Spiral bevel gears are divided into two types, one is a spiral bevel gear, whose large axle and small axle intersect; the other is a hypoid spiral bevel gear, with a certain offset distance between the large axle and the small axle. Spiral bevel gears are widely used in mechanical transmission fields such as automobiles, aviation, and mining due to their advantages such as large overlap coefficient, strong carrying capacity, large transmission ratio, smooth transmission, and low noise. Its characteristics are :

1. Straight bevel gear: The tooth line is a straight line, intersecting at the apex of the cone, shrinking the tooth.

2. Helical bevel gear: The tooth line is a straight line and is tangent to a point, shrinking the tooth.

3. Spiral bevel gears: retractable gears (also suitable for gears of equal height).

4. Cycloid spiral bevel gear: contour teeth.

5. Zero-degree spiral bevel gear: Double reduction teeth, βm=0, used to replace straight bevel gears, with better stability, but not as good as spiral bevel gears.

6. Cycloid-tooth zero-degree bevel gear: Contour teeth, βm=0, used to replace straight bevel gears, with better stability, but not as good as spiral bevel gears.

7. The tooth height types of spiral bevel gears are mainly divided into reduced teeth and equal height teeth. The reduced teeth include non-equal head clearance reduced teeth, equal head clearance reduced teeth and double reduced teeth.

8. Contour teeth: the teeth of the big end and the small end are of the same height, generally used for oscillating bevel gears.

9. Non-isotopic space shrinking teeth: the apexes of the sub-cone, the top cone and the root cone are coincident.