The Evolution of Watch Movements

by Alex McKenzie on May 06, 2021
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Back in 1505, Peter Henlein created a device. To the regular eye, it looked like a sphere made of copper, with a fitted hinge in the middle and inscribings etched on its outer surface. To those who specialise in Middle Age attire, it was a splitting image of a pomander, an object designed to carry exotic fragrances. Yet housed inside this sphere was something far more significant. Henlein’s invention, today known as the Watch 1505, was the world’s first watch.

Throughout the centuries, humankind has needed a way to track time. It’s what keeps society operating as a cohesive whole, ensuring that people show up to things when they’re supposed to, and also out of the office by the time 5pm rolls around. Millennia ago, civilisation was built upon the most basic of timekeeping measures, like the sundial or the sandglass. Of course, as society has progressed, so have the developments made in timekeeping. Clocks were installed into church towers, acting as a timekeeping hub for the local area. But even between sundials and clocktowers, you might have picked up on a significant issue: these methods were the opposite of portable.

Enter Henlein and his 1505 development. Dubbed a ‘clock-watch’, it was the first wearable timekeeping device – and it revolutionised the world. Timekeeping was liberated, with a whole new industry created off its back. The watchmaking industry that we know today, all stemmed from this single creation – and it had started with a movement. Not a political movement, but a mechanical one. 

Inside Watch 1505 was a mechanism called a movement (also referred to as a calibre), the piece of engineering responsible for keeping time. Today, all watches are powered by watch movements (wearable technology doesn’t count). There are many different types of watch movement: the mechanical watch movement, the automatic watch movement and the quartz watch movement. All three are based around the same premise: they release a flow of energy through a series of parts which regulate said energy into a consistent movement of the watch’s hands. For a more in-depth explanation of how each of these watch movement types works, continue reading… 

Watch movements explained

 

Mechanical watch movement

The mechanical movement is the original style of watch movement. Henlein would have featured the very formative version of one inside his 1505 watch. A mechanical movement is different from both an automatic and a quartz movement as it relies on its user to power the watch manually, by using the crown on the side of the case (the crown being the component that allows the user to engage with the movement’s functions). This is why, in addition to being called a mechanical watch, you might hear people refer to it as a ‘hand-wound’.

Let’s start at the beginning, and work through a watch movement’s parts in sequential order. When you turn the crown to wind your watch’s movement, the crown is attached to a stem, a shaft that engages with what’s known as the ‘keyless works’. The keyless works are a series of different positions that enable the user to engage with different functions of the watch – hand-winding, date or hand changing and so on. As you turn the crown, the energy from your hand is transferred into the watch. This passes through the stem, which engages a winding gear attached to the movement’s mainspring – the development that made Henlein’s portable clock-watch a reality.

The mainspring is the power supply of the watch. Located inside a round barrel, a long ribbon of metal is coiled around a central axel. Each time you wind the crown, this spring coils tighter and tighter, storing potential kinetic energy. As it slowly uncoils throughout the day, it rotates the barrel wheel it is sat on, releasing energy into the next stage of the system: the movement’s wheels, also known as the ‘gear train’.

The gear train, or a series of wheels to the naked eye, connect the mainspring to both the hands and the escapement and balance wheel. One of the wheels completes one full turn in 12 hours, while another wheel completes a full revolution in 60 minutes. At the far end, the escapement and balance wheel are crucial in translating the unregulated energy from the mainspring into precise timekeeping.

The escapement consists of an escape wheel, whose outer edge is covered in a number of equally spaced outer teeth, and a pallet fork. As the wheel oscillates back and forth, the fork clicks backwards and forwards. The other end of the fork is connected to the balance wheel, a wheel containing a hairspring that oscillates one way and another; it receives the burst of energy from the escapement, and returns it back to the gear train at a regulated rate. This is the steady heartbeat of the watch, playing the same role as a pendulum in a clock would.

When researching a mechanical or automatic watch, you’ll see its movement’s frequency mentioned. This refers to the number of ticks, or individual movements, that the second hand achieves each second. For example, each of the watches in our TRIBUS chronometer range have a 4Hz frequency, equating to 28,800 vibrations an hour, or eight a second. That second hand smoothly sweeping around the dial is in fact a number of individual jumps, but these happen so quickly the human eye generally perceives them to be one fluid movement. It’s thanks to the escapement and balance wheel that this is possible, all whilst being worn on someone’s wrist as they go about their everyday life. That’s what makes watch movement design so special: even when you’re not thinking about it, it’s still working away, accurate to within seconds per day.

Yet there is a downside to a mechanical watch movement’s design: as the mainspring is secured to both the barrel arbor and the wall of the barrel, excessive pressure from winding can cause this to snap, rendering the movement useless. When winding your mechanical watch, if you feel a sudden resistance, stop winding – this is the movement telling you it’s fully wound. Now, if on the other hand you wanted a watch whose movement meant you didn’t have to worry about this…
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Automatic watch movement

Until the early 20th century, watches relied upon mechanical movements – perfect for timekeeping, but dependent upon being wound every day or so, with the potential of overwinding. The automatic movement can negate the need for manual intervention by using kinetic energy to wind its mainspring. Four centuries after Henlein’s first clock-watch, the automatic movement was invented in 1924. John Harwood, the British watchmaker who invented the automatic watch movement, applied for a patent for what is also called the ‘self-winding’ watch, and now a widely used technology in modern watchmaking.

An automatic calibre uses many of the same watch movement parts as a mechanical one – the crown, mainspring, gear train and escapement all appear – but with one crucial addition. An automatic movement features a weighted rotor filled with ball bearings, sat on a central pivot. As the wearer moves their wrist, gravity and other forces cause the rotor to spin, with the energy gained from this circular motion fed down through a staff into the winding stem and gears, in turn coiling the mainspring. From here on in, the automatic movement then follows the same process as the mechanical movement.

While the automatic movement is extremely useful, gaining energy from your everyday movements, let’s dispel a mistaken truth while we’re here. An automatic watch can still stop, even if you’ve been wearing it on your wrist. Imagine you’ve been sat at your desk all day, with minimal wrist activity. The mainspring in the watch will begin to unwind, releasing its energy to the gear train, escapement and balance wheel, but without any movement to coil the spring up again, it’ll only deplete further throughout the day. This gives you two options: firstly, you can give your wrist (or watch) a shake, causing the rotor to spin on its pivot; secondly, you can manually wind the watch using the crown in an identical manner to a mechanical movement. It’s up to you – and some people appreciate the choice that the automatic movement offers. Another benefit of an automatic movement is that you can’t overwind it like you can with a hand-wound. As the mainspring in an automatic movement features a clutch mechanism, this ensures that you can keep on winding without the worry of excessive tension forming in the spring.

Both mechanical and automatic movements offer the luxury of wearing a piece of living, breathing micro-engineering on your wrist, typically running to within tolerances of +/- 20 seconds per day. But if you favour something even more accurate – try accurate to within seconds per month – the quartz movement is the way to go.
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Quartz watch movement

You wouldn’t realise it today, but the arrival of the quartz movement in the 1960s nearly killed the mechanical watch. Although it wasn’t Seiko who invented the quartz movement, they did release the first commercially available quartz watch, the Astron, on Christmas Day 1969. Over the next two decades, the quartz crisis (yes, it even had a full-blown name) saw consumers surging towards companies from the Far East who were riding the wave of this emerging technology, at the expense of the Swiss industry that had chosen to keep its distance from it (there’s something of an irony when you think that the reason the Swiss hold the position they do today is because they were only too willing to embrace innovative methods that British watchmakers wouldn’t!).

Quartz was the exciting future, mechanical watchmaking the outdated past. And it’s easy to see why people were swept up in this movement of the battery-powered variety. Electricity from the quartz movement’s battery is sent through an integrated circuit via a quartz crystal. The quartz crystal, shaped like a tiny tuning fork, oscillates precisely 32,768 times per second. The electrical circuit counts these oscillations and uses them to generate regular electrical pulses – one per second. These pulses drive a stepping motor connected to gear wheels that cause the watch’s hands tick.

There are some similarities between quartz and its mechanical cousins. Instead of the mainspring, there’s a battery; instead of the escapement, there’s a quartz crystal. Yet the levels of precision enabled by quartz elevate it into a ballpark that few mechanical movements can touch. 

 

What is the most accurate watch movement?

By now, you know how a watch movement works, and the parts involved. But what is the most accurate watch movement out there?

Mechanical movements can fall within tolerances – the time it can acceptably gain or lose – of just seconds per day, although there’s a likelihood you won’t receive this level of precision without paying extra for it. This is typically where the Contrôle Officiel Suisse des Chronomètres (COSC) comes in. A testing institute for Swiss-made watches, a mechanical watch that has been COSC-certified will operate within a tolerance +4/-6 seconds per day, placing it in the top 6% of all Swiss-made watches for accuracy whilst also carrying the label of a chronometer

Having replaced dozens of tiny parts for an oscillating crystal, quartz movements immediately trump even COSC-certified mechanical watch movements for accuracy, with a non COSC-certified movement operating with a typical tolerance of -10/+20 seconds per month. If you want a COSC-certified quartz movement, this immediately means a tolerance of +/- 0.07 seconds per day!

Nowadays, some manufacturers have managed to improve the accuracy of mechanical watch movements by combining them with quartz technology, or replacing the traditional oscillating parts with silicon parts. Time never stands still in the watch industry. So the real question is: what next?
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