Improvement of Railroad Roller Bearing Test Procedures and Development of Roller Bearing Diagnostic Techniques. Volume I: Acceptance Test

摘要

Bearing defect data from 8,000 railroad roller bearings are analyzed to determine their defect modes and defect rate distributions. Cone bore growth, brinelling, and fatigue are identified as the predominant defect modes during the first 12 years of the aging process. The results of the study show that after approximately two years of service, 10 percent of all railroad roller bearings exhibit a defect of one type or another for which at least one component would be condemned if it were in a rework shop. The present AFBMA method of calculating fatigue spalling, modified to account for lubricant film thickness effects, correlates reasonably well with the observed incidence of spalling (10 percent fatigue life of about 11 years). The problem lies in the fact that AFBMA calculation procedure does not consider the other competing defect modes which contribute far more to the overall defect rate than spalling. The relationship between defect rate and failure rate is not direct, of course, and an examination of condemning limit definitions relative to the progression of bearing failure in service is needed.