WATERPROOF DEVICE OF BEARING BOX

PURPOSE:To prevent intrusion of a water drop with simple construction, by extending a rotary shaft through an external bearing cover, extensibly forming a groove from the outside in a state of not reaching the interior of the cover and providing said groove in the lowermost part of a shaft through hole in the external bearing cover. CONSTITUTION:A rotary shaft 21 is extended through a bearing cover 23a with a fine gap g spaced, and a hollowed groove 24 is axially provided from the outside in the lowermost part of a shaft through hole of the bearing cover 23a in a state of not extending to a space 22. As a result, a water drop, intruded into the shaft through hole of the bearing cover 23a, is dropped into the groove 24 along the periphery of the rotary shaft 21 when the rotary shaft is stopped, while the water drop is followed rotating together in the periphery of the rotary shaft and shaken off into the groove 24 when the rotary shaft 21 is in rotation, and these water drops can be discharged to the outside from the groove 24.