No fewer than 744 hours. That’s how long the power reserve for the A. Lange & Söhne Lange 31 replica watch is. While not a record in replica watchmaking (I believe the Hublot MP-05 LaFerrari has the longest power reserve on the market with 50 days), it is indeed a remarkable feat, and more so because it’s a piece that you can ostensibly actually wear every day for a month. This year at SIHH 2017, Lange released this limited edition version that has a white gold case and a gray dial. I always forget that the A. Lange & Söhne Men’s Replica is in the Saxonia family, which is often seen as the entry point for the Glasshütte manufacture.
In typical Lange fashion, there isn’t a lot on the dial drawing attention to what beats within. In fact, other than the “MONATS-WERK” (Monats being “month” in German) at 9 o’clock and the large power reserve indicator, there’s not a lot that would immediately give away what makes this replica watch so special. I think the decision to go with a white gold case underlies the more discreet personality of both the replica watch and the person who wears it. You wouldn’t guess that this is Lange’s second most expensive debut this year, after the grandiose Tourbograph Perpetual Pour Le Merite.
You’ll notice that the power reserve indicator has a marker for every other day and the final two days are split up so you know when you’re reaching that “red zone” of a power reserve nearing its end. Those instantly recognizable “oversized’ (I hate that word, as they look the right size to me, personally) date windows can hypothetically do a full month’s cycle in tandem with the power reserve which is a fittingly German act of luxurious efficiency. If you’re thinking about how long it would take to wind the replica watch when the time finally comes, Lange provides a steel turning key which generates extra torque and significantly reduces the physical work needed to turn the crown. It’s also got a backstop ratchet integrated with a torque-limiting mechanism so it’s protected against an accidental counterclockwise turn.
The L034.1 manual-wind movement is unique to the A. Lange & Söhne Lange 31. The power reserve is possible due to the twin mainspring barrel. Two vertically stacked 25mm-diameter barrels contain springs that are 1,850mm long (each is around 10 times the length of a more conventional spring). Inherent to longer mainsprings comes the issue that loss of torque is more pronounced as the spring relaxes. To remedy this, A. Lange & Söhne has a patented constant force escapement which retensions a remontoir spring (a secondary spring) by 60 degrees every 10 seconds. My movement expertise can’t fully and thoroughly explain all of the mechanisms here, but I’ll take Lange at their word that this constant force escapement system ensures uniform torque for the entire duration of the 31-day power reserve.