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The Encyclopedia of Horology

Glossary · Mechanism

Escape wheel

The last wheel of the going train, whose teeth act directly on the pallets or detent to lock and release the train.

Explanation

The escape wheel is the interface between the going train and the escapement. The train delivers torque to it; the escapement locks it, releases it tooth by tooth, and takes impulse from it. Its tooth form is specific to the escapement family: the pointed, forward-raked teeth of a recoil anchor, the club teeth of a Swiss lever, the slender teeth of a cylinder escape wheel and the light, sharp teeth of a detent chronometer wheel are not interchangeable shapes.

Tooth counts and geometry matter to rate and action. A lever escape wheel commonly has fifteen teeth; club-tooth form divides lift between wheel and pallet. Wear, bent teeth or incorrect depth show as uneven unlocking, recoil where none should exist, or a train that runs down when the balance is removed. These are inspection findings for a watchmaker, not owner adjustments.

When describing a movement, name the escapement before inferring the wheel's form, and photograph the wheel only with the movement secured. A bright escape wheel in a photograph says nothing about pivot condition or depth.

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.

Distinctions at a glance

EscapementWheel characterDo not confuse with
Swiss leverClub teeth, commonly fifteenThe lighter cylinder wheel
CylinderSlender upright teeth on a flat wheelThe two-level duplex wheel
DuplexTwo tooth levels on one wheelA single-level lever wheel
Anchor or deadbeat (clock)Larger wheel acting on pallet armsA watch escape wheel

What to record

  • Name the escapement family before describing tooth form.
  • Record tooth count where documented for the calibre.
  • Keep wear observations separate from depth or beat conclusions.

Never probe the escape wheel with the mainspring let down only partially; a suddenly released train can bend teeth and pivots.

In the object catalogue

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