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The Encyclopedia of Horology

Clock escapement

Gravity escapement

Verified

Gravity arms are alternately raised by the clock train and then released to fall against the pendulum, delivering an impulse of almost constant force regardless of variation in the train's driving torque or friction.

Schematic arrangement

How it is laid out

Three-legged wheelGravity arms

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

  • Impulse is largely independent of train friction and driving-weight variation
  • Well suited to large, exposed turret-clock movements affected by wind and weather

Drawbacks

  • Mechanically more complex than a simple deadbeat or recoil escapement

Attribution and period

Nineteenth century; the double three-legged form is associated with Edmund Beckett Denison (Lord Grimthorpe) and was used for the Great Clock at the Palace of Westminster

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

Gravity escapement 2
Gravity escapement 2 — Hughhunt, Public domain. Wikimedia Commons file page
PSM V29 D195 Gravity clock escapement mechanism
PSM V29 D195 Gravity clock escapement mechanism — Unknown authorUnknown author, Public domain. Wikimedia Commons file page
PSM V29 D196 Gravity clock escapement mechanism
PSM V29 D196 Gravity clock escapement mechanism — Unknown authorUnknown author, 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.