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The Encyclopedia of Horology

Component record · Case

Crown Thread

Partially verified

The internal thread by which a crown attaches to the stem.

What it does

Secures the crown so it can wind, set and, in screw-down designs, seal the case.

How it works

The stem is threaded and the crown screwed onto it, often with a thread-locking compound in modern practice.

Evolution

Screw-down crowns added a sealing function to the same joint.

Known variations

  • Push crown
  • Screw-down crown

Identification for collectors

  • A crown that pulls off the stem has a stripped thread rather than a broken stem.

Common failure modes

  • Stripped thread
  • Corroded joint

Diagram

crownsliding clutchsetting wheelswinding pinion and ratchet
Schematic: keyless winding and hand setting. 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., Practical Watch Repairing
  2. de Carle, D., Watch and Clock Encyclopedia
  3. Daniels, G., Watchmaking

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