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Among watch enthusiasts, mechanical watches are almost always the heart of the conversation. The reason? These pieces, which embody centuries of accumulated horological expertise, represent a genuine form of excellence.
Mechanical watches are timepieces whose heart is made up of a whole array of tiny components and gears that bring them to life before our often-astonished eyes.
Among these, we distinguish two main families:
Our watchmaking guide, dedicated entirely to the subject, helps you see things clearly and make informed choices.
Let's start at the beginning and take a look at how a so-called "mechanical" watch works. As a reminder, no battery is required to power it - and that's actually where the name comes from!
Look at your watch from the front and focus on its edges. See that small ridged button - almost always on the right side? That's what's known as the watch's "crown" or "winding stem."
Watch Crown / Winding Stem
Turn that small button clockwise and you'll hear a faint click while feeling a slight resistance - that's perfectly normal. You're "winding" the watch, meaning you're feeding it energy. Think of it like charging a battery. In watchmaking terms, what you're doing is "arming" (tensioning) the mainspring inside the movement.
It consists of an extremely thin metal strip coiled around itself and enclosed in a cylindrical container known as a "barrel."
Mainspring barrel of a mechanical watch (Source: Générale Ressorts)
It stores the mechanical energy you provide with your fingers - think of it as an energy reservoir. When it is…
Some watches even feature a small indicator on the dial that lets you check the remaining power reserve at a glance. Handy, right?
Power Reserve Indicator
The correct term for a mechanical watch's maximum run time is "power reserve." To help illustrate the concept: a watch with a 38-hour power reserve, fully wound and left on a table, will run accurately for 38 hours. Simple enough. But beyond those 38 hours, the watch will continue running for a while longer - though with noticeably less accuracy, which is why maintaining sufficient energy in the barrel matters. Eventually, the watch will stop altogether.
Two tips here:
Now that you understand how a mechanical watch is powered up, you're probably wondering how it manages to display the time accurately. Totally fair question!
In reality, the energy stored in the mainspring barrel is distributed through several components. You may have noticed that the barrel features a toothed crown around its edge - that's precisely what transfers energy to the gear train. The gear train, in turn, delivers that energy throughout the movement.
But that energy has to be controlled - otherwise the gear train would spin at a completely erratic pace. That's where the escapement comes in!
Escapement of a Mechanical Watch (Source: Europa Star)
This small assembly of parts is designed to prevent energy from flowing freely - in other words, it's there to keep everything in check.
The escape wheel is connected, via its teeth, to a T-shaped component called the "lever" (or pallet fork). Its role is to alternately lock and unlock the escape wheel using its pallets. The name comes from its resemblance to a ship's anchor.
Lever escapement of a mechanical watch (Source: Chronotempus)
The lever fork then works in concert with an element known as the "impulse pin." The back-and-forth motion of the balance wheel - commonly referred to as "oscillations" - directly controls the escapement.
Balance wheel and hairspring of a mechanical watch (Source: Wikipedia)
The hairspring - also made from a coiled metal wire - then works to keep the oscillations as regular as possible.
To regulate the rate of a mechanical watch (its accuracy), the hairspring can be adjusted. It is controlled by a "regulator lever" which, depending on its position, either tensions or relaxes the spring.
Regulator lever of a vintage Omega watch (Source: Forum A Montres)
This is why you may see the markings "+/-," "F/S" (for "Fast/Slow"), or "A/R" (for "Advance/Retard") on mechanical movements.
Note that depending on the movement, the balance wheel can make between 18,000 and 28,800 beats per hour. This is referred to as "vibrations per hour" or "operating frequency." While most watches on the market run at 21,600 vph, the most high-performance mechanical models can reach an operating frequency of 36,000 vph.
In theory, the higher the operating frequency, the greater the watch's accuracy.
Operating Frequencies of Mechanical Movements
The movement of the seconds hand - known as the "sweep seconds" - is directly linked to the operating frequency of the movement. On a movement running at 28,800 vph, the seconds hand moves 8 times per second.
The higher a movement's operating frequency, the smoother the sweep of the seconds hand. On a high-frequency or "Hi-Beat" watch, the seconds hand glides with virtually no visible stepping.
Manual-wind mechanical watches are considered the most classic timepieces of all. Descended directly from the pocket watches of old, these pieces - whose movement only runs when wound by hand - were long the standard. In fact, the vast majority of mechanical watches sold during the first half of the 20th century were of this type.
Today, manual-winding mechanical watches still exist, but they are becoming increasingly rare on the new market - despite the many advantages they offer.
Keep reading to discover all their secrets!
If you've read our guide "Watchmaking: History and Evolutions," you already know that watches with mechanical movements have been around for a very long time.
It was the gradual evolution of watchmaking techniques - from the Neolithic period through the early 20th century - that gave rise to the first manual-winding mechanical watches designed to be worn on the wrist.
Remember, before the 1900s, watches were primarily designed to be carried in a vest pocket or worn directly around the neck.
In short, the history of these timepieces is fascinating!
Like everything in life, manual-winding mechanical watches come with advantages - but also a few drawbacks…
Automatic watches are today the most widespread type of mechanical watch.
For simplicity, we'll use "automatic watch" throughout to mean "automatic mechanical watch."
Let's get straight to it and discover together how automatic watches came to be.
Automatic watches are considered an evolution of manual-wind mechanical watches. But do you actually know when they first appeared?
To understand this, a brief look at history is in order. So get ready for a journey through time - one that begins precisely in 1777, when Swiss watchmaker Abraham Louis Perrelet developed a rotating rotor system capable of winding pocket watch movements.
Self-Winding Movement by Abraham Louis Perrelet, 1977 (Source: Time Transformed)
While the concept had limited appeal for pocket watches, it was a completely different story for wristwatches. Since a wrist can generate up to 40,000 arm movements in a single day, a rotor-based automatic winding system could be enormously beneficial.
In the 1920s, British watchmaker John Harwood filed a patent for an automatic wristwatch that winds itself via an oscillating weight.
Vintage advertisement for the Harwood automatic watch (Source: Paul Bouyssou)
Keep in mind, however, that the oscillating weight in Harwood watches did not spin freely above the movement - its travel was actually stopped by two shock absorbers.
In 1930, French watchmaker and jeweler Léon Hatot also filed a patent for an automatic watch with a rather unusual mechanism. In his invention, it is the entire movement that shifts and acts as the oscillating weight.
Rolls ATO Watch by Blancpain (Source: LOT-ART)
When the watch is moved, its dial appears to float on a vertical axis. This is due to its sliding movement mounted on a ball-bearing system. That's why, when you look at a watch of this type from the front, the dial seems to glide behind the crystal. It was Blancpain that would bring Léon Hatot's watch to market, under the name "Rolls Ato."
As a side note: by doing away with the crown, the watches conceived by John Harwood and Léon Hatot were also trying to solve another problem that plagued timepieces of the era - water resistance.
Shortly after, calibers heavily inspired by the automatic movement developed by Harwood began to appear. In their design, an oscillating weight - or "rotor" - moves within a limited space before hitting two cushioned stops.
While the term "bumper movement" is sometimes used to describe a movement of this type, "bumper movement" itself seems to be by far the more widely used term in everyday conversation.
Omega bumper movement (Source: Goldammer Archives)
It's worth knowing that during the 1940s and 1950s, bumper movements were used by major watchmaking houses such as Mido, Omega, Movado, Fortis, Juvenia, Richard, and others.
In 1931, Rolex unveiled its first perpetual movement, the cal 620, and 2 patents related to it were filed in 1933. The centrally positioned rotor spins freely, continuously winding the watch - hence the name "Rolex Perpetual."
Rolex 620 Automatic Movement (Source: Rolex)
The Rolex caliber 620, with its fully free-spinning oscillating weight, served as the foundation for all the automatic movements we have today. However, despite its innovative design, the crown brand's mechanism had one significant technical limitation: its rotor only wound the watch when rotating in one specific direction.
It wasn't until the 1940s that a rotor-based automatic movement capable of winding the watch in both directions finally hit the market.
This caliber, developed by Felsa, was named the "Bidynator" and came in two versions: the F 690 (without date) and the F 692 (with date).
Exploded View of a Felsa Bidynator Movement (Source: Jacques Etoile)
Several major watch houses, including Breitling, Arsa, Onsa, and Eberhard & Co., would adopt this type of movement.
In the 1950s, a brand-new type of automatic movement appeared, equipped with a mini oscillating weight known as a "micro-rotor." Patented by Swiss house Universal Genève in 1954, this caliber features a unique architecture in which the oscillating weight is housed directly within the movement. To achieve this, the rotor size must be drastically reduced - which is why it's called a micro-rotor.
Universal Genève micro-rotor movement (Source: Montres de luxe)
In 1957, the brands Buren and Piaget also joined the movement, helping to bring the concept to a wider audience.
With their discreet oscillating weight, micro-rotor movements offered a slim profile, making them a go-to choice for crafting the thinnest automatic watches of that era.
Universal Genève White Shadow Watch with Micro-Rotor (Source: Adam Vintage)
Certain vintage models from the Universal Genève Shadow line can be cited here as examples.
Their unique architecture combined the slimness of manual-winding movements with the convenience of automatic winding movements.
It's also worth noting that today, several watchmaking brands are trying to develop their own micro-rotor movement. This is notably the case with Yema and its Calibre CMM.20 - the very first French movement equipped with a mini oscillating weight. How's that for national pride!
Whether you choose a manual-wind or an automatic mechanical watch, keep in mind that either will be somewhat sensitive to shocks. But don't worry - as long as you're reasonably careful and avoid wearing your watch during heavy physical work, for example, it shouldn't be an issue at all.
Furthermore, any mechanical watch, regardless of type, will need a complete service by a watchmaker approximately every 7 to 10 years.
To better understand the world of watch movements, it's important to keep in mind that not all watchmaking manufacturers produce their own movements.
When a company develops a movement in-house with the intention of fitting it in its own watches, it is referred to as a "house movement," a "manufacture movement," or simply an "in-house movement." All of these terms - which you'll come across on watch blogs and forums - mean the same thing.
Audemars Piguet Manufacture Automatic Movement (Source: La Cote des Montres)
Developing an in-house movement takes considerable time and is above all extremely costly. It also represents a real risk for brands, which - once the movement is produced - must be able to recoup the investment over very high volumes. Watches equipped with a manufacture caliber represent a broader vision and are, more often than not, highly respected by collectors. Having an in-house caliber in your watch is considered a real mark of distinction.
When a watch brand decides to source its movements from a third-party supplier, it uses "ebauches." Simply put, ebauches are movements delivered in kit form - meaning the components are unassembled. Once received, the brand assembles them and sometimes customizes them to best suit its watches. In technical terms, the brand is said to "case" the movements.
While the most powerful and luxury brands are able to develop their own in-house movements, the majority of watch brands today turn to specialized suppliers for their ebauches.
The watchmaking world is home to a large number of ebauche manufacturers, including ETA/Valjoux (Swatch Group), Sellita, Miyota (Citizen Group), Soprod (Festina Group), SeaGull, Seiko, and La Joux-Perret… As you can see, the list goes on.
The Main Blank Manufacturers
These companies can be of Swiss, Japanese, Chinese, or French origin, making it possible to source blanks from all four corners of the world. But be careful not to assume that all blanks are created equal. They come in every price range - while some budget-friendly models are favored for entry-level watches, others at the higher end are often selected to equip the most prestigious timepieces.
Miyota 8215 automatic movement (Source: Miyota)
Some movements have been produced for decades, in the millions. That's how the Miyota 8215, the ETA 2824/2, the Valjoux 7750, and the ETA 2892 A2 became landmark calibers - names that most watch enthusiasts know by heart.
What do the following watches have in common?
Automatic Watches with Sellita SW200 Movement
They all share the same Sellita SW200 movement as their base!
You may have noticed something: several well-known watch brands like Seiko or Citizen manufacture their own in-house movements and also supply other watchmakers with ebauches. That's entirely correct.
A Miyota movement (Citizen Group) can be considered an in-house caliber when fitted in a Citizen watch. However, the same movement placed inside a watch from a brand outside the Citizen Group would not be considered a manufacture movement. It all comes down to lineage.
Also keep in mind that the same ebauche movement can be offered in different quality grades. At ETA, for example, the caliber 2824 is available in "Standard," "Elabore," "Top," and "Chronometer" grades - each offering different finishing levels and performance specs.
COSC Chronometer-Certified Valjoux 7750 Movement (Source: The Naked Watchmaker)
Names can vary from brand to brand. Sellita, for example, uses the designations "Standard," "Special," "Premium," and "Chronometer" to indicate the quality of its movements.
Finally, it's worth noting that in-house movement development is a growing trend. Several brands - including Oris with its caliber 400, Yema with its CMM.20, and Tudor with its Manufacture Calibre MT5601 - have embraced this path, which often signals a step up in quality.
The accuracy of a mechanical watch is expressed as "drift" and measured in seconds per day. While it typically falls within +/- 30 seconds per day, it can reach as low as +/-2 seconds per day on the most high-end models.
Accuracy test of a watch on a timegrapher (Source: Vintage Watch INC.)
This is worth emphasizing: no matter how high-end a mechanical watch may be, its accuracy will never match that of a quartz watch.
While mechanical watches generally deliver perfectly acceptable accuracy for everyday use, some models can gain or lose several seconds - or even minutes - within just a few days. That's why many mechanical timepieces need to be reset from time to time.
To revisit the example of the ETA movements mentioned just above, note that depending on their finishing level (called "grade"), their accuracy can vary considerably. To illustrate this, here are the regulation specs for the 2824-2 movement:
In practice, a watch rated at +/-30 seconds per day accuracy could run anywhere from -30s/day to as little as +2s/day off. When all is said and done, it's a bit of a lottery!
Tudor Watch COSC Chronometer Certified (Source: Montredo)
If you want to be certain of acquiring an ultra-precise mechanical timepiece, you'll want to look for what's known as a "chronometer watch" (not to be confused with a "chronograph watch," which measures elapsed time).
Chronometer watches are models that have passed a rigorous battery of tests to deliver an exceptional level of accuracy. Today, the most recognized certifications include the COSC, the Rolex Superlative Chronometer, METAS, the Vipère de Besançon, and the WEMPE Chronometer. Each has its own specificities and different tolerance thresholds.
The Main Chronometric Certification Bodies and Their Standards
While these 5 chronometric certifications are the most widely recognized, there are many others, including the "Poinçon de Genève," the "Patek Philippe Seal," the "Grand Seiko Standard," and the "Fleurier Quality Foundation."
As this guide has shown, manual-wind and automatic mechanical watches are the pinnacle of watchmaking. Their operation draws on a long - very long - tradition of horological expertise, which is exactly why some enthusiasts swear by them and nothing else. Both offer real advantages, but each comes with a handful of drawbacks worth weighing before you commit to a purchase.
Keep in mind that even if mechanical watches are seen as a symbol of horological prestige, their accuracy simply cannot compete with that of quartz or connected watches. It comes down to a choice between tradition and technical performance - and that's a call only you can make.
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