Taking A Closer Look At Lange’s Tourbograph Perpetual “Pour Le Mérite”

Taking A Closer Look At Lange’s Tourbograph Perpetual “Pour Le Mérite”

And to think, they have to assemble this twice.


Once the mainspring barrel is assembled, the watchmaker wraps the delicate chain around it before placing both components into the basic movement and attaching the chain to the fusée. This ensures that the flow of power to the escapement is not interrupted while the watch is being wound. The watchmaker will then adjust the final basic tension of the mainspring using a ratchet wheel placed on the square barrel arbor.


Following the preliminary assembly of the many individual parts that complete the tourbillon, several adjustments, disassembly, final finissage and the final assembly will be made before the cage is then firmly secured to the chronograph bridge by the tourbillon bridge, allowing it to rotate while suspended between two diamond endstones. A closer look at the steel arms of the tourbillon bridge reveals a glossy finish which was achieved using a unique black-polish technique.


The chronograph and rattrapante mechanism comprises 136 parts. During the assembly phase, all of the individual parts of the elaborate column-wheel ensemble must be manually tweaked and adjusted. This will allow each individual part involved in the complex switching sequences to interact in a specific order within fractions of a second.


Measuring about one centimetre long, the rattrapante hand arbor extends from the dial to the rattrapante wheel on the opposite side of the movement by passing through the hollow chronograph hand arbor. The chronograph functions are controlled by two column wheels; one of these wheels deflects the arms of the rattrapante split-seconds clamp, which is left suspended freely to enable it the arms to centre around the periphery of the rattrapante wheel and grip it with uniform pressure from both sides.


A closer look at the white-gold lunar disc reveals a deep blue hue resulting from a patented coating process, while the miniscule stars displayed on the disc have been carved out of the coating using a laser beam. The seven-stage transmission for the moonphases has also been calculated so precisely that it only requires a one-day correction after 122.6 years, while the wheel of the calendar module features several recesses and protrusions to ensure that the perpetual calendar correctly displays the different durations of the months in the Gregorian calendar and only needs to be corrected by one day in the year 2100.

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