The internal clearance of single row angular contact ball bearings and single row tapered roller bearings is only established when the bearing is adjusted against a second bearing. Usually, these bearings are arranged in pairs, either back-to-back or face-to-face, and one bearing ring is axially displaced until a given clearance or preload is obtained. For information about bearing preload, refer to Bearing preload.
The following recommendations refer only to the adjustment of the internal clearance for bearing arrangements with angular contact ball bearings or tapered roller bearings.
The appropriate value for the clearance to be obtained when mounting, depends on the bearing size and arrangement and operating conditions such as load and temperature. Since there is a definite relationship between the radial and axial internal clearance of angular contact ball bearings and tapered roller bearings, it is sufficient to specify one value, generally the axial internal clearance. This specified value is then obtained, from a condition of zero clearance by loosening or tightening a nut on the shaft or a threaded ring in the housing bore or by inserting calibrated washers or shims between one of the bearing rings and its abutment. The actual method used to adjust and measure the clearance depends largely on the number of bearings to be mounted.
One way to check the axial clearance in a bearing arrangement is to use a dial indicator attached to the hub (fig. 1). When adjusting tapered roller bearings and measuring clearance, the shaft or housing should be turned through several revolutions in both directions to be sure that there is proper contact of the roller ends with the guide flange on the inner ring. Without proper contact, the measured result will not be correct.