Skip to content
The Encyclopedia of Horology

Glossary · Mechanism

Mainspring

The coiled spring that stores energy to drive the train.

Explanation

The mainspring stores energy as a coiled strip of spring material inside a barrel. In older watches it may be carbon steel; later alloys improved resistance to set, corrosion and breakage. Material alone does not identify service condition: a modern replacement spring can be appropriate, while an original spring may be historically important but unsafe to run without assessment.

In a going barrel the spring barrel drives the train directly. Automatic watches usually use a slipping bridle so the spring can slip against the barrel wall when fully wound; many manual watches have a fixed attachment and a clear stop. Fusee systems take power through a chain or cord to moderate changing torque. These arrangements should be recorded separately rather than reduced to the single word mainspring.

Sources & references

  1. de Carle, D., Practical Watch Repairing — mainspring barrels
  2. Daniels, G., Watchmaking — mainspring and barrel construction

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

What to record

  • Identify whether the watch uses a going barrel, fusee or other power path.
  • Record fixed attachment versus slipping bridle where documented.
  • Keep replacement-spring evidence separate from originality claims.

A wound mainspring stores dangerous energy; do not open a barrel or release power without the correct tools.

In the object catalogue

Catalogued objects whose own source record mentions “Mainspring”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.