Ratchet wheel (in U.S.A. "winding wheel")

In a watch, a toothed wheel fixed by a square hole to the barrel-arbor. A click prevents it from turning in the direction for unwinding. A ratchet-wheel sometimes has a polished sink. Part of the winding mechanism.

Source: G.A. Berner 4-language Glossary, 1988 re-edition, courtesy FH, Federation of the Swiss Watch Industry, Bienne, Switzerland

External Berner Glossary Source:

• Federation of the Swiss Watch Industry: Glossary