The evolution of 9R Spring Drive’s efficient winding mechanism.

With automatic watches, the power reserve is usually regarded as an important specification that contributes to convenience, and it does. But if a watch movement can’t be wound quickly and efficiently, its lengthy power reserve may be for naught.

For the first Caliber 9R to be realized, it needed to possess the high level of functionality and ease of use that are considered essential to Grand Seiko. To that end, Caliber 9R65 was equipped with an ample power reserve of 72 hours, but it also came with a highly efficient automatic winding system to ensure that it could be powered up quickly through the natural motions of the wearer.

Developed by Suwa Seikosha (now Seiko Epson Corporation) in 1959, the Magic Lever is one of the best-known automatic winding mechanisms in watchmaking, having stood the test of time thanks to its efficiency, simplicity, and relatively small number of parts. Using a pawl-lever system to ensure the mainspring was wound regardless of the direction of the oscillating weight, it was employed in certain Grand Seiko automatic watches from the 1960s, including the 62GS and 61GS.

The first 9R Spring Drive movement, which debuted in 2004, also relied on the Magic Lever, though with significant enhancements. The version of the Magic Lever found in the Caliber 9R65 is even more efficient and responsive to wearers’ arm movements than earlier implementations. In the 21st century, thanks to numerous technologies and devices that make our lives more convenient, we tend to move our arms less than we did in the ‘50s and ‘60s. With Caliber 9R65, the resilience of the pawl lever arms and the distance they travel when the oscillating weight rotates were reviewed from the ground up to enhance performance.

The Magic Lever was improved again in the 9RA series, the latest generation of automatic 9R movements. For 9RA, numerous design and performance considerations necessitated an updated winding system; fortunately, the Magic Lever could be further adapted. The 9RA series is equipped with dual-size barrels, each containing a mainspring that needs to be wound. The shapes of the teeth on the gears of the automatic winding mechanism were improved for better winding efficiency.

Pursuing a slimmer overall movement required a new approach to movement design, as well as to the manufacture of components. A Magic Lever with crank wheel arranged offset from the center of the movement was developed, reducing the number of overlapping parts. The Offset Magic Lever allows the remarkable 5mm thickness of Caliber 9RA2, which is 0.8mm thinner than 9R65 while offering a power reserve of five days compared to three.

Challenges in power reserve, finishing, and size have shaped the development of 9R Spring Drive through the years. Overcoming each has been essential to devising and evolving a movement series that bears the name Grand Seiko. Equally important has been the quest for superb winding efficiency, a pursuit enabled by evolving a simple yet ingenious mechanism created in 1959.