How does the chronograph of a mechanical watch work?
The world of watches offers a wide variety of functions. There are moon phase displays, tourbillons, or even perpetual calendars. There is almost no limit to the sophistication of the movements that make these functions possible. One of the most well-known and popular complications is the chronograph.
Legendary watches like the Rolex Daytona as well as the Omega Speedmaster have a chronograph. But what is its function anyway?
The chronograph is a complication on mechanical watches that allows you to stop and measure the time. The chronograph can always be recognised by the additional buttons next to the crown and the two or three additional subdials. Furthermore, thanks to a tachymeter on the bezel, it is possible to determine average speeds over certain distances.
What is a chronograph?
Essentially, a chronograph is a watch that allows the wearer to measure time with greater precision.
In contrast to a regular watch, which only displays the current time, a chronograph has an additional counter, which enables the stopwatch function.
However, it is important to note, that the chronograph of a mechanical watch is not a pure stopwatch, as the movement does not stop when you stop the time. So you can stop the time and read the regular time simultaneously.
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What does a chronograph do?
The function has countless applications. Athletes, for example, use chronographs to tell the time during activities such as racing, swimming or skiing. Pilots use chronographs to determine the elapsed time between different stations.
How to recognise a chronograph watch
A characteristic main feature of a chronograph watch is initially two or three additional subdials, known as totalizers. These are usually integrated centrally into the main dial to precisely read the measured time on a separate scale ring. The subdials show the elapsed seconds, minutes, or hours.
Another unmistakable feature is the presence of special pushers or buttons, placed on the side of the case. These buttons allow the wearer to start, stop, and reset the chronograph. They are typically located on the right side of the case, to the left and right of the crown, and are therefore easily accessible for comfortable operation.
Additionally, a chronograph watch can be recognized by its distinctive bezel. Often, there is a tachymeter or telemeter scale to measure average speeds over a specific distance. In rarer cases, these scales are also on the dial.
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The history of the chronograph
First of all, it must be said that it is disputed who invented the chronograph. Numerous technical innovations were necessary before the chronograph as we know it today was invented.
Therefore, the history of the chronograph is more a fluid development than a sudden invention.
In 1816, Louis Moinet invented the first chronograph, a hand-wound device that served as a timepiece for astronomical observations.
A few years later, the French watchmaker Nicolas Rieussec developed the first portable chronograph in 1821, but it could not yet measure seconds.
Over time, the chronograph has been improved to allow more precise measurements.
The Breitling brand also played a significant role in this development. In 1915, Leon Breitling invented the first independent chronograph pusher.
About twenty years later, in 1936, Longines received a patent for the Caliber L13ZN with a flyback mechanism, which allowed the chronograph to be quickly reset and restarted during an ongoing measurement process.
Thanks to the flyback function, you can start, stop, and reset with just one button press. With a non-flyback chrono, you would need three button presses for this.
However, the chronograph did not have its major breakthrough until the 1960s, as it became an essential instrument for the aviation industry and space missions as well as motorsports.
NASA used special chronographs for its Apollo missions and special chronographs were also developed for Formula 1 racing drivers to measure speeds and lap times accurately.
The chronograph became famous in 1969 when Zenith TAG Heuer and Seiko launched the first fully integrated automatic chronographs.
The most popular chronograph is the El Primero, which was also used in the Rolex Daytona until the year 2000. Since then, Rolex has been using its in-house chronograph movement.
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How does a chronograph work?
The sophisticated complication usually has a separate movement that runs in addition to the main movement.
This consists of several components, including a switching mechanism, a chronograph movement and a hand movement.
The switching mechanism that controls the chronograph's start, stop and zero-setting functions is the core of the complication.
It consists of a frog, a ratchet wheel and a lever. When the start pusher is pressed, the lever engages the switching mechanism and brings the switching wheel into engagement with the slipping clutch. This sets the gear wheel of the chronograph mechanism in motion and the cronograph movement begins to tell time. This can then be read on the totalisers.
When the reset pusher is pressed, the lever re-engages the gearshift mechanism and lifts the gearshift wheel off the slipping clutch, resetting the chronograph wheel to the start.
When stopping, the hands of the chronograph movement remain in their current position. However, the normal timekeeping continues, and the wearer can read the exact time while the chronograph displays the measured time.
How do you use the chonograph?
The timing starts as soon as the start/stop button on the side of the case is pressed. The central seconds hand moves, and the timing begins.
To stop the chronograph, the same button must be pressed again. The central seconds hand then remains in its current position, while the normal timekeeping of the watch continues.
If you want to reset the chrono, the reset button must be pressed. This stops the chronograph movement and resets all hands back to the zero position.
If you have a watch with a tachymeter, such as the Rolex Daytona, you can also measure average speeds. The scale indicates the average speed over a distance of usually one mile or one kilometer. The seconds hand of the watch is always set to 0 during the stopping process.
This then not only shows the elapsed time, but also the average speed, which can be read off the bezel.
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Does the chronograph only exist for mechanical movements?
The answer is no. While mechanical movements are often associated with chronographs, there are also quartz watches that offer this function. In such cases, the chronograph is controlled by an electronic impulse, which allows for accurate and precise time measurement.
Nevertheless, mechanical chronographs still have a special appeal because they are considered masterpieces of the watchmaker's art.
Conclusion
In summary, the chronograph is a complex and fascinating instrument that has revolutionised timekeeping in a precise and elegant way.
The chronograph remains a flagship of the watchmaker's art that is both aesthetically pleasing and practically useful.
While the function is often associated with mechanical movements, it is also available in quartz watches.
Whether mechanical or electronic, the chronograph remains a remarkable technical feature. But above all, the fascination for mechanical watches is maintained by complications such as the chronograph.
Scource cover image: Rolex
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Q&A
What is a chronograph?
A chronograph is a function in watches that allows the time to be measured in a precise way, independent of the normal timekeeping functions.
When was the chronograph invented?
It is difficult to determine exactly when the complication was invented. The chronograph had its beginnings in the early nineteenth century and evolved over the years.
What are the most popular chronograph models?
Among the most popular models are the Rolex Daytona and the Omega Speedmaster, as well as the TAG Heuer Carrera and the Breitling Navitimer.
How do I recognise a chronograph?
You can recognise it by two or three sub-dials, which are usually integrated in the centre of the main dial, by a tachymeter on the bezel and by the two buttons to the left and right of the crown.
How do I use a chronograph?
To use a chronograph, start the timer with the upper pusher, stop it with the same pusher and reset it with the lower pusher.
Are chronographs only available on automatic watches?
No, there are also quartz watches that offer this function.
About the author
Alexander Weinberger
For me, the most fascinating thing about watches is the interplay between precise craftsmanship and artistic development. In a watch movement, hundreds of small parts have to be put together precisely so that they form a large whole.
