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The Encyclopedia of Horology

Component record · Keyless work

Clutch Wheel (Castle Wheel)

Verified

A splined wheel, also called the castle wheel, that slides along the winding stem's square section and can be shifted between winding and hand-setting positions.

What it does

Engages the winding pinion train to wind the mainspring in one crown position, and disengages to instead drive the setting train when the crown is pulled out for hand-setting.

How it works

The clutch wheel's internal splines mate with a squared or splined section of the stem, allowing it to be driven rotationally by the stem while sliding axially along it.

Pulling the crown out moves the stem, and with it the clutch wheel, along its axis via the yoke; this shifts the clutch wheel out of mesh with the winding pinion and into mesh with the setting wheel(s) that ultimately turn the hands.

Pushing the crown back in returns the clutch wheel to the winding position, re-engaging the winding pinion and disengaging the setting train.

Evolution

Keyless works with a sliding clutch wheel superseded separate winding keys through the second half of the 19th century and became close to universal by the early 20th century.

Known variations

  • Sliding-pinion (clutch wheel) systems
  • Rocking-bar keyless works, an alternative keyless mechanism using a pivoting bar rather than a sliding clutch

Identification for collectors

  • Visible under the dial as a splined wheel riding on the stem, shifting position when the crown is pulled or pushed

Common failure modes

  • Worn splines causing the clutch wheel to slip on the stem
  • Yoke or setting-lever wear preventing clean engagement in either position

Related photographs

Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 1)
Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 1) — Heidbrink, Bernard, Public domain. Wikimedia Commons file page
Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 2)
Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 2) — Heidbrink, Bernard, Public domain. Wikimedia Commons file page
Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 3)
Stem Winding and Setting Watch. - DPLA - 1690779f9826ae336aa2956bd1cf6bc0 (page 3) — Heidbrink, Bernard, Public domain. Wikimedia Commons file page

No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.

Sources & references

  1. de Carle, D., Practical Watch Repairing

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