Motor bearings, not must a piece of metal

Ordering new Motors, making maintenance of bearings and even adapt existing motors with frequency converters needs certain precaution. As motor bearings are of a high importance in the availability of drive systems the selection and handling of the bearing should be taken seriously. Not all bearings are suitable for each type of application. A universal, fitting to all purpose bearing does not exist. In this paper we describe the different types of bearing used in the cement industry and we give also an indication for which application and power what conditions have to be considered. Furthermore, it gives a variety of tips and hints to avoid problems with the bearings, caused by lubrication, greasing, motor cabling, installation and alignment. A large portion of the paper is also devoted to the supervision of the bearings in terms of temperature and vibration, both of which are vital parameters for long-term, trouble free operation. Making good maintenance needs the know-how of expected life time of the bearings in order to program maintenance activities. A large portion is also spent for the sometimes ignored problematic of bearing currents in adjustable speed drive systems its consequences and the prevention of it. Taking all the tips and hints given in the paper into consideration, sleepless nights because of bearing problems can be avoided, and, more importantly, the availability of the plant will be kept high