A. Lange & Söhne’s Zeitwerk Date: The Art Of Mastering Force By The Minute
In a world invaded by connectivity, embracing modernity while remaining traditional requires nothing short of a miracle. At this year’s SIHH, A. Lange & Söhne proved that it's possible to strike the right balance with the new Zeitwerk Date.
Ten years ago, Saxony-based A. Lange & Söhne blew the dust off traditional fine watchmaking codes by updating the finissage of its mechanical movements, introducing an innovative new watch, The Zeitwerk. The timepiece had a digital time display on its dial that recalled the famous 5-minute clock in the Semper Opera House in Dresden.
The captivating design and innovative concept behind the Zeitwerk garnered several awards in the watchmaking industry for the development and the exceptional quality of its manually wound mechanical movement. The movement was capable of generating sufficient power to simultaneously rotate all three discs atonce at the top of the hour without impacting the operating accuracy of the piece.
Constant force is the motto
Today, A. Lange & Söhne is known for its passion for precision. The brand has made a specialty of mastering the various mechanisms contributing to its celebrated "constant force." While the best known of these is undeniably the chaîne-fusée, which can be found in the "Pour le Mérite" model, it is not the only constant force movement. The one developed for the Lange 31 has a full month of power reserve.
The new manually wound calibre L043.8 has a patented constant force escapement. A spring formed of an intermediate spiral (but not found on the escapement wheel as they often are) is structurally designed to handle two tasks. It's an auxiliary spring that gains tension every minute from the primary spring, and its function is to power the balance with a consistently even amount of force for as long as the watch is running.
Thanks to the second spring, oscillations of the balance are not affected by the torque delivered by the mainspring, whether the watch is overly wound when it starts running, or nearly unwound at the end. Nor is the power transmitted to the balance wheel via the lever impeded by the jumping of the three discs serving to display the time.
Making a date with innovation
One could think that integrating a date display into the new calibre would be mere child's play. But with an innovative date display that is unconventional, and given the structure of the movement, it poses a challenge. The date is linked to the hour display, and to adjust it, the hour has to be advanced to midnight to make the date jump instantly. This kind of operation is very time-consuming, requiring winding the crown minute by minute, making the two corresponding discs jump perpetually.
To solve the problem, the watchmakers set two pushers into the side of the case-middle. Both are endowed with the extraordinary power to deliver the necessary switching impulse, which is generated not when they are pressed, but when they are released. This avoids the need to exert too high a pressure, thereby preventing damage to the movement. The watch is truly magnificent, with a case measuting 44.2mm in white gold model on an alligator strap.
The corrector, positioned at 8 o'clock, is used to quickly adjust the date. The date is displayed in red on a glass ring with printed numerals from 1 to 31. A small red color segment affixed to a second ring rotating beneath it allows the red to shine through. The second pusher is used to advance the hour digit display by one hour for quick-set purposes without having to activate the winding crown, enabling the date to switch precisely at midnight with a minimal amount of manipulation.
Every detail counts at A. Lange & Söhne, and the supremely precision-conscious craftsmen have developed a system that uncouples the hour ring from the jumping numerals mechanism every time the pusher is pressed. This ensures that the manipulations don't interfere with the operating accuracy of this superb, new-generation, manually wound mechanical calibre offering 70 hours of power reserve.