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In-Depth The Grand Seiko T0 Constant Force Concept Tourbillon, The First Tourbillon Movement From Grand Seiko

In-Depth The Grand Seiko T0 Constant Force Concept Tourbillon, The First Tourbillon Movement From Grand Seiko

As Grand Seiko has kept on developing throughout the last couple of years (the watches just became available external Japan, in various international markets, in 2010, and Grand Seiko was separated from Seiko as its own brand in 2018, as HODINKEE Executive Editor Joe Thompson announced ), its character has changed massively from the insider’s mysterious that it was in the earlier part of the 2000s. What hasn’t changed is the commitment to quality and craftsmanship, yet the company is presently available across a far more extensive range of costs than ever previously (the idea of a near-$80,000 Grand Seiko is as yet something I’m becoming accustomed to), and Grand Seiko has become, lately, an undeniable locus for the exploration of additional refinements in technical watchmaking as well. 

We have had two new calibers presented for the current year – the new  Spring Drive caliber 9RA5 , and another Hi-Beat caliber, with another escapement, the caliber 9SA5 . Both addressed significant enhancements in versatility and performance over their immediate archetypes, yet the 9SA5 was, for mechanical watch enthusiasts, without a doubt the greater news, especially since you don’t exactly hear about new escapements consistently – particularly ones that can be created on an industrial scale (however, for the occasion, the movement exists in the SLGH002, in which it was launched). 

Grand Seiko has recently announced that, in parallel with the advancement cycle for the 9SA5, it was also chipping away at an idea movement project, which according to GS helped produce data which was instrumental in the development of the 9SA5 into its final structure. This idea movement is quite fascinating in its own right – the tourbillon caliber T0, which, in addition to being the first tourbillon from Grand Seiko, is also the main watch of any sort from GS (or any other Seiko brand, for that matter) to incorporate the constant power gadget known as the remontoire.

Caliber T0, constant-power tourbillon, with dual mainspring barrels and twofold tourbillon cage.

I say that this is the first-ever tourbillon from Grand Seiko, and it is. In any case, it’s not the primary Seiko tourbillon – that was the Credor “Fugaku” tourbillon, which we had a chance to go hands-on with back in 2016 . That, in any case, was a fairly conventional tourbillon at least from a mechanical standpoint, although it certainly was a dramatic piece artistically, with an elaborate enamel dial addressing a famous print by Hokusai, The Great Wave Off Kanagawa. I think there are actually some tasteful similarities between that tourbillon and the T0 (that’s “tee zero” incidentally), although mechanically speaking, the T0 is a far more technically advanced mechanism.

The 2016 Credor Fugaku Tourbillon.

Leaving aside style, notwithstanding, I feel that the T0 tourbillon is a lot nearer relative to the 9SA5. Both are calibers which, however clearly planned as a statement of remarkably Grand Seiko feel, also are primarily worried about exactness timekeeping, which has been, thus, a primary worry with Grand Seiko since its beginning. The T0 was planned specifically to test the cutoff points reachable regarding exactness and accuracy, in a testbed movement actualizing new manufacturing cycles and innovations. The performance of the T0 throughout the 50-hour running time during which the remontoire is engaged is extremely great: ±0.5 seconds maximum deviation in rate each day. Grand Seiko is careful to bring up that this data comes from testing under laboratory conditions, which would not necessarily duplicate real-life results, yet to get rate stability, considerably under such circumstances, which enhances the chronometer spec by a significant degree, is remarkable.

Caliber 9SA5, Hi-Beat with Grand Seiko Dual Impulse Escapment.

There are not very many watches of any sort fitted with a remontoire, and the quantity of watches which incorporate both a tourbillon and a remontoire is extremely small for sure. Francois-Paul Journe was the first to fit a remontoire to a tourbillon in a wristwatch in 1991 , yet from that point forward, there have been not very many such watches presented. IWC presented the Sidérale Scafusia which, in addition to the remontoire on the tourbillon, also has a sidereal time complication. There is also the generally secret yet generally great and intriguing Haldimann H2 Flying Resonance Tourbillon which, in addition to being a resonance tourbillon with two balances on the carriage and a flying tourbillon and a resonance tourbillon, also has two remontoires on each of the two escape wheels. We ought to also not fail to remember the Andreas Strehler Trans-Axial Tourbillon , to which HODINKEE’s Nick Manousos presented us last year. There is also an incomplete pocket watch movement by George Daniels, in the London Science Museum , which has a co-axial escapement and remontoire – and perhaps quite possibly the most extraordinary watches to combine the remontoire with a tourbillon, is a pocket watch with twofold escape haggles remontoire on each escape wheel, by the late Derek Pratt . The combination of a tourbillon with a remontoire is adequately rare and unusual that each one of these watches and their calibers – including the T0 – present special features and mechanical solutions.

The motivation behind the innovation of the remontoire (the first to be placed in a watch was one planned by John Harrison for his H4 marine chronometer, although he had designed one earlier, for the H2 experimental sea clock) is that the force given by a mainspring decreases as the mainspring slows down. This, thus, will in general amplify balance and positional blunders, so ideally you would have a way of providing an unvarying amount of force to the escapement and balance. The fusée and chain was imagined to address this issue, which was generally extreme in the early days of horology thanks to the unavailability of anything other than plain steel mainsprings, and also attributable to the affectability of the skirt escapement (especially pre-balance spring) to variations in force. The fusée is a brilliant arrangement, however it occupies considerable room in the movement, and as well, it doesn’t give the most exact conceivable answer for giving constant force. Strehler put it very well in his conversation of his own tourbillon with Nick, remarking, “Because of its development with a characterized fusée spiral, the chain-and-fusée just compensates a theoretical variation of the force of the mainspring, yet not the force variation of the real mainspring, rubbing variations, impacts from complications, and so on. These factors can just be compensated by a remontoire, situated immediately before the escapement and acting like a filter.”

Tomoe symbol, the triple variant known as Mitsudomoe; image, Wikipedia.

One intriguing note on the plan: The balance wheel is designed according to a Japanese image known as the tomoe. This image takes after the Chinese Taiji symbol (informally known as the yin-yang image) and is regularly found in family peaks and in representative iconography at Shinto shrines. The image is extremely ancient and has many various degrees of meaning – semiotically polyvalent, as my lit-crit companions would say.

A remontoire is essentially a secondary mainspring, which is on one of the going train wheels (the fourth wheel) or on the escape wheel. It is periodically rewound by the mainspring, which doesn’t straightforwardly drive the balance – instead, the part of the mainspring is to keep the remontoire spring under constant pressure. As long as there is sufficient energy in the mainspring to keep the remontoire spring twisted, there will be essentially a constant amount of force conveyed to the balance. 

The inward and external tourbillon cages (blue) and the upper tourbillon connect. At about 12:30 you can see the final going train wheel that drives the external tourbillon carriage. The stop switch for the tourbillon is the blade spring obvious just underneath. The MEMS-fabricated skeletonized escape wheel is at the upper left, 11:00-12:00, and the ceramic stop wheel for the remontoire is at 5:00-6:00.

The caliber T0 was planned by a team drove by Takuma Kawauchiya over a five-year time span. Force comes from two mainspring barrels which run in parallel – mainspring barrels running in arrangement give a more extended force hold, however running them in parallel – that is, with both taking care of energy to the going train individually, and at the same time – gives twofold the force, and this is necessary in the T0 to control the remontoire, which adds considerably to the force demands of the movement overall. The theoretical running time is 72 hours, anyway the save during which there is sufficient force for the remontoire is about 50 hours (this decrease is par for the course with remontoires). Hand completing is found all through the movement (completing the components, says GS, required about a quarter of a year), and a special hardening strategy was produced for the second and third going train wheels to lessen grating at the teeth and pinions and improve power stream. The two tourbillon cages are in blued titanium, and the balance has adjustable planning screws for rate adjustment and a flat balance spring (this is in contrast to the overcoil found in the 9SA5; the overcoil was excluded in the T0 to diminish the already considerable stature of the movement). The T0 caliber is large however not inconvenient, at 36mm in diameter and 8.22mm thick with the tourbillon, and 6.09mm without; total parts tally is 340 components.

Understanding how the remontoire functions can be a bit of befuddling from the beginning – when you first glance at the T0, you think you are taking a gander at a three-legged upper tourbillon connect, under which is a solitary tourbillon cage with six blued titanium arms. What you are actually taking a gander at are two separate tourbillon cages, each with three arms. The external cage, which carries the constant power mechanism, is driven by the gear train. The constant power stop wheel, which rotates one tooth each second to keep the remontoire spring wound, and the escape wheel, are both rotating around the same fixed wheel. 

Kawauchyiya explains, “As the external carriage turns, it charges the constant power spring connecting the outer and inward carriage, and the charged energy will drive the internal tourbillon carriage. A pallet stone ‘plug’ attached to the internal carriage which networks with the teeth of the stop wheel [which is made of ceramic] is used to control the appropriation of energy from the constant power spring, and as energy of the constant-force spring is released, the energy is supplied to the inward carriage that drives the escape wheel that networks with the stationary wheel. The escape wheel presently supplies constant and uniform energy to the balance. While the internal carriage is rotating, the external carriage is halted by the engagement of the plug and the stop wheel. When the inward carriage rotates by six degrees, the engagement of the plug and the stop wheel is released and the external carriage rotates to give energy to the constant power spring. When the external carriage rotates by six degrees, the following tooth of the stop wheel engages the plug and the external carriage stops again. This succession of movements takes place in one-second cycles, with the goal that the second hand makes deadbeat motion.”

In this video given by Grand Seiko, you can actually see the external carriage executing its one-second jump.

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One other very unusual feature of the watch is that it is, relatively speaking, a beautiful high-recurrence tourbillon, at 28,800 vph (the default is by all accounts 21,600 vph in present day tourbillon wristwatches). Presently, this isn’t using any and all means the most noteworthy recurrence tourbillon at any point made – in 2012, the TAG Heuer MikrotourbillonS appeared with two tourbillons, one for the going train and one for the chronograph, and the one for the chronograph ran at 360,000 vph, which is, you know, pretty damned fast. In any case, I figure this may be the most noteworthy recurrence tourbillon ever outfitted with a remontoire.

If you want to see the T0 Tourbillon face to face, you should travel to Japan – specifically, to the Grand Seiko Studio Shizukuishi, in Morioka, which is Grand Seiko’s new manufacturing facility, inaugurated earlier this year. As this is an idea piece, it’s not available to be purchased (however it would not shock me if once the news is out that it exists, some individual, or around several people, attempt to get it anyway. Nothing provokes the curiosity of the top of the line authority like being told they can’t have something). It doesn’t always happen that fascinating idea pieces become creation watches, however it happens occasionally – the Cartier ID One and Two idea watches remain, sadly, just (presently already half-failed to remember) idea projects, yet then again, the Piaget Altiplano Ultimate Concept watch is being arrangement delivered, which I certainly didn’t expect – in microscopic numbers, yet at the same time, it’s a creation watch. I don’t know how much the remontoire would should be updated for a non-tourbillon watch (I presume the answer is “considerably”), however I wouldn’t see any problems in the least seeing a hand-wound Hi-Beat non-tourby with a remontoire. Regardless, I unequivocally presume that GS didn’t make this fascinating caliber just to give individuals who get to Morioka something to admire. In some structure, I think some about this tech will wind up out on the planet, underway watches. Time, as usual, will tell.

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