Lubrication Condition Monitoring in EHD Line Contacts of Thrust Needle Roller Bearing Using the Electrical Impedance Method

In this study, we developed the electrical impedance method which simultaneously measures thickness and breakdown ratio of oil films in elastohydrodynamic (EHD) line contacts within thrust needle roller bearings. Initially, theoretically demonstrated that film can be measured using complex is produced when an AC voltage applied to EHD contacts. To verify measurement accuracy method, monitored a bearing compared it with theoretical value. The results revealed was thinner than value immediately after starting test, being greater 0 (indicating mixed lubrication); however, decreased over time, nearly matched one hour believed running-in wear complete (i.e., ≈ 0). Furthermore, following examining race surface, confirmed had indeed occurred. These suggest monitor lubrication conditions contacts, such as those bearings, detail.