Component record · Power
Reversing Wheels
VerifiedA small pair (or set) of interacting wheels or pawls in a bidirectional automatic-winding train that convert rotor motion in either direction into a single, consistent winding direction at the ratchet wheel.
What it does
Allows the mainspring to be wound regardless of which way the automatic rotor is currently swinging, rather than only capturing energy from one direction of wrist motion.
How it works
A pair of small reversing wheels is arranged so that, whichever way the rotor turns, one wheel is engaged and transmits drive forward to the winding pinion while the other idles (or the two act via click/pawl faces so that only forward-direction transmission occurs from either wheel).
This lets the winding train present a single, one-way rotation to the ratchet wheel and click regardless of the rotor's instantaneous direction, so that wrist motion in either rotational sense contributes to winding rather than half of all motion being wasted.
Reversing systems vary by manufacturer in detail (some use claw-and-pawl reversers, others use small reversing wheels with internally toothed friction or ratchet surfaces), but all serve the same purpose of direction-rectifying the rotor's oscillation.
Evolution
Introduced as a refinement over early unidirectional automatic systems once manufacturers sought to capture winding energy from the full range of natural wrist motion rather than only one swing direction.
Known variations
- Claw/pawl-type reversers
- Small reversing wheel pairs with internal ratchet surfaces
Identification for collectors
- Present in essentially all modern bidirectional automatic calibres; visually identifiable as a small cluster of wheels between the rotor pivot and the barrel bridge on the automatic winding side of the movement
Common failure modes
- Worn or chipped reverser teeth reducing winding efficiency in one rotational direction
- Dried or contaminated lubrication causing sluggish or noisy reversing action
Related photographs
No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.
Sources & references
- de Carle, D., Watch and Clock Encyclopedia
Where sources disagree, the disagreement is stated rather than resolved silently.