A device that allows rotation of a wheel or handle in one direction, but prevents its turning in the opposite direction. A ratchet assembly consists of a toothed wheel and a pawl. The pawl is a lever that rides over the teeth when the wheel is turned in one direction, but engages the teeth to prevent the wheel turning in the opposite direction. Most ratchets have a method of reversing the pawl so the ratchet will work in either direction.