The self-winding mechanical caliber that combines two of the most useful everyday complications of Patek Philippe's specialties includes the clock and the universal time.
However, while both complications are relatively prevalent in the manufacturer's catalogs, their association is rarer. In fact, we uncover in the archives a unique piece dating from 1940, implying that Patek Philippe made only one known world-time chronograph watch in the past.

The Backstory

Number 862442 from 1940, a one-of-a-kind piece with a dial with plyometric and asthma metric scales, a clock that most likely belonged to a doctor, was launched at the Basel show in 2016. Patek was thus offering this pair of complications for the first time in its current line, clearly bringing it up to 21st-century technical standards, as the brand recalled in its press announcement.

Building a chronograph on which the sun never sets because it always displays the 24 time zones is a challenge to the 100th of a millimeter. In fact, the classic world time does not have a second hand, whereas the chronograph has a slim second hand and a 30-minute counter with the scale divided into fractions of a second. The watch is equipped with two moveable discs. the city disc, which has 24 place names, each of which represents one of the two time zones.

Two Time Zones

5930 Two Time Zones

The city disc and 24 time zones, As a result, 24 hours representing the local time in the zone opposite the dial of the Chrono combines together a set number of indicators operated by several processes that must work in perfect harmony.

The well-known Patek Philippe universal time system allowed us to see what the truth is, this innovative technique is based on a notion by geneva watchmaker Louis cottier originating from the 1930s, which the product producer then enhanced by patenting two important advances in 1959 and 1999. Watchmakers worked for a long time to adapt these two mechanisms to each other; they moved axles, thinned and rebuilt bridges, changed spacings, and in the end, the ch 28 528 can be presented as a new Movement; as with all watches from the manufacturer, the method of use has been designed to be as simple as possible.

The Flyback Function

5930P Flyback function

The chronograph has a start/stop push button at two o'clock and a reset push button at four o'clock, which also serves as a flyback function. If this pusher is pressed while the second hand is rotating, the second hand immediately returns to zero and a new timing begins, thanks to the presence of a vertical clutch. The chrono hand can be used as well.

The hu function is further distinguished by its ease of usage, with minimal wear and without impairing precision and power reserve as a second hand. The central hour and minute hands show the time of the time zone whose name appears at 12 o'clock. The hours of the other 23 time zones are shown at a glance.

The split of the ladder into white and black zones is made possible by the city disc and the 24-hour disc, which are positioned slightly more in the middle.
When a traveller arrives in another time zone, all he has to do is activate the pusher at 10 o'clock the city and 24-hour discs then rotate in one hour steps counterclockwise while the central hour hand moves clockwise in one hour steps the correction is complete when the name of the desired city is at 12 o'clock during this process the hu mechanism and the central hour hand
To avoid any disturbance in the amplitude of the balance, the hour hand is detached from the basic movement.