Manual-winding 8-Day Spring Drive

Calibre 9R01

All Spring Drive movements already offer a remarkable 72 hours of power reserve. The challenge was clear. Could this be extended still further?

The team at the Micro Artist Studio thought so and the Grand Seiko 8-Day Spring Drive is the result. To maintain perfect timekeeping for up to eight days (192 hours) requires greatly increased power, which is provided by a linked series of three barrels. This remarkable calibre, 9R01, has also been designed throughout to maximize energy efficiency, reducing friction between parts that would otherwise lead to loss in the transmission of the energy derived from the mainspring.

Specifications

Winding mechanism Manual winding
Accuracy ±0.5 seconds per day (±10 seconds per month)
Power reserve Approximately 192 hours
Number of jewels 56 jewels
Features -Power reserve indicator
-Quick correction function of time difference

THE 3 BARRELS

The 3 barrels for increased power and reduced energy transmission loss

In order to realize the eight-day (192 hours) power reserve of Calibre 9R01, three barrels are used. They are arranged in sequence for expanded capacity.

The whole movement has been designed to reduce friction between parts that would otherwise lead to loss in the transmission of the energy derived from the mainspring. Precise manufacturing and polishing delivers reduced friction, as does the removal of the intermediate wheel which increases the efficiency of the energy transfer by 10%.

What makes 9R Spring Drive special?

Spring Drive, one of the great innovations in modern watch making history, regulates a spring-driven movement with state-of-the-art electronic technology that functions without batteries or other external power source. Its sole power source is a mainspring, which drives a series of gears. A rotor, connected to the end of these gears, generates a small electrical charge that activates an electronic circuit and quartz oscillator. Its accuracy is unprecedented for a watch wound by a mainspring. The development of the 9R Spring Drive movement was possible only because Grand Seiko is one of the few manufacturers with expertise in both mechanical and electronic watches.

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