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Spring Drive

Spring Drive is a unique watch technology. It generates energy like every other luxury mechanical watch but combines this with an electronic regulator to deliver a level of precision that no mechanical watch can match.
The development of Spring Drive was possible because Grand Seiko is one of the very few manufacturers with mastery of both electronic and mechanical watchmaking.


Bringing together mechanical
and electronic watchmaking for the best of both worlds.

The two key elements behind the function of any watch are its power source and its time control system.

Spring Drive is a unique movement that combines the high torque of a mechanical watch with the high precision integrated circuit (IC) control system of an electronic watch.

Power source

Control system

Mechanical watch

High torque 

(motive force driving the watch)

The wound-up mainspring exerts force to turn gears at a set speed as it unwinds, while the speed control and escapement mechanism consisting of the balance, pallet, and escape wheel govern overall precision. While precise. even the most accurate Grand Seiko models cannot compete with the accuracy of a quartz watch, with a daily rate of +8/-1 seconds.

Quartz watch


Lower torque compared to
a mechanical watch

The battery sends electricity to a quartz oscillator, whose precise vibrations are detected by an integrated circuit (IC). The IC then moves the gears forward by exactly one second. The precision control of the IC allows for a high standard of accuracy, with Grand Seiko quartz models achieving a yearly rate of ±10 seconds.


Powered by the mainspring

Spring Drive is powered by a mainspring, just like all other mechanical watches. This traditional way of generating power allows the watch to be entirely autonomous, with no need for a battery or other power source.

Winding the mainspring by turning the crown or by moving the wrist stores energy which is then transferred to gears and used to move the watch hands as the spring unwinds over time.

By taking advantage of the high level of torque afforded by the mainspring, the caliber needs no other power to move the long, wide hands in the smooth glide motion that is Spring Drive’s signature.


The Tri-synchro regulator

Spring Drive utilizes an exclusive speed control mechanism, incorporating an IC, an electronic brake and a quartz crystal.

Without a mechanism to adjust the speed at which the mainspring returns to its unwound state, it would unwind rapidly and the watch would come to an abrupt stop. To realize the goal of precise timekeeping, a mechanism to control the speed at which the spring unwinds is needed.

The Tri-synchro regulator developed for Spring Drive fulfills this role.

As its name suggests, the Tri-synchro regulator uses three types of energy to regulate the moving parts and establish synchronicity:

  • 1. Mechanical power, from the mainspring
  • 2. Electrical power, creating a reference signaling via an IC/quartz oscillator
  • 3. Electromagnetic power, to apply a brake via a rotor/stator.

These three forces work in harmony to regulate the way the spring unwinds and to make possible the precise movement of the second hand.


Generating electrical power from the unwinding mainspring

Spring Drive uses a system identical to that of a pedal-powered bicycle light to generate electrical power. A rotor connected to the end of the gear train acts together with a stator wound by wire to generate power. In a Spring Drive watch, the rotor, or glide wheel, makes eight full revolutions every second, generating a slight electric current.


Transmitting a precise signal through a quartz crystal oscillator

The electrical power generated by the glide wheel is used to activate a quartz oscillator and IC.
The quartz oscillator vibrates at exactly 32,768 Hz, transmitting a precise reference signal to the IC.


Applying the brake to control speed

The IC compares the reference signal from the quartz oscillator with the revolution speed of the glide wheel, and intermittently applies a magnetic brake when it detects that the glide wheel is operating too fast. This regulation of the glide wheel is transmitted to the gear train, ensuring that the watch hands move with precision.


Master craftsmanship in assembly and adjustment

Spring Drive combines the best elements of both mechanical and electronic watches. While three-hand versions have over 200 components, versions with more functions, such as the Spring Drive chronograph have well over 300, all of which are assembled by hand.

The application of lubricating oils ensures the smooth interaction of all the components and there are no fewer than 80 lubrication points in the three hand caliber and 140 in the chronograph. The oils are applied by hand and both time and great skill are required to ensure that that the oils are applied with precision.

Design plans are based on tolerances down to the one hundred 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.


In 1977, Yoshukazu Akahane, a young watch engineer, decided to attempt the seemingly impossible, the creation of an ‘everlasting’ watch. His aim was a traditional watch, powered by a mainspring, that would deliver the one-second-a-day precision of which the company’s electronic watches were already capable. 28 years and 600 prototypes later, he realised his dream and Spring Drive was presented to the world. In 2007, and in the spirit of Akahane’s relentless pursuit of perfection, the Grand Seiko Spring Drive chronograph was born.



MovementAccuracyPower reserveNumber of jewelsFeatures
Caliber 9R01
(Manual winding)
±10 seconds per month
(±0.5 seconds per day)
Approximately 192 hours 56 jewels-Power reserve indicator
-Quick correction function of time difference
Caliber 9R02
(Manual winding)
±15 seconds per month
(±1 second per day)
Approximately 84 hours 39 jewels-Torque Return System
-Dual-Spring Barrel
-Power reserve indicator
Caliber 9R86
(Automatic with manual winding)
±15 seconds per month
(±1 second per day)
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
Caliber 9R66
(Automatic with manual winding)
±15 seconds per month
(±1 second per day)
Approximately 72 hours30 jewels-Power reserve indicator
-Dual time function with 24-hour hand
-Quick correction function of time difference adjusting to a calendar
Caliber 9R65
(Automatic with manual winding)
±15 seconds per month
(±1 second per day)
Approximately 72 hours30 jewels-Power reserve indicator
-Date display
Caliber 9R31
(Manual winding)
±15 seconds per month
(±1 second per day)
Approximately 72 hours 30 jewels-Dual-Spring Barrel
-Power reserve indicator