What are the basic conditions for two gears to mesh?

[ZoeMarie]

The basic conditions for two gears to mesh are as follows: 1. Pitch: The base circle pitch of a pair of gears must be equal. The main reason is the standardization of the cutting tools for involute gears. 2. Contact ratio: Must be greater than 1. The meshing points of the working side tooth profiles of a pair of involute gears must simultaneously lie on the meshing line N1N2. If two pairs of teeth are engaged at the same time, the meshing points of the working side tooth profiles of both pairs must simultaneously lie on the meshing line. 3. Smoothness: Closed gear transmissions generally operate at higher speeds. To improve transmission smoothness and reduce impact vibration, it is preferable to have more teeth. For open (semi-open) gear transmissions, since tooth wear is the primary failure mode, the pinion should not have too many teeth to prevent the gear from becoming too small.