Dr. Ito's thorough analysis of mechanical watches!! Vol.19 ~About the chronograph function~

Good evening, everyone!

This column discusses mechanical watches from an engineer's perspective. For our 19th installment, we will be discussing:

"The Functions of a Chronograph"

I will be talking about this topic.

Chronographs are featured in many popular models, such as the Rolex Daytona. My impression is that many people choose a chronograph simply because it "looks cool!" However, there may be some who aren't very familiar with its essential functions. So, this time, I'd like to focus on "the functions of a chronograph" and explain them. Please read until the end!

What is a Chronograph?!

A chronograph is a "mechanism for measuring elapsed time." In simpler terms that anyone can understand, it's a stopwatch function. A typical chronograph has a "chronograph hand" in addition to the hour and minute hands. This hand is controlled by start and stop buttons to measure arbitrary elapsed time.

As mentioned at the beginning, chronographs are also known for their exquisitely designed dial arrangements, beyond their functionality, which is one reason for their widespread appeal. As a result, chronograph-equipped models are almost always included in the standard lineups of various brands.

How to Use a Chronograph

When you hear the name "chronograph," you might assume its usage is complicated, but in reality, it's quite simple. Measurement is performed in three stages: "① Start → ② Stop → ③ Reset."

Although the operation method is simple, chronographs in mechanical watches are designed with extreme precision, unlike battery-powered stopwatches. Incorrect operation can lead to malfunctions. I will explain the correct operation method, so please refer to it.

① Press the push-button at the 2 o'clock position to start

Generally, a chronograph starts measuring by pressing the button at the 2 o'clock position, located above the crown. However, depending on the model, the position may vary, so be sure to check your watch's instruction manual. Also, the feel of the push-button varies between models; some are easy to press, while others require a deeper press to activate.  

② Press the push-button at the 2 o'clock position again to stop  

Pressing the push-button at the 2 o'clock position again stops the measurement. If you wish to resume measurement from the stopped state, press the same button again. In other words, pressing the 2 o'clock button repeatedly cycles between "start" and "stop."

③ Press the push-button at the 4 o'clock position to reset

Once the measurement is complete, pressing the push-button at the 4 o'clock position resets it. Similarly, some models can be reset with a light press, while others require a firm, deep press to reset properly. Try to operate the watch according to its specific model.

Chronograph Derivatives

There are various types of chronographs, but here I would like to explain two particularly famous mechanisms: "flyback" and "split-seconds."

① Flyback Mechanism

With a regular chronograph, once a measurement is finished, you need to "stop," "reset," and then "restart" to measure again. However, with a "flyback chronograph," a superior chronograph mechanism, you can measure the next interval without stopping the current measurement.

With a typical chronograph, you should not press the push-button at the 4 o'clock position during measurement (or it is designed so that it cannot be pressed). However, a flyback chronograph has a function that resets all measuring hands when this 4 o'clock push-button is pressed during measurement. Moreover, it doesn't just reset; a key feature is that it returns to zero and resumes measurement the moment you release your finger from the push-button. This allows for even more precise measurement.

If you want to stop the hands during measurement, you press the push-button at the 2 o'clock position, just like a regular chronograph, and then press the push-button at the 4 o'clock position to reset the hands. Other than being able to reset and restart by pressing the 4 o'clock push-button during measurement, the operation is the same as a regular chronograph. However, some flyback chronographs can be stressed if this reset/restart is repeated, so it is not recommended to "flyback" too many times just for fun.

② Split-Seconds Mechanism

A split-seconds chronograph refers to a chronograph that can measure multiple lap times using two chronograph seconds hands. When the start button is pressed, both seconds hands move simultaneously. When the split button is pressed, only one hand stops, while the other chronograph hand continues to measure. If the split button is pressed again, the stopped hand instantly catches up to the active chronograph hand, and both hands move simultaneously again. Furthermore, if you reset both hands while they are stopped, even if their positions are different, they will simultaneously return to the zero position, which is a unique feature of this mechanism.

Because it operates with a highly complex mechanism, not many models feature it. However, as the name suggests, the design, with its "split" and "second" hands, is artistic and captivating.

The position of the split button, of course, varies by model, but it is generally located at the 10 o'clock position or in the center of the crown. The split-seconds chronograph is also known as "rattrapante" in French.

Precautions When Buying a Chronograph

The chronograph mechanism, which can measure time and distance solely through machinery, holds a certain allure. The beauty of the hands spreading across the dial offers a charm unlike any other watch.

However, there is one point you should be aware of: the maintenance cost. Since chronographs are very complex mechanisms, the cost of overhaul and repair is higher than for a regular three-hand model, with maintenance fees typically averaging about 1.5 times more.

To reduce these high maintenance costs even a little, it's important to know the "correct handling method."

Many precise chronographs are susceptible to vibrations and impacts, and issues like misaligned hands or detached push-buttons are common. Therefore, it is even more important than with regular three-hand models to take them off during strenuous activities and to be careful about dropping them.

Also, using the chronograph hand as a running seconds hand is forbidden as it accelerates component wear. When not in use, keep it stopped at the zero position. However, for Patek Philippe models that use a vertical clutch, it is reportedly fine to use the chronograph as a running seconds hand. That's Patek Philippe for you!

Summary

How was it? 

In the world of luxury watches, many popular models feature chronographs. Therefore, knowing what a chronograph mechanism is and how to use it will deepen your understanding, and you'll likely grow to appreciate the mechanism itself, not just its design.

I hope this article provides useful information and sparks even a little interest in luxury watches! Also, if you have any questions, please feel free to ask us directly, and we will be happy to answer them thoroughly. We look forward to your visit and inquiries.

Stay tuned for the next installment! See you then!