Ratchet

^{(In French: ratchet)}

A saw-toothed wheel.

The ratchet wheel in a watch is a toothed wheel that is fixed by a square hole to the barrel arbor. A click (pawl) prevents the ratchet wheel from turning in the unwinding direction.

In a striking mechanism, the hour-ratchet or hour-rack is a toothed sector that lifts the hammer to strike the hours.