A ratchet, also called a noisemaker (or, when used in Judaism, a gragger or ra'ashan), is an orchestral musical instrument played by percussionists. Operating on the principle of the ratchet device, a gearwheel and a stiff board is mounted on a handle, which can be freely rotated. The handle is held and the whole mechanism is swung around, the momentum causing the board to click against the gearwheel, making a clicking and rattling noise. Alternatively, smaller ratchets are sometimes held still or mounted and the handle turned rapidly by the player.   Wikipedia