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Power reserve: 744 hours

The LANGE 31 is the world’s first mechanical wristwatch with a power reserve of 31 days and a patented constant-force escapement. To deliver a power reserve of this magnitude, the movement must be able to store a large amount of energy. This task is handled by two mainsprings that are both 1850 millimetres long – about ten times as long as in mechanical wristwatches with a conventional power reserve.

The energy for a running time of 31 days can be transferred to the twin mainspring barrel using a winding key especially designed for the LANGE 31.
The patented constant-force escapement of the LANGE 31 in white gold ensures maximum rate stability and consistent accuracy.

Mainsprings of this length imposed considerable challenges on the engineers. The first obstacle was to transmit their tremendous energy to the movement in a gentle and uniform manner. For this purpose, they developed a patented constant-force escapement. The second challenge presents itself when winding the watch, a very time-consuming and cumbersome task, given the length of the springs. This is why the LANGE 31 is wound with a key. It generates much more leverage than a winding mechanism based on a crown.

LANGE 31 – A. Lange & Söhne

Discover the model

1 Model of the LANGE 31

Movement L034.1

Number of movement parts


Number of rubies


Number of screwed gold chatons


Power reserve

744 hours when fully wound

Oscillation system

Frequency: 21600 semi-oscillations per hour

Beat-adjustment system: Screw balance

Movement measures

Diameter: 37.3 mm; height: 9.6 mm

Movement Movement
Movement Movement