hand-winding watch movement from A. Lange & Söhne and used in the Lange 1.
When A. Lange & Söhne was preparing to relaunch, they decided to make a splash with a truly unique watch, the Lange 1. The hallmarks of that watch, and this movement, are the asymmetric dial arrangement and two-window big date. This latter complication was designed to resemble the 1841 Five-Minute Clock at the Semper Opera House in Dresden and gave the new manufacture its first patent. Although the dial is not centered, it does have a pattern: The hour and minutes dial, date window divider, and subsidiary seconds dial form the point and two leg apexes of an isosceles triangle, with the power reserve indicator centered at this base.
All L901 calibres are based on this original design, and all feature the same basic complications: Big date at 1 00, power reserve indicator at 3 00, small seconds at 5 00, and hour and minute hands at 9 00. The movement is constructed with a three-quarter plate, made of untreated German silver and decorated with Glashütte Stripes, in traditional Glashütte style. It features nine gold chatons and blued screws. In all, there are 53 jewels synthetic rubies.
For an accurate rate result the screwed balance with Nivarox 1 hairspring is responsible. It is shock-proofed, makes 21,600 vibrations per hour and is adjusted in five positions. On the hand-engraved balance cock, the Swan's neck fine regulation is mounted. Its patented beat adjustment mechanism makes it possible to accurately set the impulse pin relative to the pallet fork without removing the balance wheel.