Clock type · Specialist

Electric-Mechanical Clocks

Needs research

Clocks in which an electrical element (typically a battery-driven electromagnet and contact) replaces the mainspring or weight as the source of motive power, while the going train, escapement and hands remain conventionally mechanical.

Movement & mechanism

A battery powers an electromagnet that periodically re-impulses a balance or pendulum, avoiding the need for manual winding
Conventional mechanical gear train and hands driven from the electrically-impulsed oscillator
Distinct from purely electronic or quartz clocks, which have no mechanical oscillator at all

Identification

A battery compartment combined with a conventional-looking pendulum or balance escapement
No winding arbor or keyhole, distinguishing it from spring- or weight-driven clocks of similar external appearance

Terminology

Electromagnetic impulse — the periodic magnetic 'push' replacing mainspring or weight torque
Free-pendulum clock — an electric-mechanical design in which the pendulum swings largely undisturbed except for brief impulses (used in some master clocks)

Known variations

Battery-impulsed pendulum clocks
Battery-impulsed balance-wheel clocks
Free-pendulum master systems (see master/slave entry)

Collecting notes

Early electric-mechanical clocks (from the mid-to-late nineteenth century) are a specialist collecting field of historical rather than mass interest, valued for documenting the prehistory of electrical timekeeping.

Electric Mechanical Clock That Drives The Hands Of A Turret Clock — Andres Rueda, CC BY 2.0. Wikimedia Commons file page

Sources & references

General surveys note early electric clock experiments (e.g. Alexander Bain, mid-19th century); detailed and reliably sourced individual histories are not yet compiled here.

Where sources disagree, the disagreement is stated rather than resolved silently.