An Investigation into Temperature Trending in Railroad Tapered Roller Bearings Through Vibration Monitoring Techniques

A series of laboratory experiments have been conducted at The University of Texas-Pan American to investigate the cause of bearing “temperature trending.” A combination of theoretical and experimental studies has identified potential sources for the abrupt changes in temperature often seen in railroad bearings. Previous studies suggest the possibility of vibration induced roller misalignment as the root cause for temperature trending. Subsequent research conducted by the UTPA team was designed to provide evidence through vibration monitoring techniques for the proposed hypothesis. To that end, a dynamic bearing tester was used to run four bearings at various speeds and loads experienced in the field. A “trigger” bearing with a known raceway defect on the cup was used as a source for vibration to induce roller misalignment on defect-free bearings. Experiments demonstrated that a bearing’s vibration energy would decrease prior to an increase in temperature. In theory, a misaligned roller would vibrate less, leading to a decrease in the overall vibration energy of the bearing; by the same token, it would produce enough friction to account for the temperature increase. Typically, rollers realign themselves through geometrical expansions or changes in operating conditions; thus, returning to normal temperature and vibration levels