Big Numbers: Testing the A. Lange & Söhne Zeitwerk

In this feature from the WatchTime archives, we test the original Lange Zeitwerk, A. Lange & Söhne’s mechanical digital watch, which combines a groundbreaking design concept with classic Lange features. Photos provided by Lange and by WatchTime’s Marcus Kruger.

Emotions are sure to run high among fans of A. Lange & Söhne watches when the new Lange Zeitwerk appears in jewelers’ display windows. Some will love the offbeat design concept, while others may dismiss it as straying too far from the “classic” features they expect. Many will compare it to the Lange 1, a watch that became the German manufacturer’s most recognizable and successful model thanks to its unconventional, offset display. The Zeitwerk has achieved similar notoriety, with its new design concept that may very well influence the style of Lange models in the future. The watch cuts a striking figure. Its most dramatic feature is the winged German silver time bridge that extends over the dial to frame the digital hour and minutes displays as well as the small seconds subdial, effectively unifying all these elements. Besides its aesthetic appeal, this bridge is also a functional part of the movement: it holds the arbor for the two minute disks with an unusual colorless jewel and is secured visibly to the mainplate by a screw. In conjunction with the two digital displays this creates a harmoniously balanced image. The Zeitwerk is immediately recognizable as a Lange product, with its “auf” (up) and “ab” (down) indications on the power display and unique shape of the hands. The shape of the case reflects typical Lange styling, and even the digital displays have a familiar look: they use the same type of numerals as do the large date indications on many other Lange watches. Lange dispensed with the usual bar between the first and second digits of the display (shown with two disks), which is an appealing aesthetic touch.

A. Lange & Sohne Zeiwerk - side

Historically speaking, the Zeit-werk is preceded by the Dresden Semperoper five-minute watch, built by J.C. Friedrich Gutkaes (Ferdinand A. Lange’s teacher and later father-in-law) in 1841. In that watch, the hours appear as Roman numerals in the first window while the second window, showing the minutes, advances only every five minutes (i.e., the numerals 00 are followed by 05, then 10, and so on). The minute indication on the Zeitwerk is much more precise and involves a shift every minute. This “jumping” minute indication has presented a massive challenge for other watch companies that have attempted it. Harry Winston, for example, did not get its Opus 3 to work until six years after its introduction, and the Porsche Design Indicator, with digital display of chronograph hours and minutes, had to be redesigned after its debut. The problem is the enormous force required to move the disks. While the date disk advances only once per day, the three disks needed for displaying the hour and the two digits for the minutes require a total of 1,608 advances per day. The strong spring that is needed for this is the reason for a significant difference in power between the watch’s fully wound and nearly unwound state. In fact, an even stronger spring would be needed in order to utilize only the relatively constant mid-range torque. And while A. Lange & Söhne has experience with strong springs, as in the Lange 31 with its entire month of power reserve, the spring in the Zeitwerk had to be even stronger than that.

Lange Zeitwerk movement with tools
The caliber developed for the Zeitwerk, with its skeletonized bridge for the constant-force escapement and numerous decorative finishes, is a feast for the eye.

Lange created and patented an innovative barrel with the goal of keeping the watch’s dimensions relatively small. This design reverses the conventional principle of winding up and winding down. The high-friction bearing for the spring barrel is used for winding the movement; this ensures that the barrel wheel can turn in a minimized friction bearing as the watch winds down, leaving more energy in the mainspring for powering the disk mechanism. Since too much power can damage the mechanical components, a tiny governor within the Lange Zeitwerk turns exactly 525,600 times per year. The outer minute disk advances by one step while a fly vane decelerates it. This component — shaped like a tiny revolving door — creates air resistance to slow the movement but still allows the disk to advance within a fraction of a second each minute. Lange used the ingenious constant-force mechanism to solve the problem of decreasing rate precision due to energy required for advancing the disks. This refined yet complicated technology was used in a slightly different way in the Lange 31. It ensures that a constant amount of torque is delivered to the balance wheel independent of the state of the mainspring. Lange produces its own hairsprings in addition to the spring for the constant-force escapement, bringing the number of components in the Zeitwerk to an impressive 388.

Lange Zeitwerk - movement - rubies
The movement’s remontoir bridge features partially blued screws, screwed gold chatons and a line finish.

Close examination of the constant-force escapement reveals that its pallet must hold back the entire torque of the powerful barrel alone, so it is essential that the pallet stone be fastened securely. There were no problems with the company’s own test watches (which were set to run at 12 times normal speed, the equivalent of 10 years of operation, while also being subjected to extreme impact tests). However, our test watch contained one of the first production movements and stopped advancing correctly after only a short time because a pallet stone had shifted out of place. Afterward, Lange replaced the shellac it had been using with a strong adhesive in all completed watches. In addition, the company redesigned the column wheel to be sturdier and more reliable. After this repair, our test watch ran perfectly for the entire duration of the three-week test. The sapphire crystal caseback provides an excellent view of the large movement, which is truly a work of art: Every part exhibits hand-executed finishes and brilliant gold-finished engraving; details like the screwed gold chatons and hand-engraved balance and pallet bridges radiate the highest level of craftsmanship. The three-quarter plate for the escape wheel is decorated with a Glashütte stripe finish, the mainplate with perlage, and visible gears with a Glashütte sunburst finish. The end plate of the escape wheel is high-polished, and the screws are polished and partially blued. The delicate bridge for the constant-force escapement shines with a line finish and two screwed gold chatons. Some (but not all) of the mainplate’s edges are beveled and polished. As in the Richard Lange watch, the large balance wheel has eccentric regulating weights instead of regulating screws.

The movement was adjusted as carefully as it was decorated. Measurements on the timing machine showed a minimal positional error of only four seconds. The Zeitwerk ran slightly ahead in all positions, and the average deviation was quite low, at only +1.5 seconds per day. Moreover, even after the watch had been worn under real conditions for three weeks, the watch showed exactly the same results. It takes some time to become accustomed to reading the disks within the windows; a standard digital display reads much differently. However, while it is much easier to read the approximate time on a standard analog watch dial, reading the exact time is actually easier on this watch thanks to the large numerals in the windows. And if only the right third of the watch is peeking out from under your sleeve, you can still easily read the minutes — a practical feature, since most of us usually know the hour.

Lange Zeitwerk - movement -numeral disks
The numeral disks have a multi-layered design.

The barely audible click that occurs when the minute disks advance sounds like a tiny lock snapping into place, and is only slightly louder than the ticking of the Lange movement. Less pleasing is the warning sound we all know from mechanical clocks, which is caused by the minute disk being slightly offset downwards about six seconds before it jumps. The case, with its satin-finish center section and narrowing lugs, is the picture of reserved elegance. The slightly raised caseback has a concave edge that makes the watch appear flatter than it actually is. Every surface boasts excellent polishing and finishing.

The hand-stitched crocodile strap has fully turned edges and an attractively large pattern. The distinctly shaped pronged buckle might have been more carefully polished on its inner surface, but the clever strap design ensures that the clasp lies snugly against the inner wrist and the strap bends very little. Fortunately, the rather sharp edges of the clasp are not very noticeable when wearing the watch. Despite its large size (almost 42 mm) the Zeitwerk lies comfortably on the wrist. Though the strap is initially quite stiff, it did become more supple after a short period of wear; and the crown, though placed very near the bottom edge of the case, does not touch the wrist thanks to its strategic position at half past one o’clock. The Zeitwerk’s price ($70,100) is high, but worth it. A comparable model, the Lange 31, was introduced in 2007 with a power reserve of one month and a constant-force escapement. It has similar complications and costs substantially more. If the Zeitwerk had been introduced before the financial crisis, its price would have surely been much higher, so prospective customers might find it to be quite a value for the price.

A. Lange & Sohne Zeitwerk_front

+ Ingenious design
+ Innovative movement technology
+ Value for the price

– Visible difference in height between first and second minute digits
– Minute disk moves slightly before jumping to the next minute

Manufacturer: Lange Uhren GmbH, Altenberger Strasse 15, 01768 Glashütte, Germany
Reference number: 140.029
Functions: Jumping hours and minutes (digital), small seconds, power reserve indication
Movement: L043.1, manual-winding; 18,000 vph; 68 jewels; Incabloc shock absorption; Glucydur balance; eccentric fine regulation; swan neck fine regulation for the beat; in-house hairspring; constant-force escapement with in-house spring, hand-engraved balance bridge and escape wheel bridge; diameter = 33.6 mm; height = 9.3 mm; 36-hour power reserve
Case: White gold, sapphire crystal in front and back, caseback held by six screws, water-resistant to 30 meters
Strap and clasp: Hand-stitched crocodile strap with white-gold pronged clasp
Rate results (deviations in seconds per 24 hours):
Dial up    +3
Dial down    +4
Crown up    0
Crown down    +1
Crown left    0
Crown right    +1
Greatest deviation:        4
Average deviation:        +1.5
Average amplitude:
Horizontal positions    292°
Vertical positions    255°
Dimensions: Diameter = 41.9 mm, height = 12.6 mm, weight = 141 g
Variations: Rose or yellow gold; platinum ($75,900)
Price: $70,100

Strap and clasp (10): The beautifully patterned crocodile strap is carefully hand-stitched, but the attractive and practical buckle closure could have been polished more carefully.    9
Operation (5): The large crown is easy to pull. A hack mechanism stops the balance, and minutes can be set either forward or backward.    4
Case (10): The white-gold case is polished with exquisite care. The caseback makes the watch appear flatter than it really is.    9
Design (15): The digital display features a groundbreaking design that could, like the Lange 1, be a trendsetter without fully breaking from tradition.    15
Legibility (5): The time can be read quickly and much more accurately than on a watch with hands, though the large numerals remain dark at night.    4
Wearing comfort (10): Despite a case diameter of almost 42 mm, the watch is comfortable to wear, thanks to the sloping lugs and pronged buckle.    9
Movement (20): The jumping time indication requires a great deal of maintenance, but the newly developed barrel and constant-force escapement with governor and fly vane provide an excellent solution. The movement is also a feast for the eye, thanks also to Lange’s elaborate surface finishes.    19
Rate results (10): The in-house springs for the balance and constant-force escapement paid off with low positional errors and an excellent average deviation.    9
Overall value (15): The price of the watch is high but appropriate due to its superior quality and technical innovations.    13
TOTAL:     91 points

This article was originally published in 2013 and has been updated.

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    • macewindufan

      the innovations are well worth the high price…i’d get this over a Patek perpetual Calendar, the 5270G-014 i mean)

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