Vibrational characteristics of a tapered roller bearing cage related to fatigue life

One of the most important components of a tapered roller bearing is the cage. The main function of the cage during operation is to maintain roller spacing. Although being one of the more complicated parts of a tapered roller bearing historically, very little specific engineering has been done to provide a design basis for the cage. This dissertation analyzed specifically the cages from tapered roller bearings as used in the railway industry. Metallurgical testing of cages with cracks has revealed that the failure mode of the cages was fatigue fracture which initiated at the small-end cage pocket. Factors which contributed to the fatigue failure were determined. Analysis included vibration and finite element analysis (FEA). Cages analyzed included 6 1/2 x 12 and 7 x 12 steel cages and 6 1/2 x 12 plastic cages. The natural frequencies of the cage were determined and then compared to the exciting frequencies of the bearings. Vibrations, internal and external to the bearing, were considered. The magnitude and frequencies of these excitation vibrations were input into the finite element modeling software, Algor, to find response of the cage. It was found that the stresses generated in the small end cage pocket of larger 7 x 12 steel cages were as much as twice that of the 61/2 x 12 steel cages. The stress generated at the pocket of the 6 1/2 x 12 plastic cage was smaller than the 6 1/2 x 12 steel cage