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The Encyclopedia of Horology

Continental Europe, adopted widely in England · Documented from the 16th century; refined stopwork forms common by the 17th–18th centuries

Fusee Stopwork (Maintaining Power and Overwind Prevention)

Needs research

A small but essential piece of fusee-watch and fusee-clock engineering that prevented damage to the mainspring and chain, and is a useful dating/quality indicator when examining a movement.

Stopwork limits the number of turns the fusee can take, preventing the chain or gut line from being wound off the cone or overtightened against the barrel, and typically uses a pair of shaped plates ('Geneva stop'-like blocking work is a related but distinct device, see the Geneva stop entry) or a simple pinned-wheel arrangement.

Because stopwork is a shop-floor mechanical solution rather than a single patented invention, there is no founding patent to cite; its history is documented through surviving movements rather than filings.

Background

Most fusee clocks and watches include a winding stop mechanism to prevent the mainspring and fusee from being wound up too far, possibly breaking the chain. The mechanism functions by responding to the position of the fusee chain as it reaches the top of the fusee during the winding process. This action engages a mechanical barrier that inhibits further rotation of the fusee.

Written from the encyclopedia entries listed under Sources; each statement was checked against the cited text.

How it works

  • A metal blade is positioned to obstruct a physical projection located on the edge of the fusee to halt the winding.

How to verify this yourself

There is no patent office record to search for stopwork generally; consult movement-survey literature and museum catalogues (e.g. British Museum, Science Museum Group) for dated examples instead.

Manufacturers known to have used it

  • English and Continental fusee-clock and fusee-watch makers generally

Photographs

English fusee with Geneva stopwork? - Identify This Movement or Watch - Watch Repair Talk
English fusee with Geneva stopwork? - Identify This Movement or Watch - Watch Repair Talk — watchrepairtalk.com, Rights unverified — web image search result, review pending. Web page (watchrepairtalk.com)

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Fusee (horology), Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
  2. Britten, F. J., Old Clocks and Watches and Their Makers
  3. Science Museum Group collection notes on fusee movements

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