Regulators pt. III

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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

 

In our previous chapter, we went hardcore into oscillators and what makes them tick. (I offer zero apologies for this super basic play on words. There is far worse to come. Get used to it.) It’s now time to venture into the perilous realm of energy management and escapements. Be brave. You’ll survive it and come out stronger. But you should probably call your family and tell them you love them anyway.

At this point, we understand the function and operation of the balance in a wristwatch. It is the steady metronome at the heart of a watch movement; its oscillations count off regular fractions of a second so that we can group them into fundamental units of time — seconds, minutes, hours, days, weeks, months, years etc. It’s hard work, and hard work requires energy. Without being fed a steady stream of energy, all oscillators eventually lose momentum and stop oscillating. If you set a simple pendulum swinging in the morning and it’s still going strong at the end of the day, either you live in a world where the laws of physics do not apply or you should probably look up the number of a good exorcist.

All timekeepers therefore incorporate a source of energy that keeps the oscillator in action for extended periods of time. If you’ve ever had to wind up a grandfather clock, you’ll know that this is achieved by heavy weights, attached to a chain that is wound around a pulley. Gravity acts on the weights, pulling them downwards and making the pulley rotate. The pulley is connected to the wheels of the clock mechanism, making them rotate in turn. This kinetic energy is ultimately passed on to the clock pendulum, which allows it to keep swinging over a number of days, no ghostly intervention required.

In a mechanical wristwatch, the energy source is a coiled spring, known as the mainspring, which is housed in what we call the mainspring barrel, a hollow drum-shaped container with gear teeth on its exterior surface. The mainspring is wound up so that its coils are tightly packed together at the centre, and as it unwinds, its expanding coils make the mainspring barrel rotate. The teeth of the mainspring barrel are engaged with the wheels of the watch mechanism, which then also rotate and transmit kinetic energy to the balance. RegulatorsNow, the more astute among us will have figured out a hitch in this transfer of energy between the mainspring and the balance. The mainspring barrel rotates; it goes round and round and delivers continuous rotational energy in one direction. The balance oscillates; it turns one way and then another way, requiring discrete energy input, ideally in both directions. How do we convert the energy given by the mainspring into a format that can be received by the balance?

Think of a playground swing, another example of an oscillator. It needs to go back and forth, not round and round. If you attached a motor to the back of a swing, driving it continuously in one rotational direction, not only would that defeat the purpose of a swing, it would also put you at risk of child endangerment charges.

Back to the mechanical watch. The gear train, consisting of continuously rotating wheels powered by the uncoiling mainspring, needs to be fitted with an additional mechanism that will release discrete bursts of energy to the balance only when required, and not all the damn time. In this way, the balance will be able to oscillate in perfect tranquillity, unlike the sweating petrified child clinging on for dear life to your murder swing from hell.

This mechanism, which releases the energy of the mainspring in safe, well-regulated doses, is called the escapement (because it controls how energy escapes from its source).

Regulators

Study the above image. Memorise the labelled parts. Imprint it upon your heart and mind. Because now that you know what an escapement is and what it does, our next chapter tells you how it does what it does. Take your vitamin E, get your full dose of magnesium and zinc. You want your brain in top form for tomorrow.

 

 

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. 

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