Feature: The Tourbillon
The tourbillon is perhaps the most impressive complication in watchmaking. It’s also not really a complication, nor is it, in a wristwatch, particularly useful. So, what is it, how does it work, and if it’s so useless, why are we so obsessed with it?
You may have heard of a guy called Abraham-Louis Breguet. He was a watchmaker in the 1700s and was kind of a big deal. Of the many things he contributed to the fine, mechanical art of watchmaking, one of them was the tourbillon. If you speak French, that means whirlwind; if you speak watchmaking, it means you’re in for a treat.
Let’s first understand why the tourbillon exists before we uncover why it doesn’t need to. When someone—like our good friend monsieur Breguet—makes a mechanical watch, they’re harnessing the power of motion in order to tell the time. Like a row of dominos, a mechanical watch passes motion down a line of parts all fine-tuned to make sure that motion stays in check.
You can see that clearly in this Ulysse Nardin, which the company has kindly skeletonised to demonstrate the point. The mainspring, coiled up in the barrel at the top, turns slowly, passing that motion on to a string of gears that feed the hands to represent the passage of time. But there’s a problem, one that took centuries to solve: regulation.
The word regulation brings to mind feelings of order, uniformity, regimented stability, and that’s exactly what the escapement in a watch hopes to achieve. As anyone who’s ever blown up a balloon and let it go will know, elastically stored energy is not easily released in a gentle, uniform flow: left to its own devices, it blasts out as fast as it possibly can, making a humorous noise as it does.
And so, the escapement brings order to chaos, pinching the neck of the balloon and letting energy out in bursts so short and so controlled they would have Corporal Dwayne Hicks proud. Although there have been many ways of doing this, the most prevalent is the Swiss lever escapement, which combines an escape wheel, pallet fork and balance wheel to act as the fingers pinching and releasing the progress of motion through the movement many times per second.
Let’s break that process down. The pinching part is easy; all you need is to jam the wheels and the mechanism stops; the tricky part is getting it going again. But in actuality, the motion never ceases—it’s merely transferred. When the pallet fork—which does the jamming—is knocked into place by the escape wheel—which gets jammed—and the movement is stopped, the other end of the pallet fork also gives the balance wheel a nudge. The balance wheel spins one way, coiling the balance spring at its centre, which then uncoils and spins the balance wheel back again, preserving the motion of the movement while it is locked. On its return, the balance wheel gives the pallet fork a tap, unlocking it and starting the whole process over.
As you can imagine, the tolerances involved here are tighter than a supermarket parking space, and such delicate machinations are very easily influenced by outside forces—such as gravity. Here’s where the tourbillon comes in, because our old mate Breguet had an idea: what if he could build an escapement that ignored gravity altogether.
The tourbillon, as Breguet proposed it, is ridiculous. All of that complexity, delicacy—his plan was to contain it from gravity. Gravity. The thing that keeps us all stuck to the ground, that stops the moon floating off into space, Breguet decided that he would just make it null and void. And if that sounds crazy, his plan for achieving it is even crazier: he wanted to take the entire escapement, all those parts moving in sync together, and rotate them, not once, not twice, but perpetually.
And would you believe it, he managed to pull it off. In 1795. By hand. This tourbillon, as he called it, really did encapsulate the regulating system of the watch and set it on a spin, thereby taking every angle of its action and presenting it to the force of gravity equally, effectively cancelling it out. The complexity of this mechanism remains one of the most impressive to this day, and—despite not offering any additional functionality—is heralded by many as the pinnacle of watchmaking.
But how does it actually work? The impressive display seems impenetrable at first glance, but the reality is that it’s really, surprisingly, rather straightforward. Don’t confuse this sentiment with it being easy to make—it’s not—but the efficiency of the design means that Breguet only needed to add one extra step to the standard mechanism. Rather than have the last wheel in the chain drive the escape wheel, it instead turns a cage into which the escapement is fitted. This is called the tourbillon cage and is the structure that gives the tourbillon its trademark appearance.
The connection between the escapement rotating within the cage and the rest of the movement is what’s really clever. A gear, stationary and undriven, sits below the tourbillon cage, seemingly doing nothing. But peer at the underside of the escape wheel and you’ll see that it does indeed serve a purpose. Hanging from the escape wheel is a small gear, and as the tourbillon cage rotates, this smaller gear orbits the larger stationary gear, which meshes with it, making it turn. This then spins the escape wheel, which drives the escapement itself as normal. Genius.
Whilst the concept itself is surprisingly simple, the complexity comes in the execution. When you realise that watchmakers have to consider the torque implications of having a hand that’s a bit too big, the headache derived from propelling an entire tourbillon around whilst keeping its mass evenly distributed becomes apparent. Despite being asymmetric, it must be completely balanced and as light as possible; in the case of this Ulysse Nardin Skeleton Tourbillon, the use of silicon and a 170-hour power reserve gives it the poise and grunt it needs to run.
So why is this fascinating bit of engineering considered null and void? Well, it’s simple: when Breguet had his idea, he wasn’t thinking about wristwatches, he was thinking about pocket watches. A pocket watch hangs on end all day, balance wheel orientated to the ground like the wheel of a car, constantly fighting the pull of gravity. A watch? It mostly moves about, and when it is resting, the balance wheel is usually parallel to the ground and less imbalanced by gravity, so the tourbillon doesn’t really have any work to do.
But before we all reach for our pitchforks, remember this: there may be no need for the tourbillon any more, but then there’s no need for mechanical watches, either. So, why do these things still very much exist, then? Because, in a world of instant information, fast food, high-flying, rat-racing, social media feeding frenzy, never stopping, never resting, never breathing—they make us take a minute, slow down, appreciate every tick and every tock—and that’s got to be a good thing.
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