Study of ball bearings failure modes in an eddy current dynamometer

Eddy current dynamometers are one of the most important equipment of internal combustion engine test cells in powertrain companies. Failure of rolling element bearings in these assets is a common reason for downtime hours of engine test beds. Insufficient information in this field not only imposes unwanted expenses, but also would result in wrong engine testing data. The purpose of this article is the identification and classification of rolling element bearings failure modes in the eddy current dynamometers. This is an essential research for choosing an appropriate maintenance plan in engine testing laboratories. More than 30 faulty ball bearings of different eddy current dynamometers are collected to study different modes in which the bearings actually fail to operate properly. In addition, metallurgical studies have been applied on the failed parts to specify possible root causes of failure. The dynamometers whose bearings are under study have been employed in different engine testing procedures that an eddy current dynamometer is capable of performing e.g. endurance tests, over-speed tests, etc. so that a diversified collection of modes is available which would happen in any eddy current dynamometer. The recognized cases are then classified to prepare a practical basis for condition monitoring of dynamometers using vibration analysis or other methods.