Detached escapement
Lever escapement
VerifiedA pivoted lever with two jewelled pallets locks the escape wheel and transmits impulse to the balance through a fork and impulse pin, leaving the balance detached for most of its arc.
Schematic arrangement
How it is laid out
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
- Robust
- Self-starting
- Good isochronism
- Suits mass production
Drawbacks
- More parts than frictional-rest designs
- Requires accurate pallet geometry
Attribution and period
Attributed to Thomas Mudge, c. 1754; developed through the nineteenth century
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.
How to recognise it
- A pivoted lever carrying two pallet stones, with a fork engaging an impulse pin on the balance roller.
- Banking pins or banking walls limiting the lever's travel.
- The balance is free (detached) through most of its arc; the escape wheel moves in discrete steps with an audible even tick.
Servicing and conservation
Pallet-stone setting, banking and lock depth are interdependent; a lever that overbanks or knocks is usually a geometry problem rather than a cleaning problem. Escape-wheel teeth and pallet stones are the first places to inspect for magnetism, dried oil and glazed contact faces.
Work on an antique escapement by a qualified watchmaker or clockmaker. Conservation of original parts is preferred to replacement wherever the object will still run.
Bibliography
- Daniels, George, Watchmaking
- de Carle, Donald, Practical Watch Repairing
- Gazeley, W. J., Clock and Watch Escapements
Photographs
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.