METHOD OF SECURING SLEEVE BEARING LUBRICATION OF A MULTIPLE SPEED ROTATIONAL DEVICE, CONTROL ARRANGEMENT FOR CARRYING OUT SAID METHOD, AND USE OF SAID METHOD AND CONTROL ARRANGEMENT IN REGULATING A FAN

摘要

Apparatus and a method are disclosed for prolonging life of a multiple speed rotational device and regulating its speed. A rotating shaft is supported by a sleeve bearing and power is supplied to the rotating shaft. The shaft is operated at a minimum speed which allows establishing of a lubricant film between the shaft and the bearing upon startup prior to being operated at a reduced rotational speed. Once the lubricant film is established, this film is maintained during reduced speed operation and bearing life is prolonged. A tapped transformer is used with a standard fan motor for providing selected motor speeds. A high winding temperature region is identified such that the motor is not operated with a power supply having a voltage output which results in high motor winding temperatures. Specific relay circuit means are provided for operating the motor at various voltage levels.