Maintenance schedules normally appear on the motor nameplate or terminal box cover. They may be included on a separate instruction sheet. The type of bearings installed in the motor determines the method and frequency of lubrication. When a motor's bearings require frequent service but the motor is inconveniently located, proper maintenance is often neglected. Therefore, the intended mounting position of the motor is an important factor to consider when selecting a bearing type.
Most modern motors have a tight bearing housing that stores a generous volume of lubricant.
Dirt introduced into the bearings during the lubrication process causes more bearing malfunctions than the lack of lubrication. Too much grease packed into the bearings causes excessive heating. Also, surplus lubrication often seeps into the motor, collecting dirt and causing the insulation to deteriorate. Motors rated at or below 10 horsepower normally have pre-lubricated bearings designed to allow long periods of operation under normal service conditions with no bearing maintenance. The bearings in these motors should never be lubricated.