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.

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