Technical: Satellite Hours

When it comes to telling the time, we’re taught the basics from a young age: the little hand points to the hour and the big hand shows the minutes. Not so for forward thinking watchmakers Urwerk for whom reading hands on a dial was simply not enough. Founded by watchmaker Felix Baumgartner and designer Martin Frei, Urwerk introduced itself to the world with prototypes for the UR-101 and UR-102 in 1997. With a brand ethos of creating art that tells the time, Urwerk translates its futuristic vision into a range of groundbreaking and visually stunning timepieces.

Setting a precedent for an unparalleled level of watch innovation, Urwerk’s out-of-the-box strategy brought us the satellite hours system, first seen in the Opus V, a collaboration with high-end jewellers and purveyors of rare timepieces Harry Winston. The Opus V dispenses with a traditional dial in favour of a complex three-dimensional system. Using a complication for the hour display that had never been seen before, the watch utilises three cubic satellites to mark the hours. The cubes orbit in a circular motion via a central carousel, and rotate upon themselves using Geneva crosses, placed at ninety degrees to the usual conventions. This system has now been patented, despite the initial scepticism of more than one experienced watchmaker.

This Geneva cross method evolved from the star wheel system used to turn the hour disks in Urwerk’s early prototypes, an arrangement similar to that used within the Audemars Piguet Starwheel watch. The star wheel concept uses extensive energy due to the spring being under permanent tension on the wheel, which in turn reduces the power reserve. In contrast, the Geneva crosses create less friction as there is no spring tension, and unlike the star wheel concept, there is no spring to overcome in order to change to the next position, removing the possibility of the wheel jumping an extra step if turned too quickly. The early layout of Urwerk’s Geneva cross idea used three U-shaped slots corresponding to the three hours displayed upon each satellite, although the Opus V simplified this arrangement by incorporating the cross into the base of each satellite.

Three specially shaped springs are housed underneath the satellite system, allowing it to orbit counter clockwise without damage. The addition of these springs also provides the bounce motion that occurs when the minute hand returns to zero. The left hand side of the ambitious time display houses a crescent shaped retrograde minute scale; this layout, alongside the circular motion of the hour display ensures that the minute hand always remains equidistant from the scale itself.

As if not complex enough in its own right, the use of the satellite hours system created an additional hurdle in the construction of the Opus V; with the retrograde mechanism traditionally controlled by the centre axis, this position was already occupied by the satellite complication. Knowing of no other retrograde mechanism that competed with another complication, Baumgartner wanted to overcome this obstacle by attaching the minute hand to a large diameter ball-bearing, powered by a double star to circle the satellite system. He was told that this style of bearing couldn’t sustain such a thin-cross section. Persevering, the Opus V not only found its bearings, but the ideal traction springs; the part that returns the retrograde eventually came down from 12mm to a tiny 0.05mm. The trial and error was worth it, with the retrograde mechanism eventually only using 15% of the movement’s power.

The orbiting satellite display takes its inspiration from the wandering hours principle, which introduced the concept of telling the time in three dimensions. An innovation first seen in 1656, the idea of wandering hours originated when the Campanus brothers replaced the conventional hands of the clock they had built for Pope Alexander XII with hour figures on rotating disks. Urwerk has taken this invention to new heights, incorporating rotating cubes, spinning conical discs and retractable retrograde pointers into its ranges. Despite its early origins in clocks, the wandering hours display has only been seen in wristwatches over the past few decades, with the orbiting satellite display becoming a trademark feature for Urwerk, having used the technology premiered in the Opus V in subsequent models.

Innovations such as the satellite hours display have placed the Opus V and Urwerk firmly on the horological map. With the brand’s name referencing Ur, the location where the concept of measuring the time was invented, it only remains for Urwerk to strive to reinvent it.

Believe it or not, Urwerk’s ingenious satellite hours system is a lot less complicated than it first appears. This is a credit to Martin Frei’s ability to design efficient and compact mechanisms, and to Felix Baumgartner’s desire to offer a pure (if unusual) display to read the time from. The result is simply mesmerising; watch the video above to see for yourself.