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The Encyclopedia of Horology

Detached escapement

Detent (chronometer) escapement

Verified

A spring or pivoted detent locks the escape wheel; the balance unlocks it once per revolution and receives a single direct impulse, remaining otherwise entirely free.

Schematic arrangement

How it is laid out

Escape wheelSpring detentBalance, impulse roller

Outline schematic only, drawn to show the characteristic arrangement of wheel, locking member and oscillator. It is not a dimensioned working drawing and should not be used for setting up or repairing a movement.

Advantages

  • Finest rate of the classical escapements
  • Minimal interference with the balance

Drawbacks

  • Not self-starting
  • Vulnerable to shock — unsuited to pocket use

Attribution and period

Late eighteenth century, associated with Earnshaw and Arnold

Horological firsts are frequently contested. Where an invention is attributed to a named maker, that attribution is recorded as such rather than treated as settled fact.

Photographs

Description of the Le Roy detent escapement mechanism 14 August 1748
Description of the Le Roy detent escapement mechanism 14 August 1748 — Academie des Sciences, France 14 August 1748, Public domain. Wikimedia Commons file page
British Museum Marine Chronometer 1
British Museum Marine Chronometer 1 — Photograph by Mike Peel (www.mikepeel.net)., CC BY-SA 4.0. Wikimedia Commons file page
Diagram of the chronometer detent escapement Britten's Clock and Watchmaker's Handbook 9th Edition 1896
Diagram of the chronometer detent escapement Britten's Clock and Watchmaker's Handbook 9th Edition 1896 — F.J. Britten, Public domain. Wikimedia Commons file page

Photographs are matched automatically from freely licensed Wikimedia Commons material. Each caption states the actual subject of the image and credits its author; where a close match for this escapement does not exist, a related mechanism may be shown instead.