Glossary · Mechanism
Click and ratchet
The ratchet wheel on the winding arbor and the click that prevents the mainspring from unwinding back through the winding work.
Explanation
The ratchet wheel sits on the barrel arbor (or fusee great-wheel arbor) and turns with it during winding. The click is a pawl whose tip engages the ratchet teeth, held by a click spring, so the arbor cannot turn backwards when the winding key or crown is released. The familiar winding clicks are the sound of the pawl riding over the teeth.
Failure modes matter to safety. A worn click tip, broken click spring or damaged ratchet teeth can let a fully wound spring release through the winding train in an instant, damaging the movement and the hand holding the key. A click that feels weak, slips, or lets the key kick back is a stop-and-service signal, not a reason to wind more carefully.
Record click and ratchet condition from service notes, and in photographs distinguish the ratchet wheel from the crown wheel of keyless works, which meshes with the winding pinion rather than holding the spring.
Sources & references
- de Carle, D., Practical Watch Repairing — technical further reading; exact procedures require calibre documentation
- Reymondin et al., The Theory of Horology — construction and terminology further reading
Where sources disagree, the disagreement is stated rather than resolved silently.
Distinctions at a glance
| Part | Function | Failure sign |
|---|---|---|
| Ratchet wheel | Turns with the arbor during winding | Damaged teeth can release the spring |
| Click | Pawl preventing reverse rotation | Worn tip slips under load |
| Click spring | Holds the click into the teeth | A broken spring silences the clicks |
| Crown wheel | Meshes with the winding pinion in keyless work | Not the part that holds the spring |
What to record
- Note any slip or kick-back during winding as a condition record.
- Distinguish ratchet wheel from crown wheel in descriptions.
- Keep click-spring condition with the service history.
Stop winding immediately if the click slips or the key kicks; continued winding risks a violent uncontrolled release.