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The Encyclopedia of Horology

Movement record · Switzerland

Eterna-Matic calibre family

Partially verified

Automatic calibre using a ball-bearing-mounted rotor

Technical specifications

Diameter
Approx. 27 mm
Height
Not recorded in the sources consulted
Jewels
21 (variants differ)
Frequency
18,000 vph (2.5 Hz)
Power reserve
Approx. 40 hours
Winding
Automatic with manual winding
Setting
Pendant set
Escapement
Swiss lever
Balance
Monometallic balance
Complications
Centre seconds, Date in variants

Identification features

  • Ball-bearing rotor mounting, a defining feature of the Eterna-Matic system

Known variants

  • Date and no-date versions
  • Later generations with revised winding

Servicing notes

Cleaning, lubrication, mainspring and pivot work belong with a qualified watchmaker working from calibre-specific documentation. Conserve original parts: replacing a worn component with a modern substitute changes the object, and refinishing plates or dials destroys evidence.

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

Historical significance

Introduced ball-bearing rotor mounting into series production, an approach later widely adopted across the industry.

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. de Carle, D., Watch and Clock Encyclopedia
  2. Period trade material catalogues and calibre reference compilations (edition-dependent)
  3. Published manufacturer technical documentation where available

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