Gears can be classified according to tooth profile, gear shape, tooth line shape, surface of gear teeth and manufacturing method, as follows:
1. Gears can be classified into tooth profile curve, pressure angle, tooth height and displacement according to tooth shape;
2. Gears are divided into cylindrical gears, bevel gears, non-circular gears, racks and worm worm gears according to their shape;
3. According to the shape of tooth line, gears are divided into spur gears, helical gears, herringbone gears and curved gears;
4. According to the surface of the gear, the gear is divided into external gear and internal gear. The top circle of the external gear is larger than the root circle, while the top circle of the internal gear is smaller than the root circle;
5. According to the manufacturing method, gears are divided into cast gears, cut gears, rolled gears, sintered gears, etc.
6. The rack is mainly divided into straight tooth and helical rack, which are matched with straight tooth cylindrical gear and helical tooth cylindrical gear respectively; The tooth profile of the rack is a straight line rather than an involute (plane for the tooth surface), which is equivalent to a cylindrical gear with an infinite radius of the indexing circle.
