It's A Date! Taking A Closer Look At The Most Popular Complication Of Them All: The Calendar

The calendar was introduced in wristwatches at the beginning of the twentieth century, but that date by no means marked the inception of the complication Since its invention, calendar complications in wristwatches has improved exponentially from simple watches displaying just the date right up to incredibly complex perpetual calendars - and everything in between The direct-drive calendar is the most obscure and primitive date design, and it is rarely seen in movements today.

The date disk is in constant engagement with the pinion, meaning there is no definitive "Jump" of the date from one day to the next at midnight It makes use of a date "Jumper," which controls when the date numeral will make its jump We previously spoke about the 24-hour wheel with a mounted finger; that finger is what advances the date forward by pushing a tooth on the calendar disk and allowing it to advance.

If the date were to be advanced via a rapid set at this point, the tooth of the calendar wheel would be pushed into that date finger, likely causing damage that the watch may not be able to recover from without intervention. . Source