A. Lange & Söhne caliber L043.9
Second-generation Zeitwerk movement. In the second generation as well, a patented constant-force escapement controls the complex switching processes and at the same time handles two important functions: on the one hand, it generates the impulse for the jumping advance of the time display. On the other hand, it drives the balance with nearly uniform power across the entire run time. This keeps the amplitude constant, which has a positive effect on rate stability.
The integration of a pusher for correcting the hour indication, first introduced in the ZEITWERK DATE, required considerable effort from the designers and increased the number of movement parts to 462. To enable the correction independently of the switching cycles of the time display, a clutch uncouples the hour ring from the jumping numerals mechanism each time the pusher is pressed. The setting of the minute display in both directions is performed with the crown located at 2 o'clock.