In the development phase, the integration of a perpetual calendar in the TOURBOGRAPH PERPETUAL “Pour le Mérite” presented the engineers of the Saxon manufactory with a formidable challenge: to orchestrate the interaction of the complex mechanisms in such a way that mechanical conflicts or unwanted energy losses could be prevented. In this project, the perpetual calendar mechanism had to be built around the tourbillon. Consequently, only about two thirds of the movement surface were available, and this necessitated a redesign of the basic calibre. At the same time, the developers did not want to noticeably increase the height of the movement.
During the development of the calendar module to be built around the tourbillon, great emphasis was placed on space-saving architecture.
Of the 684 parts of the new L133.1 manufacture calibre, no fewer than 206 constitute the perpetual calendar with its analogue displays. It will correctly indicate the duration of each month until 2100. A one-time correction will be needed on the last day of February in this secular year. From then on, the calendar will again be correctly calibrated for the next hundred years. It has three subsidiary dials. The date at 12 o’clock and the day at 9 o’clock are indicated with rhodiumed gold hands. The month and leap year are both displayed at 3 o’clock. The upper half of the analogue date also accommodates the moon-phase display which is calculated to remain accurate for 122.6 years. Its deep-blue disc is made of solid gold. During the development of the calendar module to be built around the tourbillon, great emphasis was placed on space-saving architecture.
The development of highly complex chronographs and their meaningful interaction with other functions is among the Saxon manufactory’s key skills. Apart from the two chronograph pushers on both sides of the crown, a third button at 10 o’clock modestly reveals that the TOURBOGRAPH PERPETUAL “Pour le Mérite” deserves a place in the top-tier category of split-seconds chronographs. The combination of a perpetual calendar with a split-seconds chronograph is very rare. Power management is an especially challenging undertaking. In particular, the simultaneous use of several functions calls for mechanical ingenuity, for instance when the calendar indications advance around midnight and the stopwatch function is used at the same time. Assembling such a movement requires considerable experience and exceptional sensitivity when adjusting and harmonising the mechanisms.
In the way they flawlessly interact, the tourbillon and the fusée-and-chain transmission offset two disruptive phenomena in a mechanical movement: gravity and waning spring force. Thus, they contribute to improved rate stability and rate accuracy.
The results of A. Lange & Söhne’s efforts to develop intelligent energy management systems for mechanical movements – and thus to compensate for the unavoidable torque loss of the mainspring barrel – include three different constant-force escapements as well as the fusée-and-chain transmission which was integrated in a wristwatch for the first time in 1994. It is the technical hallmark shared by all timepieces identified by the attribute “Pour le Mérite” in reference to the erstwhile Prussian order conferred for exceptional scientific merit.
The TOURBOGRAPH PERPETUAL “Pour le Mérite” is being crafted in a limited edition of only 50 platinum-cased watches. The finish of the manufacture calibre complies with the highest standards of Saxon watchmaking artistry. Thermally blued screws, screwed gold cha-tons, bridges and plates made of untreated German silver and decorated with Glashütte ribbing and perlage as well as the hand-engraved chronograph bridge round out the high-lights of the classic complication