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The Encyclopedia of Horology

Component record · Regulation

Crutch Pin

Partially verified

The pin or fork through which the crutch drives the pendulum.

What it does

Transmits escapement impulse to the pendulum rod.

How it works

A loose fit gives audible slap and lost motion; too tight a fit binds and stops the clock.

Evolution

Precision clocks minimised crutch contact to reduce disturbance.

Known variations

  • Pin-in-slot
  • Fork engaging the rod

Identification for collectors

  • A clicking or uneven tick often traces to crutch fit.

Common failure modes

  • Wear producing lost motion
  • Bent crutch altering beat

Diagram

crownsliding clutchsetting wheelswinding pinion and ratchet
Schematic: keyless winding and hand setting. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. de Carle, D., Practical Watch Repairing
  2. de Carle, D., Watch and Clock Encyclopedia
  3. Daniels, G., Watchmaking

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