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 – $10,500
03

2025 • NEW SPRING DRIVE

9RB

±20 SECONDS / YEAR
  • 3 Day PR
  • Titanium
  • $10,900
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 generates the electrical energy used by the 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 and regulation system. BARREL GEAR TRAIN GLIDE WHEEL REGULATION I.C. + MAGNETIC BRAKE 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.
U.F.A.

9RB

  • 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
TITITANIUM