The Zeitwerk Minute Repeater is the first A. Lange & Söhne model with a striking mechanism that sounds the hours, ten-minute intervals, and minutes. The acoustic sequence precisely reproduces the digitally displayed time whenever the striking mechanism is triggered with a pusher, in place of the conventional slide. The dial time is sounded with a low-pitched tone for each elapsed hour, a double tone for each elapsed ten-minute period, and a high-pitched tone for each elapsed minute: seven low tones, five double tones, and two high tones are struck at 7:52.
The time being displayed with an hour ring and two minute discs instead of with hands, three snails connected with these mechanical display elements separately sample the number of hours, ten-minute intervals, and minutes to be acoustically indicated.
To rule out unintended, potentially damaging manipulations, the designers incorporated a very useful safety feature. Since mechanical conflicts would occur if the owner were to set the time during a chiming sequence, the crown cannot be pulled while the striking mechanism is active: when activated, the winding train is uncoupled from the ratchet wheel that powers it. Additionally, the switching of the numeral discs is delayed until the chiming sequence has ended. This takes about 20 seconds for the maximum succession of tones at 12:59. The acoustic time indication therefore always corresponds to the time displayed on the dial.
To assure that the repeater sequence is not prematurely interrupted due to the depletion of the mainspring’s power, the striking mechanism can no longer be activated if the remaining power reserve is less than twelve hours. On the power-reserve indicator, this point is identified with a red mark. Because the mainspring powers the striking mechanism via the ratchet wheel, the number of minute repeater activations and their duration will influence the availability of the underlying power reserve of 36 hours. The patented constant-force escapement delivers a uniform amount of energy during the entire power-reserve period.
The L043.5 manufacture calibre inside the platinum 42,5mm case of the Zeitwerk Minute Repeater is hand-finished and includes 771 components. Beneath the hand-engraved balance cock, the balance wheel with eccentric poising weights and a free-sprung balance spring crafted in-house breathes at 18,000 semi-oscillations per hour.
The solid-silver dial shimmers with a rhodié hue. Made of black-rhodiumed German silver, the time bridge prominently frames the hour and minute numeral apertures that are located on the same plane. The black-polished steel gong hammers are visibly arranged on both sides of the subsidiary seconds dial. The hours are struck on the left, the single minutes on the right. For the double-tone ten-minute counts, both hammers strike both gongs slightly offset in time.
The watch is worn on a black hand-stitched alligator leather strap, completed with a deployant buckle in platinum.