Commonly used gear tooth profile: involute tooth profile and arc tooth profile. See GB/T1356-1988 for the basic tooth profile of the involute tooth profile. Features of involute tooth profile meshing transmission: 1. The transmission ratio is constant; 2. The change of center distance does not affect the transmission ratio; 3. The meshing line is a straight line passing through the node, but I believe many people will have a doubt, why the teeth of many gears are oblique? This mainly considers the following three reasons:

1. Compared with flat teeth, the position of the shaft is more free: for example, the differential drive shaft with oblique bevel teeth does not have to be on the same level as the rear axle. If it is flat bevel teeth, it is necessary.

2. Noise reduction, the helical tooth has less noise than a flat tooth at the same speed: the reason is that the surface of the helical tooth is first in point contact, then transition to surface contact, and then to point contact. The flat tooth is the contact between the surface and the line. The transition of helical teeth is smoother. Therefore, the noise generated by the sudden change of contact is much smaller than that of a flat tooth.

3. Convenient production. The gear hobbing machine can produce various numbers of gear teeth on the cylindrical blank. A set of helical teeth with the same surface width of the gear assembly can be cut into different face widths according to customer needs.

The disadvantage is that because the oblique force will produce axial force, ordinary ball roller needles are not competent. Use paired angle roller bearings or thrust bearings.