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The Encyclopedia of Horology

Movement record · Germany

A. Lange & Söhne Calibre L901.0

Needs research

The manual-wind movement introduced in the Lange 1, the flagship model of the relaunched A. Lange & Söhne after German reunification, notable for its asymmetric dial layout and dual-barrel long power reserve.

Technical specifications

Diameter
Not fully documented in accessible sources
Height
Not fully documented in accessible sources
Jewels
Approx. 53
Frequency
21,600 vph (3 Hz)
Power reserve
Approx. 100 hours (two mainspring barrels)
Winding
Hand wind
Setting
Pull-out crown
Escapement
Swiss-type lever, in-house manufacture
Balance
Screwed gold balance with in-house hairspring in later production
Complications
Outsize date (Grossdatum), Power-reserve indicator

Identification features

  • Lange three-quarter plate in German silver with hand-engraved balance cock
  • Outsize date display

Known variants

  • Later revised calibres in subsequent Lange 1 generations

Servicing notes

Serviced almost exclusively through A. Lange & Söhne's own service network.

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

Historical significance

The defining calibre of Lange's post-reunification revival and a benchmark of the modern German school of finishing.

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. A. Lange & Söhne literature; precise dimensional specification not independently confirmed here

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