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The Encyclopedia of Horology

Component record · Escapement

Cylinder Escapement

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A frictional-rest escapement in which a hollow steel or ruby cylinder, cut away over part of its circumference, forms part of the balance staff and is alternately entered and released by the teeth of a specially shaped escape wheel.

What it does

Locks and releases the going train once per balance vibration in a manner that is quieter and thinner than the verge, while still resting the escape wheel's tooth against the cylinder wall for part of each cycle (unlike a fully detached escapement).

How it works

The escape wheel's teeth are shaped with a shoulder and a point; as the wheel turns, a tooth enters the hollow cylinder through its cutaway section, rests briefly against the cylinder's inner or outer wall (locking), then is released as the cylinder's rotation brings the cutaway back round, giving impulse to the balance as the tooth slides out.

Because the escape wheel tooth is in sliding contact with the cylinder wall for a substantial part of each cycle, the cylinder escapement is a frictional-rest rather than detached escapement, giving it more running friction and generally poorer long-term timekeeping stability than a lever escapement, but allowing a notably slim, simple, jewel-free (in its cheaper form) construction.

A cracked or chipped cylinder wall — common because the wall is thin and the ruby or steel is brittle at that thickness — causes the watch to stop or run erratically, and is one of the most frequently cited failure points of the type.

Evolution

Widely used in fine Swiss and French ladies' and dress watches through the eighteenth and much of the nineteenth century, prized for slimness; progressively displaced by the lever escapement as lever movements became compact and affordable enough for small calibres.

Known variations

  • Steel cylinder (earlier or cheaper watches)
  • Ruby cylinder (higher-grade nineteenth-century watches, notably associated with Swiss production)
  • Cylinder escapements built to differing tooth-count and cylinder-diameter standards across makers

Identification for collectors

  • Balance staff itself is a hollow cylinder rather than carrying a separate roller and impulse jewel
  • Escape wheel teeth have a distinctive shouldered, D-shaped profile unlike a lever escapement's club teeth
  • Common in slim eighteenth- and nineteenth-century French and Swiss watches, particularly ladies' watches

Common failure modes

  • Cracked or chipped cylinder wall, a frequent and serious fault given the thin, brittle section involved
  • Wear from sustained frictional-rest contact between escape wheel teeth and cylinder walls
  • Cylinder banking or timing errors from wear making the watch difficult to regulate accurately

Photographs

Cylinder watch movement (AM 5906-1)
Cylinder watch movement (AM 5906-1) — George Graham, CC BY 4.0. Wikimedia Commons file page
Cylinder watch movement (AM 5906-2)
Cylinder watch movement (AM 5906-2) — George Graham, CC BY 4.0. Wikimedia Commons file page
Cylinder Watch Movement (48709170233)
Cylinder Watch Movement (48709170233) — Auckland Museum Collections from Auckland, Aotearoa New Zealand, CC BY 2.0. Wikimedia Commons file page

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

Sources & references

  1. Britten, F. J., Old Clocks and Watches and Their Makers
  2. Daniels, G., Watchmaking

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