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Caliber 9R01


Caliber 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 caliber, 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.

Driving system Manual
Accuracy ±1 per day (±15 seconds per month)
Power reserve Approximately 192 hours
Vibrations 36,000 vibrations per hour (10 beats per second)
Jewels 56 jewels
Remarks Power reserve display function, Quick correction function of time difference adjusting to a calender


The 3 barrels for increased power and reduced energy transmission loss

In order to realize the eight-day (192 hours) power reserve of Caliber 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 escape wheel which increases the efficiency of the energy transfer by 10%.


A solid, one-piece bridge for enhanced durability

In the assembly of most watch movements, the gears and other components are placed on the main plate which acts as a base and these parts are then held in place on the main plate by a second component, known as a bridge. For Caliber 9R01, however, Grand Seiko developed a new system in which these two parts are fused into a single, one-piece bridge. This system delivers enhanced durability and is, we believe, a unique design.

The thickness of this one-piece bridge is some three times greater than any other Spring Drive caliber. Made possible by very high precision engineering, it provides a totally solid base on which all the components are secured in place more precisely.
In addition, the greater thickness of the bridge enhances the durability of movement as the gear shafts are better protected in the event of impact or other shock.

The Micro Artist Studio's first Spring Drive watch

Caliber 9R01 is the first Grand Seiko Spring Drive movement to be created by the Micro Artist Studio in Shio-jiri in the mountains of central Japan. This remarkable Studio has been responsible for many of the company’s great achievements, including the Credor Spring Drive Sonnerie and Minute Repeater.

What is the Spring Drive?

Spring Drive is a unique watch technology that combines the power derived from a mainspring with the high accuracy of an electronic watch. Like all other mechanical watches, Spring Drive uses the energy generated by the movement of the wearer’s wrist to move the hands, but it also uses this to create electrical energy that powers a unique regulator that is up to ten times more accurate than any traditional escapement.

The Tri-synchro regulator combines three types of power:

1. Mechanical power (to generate and store energy in a mainspring)
2. Electrical power (to activate an IC and quartz oscillator)
3. Magnetism (to apply a brake to the hands via a rotor/stator)

The combined operation of these three functions delivers one second a day precision and gives Spring Drive its unique signature, the elegant glide motion of the second hand as it moves around the dial, accurately, smoothly and silently.

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.