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The Sultans of Spin: Greubel Forsey’s Invention Piece 2 with quadruple tourbillon

Date: Aug 28, 2011,14:03 PM -  (view entire thread)



Take it from me: this is the watch of the year! I saw it first at SIHH in January; and then again, just the other week when I was introduced to the rose gold/charcoal ruthenium version. In my (perhaps) jaded and tired view of most of the watch industry, the watches that really ‘rock the boat’, are far and few between. All too often there is the hyperbol and the sound bites that this is now the "latest and the greatest" and "how could we have had any watch other than this before now!" Most are not truly inventions or innovations, but simply a wrinkle on something that already exists. Some simply repackage existing movements. And then there is an invention and the watch that showcases that invention that does deliver. Greubel Forsey presented their Invention Piece 2 at SIHH detailing and illustrating the working of their Quadruple Tourbillon with the Spherical Differential at the heart of the watch. Where the Invention Piece 2 presents a new version of the quadruple tourbillion, over the regular Quadruple Tourbillon, lies in how the plates have been cut away and the movement re-arranged to allow the inner workings of the watch to be seen. This is not simply cutting away plates to reveal the inner workings of the watch's movement, this is an entirely reworked watch and movement, with a new configuration of the four tourbillon's, the Spherical Differential , the winding barrels and power reserve, and the display for telling the time.



[From right to left: IP1, IP2, and IP3. In the same order, the watches show case the inventions of: the Double Tourbillon (30°), the Quadruple Tourbillon and spherical differential, the 24 second tourbillon incline.

To my mind this is a noted return to form for Greubel Forsey in their Invention Piece series. The Invention Pieces by both their numbering and design are intended to 'showcase' Greubel Forsey's fundamental inventions. I (and a number of others for that matter as the watch sold out almost immediately upon release) thought the Invention Piece 1 was stunning in both the aesthetic design and in how traditional watch making techniques (the difficult black polishing of the flat tourbillon bridge or the frosted finish on a number of different surfaces) could be used to still produce a watch that was innovative and futuristic in appearance. For Invention Piece 2, the invention is clear, visible, superbly finished, and a joy to behold. Invention Piece 3 (introduced in between Invention Pieces 1 and 2!) was a slightly different aesthetic in terms of show casing the invention. There was less in terms of cutting away the plates, and more on the creation of an aesthetic that would draw the eye to concentrate on the 24 second inclined tourbillion. The sapphire crystal with the numbers for the hours (a 24 hour dial) was created specifically to allow a better view of the tourbillon cage. As with other Greubel Forsey IP watches, Invention Piece 3 was sold out upon release and remains sought after among collectors.



The Quadruple Tourbillon had been the watch that Greubel Forsey had entered in the 2009 International Chronometry Competition at the Musée d'Horlogerie du Locle (MIH), as Greubel Forsey felt that this timepiece had (and has) great timekeeping potential. The watch was entered at the last moment, did not fail, and completed the month long course of daily abuse and time checking. The International Chronometry Competition tests were different and less severe than the tests used as part of Greubel Forsey’s EWT (Experimental Watch Technology). The tests of Chronometry Competition were more akin to the COSC, tests on for a 24 hour cycle. Greubel Forsey EWT tests the whole useful power reserve (which equates to a maximum of three quarters of the possible running time ): which is 50 hours for the Quadruple Tourbillon, 72 hours for the Double Tourbillon 30°, and 120 hours for the Double Tourbillon 30° Technique. Hence, the EWT tests the time keeping for the watch over the most efficient level of the watches' power reserve; namely whether it is 50 hours or 72 hours or 120 hours depending on the watch. For the Chronometry Competition Greubel Forsey had to adapt the Quadruple Tourbillon specifically for the competition tests; even the rigorous shock and magnetism testing were nothing new for the mechanism, and the Quadruple Tourbillon proved itself a robust (as well as refined) mechanism for timekeeping and reliability. The EWT was always an experimental approach to understanding how one variant of a mechanism, or a change to the escapement, provides an improvement (or not) to the accuracy, consistency and reliability of the time keeping properties of the watch (http://ahci.watchprosite.com/?show=forumpost&fi=16&pi=3060676&ti=506876&msid=&s=).







[The co-axial Spherical Differential lying between the two double tourbillions, and between the main springs – beneath the display – and the power reserve indicator]

The Spherical Differential at the heart of the Quadruple Tourbillon was always intended to be an averaging device in terms of the two double tourbillons that were coupled to it. In much the same way as a car’s axle differential averages speeds across the wheels when a car turns the corner. The differential averages the rotational speeds on the four minute tourbillon cycle from the individual double tourbillons and transmits that average rotation to the hands. The Quadruple Tourbillon was never intended as a resonance effect. The proximity of the two double tourbillons was simply a result of the way the movement was designed. Fitting two double tourbillons, a main spring with sufficient reserve, and the necessary gear train along with the Spherical Differential had required that the two escapements were close. However, the time keeping properties of the invention come from the averaging of the double tourbillons that may be in different angles at different times, and therefore, on average, the two averaged across each other for the duration of the power reserve would prove a superior time keeper than one double tourbillon, or indeed a single tourbillon. In fact, if you think about the movement of the double tourbillons for a moment, there is every possibility (because of the varied movement and angles of the two one-minute 30 degree balance wheels) that the escapement wheels will not be able to synchronize as the resonance idea would require.



The initial impeteus for the Double Tourbillon 30° had been to find a Tourbillon construction that would average out the positional irregularities over the whole useful power reserve running time of the watch. Inside an outer four minute rotational cage, a one minute tourbillon rotates at an angle of 30 degrees. A standard escapement can be improved using a single tourbillon if the watch is in a vertical plane. That would probably works for a pocket watch that tends to remain vertical most of the time as it sits in the pocket or on a stand. However, a wrist watch can be in a number of positions over the course of the day; but generally in only one position at night (namely, dial up). The benefits from a standard tourbillon are therefore marginalised to the hours and minutes spent on the wrist in a vertical position. The Double Tourbillon 30° was designed to average out the positional irregularities and delivered excellent performance. However Greubel Forsey did not rest there, realisng that a movement combining two Double Tourbillon 30° systems would for the first time ever house two oecsillator and escapement systems working together to push the overall timekeeping performance even further than before. Despite the additional complexity, the differential allows the two double tourbillons to average time keeping across them. By averaging over the myriad of different positions that a wristwatch is subjected to and responding to the challenge of the watch being in one position while not on the wrist, the Quadruple Tourbillon will keep time without being subjected to possible positional irregularities.



[A progression of form: the Quadruple Tourbillon prototypes – the first on the left, the second in the middle, and the third on the right].

A better understanding of the difficulties faced in developing IP2 can be found in tracing the development of the Quadruple Tourbillon itself. I have to confess that I have always enjoyed looking at and examining the Greubel Forsey EWT movements from the inception of an idea to the finished piece. The idea started off with taking the movement from the Double Tourbillon 30°, removing the central double tourbillon, and then engineering in two Double Tourbillon 30°, and the spherical differential. You can see how the movement has been altered to test the idea of the two double tourbillons moving through the differential. The best part of the alterations lies on the dial side. The same second hand that was used on the Double Tourbillon 30° was then attached to each arm of the new Quadruple Tourbillon. The only problem being that the hour hand was now too low in terms of the repositioned second hands. The initial solution was to cut off the end of the hour hand although as sharp eyed Purists will note, the first EWT prototype can lead to the final version of the Quadruple Tourbillon with the sapphire bridge opened at 8 o’clock to allow the hand to pass.





[The back and front of the first prototype Quadruple Tourbillon: note the initially it housed a flat planetary form of the differential, then later a spherical one between the two double tourbillon’s; and the cut-off hour hand on the dial side].

Once the basic principle had been tested, the movement was refined through EWT. In this instance, with the Quadruple Tourbillon, Greubel Forsey looked aesthetically at different bridge designs and incorporating the second double tourbillion; in a technical development, the differential went from being flat in the first prototype to spherical in the second to final versions of the movement.





[The front and back of the Quadruple Tourbillon movements for the second prototype: note the change in the form and shape of the differential from a flat to a spherical form; the change in the bridges; and the cut back barrel bridge starting to take shape].

The movement that was once a very basic modified form of the Double Toubillon 30°had changed to one that has its own distinctive architecture for instance the cutaway on the barrel bridge for the main springs. The double tourbillons remain in the same position. The dial side of the movement is also beginning to resemble the final watch with a second hand and power-reserve indicators.





[The front and back of the third prototype, and near final form, for the Quadruple Tourbillon movement.]



[From left to right, from the first prototype to the final form]

The four tourbillons also remained in the same position for the 3rd iteration of the movement, but now the familiar steel bridges are in place, and the cutaway detailing have appeared on the barrel bridge covering the main springs. For all intents and purposes, this was the final form of the movement; but for an adjustment that Robert suggested. Robert felt that the 8 o’clock double tourbillon cage should be moved upwards a small amount to achieve the desired aesthetics for the timepiece. Despite the small movement of the double cage, the complete movement had to be redesigned and the various parts that make up the movement (4th iteration) had to be moved accordingly. This allowed some final technical improvements with an improved power reserve thanks to space for larger barrels. The difference between the third and the final iteration of the Quadruple Tourbillon is small, but noticeable (see photo below).



[The IP2 – face side – showing the complete mechanism on the face side of the watch]



[The IP2’s inverted double tourbillon seen through the side window]

For the IP2 watch, rearranging the two sides of the Quadruple Tourbillon, along with the power reserve and the main springs, with the differential at the heart of the movement was not a straightforward task. It required a complete new construction of the movement. One side of the Quadruple (one of the double tourbillons) had to be inverted so that the differential could be shown as part of the exposed movement. This was both for aesthetic and engineering reasons. On the one hand inverting one of the double tourbillons allowed the underside of the 30 degree double tourbillon to be shown on the face side of the watch and allowed the complete mechanism to be visible on display side of the watch: both upper and lower views of the double tourbillon 30° cage along with the spherical differential. With the double tourbillons re-positioned, it was then possible to reposition the winding barrels. Learning from the work on the Double Tourbillon 30°Technique, Greubel Forsey have stacked and positioned the winding barrels underneath the time display. This made room for the double tourbillons and Differential to be made the aesthetic centre of the watch as this was at the heart of the second fundamental invention. However, the repositioning of the winding barrels beneath the time display required that Greubel Forsey innovate and re-engineer the Spherical Differential to be co-axial in order for the power reserve to be connected the hours remaining on the wound barrels. The second hand for the four minute cycle on one of the double tourbillon's, along with the 60 second indicator, had to be replaced with a four-pronged sapphire crystal double indicator, and a fixed point indicator (respectively).



The IP2, to my mind, showcases the Quadruple Tourbillion and spherical differential as a stunning example of Greubel Forsey’s technical, aesthetical and qualitative pursuit of excellence that is evident in all their watches. I cannot conceive of a watch as technically and aesthetically accomplished released in the past year; or past few years for that matter. Although beyond the reach of most mere mortals, such as myself, and while demand for the IP2 watches far exceeded supply (by some order of magnitude), such watches are necessary. The IP2 will be the grail piece for some, a museum piece for others, but perhaps most of all, a testament to what is possible. Whichever way you want to look at it, it is the very pinnacle of invention and innovation in haute horlogerie.

Andrew H

Authors note. It should be noted that Greubel Forsey kindly allow me access to and to photograph the prototype watches. There are some small differences between the finished piece and the prototype for the released version of the IP2 watch. 

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