AMERICA TRAINING ← Training Library

SPRING DRIVE U.F.A. • 超高精度

PRECISION
REDEFINED.

Grand Seiko’s pursuit of high accuracy advances from seconds per month to an annual rate of ±20 seconds with the 9RB series.

Explore the evolution See how Spring Drive works ↓
CALIBER 9RBU.F.A.
±20

SECONDS PER YEAR

EXPLORE

EVOLUTION OF SPRING DRIVE • 1977—2025

A pursuit measured
across generations.

The pursuit of high accuracy has always been a cornerstone of Grand Seiko’s philosophy. Spring Drive development began in the late 1970s, passed through decades of prototyping and continued refinement, and culminated in the 9RB series.

01 / 06

Spring Drive Development
Begins

The first development period spans 1977–1982, with the first prototype completed in 1982.

FIRST PROTOTYPE1982

THE PURSUIT OF HIGH ACCURACY • 精度

Month.
Month.
Year.

From the 9R6 series in 2004 to the 9RA series in 2020 and now 9RB, the stated accuracy standard advances dramatically—from ±15 seconds per month, to ±10 seconds per month, to ±20 seconds per year.

01

2004 • SPRING DRIVE

9R6

±15 SECONDS / MONTH
  • 3 Day PR
  • Steel & Titanium
  • $4,800 – $6,900
02

2020 • SPRING DRIVE

9RA

±10 SECONDS / MONTH
  • 5 Day PR
  • Steel & Titanium
  • $9,300+
03

2025 • NEW SPRING DRIVE

9RB

±20 SECONDS / YEAR
  • 3 Day PR
  • Titanium
  • $10,200+
U.F.A. • ULTRA FINE ACCURACY

Accuracy is no longer framed in seconds per day, week, or month—but over the course of an entire year.

HOW ALL SPRING DRIVE MOVEMENTS WORK • 機構

Mechanical energy.
Electronic regulation.

Spring Drive begins with energy stored in a mainspring. A gear train transmits that mechanical energy to a glide wheel. The glide wheel interacts with a stator to generate a small amount of electricity that powers the quartz oscillator and integrated circuit, while a magnetic brake regulates its speed. There is no battery.

Spring Drive energy flow Animated diagram showing barrel, gear train, glide wheel, stator and regulation system. BARREL STATOR COIL-WOUND COMPONENT GEAR TRAIN GLIDE WHEEL REGULATION QUARTZ OSCILLATOR + I.C. NO BATTERYMAINSPRING POWERED
01 • BARREL

Mechanical energy is stored in the mainspring—no battery is used.

INTERACTIVE SPRING DRIVE LAB • 体験

Understand it.
Feel the difference.

Four hands-on demonstrations turn Spring Drive's regulation, power generation and precision into something you can see and control.

01MAGNETIC BRAKE LAB

Can you regulate it?

Adjust the electromagnetic brake and try to bring the glide wheel to exactly 8.00 revolutions per second.

GLIDE WHEEL8.66REV / SEC
SIMULATED RATE ERROR +7,128 Sec / Day
TOO FAST

Training simulation: the control illustrates regulation behavior rather than reproducing the movement's control algorithm.

02ACCURACY OVER TIME

Twenty seconds. One year.

Move through a full year and compare how small the U.F.A. annual tolerance remains against earlier Spring Drive ratings.

365DAYS ELAPSED
9R6±15 sec / month
±182.5s
9RA±10 sec / month
±121.7s
9RB U.F.A.±20 sec / year
±20.0s

Illustrative proportional scaling of the stated rating periods; real-world deviation is not assumed to accumulate linearly.

03GENERATE ELECTRICITY

Mechanical in. Electrical out.

Increase glide-wheel speed and watch the stator convert mechanical energy from the barrel into electrical energy that powers the quartz oscillator and integrated circuit.

QUARTZ32,768 Hz
INTEGRATEDI.C.
GENERATED ELECTRICITY
0.0 nW
MAX OUTPUT 25 NANOWATTS
INCREASE SPEED TO GENERATE POWER

The energy meter is a conceptual training visualization, not a measurement of electrical output.

04SECONDS-HAND MOTION

Tick. Step. Glide.

Watch the same second expressed three ways: a mechanical movement in discrete beats, quartz in one-second steps, and Spring Drive in continuous motion.

SECONDS HAND MOTION Spring Drive
Continuous glide

Switch between quartz, 28,800 vph, 36,000 vph, and Spring Drive to compare how each movement expresses the passing second.

SPRING DRIVE BENEFITS • ADVANCEMENT

Same principle.
Higher standard.

ALL

Spring Drive

  • Less maintenance.
  • Higher level of accuracy vs mechanical movements.
  • Accuracy is consistent over time.
9RA

5 Day

  • Power reserve increases to 5 days.
  • Accuracy improves to ±10 seconds per month.
  • Thinner caliber allows slimmer watches.
  • Enhanced movement finishing.
9RB

U.F.A.

  • Accuracy improves to ±20 seconds per year.
  • Thinner caliber allows slimmer watches; smaller diameter allows smaller case sizes.
  • Enhanced movement finishing.

2025 • CALIBER 9RB

Twenty seconds.
One year.

The 9RB series sets a new benchmark among wristwatch movements powered by a mainspring by expressing its stated accuracy over an entire year.

±20SEC / YEAR
3DAY PR
13.45%THINNER MOVEMENT