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The Encyclopedia of Horology

Movement record · Switzerland

ETA 2892-A2

Partially verified

Thin automatic bridge calibre

Technical specifications

Diameter
25.6 mm
Height
3.6 mm
Jewels
21
Frequency
28,800 vph (4 Hz)
Power reserve
Approx. 40 hours
Winding
Automatic with manual winding
Setting
Pendant set with quick-set date
Escapement
Swiss lever
Balance
Monometallic balance with alloy hairspring
Complications
Date, Centre seconds

Identification features

  • Thin automatic with a distinctive off-centre rotor bearing arrangement
  • Frequently found beneath added complication modules

Known variants

  • Chronometer-grade versions
  • Module-equipped derivatives

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

A widely used thin automatic base calibre whose thickness made it the standard platform for modular complications.

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.