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