Manual-winding Spring Drive

Caliber 9R31

A manual-winding Spring Drive caliber made in the Shinshu Watch Studio, 9R31 has an innovative dual-spring barrel that contains two mainsprings set in parallel and delivers a power reserve of 72 hours.


Winding mechanism Manual winding
Accuracy ±15 seconds per month(±1 second per day)
Power reserve Approximately 72 hours
Number of jewels 30 jewels
Features -Dual-Spring Barrel
-Power reserve indicator

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.