Finding NEMA

If you are using an electric motor to run your belt drives and are having problems with the life of the bearings and/or shafts, your motor pulley may be smaller than recommended. As the pulley size on the motor decreases, the magnitude of the belt pull increases, thus exerting a higher load on the bearings and shafts of the motor. NEMA (National Electrical Manufacturers Association) issues a list of minimum recommended sizes for various NEMA frame electric motors. Staying above these values should extend the life of the bearings and shafts on the motor and should prevent any premature failures from occurring. Below is the NEMA table taken out of the Gates Polychain Carbon Drive Design Manual:

These standards can be found on the NEMA website at http://www.nema.org/, or in any of the Gates Drive Design Manuals found at www.gates.com/partview