Classification of ratchet mechanism by engaging way can be divided into external ratchet mechanism and internal ratchet mechanism. External ratchet mechanism of pawls or wedges are installed outside of the Ratchet and pawl or wedges of the internal ratchet mechanism both internal to ratchet. External ratchet mechanism because processing, convenient installation and maintenance, is widely used. Internal ratchet mechanism characteristic of compact structure, smaller size. Made up a one-way ratchet and pawl mechanism with intermittent motion. Ratchet mechanism is used in a variety of machine tools and Automatic intermittent feeding or rotary table on transposition, also used on the Jack. Ratchet mechanism for one-way driving in the bike, in a manual winch pawl mechanism used to prevent reverse. Ratchet mechanism often associated with noise and vibration, so that its working frequency not to expect too much.