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The Encyclopedia of Horology

Clock escapement

Grasshopper escapement

Verified

A pair of pallets pivoted so that they swing almost clear of the escape wheel and of each other, giving impulse to the pendulum with very little frictional contact and, in Harrison's own view, no need for lubrication.

Schematic arrangement

How it is laid out

Escape wheelPivoted grasshopper pallets

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

  • Extremely low friction
  • In principle needs little or no lubrication
  • Excellent long-term rate stability when correctly made

Drawbacks

  • Delicate and difficult to proportion correctly
  • Rarely reproduced successfully outside specialist restoration work

Attribution and period

c. 1722, John Harrison

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

Grasshopper-escapement colored
Grasshopper-escapement colored — Grasshopper-escapement-005.gif: en:User:Bariton-pop, upload by Roland zh on 14. September 2008 derivative work: Jahobr (talk), CC BY-SA 3.0. Wikimedia Commons file page
Grasshopper escapement
Grasshopper escapement — Unknown authorUnknown author, Public domain. Wikimedia Commons file page
Grasshopper 01
Grasshopper 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.