Review: A. Lange & Söhne Zeitwerk - The Mechanical Digital Wristwatch

Sitting at either end of the watchmaking spectrum, there are mechanical watches and there are digital watches. They couldn't be further apart. Think digital watch and you think of the Casio G-Shock, the modern face of timekeeping; think mechanical and you think of one of Patek Philippe's micro-engineering masterpieces, a bastion of tradition. But there's a strange overlap that exists where the two meet, a sort of watchmaking twilight zone where two polar opposites come together and digital becomes mechanical. Welcome to the A. Lange & Söhne Zeitwerk, the mechanical, digital wristwatch.

Watch our video review of the A. Lange & Söhne Zeitwerk 140.029

If you're scratching your head wondering where the dot matrix screen is on this digital watch, then it will probably help to know that digital doesn’t strictly refer to an electronic display. Digital, from the Latin digitus, originally referred to fingers, to pointing, which was then expanded in the fifteenth century to also mean any number up to ten—basically, the number of fingers we have.

It was then in the early days of computing, when continuous voltage analogue machines evolved into ones that used discrete digits—ones and zeros, specifically—that the word digital became synonymous with computing. But it was the use of digits for the computation that determined the word digital, not the electronic power source.

Zeitwerk - the mechanical digital watch

In the case of a watch display, the misunderstanding is similar. A digital watch is not one that's powered by electricity, but one that displays the time through discrete digits. The opposite, like with computing, is the analogue display—a continuous readout, or hands.

The mechanical digital display has been used in watchmaking since the pocket watches of the 19th century, but never left to right, and never with an instantaneous change. That is, not until now.

There are a lot of mechanical innovations used in the Zeitwerk to allow it to have the hours and minutes aligned left to right with instantaneous change. The power source, for example. Compared to traditional, continuously moving hands, the need to move up to three large disks imperceptibly in a fraction of a second requires a huge amount of torque. Naturally, the Zeitwerk has a thicker mainspring than usual—you can feel it in the crown—and Lange could have settled for just that, but the brand went one step further.

The unusual dial needs an unusual movement

Typically, mainsprings are wound from the inside of the barrel and unwind from the outside, but this design loses the precious torque needed to jump the disks. So, Lange turned the barrel upside down and suspended it so it could be wound from the outside and unwind from the inside instead. This allows lower friction bearings to be used, rather than the power-sapping alternatives.

All this torque needs to be kept under control, and so a star wheel arrangement atop the barrel was added to prevent the mainspring being wound beyond its 36-hour maximum.

But this is nothing compared to the remontoir system used to actually deliver that power. It acts as a mechanical capacitor, storing the huge chunk of torque needed to spin the minute and hour discs instantaneously. It works like a secondary mainspring, wound by the movement and locked in place over the course of a minute. As each minute comes to an end, the y-shaped lever blocking it from unwinding slips free, allowing that pent-up torque to discharge while preventing it from being wound further until the jump is complete.

Hours on the left, minutes on the right, seconds below

But that sudden explosion of power needs an outlet to avoid damaging the mechanism. Lange's got this covered, too. The last link in the chain for the remontoire system is a free-spinning flywheel damper that uses blades to drag against the air and bring the mechanism to a controlled, gentle halt.

It's a deliciously complex and truly astonishing mechanism, which can be clearly seen working through the sapphire caseback. It's a watch that provides as much pleasure upside down as it does right way up.

An engineering masterpiece from Germany

The Zeitwerk may be a big, thick watch by A. Lange & Söhne's usual standards, but considering the workmanship going on inside, it's easily forgivable. In a world where tradition is king, seeing such an inspired, left-field alternative is beyond refreshing, and to have it undertaken by one of the best watchmakers in the world is even better. Long may the anti-tradition continue.

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