Caliber 9F with Spring Drive technology is a remarkable innovation in the advancement of mechanical watches. Grand Seiko combines electronic and mechanical control technologies in their timepieces to provide a level of precision that cannot be matched. The development of the Spring Drive was certainly possible because Grand Seiko is one of the manufacturers with a mastery of both electronic and mechanical watchmaking.
The hallmark of Spring Drive is the smooth sliding motion of the second hand. This technology combines the high torque of a mechanical watch with the high-precision integrated circuit (IC) control system of an electronic watch. Spring Drive uses a proprietary speed control mechanism incorporating IC, electronic brakes, and a quartz crystal.
Tri-Synchro Regolator
Grand Seiko conducting the development of Spring Drive to regulate moving parts and establish synchronicity. Spring Drive uses a Tri-synchro regulator that controls it all:
• Mechanical Power to generate electricity from the non-rotating mainspring
• Electrical Power to transmit precise signals via a quartz crystal oscillator
• Electromagnetic Power to apply speed control brakes
Powered by the Mainspring
The Spring Drive is also supported by the mainspring to store the energy used to move the hands when the spring is released over time. Winding the mainspring by turning the crown or moving the wrist without the need for a battery or other power source like other mechanical watches.
Design plans are based on tolerances down to the one hundredth of a millimeter. The final adjustments and refinement of the components are completed by hand, because no machine can match the skills of our craftsmen and women – watchmakers whose superior craft gives rise to the extreme precision of Spring Drive.
Movement Comparison
Movement | Accuracy | Power reserve | Number of jewels | Features |
Spring Drive 5 Days Caliber 9RA2 (Automatic with manual winding) | ±10 seconds per month (±0.5 second per day) | Approximately 120 hours (5 days) | 38 jewels | -Offset Magic Lever -Dual-size Barrels -One-piece Center Bridge -Power reserve indicator |
Spring Drive 5 Days Caliber 9RA5 (Automatic with manual winding) | ±10 seconds per month (±0.5 second per day) | Approximately 120 hours (5 days) | 38 jewels | -Offset Magic Lever -Dual-size Barrels -One-piece Center Bridge -Power reserve indicator |
Manual-winding 8-Day Power Reserve Spring Drive Caliber 9R01 (Manual winding) | ±0.5 seconds per day (±10 seconds per month) | Approximately 192 hours | 56 jewels | -Power reserve indicator -Quick correction function of time difference |
Manual-winding Spring Drive Caliber 9R02 (Manual winding) | ±1 second per day (±15 seconds per month) | Approximately 84 hours | 39 jewels | -Torque Return System -Dual-Spring Barrel -Power reserve indicator |
AUTOMATIC SPRING DRIVE 3-DAY CHRONOGRAPH GMT Caliber 9R96 (Automatic with manual winding) | ±0.5 seconds per day (±10 seconds per month) | Approximately 72 hours | 50 jewels | -Power reserve indicator -Dual time function with 24-hour hand -Quick correction function of time difference adjusting to a calendar -Stopwatch function |
Automatic Spring Drive 3-Day Chronograph GMT Caliber 9R86 (Automatic with manual winding) | ±1 second per day (±15 seconds per month) | Approximately 72 hours | 50 jewels | -Power reserve indicator -Dual time function with 24-hour hand -Quick correction function of time difference adjusting to a calendar -Stopwatch function |
Automatic Spring Drive 3-Day GMT Caliber 9R66 (Automatic with manual winding) | ±1 second per day (±15 seconds per month) | Approximately 72 hours | 30 jewels | -Power reserve indicator -Dual time function with 24-hour hand -Quick correction function of time difference adjusting to a calendar |
Automatic Spring Drive 3-Day Caliber 9R65 (Automatic with manual winding) | ±1 second per day (±15 seconds per month) | Approximately 72 hours | 30 jewels | -Power reserve indicator -Date display |
Manual-winding Spring Drive Caliber 9R16 (Automatic with manual winding) | ±0.5 seconds per day (±10 seconds per month) | Approximately 72 hours | 30 jewels | -Power reserve indicator -Dual time function with 24-hour hand -Quick correction function of time difference adjusting to a calendar |
Manual-winding Spring Drive Caliber 9R31 (Manual winding) | ±15 seconds per month(±1 second per day) | Approximately 72 hours | 30 jewels | -Dual-Spring Barrel -Power reserve indicator |