The main external dimensions of the motor bearing refer to the bearing inner diameter, outer diameter, width or height and chamfer dimensions, etc., which represent the contour of the bearing, and are the necessary dimensions when the bearing is installed on the shaft and in the housing. These main dimensions have been standardized by the international standard (ISO15), and GB307 (the main dimensions of rolling bearings) is also based on the ISO standard. The main dimensions are specified in the national standards, and the specific bearing dimensions are listed in the following product catalog. Dimensional determination of radial bearings (except for tapered roller bearings) d: Nominal inner diameter of the bearing D: Nominal outer diameter of the bearing B: Nominal width of the bearing r: Inner and outer ring chamfered dimensions The outer dimensions of the bearing conform to the outer dimensions of the radial bearing And overall dimensions of the overall plan; the outer dimensions of the deep groove ball bearings for motors conform to GB/T281, the outer dimensions of cylindrical roller bearings for motors conform to GB/T283, and the outer dimensions of spherical roller bearings for motors conform to GB/T288, angular contact for motors The outer dimension of the ball bearing conforms to GB/T292. Choose the outer dimension according to the size, limit rotation, fatigue life or rated static load safety factor of the shaft, and choose the outer dimension of the standard bearing as much as possible to save the cost.