Complication · Striking & chiming
Alarm
Partially verifiedA mechanism sounding at a pre-set time.
Definition
A mechanism sounding at a pre-set time.
Historical origin
Alarm work predates accurate timekeeping, appearing in early domestic clocks and later miniaturised for watches; the mid-twentieth-century alarm wristwatch made it a mainstream feature.
How it works
A separate spring and train drive a hammer, released when an alarm disc set by the wearer reaches the going train's position.
In wristwatches the hammer often strikes the case back or an internal membrane to gain volume.
Pocket watch context
Alarm pocket watches were made in modest numbers, particularly in Swiss and French production.
Wristwatch context
A practical mid-century wristwatch complication, associated with travel and professional use.
Clock context
Alarm clocks are the oldest and commonest domestic application, with a separate train and bell.
Identification
- A second crown or a central alarm-setting disc
- An additional barrel visible in the movement
Servicing notes
This is specialist work. Levers, springs and cam profiles in complicated work are calibre-specific, and incorrect reassembly commonly damages parts that cannot be bought. Refer the movement to a watchmaker experienced with this mechanism.
General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.
Diagram
Sources & references
- de Carle, D., Watch and Clock Encyclopedia
- Britten, F. J., Old Clocks and Watches and Their Makers
- Horological Journal (British Horological Institute), technical articles
Where sources disagree, the disagreement is stated rather than resolved silently.