One: gear can be installed on the outside of bearings, driven by bearings, while gears rotate while driving other gears. Bearings and gears are two indispensable.
Two: the gear mainly provides a mutual bite force and torque, and the bearing is mainly to provide a transmission function. The gear transmission needs to be installed on the shaft, while the bearing is a supporting component for the shaft. With the support of the bearing, it is easier to make the shaft and the axle components have more accurate operation accuracy, and the bearing rolling element can reduce the friction between the bearing and the shaft.
Three: the bearing belongs to the vulnerable parts. It can be replaced and maintained after the damage, which can reduce the wear of the bearing.