A ratchet is a mechanical gadget which allows continuous linear or rotary movement in only one direction while avoiding motion in the opposite direction. 
Ratchets are widely used in machinery and equipment. A rachet Ratchets Wheel contains a round gear or a linear rack with the teeth, and a pivoting, spring-loaded finger known as a pawl (or click, in clocks and watches[1][2]) that engages the teeth. The teeth are uniform but asymmetrical, with each tooth having a moderate slope using one advantage and a much steeper slope on the additional edge.
When the teeth are relocating the unrestricted (i.e. forward) direction, the pawl quickly slides up and over the softly sloped edges of one’s teeth, with a spring forcing it (frequently with an audible ‘click’) into the depression between your teeth since it passes the suggestion of each tooth. When one’s teeth move in the opposite (backward) direction, nevertheless, the pawl will catch against the steeply sloped edge of the first tooth it encounters, thereby locking it against the tooth and stopping any further motion in that direction.
Specifications
Angle of teeth 60°
Material S45C
Heat treatment Induction hardened teeth
Tooth hardness 50 ～ 60HRC