TopicWatches Mechanics Eternity
This year, on February 29, special parties were organized in some cities around the world for lovers of complex clockworks to mark the advent of a leap day - an extra day of the year designed to compensate for the imperfection of the existing calendar system. At the party, of course, it was recommended to wear a watch with a perpetual calendar - the opportunity to clearly demonstrate the advantage of a complex device is quite rare, only once every 4 years. We also decided to take the opportunity to tell as much as possible about this amazing device.
Watches with a perpetual calendar or, as it is customary to say “evening” in jargon, are included in the group of classic complications of the Grand Complications category, that is, especially complex mechanisms requiring highly skilled craftsmen to create them. In the past few years, the "eve" has been focused on the active attention of various manufacturers of the highest echelon. Even despite the fact that the perpetual calendar is not eternal, <a href="http://sciencemission.com/forum/index.php?page=topicview&id=general-chat/5-reasons-why-apple" target="_blank" rel="noopener">such a watch is one of the most obvious ways to demonstrate the beauty of watch engineering.
A. Lange & Sohne Datograph Perpetual Tourbillon Watch
A. Lange & Sohne Datograph Perpetual Tourbillon with L952 caliber, 41 mm platinum case, limit of 100 pieces
Like any hourly complication, the perpetual calendar has its own problems and various design options associated with it. The main difficulty is associated with the convenience and safety of its use. The fact is that the classic traditional scheme of the perpetual calendar involves the use of the so-called big lever (in French grand levier) and goes back to the famous Breguet No. 160 "Marie Antoinette". The “memory” of the perpetual calendar of this watch is part of the cochlea of the equation of time, which has a complex form of analemma and makes one revolution per year. This snail has four pins for months with 30 days (April, June, September and November). As this snail rotates at the right moment, they push a very large L-shaped lever, which is an iconic design element of Marie Antoinette, and he switches the staff of the retrograde date to the 1st number. For February, there is a separate four-toothed sprocket, which makes a revolution every 4 years. On each of her teeth there is a pin that pushes the L-shaped lever in late February. Only on one tooth the pin is located deeper than on the previous three, so in the leap year it pushes the lever not on February 28, but a day later.
Gerald Genta Perpetual Calendar Ref. G.2994.7
Gerald Genta Perpetual Calendar Ref. G.2994.7, released in the 1980s, case and mechanism signed by the master
In fact, the aforementioned L-shaped lever is a prototype of the large lever that is now used by most brands in the classic design of the perpetual calendar. Instead of a snail-analemma, a special program wheel with recesses is used. This software wheel - the brain of the perpetual calendar - makes one revolution in 4 years, and each recess corresponds to the month of the year with the number of days less than 31. The large lever has several branches - “legs” that interact with all calendar wheels and indicators, respectively, that is, simultaneously switch the date, day of the week and month. The moon phase indicator is directly connected to the central wheel. Also, the large lever has a probe that “reads” information from the soft wheel. If there is no recess, then the lever switches all calendar indicators until the 31st day inclusive. The deeper the notch the more the lever can turn and the earlier it will switch the date at the end of the month. Thus, such a scheme, by default, considers that the month is 31 days, and the software wheel "subtracts" the required number of days for each month.
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