Diagnosis of Marine Electric Motor Bearing by Shock Pulse Method

Abstract

In most cases the marine auxiliaries are driven by the electric motor. The most frequent causes of trouble with the electric motor is those related to its bearing.
New technology has been developed to analyze the condition of the bearing and new methods enable to decide whether replacement is necessary or not.
The Shock Pulse Method (SPM) is one of such methods. By theory, mechnical impact wave is produced by an impact between two solid materials - the raceways and rolling elements. And by a transducer, it's wave is detected as the shock pulse from the bearing housing in an instant of impact. Extensive experience proves that there is a simple relationship between the conditions of bearings and the degree of shock pulse in the operation.
The aim of the SPM method is to fully utilize the life of the bearing so as to avoid needless replacement and to catch early warning of impending failure.
Systematic supervision of the bearing condition reduces the amount of unscheduled and unnecessary maintenance as well as the rate of breakdown occurrance.
Up to this present stage this method has been utilized to check the bearing condition for over 200 vessels, and is recognized as a very effective and efficient instrument in the maintenace of vessels.
The following are explanations of the SPM method, which we have used and the results obtained from our test performance.