, micro-rotor driven, stop-seconds flying tourbillon with Geneva Seal and COSC certification makes it, to me, the most extraordinary timepiece in the tourbillon category hands down.