The finest 9R Spring Drive movements boast long power reserves.

Since 2000, the Micro Artist Studio has been home to some of Japan’s best watchmakers and artisans. While much of the elite workshop’s acclaim comes from the high level of finishing applied to its watch movements, its technical innovations represent another strong suit.

To wit, the Calibers 9R01 and 9R02, which are produced exclusively for Grand Seiko as the pinnacles of 9R Spring Drive by the Micro Artist Studio, feature impressive hand finishing in addition to a range of technical innovations, setting them apart from many other watch movements. Each uses a different approach to achieve its long power reserve. With Caliber 9R01, three barrels work together to deliver eight days of running autonomy. With Caliber 9R02, the innovative Torque Return System is deployed to recoup energy that would otherwise be wasted from a pair of mainsprings, boosting the power reserve from 72 hours to 84.

Caliber 9R01
Caliber 9R01 was the first Grand Seiko movement created by the Micro Artist Studio, and every aspect of its design was carefully considered for aesthetic beauty and functional performance. On the surface, the movement is not merely beautifully finished, but represents the geography of the part of the area from which all Spring Drive movements hail. The rubies recall the lights of Suwa City; the power-reserve indicator represents Lake Suwa; and a portion of the large, durable bridge is in the iconic shape of Mt. Fuji, next to which rotates the glide wheel, representing the sun. Beneath this large and sturdy bridge, three barrels turn to give Caliber 9R01 its impressively long power reserve.

It was desirable for these three barrels to be connected directly to one another, as an intermediary wheel between barrels would lead to a loss of energy. Additionally, a horizontal arrangement of the barrels would result in a movement that was quite large. For efficiency in power transmission, while avoiding an overly large movement, the three barrels were arranged three-dimensionally. The first and second barrels are next to one another, on top of the third barrel.

To efficiently use the power from this triad of barrels and achieve a long power reserve, it was important to minimize friction as much as possible. In Caliber 9R01, rubies are set into the barrels to reduce friction with the barrel arbors. Precise manufacturing and polishing of various pivots and pinions reduce friction and increase the power reserve.

Since Caliber 9R01 is a manually wound movement, turning the crown with ease and comfort is paramount. Looking closely at the profile of SBGD201, one will notice that the bezel rising above the case is thin. There is also a concave curve to the outer circumference of the case back. While minor details these may seem, they are carefully considered design attributes chosen to enable the watch’s owner to turn the watch’s crown with ease.

The experience of turning the crown is easy yet satisfying thanks to the good engagement of the click and the first ratchet wheel; one feels the appropriate resistance due to the reduction ratio of the manual winding gear train in consideration of the characteristics of the mainspring.

Viewed through the sapphire crystal case back, one notices the power-reserve indicator aligns with the crown, a choice made with the user in mind. He or she can enjoy watching the power reserve increase with each turn of the crown.

Caliber 9R02
Unlike Caliber 9R01, the 9R02 movement has only a single barrel. A desire for a movement that would power a smaller and more elegant dress watch prevented the use of multiple barrels in this movement’s architecture. Nonetheless, a long power reserve was achieved by other means, namely the Dual Spring Barrel and the Torque Return System.

One way to increase the power reserve of a spring-powered watch with one barrel is to make the mainspring thinner and lengthen it. While this can provide a long duration, a thin mainspring will lack torque. To compensate for this shortcoming, Grand Seiko places two mainsprings in parallel within a single barrel, what Grand Seiko calls the Dual Spring Barrel. This provides sufficient torque to turn the substantial hands of a 9R Spring Drive watch.

The Torque Return System is a revolutionary mechanism that captures energy that would otherwise be wasted and uses it to rewind the watch’s mainspring. When fully wound, a 9R Spring Drive movement exerts 25% more energy than is needed to turn the watch’s hands and accurately display the time. The Torque Return System extends the power reserve by using this extra energy to make the barrel turn the torque return wheels, the last of which turns the ratchet wheel. The system operates for 48 hours, then the torque-transfer lever turns the system off. These two innovations, operating in tandem, allow Caliber 9R02 to maintain a thinness of 4mm while delivering a power reserve of 84 hours.

Both of the 9R Spring Drive movements created by the Micro Artist Studio pursue a long power reserve, though each does so differently. Calibers 9R01 and 9R02 provide satisfaction to watch enthusiasts, appealing to a fascination with mechanics as much as to a sense of beauty. They are the pinnacle of the 9R Spring Drive movement series, which owes its very existence to the dream of one engineer nearly half a century ago. Carrying that dream forward while reflecting the quiet flow of time, 9R Spring Drive continues to evolve.