Ratchets and pawls are mechanical assemblies that are used to transmit intermittent rotary motion, or to permit a shaft to rotate in one direction but not the other. Ratchets and pawls are usually made of steel, stainless steel, cast iron, brass, or other metal materials. Ratchets are sometimes called ratchet wheels because they consist of a rotating gear or rack with angled teeth. Pawls, which are sometimes misidentified as ratchets, are thin protrusions that rest against a ratchet to restrict its motion. When the ratchet is rotated in one direction, the pawl is raised and moves smoothly between the angled teeth. When the ratchet’s rotation stops, the pawl rests between the teeth and makes a clicking noise. Ratchets and pawl that permit rotation in only one direction cause the pawl and teeth to clash if the ratchet is turned the opposite way. Applications for these single-direction devices include turnstiles, spanners, winders and jacks. The action of a ratchet can be either harsh or smooth, depending on the configuration of the ratchet teeth and pawl.