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The Encyclopedia of Horology

Frictional rest escapement

Duplex escapement

Verified

A single escape wheel carries two sets of teeth — long locking teeth and short impulse teeth — delivering one impulse per two vibrations to a roller on the balance staff.

Schematic arrangement

How it is laid out

Long locking + short impulse teethRoller on balance staff

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

  • Excellent rate when clean and correctly adjusted
  • Very small energy loss

Drawbacks

  • Will not self-start reliably
  • Extremely intolerant of dirt or shock

Attribution and period

Eighteenth century; refined in England and later used in American production

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

Duplex Escapement
Duplex Escapement — Harry Leonard Nelthropp, Public domain. Wikimedia Commons file page
Duplexhemmung
Duplexhemmung — F. J. Britten, Public domain. Wikimedia Commons file page
Duplex 01
Duplex 01 — Manfredgoellner, CC BY-SA 4.0. 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.