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The Encyclopedia of Horology

Movement record · Switzerland

Jaeger-LeCoultre Calibre 920

Partially verified

An extremely thin automatic movement using a 22-carat gold peripheral micro-rotor rather than a full rotor, allowing exceptional slimness; supplied by Jaeger-LeCoultre to several prestige houses and adapted as the basis for celebrated in-house calibres elsewhere.

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Technical specifications

Diameter
Approx. 28 mm
Height
Approx. 2.45 mm
Jewels
Approx. 28
Frequency
19,800 vph
Power reserve
Approx. 40 hours
Winding
Self-winding with a peripheral micro-rotor
Setting
Pull-out crown
Escapement
Swiss lever
Balance
Conventional balance with flat hairspring
Complications
Date on some applications

Identification features

  • Micro-rotor construction visible from the case-back
  • Exceptional thinness for an automatic movement of its date
  • Full rotor running on a peripheral rail rather than a central bearing
  • Height about 3.05 mm with date

Known variants

  • Manufacturer-specific finishing and branding of the shared base architecture
  • Audemars Piguet 2120 / 2121
  • Vacheron Constantin 1120
  • Patek Philippe 28-255 C

Servicing notes

Specialist high-end servicing recommended given the movement's thinness and the finishing standards expected of its applications.

General guidance only. Antique movements should be serviced by a qualified watchmaker.

Historical significance

Ultra-thin full-rotor automatic of 1967, supplied to Audemars Piguet, Patek Philippe and Vacheron Constantin and famous as the movement of the first Royal Oak, Nautilus and Overseas-generation sports watches.

Photographs

Balance of a wristwatch Jaeger-LeCoultre Master Eight Days Perpetual Squelette
Balance of a wristwatch Jaeger-LeCoultre Master Eight Days Perpetual Squelette — Jaeger-LeCoultre_MasterEightDaysPerpetualSquelette.jpg: Ghilt derivative work: PawełMM (talk), CC BY-SA 3.0. Wikimedia Commons file page
Jaeger-LeCoultre caliber K916 with EU version rotor
Jaeger-LeCoultre caliber K916 with EU version rotor — Ghilt, CC BY-SA 4.0. Wikimedia Commons file page
I Am Legend — The Jaeger-LeCoultre Calibre 920 - Revolution Watch
I Am Legend — The Jaeger-LeCoultre Calibre 920 - Revolution Watch — revolutionwatch.com, Rights unverified — web image search result, review pending. Web page (revolutionwatch.com)
Audemars Piguet Calibre 5134, an ultra-thin perpetual calendar movement based on the Jaeger-LeCoultre Calibre 920 ébauche
Audemars Piguet Calibre 5134, an ultra-thin perpetual calendar movement based on the Jaeger-LeCoultre Calibre 920 ébauche — Revolution Watch, Rights pending — permission not yet requested. Web page (revolutionwatch.com)
Patek Philippe calibre 28-255 movement, based on the Jaeger-LeCoultre calibre 920 ébauche
Patek Philippe calibre 28-255 movement, based on the Jaeger-LeCoultre calibre 920 ébauche — A Collected Man / Revolution Watch, Rights pending — permission not yet requested. Web page (revolutionwatch.com)

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Jaeger-LeCoultre and licensee historical literature
  2. Independent watch-industry technical histories
  3. de Carle, D., Watch and Clock Encyclopedia
  4. Period trade material catalogues and calibre reference compilations (edition-dependent)
  5. Published manufacturer technical documentation where available

Where sources disagree, the disagreement is stated rather than resolved silently.