Principles of bearing selection and application Cylindrical roller bearings Cylindrical roller bearings can only be preloaded radially († fig. 37). Bearings with a tapered bore are preloaded by driving the bearing inner ring up onto its tapered seat. The resulting interference fit causes the inner ring to expand and to obtain the necessary preload. To accurately set preload, internal clearance gauges should be used. For additional information, refer to Mounting († page 280) or Adjusting for clearance or preload († page 278). Angular contact thrust ball bearings Angular contact thrust ball bearings can only be preloaded axially († fig. 38). The standout of angular contact thrust ball bearings is precision ground so that when the two halves of the bearing are assembled, a given preload is obtained without further adjustment. Keep in mind that preload is also influenced by the interference fit and the operating conditions. Under load, angular contact thrust ball bearings exhibit similar characteristics as angular contact ball bearings. Therefore, the information provided for angular contact ball bearings is also valid for these bearings. The lifting force for single direction angular contact thrust ball bearings for screw drives in the BSA and BSD series is the same as for angular contact ball bearings († table 21, page 92). For double direction angular contact thrust ball bearings in the BTW and BTM series, the lifting force can be estimated from K a1 = 2,85 F0 where K a1 = lifting force F0 = preload on bearings before external axial load is applied
94
Fig. 37
Fig. 38