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The Encyclopedia of Horology

Component record · Dial & hands

Hour Wheel

Verified

A larger, tube-mounted wheel that carries the hour hand and completes one revolution every twelve hours.

What it does

Displays the hour by rotating the hour hand at one-twelfth the speed of the minute hand, driven through the minute wheel reduction.

How it works

The hour wheel's tube (pipe) fits loosely over the cannon pinion post, sharing the same centre as the minute hand's arbor but turning independently and more slowly, geared down through the minute wheel.

Because it is friction-free relative to the cannon pinion (riding freely on the pipe), the hour wheel's speed is set purely by the motion works gear ratio, not by any separate friction fit.

Evolution

Stable in design principle since the introduction of separate motion works.

Known variations

  • Standard 12-hour wheel
  • 24-hour wheel variants used in some military, railroad, and specialty watches

Identification for collectors

  • The larger of the two dial-side hand-carrying wheels, sitting beneath the hour hand

Common failure modes

  • Worn or loose pipe fit causing the hour hand to wobble or slip
  • Cracked pipe from careless hand-fitting

Photographs

Watch, Movement (48708927298)
Watch, Movement (48708927298) — Auckland Museum Collections from Auckland, Aotearoa New Zealand, CC BY 2.0. Wikimedia Commons file page

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. de Carle, D., Practical Watch Repairing

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