A. Lange & Söhne ZEITWERK. The second generation of the digital watch with a mechanical heart.

The A. Lange & Söhne ZEITWERK has a patented mechanism with three jumping numerals discs that make a glance at the watch a special experience. The hours and minutes are displayed from left to right by large-format numerals that are 2.9 millimetres high and 2.3 millimetres wide. The harmonious arrangement on the curved time bridge and the size of the displays ensure superb legibility. Additionally, this aesthetically original and technically elaborate display endows the dial with vibrancy and verve because the underlying mechanism switches the three numerals discs – one displays the hours, the other two display the units and the tens digits of the minutes – within fractions of a second. The most exciting event happens at the top of the hour when all three numerals discs are simultaneously advanced by one increment. With this precise choreography, the moment becomes the event.
To create this lucid and innovative display, Lange’s designers questioned the conventional principles and rules of precision watchmaking afresh. This was necessary, because the challenge of fitting the mechanism in the limited dimensions of a wristwatch and at the same time providing enough energy to produce the synchronised switching steps was enormous. Some key figures make this impressively clear: For instance, the hour ring with a diameter of 30.0 millimetres extends to the outer circumference of the movement. In addition, there are two discs – the tens-minute and units-minute discs. Their diameters are 19.0 and 12.7 millimetres, respectively. Both discs are separated by a height difference of merely 0.2 millimetres, which calls for highly precise settings by the watchmaker.
“To switch the discs of the jumping numerals mechanism to forward on time every minute, the movement requires much more energy than a classic time display,” explains Anthony de Haas, Director of Product Development. “Not only are the numerals discs very heavy by watchmaking standards, but they also have to be quickly accelerated and braked again. This calls for considerably higher forces than the uniform rotation of a pair of hands of much less weight. The greatest amount of energy is needed at the top of the hour when the movement advances all three discs at the same time.”
Also, the incremental step must be executed precisely after 60 seconds. This challenging operation is handled by the patented constant-force escapement. As a multitalented device, it even makes a further contribution: It assures that the movement is also powered by a uniform amount of force; this benefits rate stability.
While these challenges were already intelligently mastered by the first-generation A. Lange & Söhne ZEITWERK, the new generation goes a step further with the refined calibre L043.6.
Thanks to a patented barrel design with two mainsprings, it was possible to double the power reserve from 36 to 72 hours. Or, to express it with other numbers: When fully wound, the A. Lange & Söhne ZEITWERK now has sufficient energy to perform 4,320 minute jumps or, more precisely, 72 jumps with all three discs, 360 jumps with only two discs, and 3,888 jumps with only one disc. Another improvement versus the predecessor model is the simplified setting of the hour. A pusher at four o’clock can now separately advance the display, which is particularly useful when the time zone changes during a trip. The pusher is an inverted type: Nothing happens when it is pressed but the display switches forward when the pusher is released.
The integration of a pusher for correcting the hour indication, first introduced in the A. Lange & Söhne ZEITWERK DATE, required considerable constructional effort. To enable the correction independently of the switching cycles of the time indication, a patented vertical clutch uncouples the hour ring from the jumping numerals mechanism each time the pusher is pressed. The setting of the minute indication in both directions is still performed with the crown at two o’clock.
In its second generation, the ZEITWERK also features an oscillation system with its own balance spring and patented beat-adjustment system. It oscillates with a frequency of 18,000 semi-oscillations per hour (2.5 hertz). As with all of the manufactory’s calibres, the artisanal finissage of the 451-part movement complies with the most ambitious Lange standards. With a glance through the sapphire-crystal caseback, connoisseurs can admire the hand-engraved balance and escape-wheel cocks, the solarised winding wheels, the 59 jewels, and the intricate, straight-grained remontoir bridge that accommodates two recessed, screwed gold chatons.
The new ZEITWERK has a case diameter of 41.9 millimetres and a height of 12.2 millimetres. It is available in two versions. It comes in pink gold with a black dial and a time bridge made of untreated German silver. The platinum edition has a rhodié dial made of solid silver. The time bridge is black rhodiumed.