Regulators pt. IV

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Regulators pt. I - Everything You Need To Know
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Go from rookie to expert with our essential geek guide to the heart of a watch mechanism

 

Today’s lesson is limited to just one thing — how an escapement works. I’ve kept it deliberately so, because what we’re about to cover is intense. You could come across a hundred so-called watch experts or watch lovers in your circle, and it’s very likely that not one of them will be able to tell you how a watch escapement works. And why should they? You don’t need to know how a watch escapement works in order to love watches. You don’t need to know how a film camera works in order to enjoy a movie. Lots of people love food without knowing how to even boil an egg. But we’re committed to delivering the premise of this article series. If, for whatever reason, you need to know how a regulator works (to better appreciate your mechanical watch, to understand what your watchmaker is trying to tell you, to win an online argument against that jackass who thinks he knows watches better than anyone), this is where you should be.

So far, we know what a regulating organ is; it comprises the oscillator and escapement. We’ve covered the oscillator; it measures discrete units of time that can be translated into seconds, minutes, hours and so on and so forth. We’ve learned how the escapement is the essential element that converts the continuous rotational energy from the mainspring into the discontinuous bi-directional energy needed by the balance. But how does it do that?

Regulators

The escapement we find in the vast majority of mechanical watches is the variety known as the lever escapement. It comes in a few configurations, the most common of which is the Swiss lever escapement. It consists of two components: the lever (also known as the anchor, or pallet fork) and the escape wheel. Together, these two components act as an energy valve. They block and release the rotation of the gear train, locking and unlocking the flow of energy from the mainspring according to the oscillation of the balance, and simultaneously transferring each released dose of energy to the balance in order to keep it going.

Regulators

Here’s how the escapement draws energy from the mainspring and releases it to the balance in a controlled way. The following steps take place in the order as described, but so quickly that they seem instantaneous. As the balance swings clockwise, the impulse jewel strikes the pallet fork, causing it to pivot anti-clockwise.

Regulators

At the opposite end of the pallet fork, this pivoting motion causes the exit pallet to slide along a tooth of the escape wheel.

Regulators

Just as the exit pallet is about to move away entirely from the escape wheel, there is a brief instant where the escape wheel is now free to turn but is still in contact with the exit pallet. Remember, the escape wheel is under tension from the mainspring (via a bunch of other wheels in between). It wants to rotate clockwise, but has thus far been prevented from doing so by the exit pallet blocking one of its teeth. This is the escape wheel’s chance. Imagine a prisoner making a wild break for it when he sees his cell door creaking ajar, charging out with such force that he bashes the hapless gaoler (still with his hand on the keys in the door) in the face. The prisoner is the mainspring energy, the cell door is the escape wheel tooth, and the gaoler is the exit pallet.

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With me so far? Great. So the exit pallet unlocks the escape wheel and gets shoved in the face. Too bad for the exit pallet, but hurrah for the balance, because that shove is transmitted through the pallet fork and passed on to the balance via the impulse jewel. You might say the pallet fork is an “eye for an eye” kind of guy. He does not turn the other cheek and meekly accept abuse. Three paragraphs ago, I described how the impulse jewel strikes the pallet fork hard enough to make him pivot anti-clockwise. Here, you see how the pallet fork instantly retaliates with a perfectly placed right hook that sends the balance wheel flying. Welcome to Horological Fight Club. I’m afraid I’ve already broken the first two rules.

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Let’s check in on the escape wheel again. We all admire and cheer on a perfectly executed prison break, but don’t get too excited, because the escape wheel’s moment of liberation is tragically brief. Because the exit pallet is now pivoted completely away from the teeth of the escape wheel and the pallet fork is taking care of business on the other side with the impulse jewel, you might think the escape wheel is now free to rotate as he wishes. Surprise! The pallet fork’s other pallet, the entry pallet, steps forward to re-block the escape wheel.

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Remember, all of this takes place pretty much instantaneously. And then the same thing happens again with the entry pallet when the balance swings anticlockwise and the pallet fork pivots clockwise.

The below animation demonstrates how everything comes together. When you listen to your watch ticking, each tick is a combination of the three near-simultaneous sounds produced when the impulse jewel hits the pallet fork (unlocking), pallet fork hits the impulse jewel back (impulse) and the escape wheel hits either of the pallets (locking). Watchmakers have special machines that can pick up these sounds and analyse them to diagnose the health of your watch when it comes in for servicing.

Regulators

That’s how the balance gets its recommended daily dose of energy from the mainspring, and it’s all thanks to the hardworking and long-suffering escapement (the Tyler Durden of watch components), who really deserves a big round of applause for getting smacked around constantly (about 1.4 million times over the course of a standard 48-hour power reserve, assuming a 4Hz balance) without having a complete physical breakdown. If all this looks and sounds very complex, that’s because it is. Watchmakers are skilled individuals who spend years learning how to work with these mechanisms. Do not try this at home; I don’t care how many YouTube tutorials you’ve watched. Leave it to the professionals.

On that note, we’re ending today’s lesson. It’s time to head to the bar and get a well-deserved drink. The next chapter is all about making that final link between what goes on inside a watch movement and what we see on the dial. Compared to what we learned today, it’s a piece of cake. And everyone likes cake, especially just after a nice drink.

 

This article series is dedicated to Dr Rebecca Struthers, who kindly offered her expert comments on the text. Dr Struthers is the co-founder of Struthers Watchmakers and the first British watchmaker to receive a PhD in horology.