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It’s A Date! Taking A Closer Look At The Most Popular Complication Of Them All: The Calendar - Reprise | Quill & Pad

It’s A Date! Taking A Closer Look At The Most Popular Complication Of Them All: The Calendar – Reprise | Quill & Pad

Date windows on wristwatches can be a touchy subject among watch aficionados.

Many feel they are absolutely terrible and obliterate the appearance of a decent watch, whereas others swear by them as the most helpful and affordable complication.

Whatever camp you may end up in, this calendar function can be the cause of considerable anguish, particularly the rapid set mechanism.

The calendar was introduced in wristwatches at the start of the 20th century, yet that date in no way, shape or form marked the inception of the complication. Astronomical watches dating back to the seventeenth century were furnished with complex calendar functions displaying a gaggle of information.

Since its creation, calendar complications in wristwatches has improved exponentially from basic watches displaying only the date straight up to incredibly complex perpetual calendars – and everything in between.

Rapid date change

One of the most helpful upgrades the unassuming calendar has received would have to be the rapid-date or quick-set change mechanism. Before the rapid set was added, correcting the date was an arduous process that took considerable time. In the event that you are a vintage watch enthusiast you will be all excessively familiar with the exhausting process of having to advance the hands until the correct date appears.

Along with the introduction of the rapid-set corrector came another issue: the delicate gearing could become damaged whenever engaged when the time appeared on the watch was close to midnight.

I’m confident the majority of you will have heard that we shouldn’t utilize our rapid-date change function between the long stretches of 10:00 pm and 2:00 am to avoid damage.

But, is that the entire story? Not exactly, so we should examine in more detail.

Watches with a quick-set mechanism fall into two camps: one that has a safety device and one that doesn’t. In any case, before we dig into the mechanics of the safety device, we should initially understand how various calendars function.

There are three main kinds of calendars: direct drive, semi-instantaneous, and instantaneous.

Direct-drive calendar

The direct-drive calendar is the most obscure and crude date plan, and today is rarely found in developments. This style of mechanism makes no utilization of a date “jumper,” depending instead on the 24-hour haggle pinion to engage the teeth of the date disk.

The date plate is in constant engagement with the pinion, meaning there is no conclusive “hop” of the date starting with one day then onto the next at 12 PM. It just makes its way around the dial and changes in a general movement around midnight.

Semi-instantaneous calendar

This style of date change is much more normal and seen for the most part today in watches like the ETA 2892 and ETA Valjoux 7750.

ETA 2892

It makes utilization of a date “jumper,” which controls when the date numeral will make its bounce. This style is safer as it doesn’t depend on geared teeth to work, yet rather a sharp steel jumper between two teeth. It allows for no error.

ETA Valjoux 7750 with date ring (photograph courtesy

Close to 12 PM, the 24 hour wheel, which has a mounted finger, will start to engage one tooth of the date plate. As the wheel makes its way further around, the spring-loaded jumper starts to drag over the tip of the tooth on the date wheel. As it passes the final turning point it is forced to snap down in the middle of the following two teeth of the circle, allowing the calendar plate to be displayed in the correct situation on the dial.

Instantaneous calendar

The instantaneous style is the most sophisticated of the three as it allows date change to take place exactly at midnight.

It utilizes a spring to accumulate energy throughout some stretch of time and then releases that energy at 12 PM, causing an abrupt snap that advances the date circle one tooth forward. 

Rapid date change: the mechanics 

The rapid-date change can be categorized into two camps, at that point reduced further into two more subcategories.

The first is a mechanism that utilizes an autonomous corrector, usually on the case. The second is a style that is incorporated into the winding stem.

The two sub-categories that follow are those with a safety device and those without.

Rapid-date change corrector

Rapid-date change correctors are usually found in complicated watches that display something beyond the date. They are commonly found in triple calendar developments, however really any watch can make utilization of one.

Two calendar correctors are obvious between the carries of this Patek Philippe Reference 5074P

Easily recognized as a small push piece outwardly of the case, correctors are extremely basic mechanisms to repair and operate. You basically press the corrector downward and the date advances one increment. The push piece will at that point spring back once discouraged, ready to play out its service all over again.

The push piece itself is connected to a switch inside the development, which thusly acts against a toothed star wheel that advances one tooth forward. The star wheel can either have the hand directly attached to its arbor or it can transfer capacity to another wheel down the line.

Winding stem

Rapid-date change via the stem is arguably the more normal variety as today is found inside most games watches. It is popular among that style because it doesn’t need another passage point into the case, which can be a weakness for water resistance.

The most common style includes hauling the crown out to the primary situation after winding and turning the crown one way to cycle through the date. There are styles that include rapid cycle in the two directions and others still that are spring loaded and don’t need turning at all; with the latter, maneuvering the stem into position is enough.

The generally common, as stated, is the previous. At the point when the crown is turned in this position, a wheel is engaged that thus engages another wheel. That wheel at that point makes contact with the tooth of the calendar plate, which advances the date one number forward.

A closeup on the date-change mechanism (photograph courtesy Ashton Tracy)

Calendar safety device

Every 24 hours the date advances one number forward, yet that process starts a long time before midnight.

We recently talked about the 24-hour wheel with a mounted finger; that finger is what advances the date forward by pushing a tooth on the calendar plate and allowing it to advance.

As the time leads up to 12 PM, that finger is situated between two teeth on the calendar plate. On the off chance that the date were to be advanced via a rapid set at this point, the tooth of the calendar wheel would be driven into that date finger, likely causing damage that the watch may not have the option to recover from without intervention.

To avoid this happening certain watches are fitted with a safety device. Watches with a winding-stem rapid set usually utilize a spring-loaded finger mounted on the 24-hour wheel. At the point when the rapid-set function is engaged, the finger is just pushed far removed and gets back to its original position once the date plate tooth is clear.

Watches equipped with a push-piece rapid set work somewhat better utilizing a movable finger that is mounted out on the town driving wheel. This style utilizes a spring to push that finger far removed when the corrector is used.


While there is some fact to the claim that a rapid date change shouldn’t be made somewhere in the range of 10:00 and 2:00, it certainly doesn’t tell the entire story.

One thing is abundantly clear: always adhere to the manufacturer’s instructions as not doing so can be a costly mistake.

* This article was first distributed on June 10, 2018 at It’s A Date! Taking A Closer Look At The Most Popular Complication Of Them All: The Calendar .

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