Does your watch automatically correct itself? Learn about the structure of perpetual calendars, permanent calendars, tourbillons, and moon phases

How does the perpetual calendar, the highest quality structure of a mechanical watch, work?

Mechanical watches are made of complex mechanisms.
Among them, the three most complex ones are:
"Perpetual calendar", "Tourbillon" and "Moon phase".

I would like to explain these three complications in more detail below.

This time, let's start with the perpetual calendar.

It's very convenient to have a watch that always displays the date and day of the week.
However, the number of days in a calendar varies from month to month, and there is a leap year every four years.
It's quite complicated.

How to accurately display such a calendar on a mechanical watch?
That's the "perpetual calendar"! It is also called a perpetual calendar.

A solar year, determined by the Earth's revolutions, lasts 365 days, 5 hours, 48 ​​minutes and 46 seconds.
However, because the calendar must be expressed as integers, leap years were established.
Every four years, the number of days in February is adjusted by adding one more day.

Such a complicated calendar system is not controlled by an electronic program,
A perpetual calendar is a device that displays all the information using a mechanical mechanism.

However, it still gets delayed a little every year,
An exception was made that years with the last two digits of the number 00 are not leap years.
Furthermore, there is a further exception: years divisible by 400 are not leap years!

This means that there will be only three non-leap years in any 400 year period.

The next time this exceptional case will occur will be in the year 2100.

This is the only part that cannot be automatically adjusted by the "perpetual calendar", so
The currently existing perpetual calendar will automatically function as a "perpetual calendar" until February 28, 2100.
It will continue to be the same, but at that point you will need to have a watchmaker correct the display.

So let's explain this complex mechanism!



Among the calendar mechanisms built into the watch, the one at the bottom right is
The two cams, stacked one above the other, play the most important role.
This is a cam that adjusts the month over a four-year period, and a cam with 48 teeth so that it completes one rotation every four years.

The 48 gears on the bottom mesh with the date cam on the top right for displaying the date.
When the date advance cam makes one rotation (= one month), each of the 48 cams moves one tooth.

The cam that adjusts the moon has different cut depths for each tooth.
These represent months with different numbers of days.
In order of shallowness of teeth, the long month (31 days), the short month (30 days), February of a leap year (29 days),
It falls on a normal February day (28th).

The depth of the groove in this tooth operates the date advance lever, which advances the date by the required number of days.
For example, if the cut is at its deepest on the 28th, the date will be moved forward by three days.

The 12-tooth cam meshes with a 48-tooth cam,
The Gregorian calendar display changes every year.

Next, we will look at the three major complications of mechanical watches.

Tourbillon

I would like to introduce you to...

The high-precision chronometers once used on ships were fixed in the cabin and always maintained in the same position.

However, when you carry a watch around with you, such as a pocket watch, the position of the watch will change depending on the time: it may be held vertically, horizontally, with 12 o'clock at the top, or with 6 o'clock at the top.

As a result, the escapement and regulator, which are the heart of the clock mechanism, were affected by gravity, causing the accuracy to be affected and resulting in errors.

This loss of accuracy due to the way a watch is placed is called "posture difference."

There was a need to somehow eliminate this difference in posture. This was the idea that the French watchmaker Breguet came up with.

Breguet has become a major watch manufacturer and its watches are still loved all over the world as beautiful luxury watches.

Well, this is the mechanism that Breguet came up with.

If differences in position would cause errors in the escapement and regulator, the idea was that these two mechanisms could be combined together and kept rotating constantly.

Breguet named this device "Tourbillon," a French word meaning "swirl," and patented it in 1801.

Now let me explain in detail how it works.

In a tourbillon, the escapement and regulator are housed in a cage called a carriage and rotated.

In a normal watch, the gears are arranged in the following order: first wheel, second wheel, third wheel, fourth wheel, and escapement regulator, and they transmit power together.

In a tourbillon, the carriage is placed on top of the fourth wheel, which is fixed to the lower plate, and the third wheel engages with a pinion (a small gear) on the carriage's rotating shaft to transmit the power that rotates the carriage.

The escape pinion, which is on the same axis as the escape wheel, engages with the gear of the fourth wheel. When the escape wheel rotates, the escape pinion also rotates, and revolves around the fixed fourth wheel. The rotation of the carriage is regulated in accordance with this movement.

In modern watches, the carriage rotates once per minute and also functions as a small second.

To make a tourbillon, all parts, including the carriage, must be light and strong. Also, because the carriage rotates, it is much more difficult to adjust than a normal watch.

Therefore, tourbillon adjustments can only be performed by watchmakers with the highest skills or in specialized workshops. In addition, the price of these watches is also high, at over 10 million yen.

Nowadays, the materials used for hairsprings have improved and the precision of watches has improved dramatically. Therefore, the appeal of the tourbillon is not so much its practicality, but rather the admiration and respect for the movement of its complex mechanism.

We encourage you to come and see the real thing and appreciate the incredible mechanism that was invented over 200 years ago.


The last one is

Moon Phase

It will be.

This mechanism displays the phases of the moon on the dial. A picture of the moon is displayed in a semicircular display window, showing its size and shape at that time.

The moon has been closely linked to human life since ancient times, so the moon phase mechanism has been established since the era of pocket watches.

In particular, knowing the phases of the moon was essential for navigation, because the tides are caused by the gravitational pull of the moon. With this moon phase indicator, you can easily see the phases of the moon even on rainy or cloudy days when the moon cannot be seen.

The moon phase mechanism used in the watches Breguet made in the late 18th century was apparently already the same as the one used today.

So let's see how it works.

The lunar cycle is about 29.5 days. However, it is impossible to make a gear with a half tooth, so a gear that rotates once every 59 days is used. Two moons are drawn on the disk, and only a half circle (29.5 days) is visible on the dial.

What a well-designed system it is.

However, since the actual lunar cycle is 29.530589 days, there will be an error of one day every few years due to the fraction that is rounded down. Therefore, it becomes necessary to make corrections by referring to a lunar age table.

Recently, more realistic visualizations of the moon phases have been developed using mechanisms different from those used long ago.

With so much information available today, there is frankly little need to display the phases of the moon on a wristwatch. And yet the moon phase is still very popular. After disappearing from luxury watches for a time, it has made a comeback and become a staple once again.

Perhaps it is because people feel a sense of romance in the moon phases, which not only tells them the exact time but also allows them to sense the workings of nature, which have remained unchanged since ancient times.

What did you think.

It's a very intricate and complex mechanism.

Therefore, we also repair and adjust the perpetual calendar, tourbillon, and moon phase.
It seems like it would be difficult unless you were an experienced craftsman.

However, while looking at the display of a mechanical watch,
So that's how the gears moved and changed the display.
Once you know that, it becomes even more appealing.