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The Encyclopedia of Horology

Glossary · Mechanism

Ratchet wheel

A wheel in a winding system associated with a click that prevents reverse release of stored power.

Explanation

In a common going-barrel watch, the ratchet wheel is secured to the barrel arbor and is driven during winding. The click engages its teeth to resist unwinding through that route. The click spring positions or loads the click; wheel, click and spring are separate parts. Clock and fusee winding arrangements can place the retaining mechanism differently, so the familiar watch layout is not universal.

An automatic winding system can also contain reversers or other directional devices; those should not be called the ratchet wheel merely because they transmit motion one way. A slipping bridle at the mainspring's outer end has a different job from the click. A snap-back symptom or damaged tooth warrants examination, but neither wheel appearance nor winding feel alone establishes the full fault or the remaining spring load.

Sources & references

  1. de Carle, D., Practical Watch Repairing — technical further reading; exact procedures require calibre documentation
  2. Reymondin et al., The Theory of Horology — construction and terminology further reading

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

What to record

  • Identify the winding route and barrel-arbor connection.
  • Distinguish wheel, click and click spring.
  • Record retaining-system damage without releasing power.

Do not lift a click on a wound movement; stored energy can be released suddenly.

In the object catalogue

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