Antifriction bearing unit and water pump

摘要

An antifriction bearing unit comprises a rotating shaft, an outer ring, and rolling members. The rotating shaft comprises a large-diameter shaft portion (11) serving as an inner ring and a small-diameter shaft portion (12), which is hollow and has a fitting portion (12a) of increased diameter at one end thereof. The large-diameter shaft portion (11) has an end portion fitted and fixed in the fitting portion (12a) of the small-diameter shaft portion (12). The fitting portion has an outward flange integral with an end thereof. The outer ring is fixedly provided with a seal member (15a) having lips slidable in contact with the flange and the outer peripheral surface of the large-diameter shaft portion, respectively.