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The Encyclopedia of Horology

Movement record · Switzerland

Vacheron Constantin calibre 1120

Verified

Vacheron Constantin's version of the ultra-thin automatic designed by Jaeger-LeCoultre as the 920, in which the rotor sits within the movement's outer diameter rather than above the plate.

Technical specifications

Diameter
28.4 mm
Height
2.45 mm
Jewels
36 jewels
Frequency
19,800 vibrations per hour
Power reserve
Approximately 40 hours
Winding
Automatic, by a peripheral rotor running on ball bearings at the movement edge
Setting
Crown setting
Escapement
Swiss lever
Balance
Free-sprung with adjustable mass
Complications
Base calibre; developed into perpetual calendar and skeleton versions

Identification features

  • Peripheral rotor at the movement edge
  • Geneva hallmark on many examples

Known variants

  • Perpetual calendar versions
  • Skeletonised versions

Servicing notes

Specialist service only; the peripheral rotor bearings are the usual point of wear.

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

Historical significance

One of the three houses' shared use of a single ultra-thin automatic design, and a rare case of a calibre remaining competitive for over fifty years.

Diagram

top plate or bridgespillar platebalance and cockwheel train between the plates
Schematic: plate and bridge layout. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. Manufacturer and specialist descriptions of the 920 / 1120 / 889 family
  2. The same base design is used by more than one house, so attribution should name the design origin.

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