Provided is a hub unit bearing wherein a cover can be firmly fitted with an outer ring member, and it is difficult for foreign matter to enter inside through a water drainage hole formed in the cover. The cover that covers the inside end section in the axial direction of the hub unit bearing includes a disk section, a small-diameter cylindrical section bent in the axial direction from the outer perimeter edge section of the disk section and a large-diameter cylindrical section. A cut and raised section that is cut and raised toward the inside in the radial direction is formed in the small-diameter cylindrical section, and a water drainage hole that passes through from inside to outside the cover is provided in the portion that is cut and separated from the small-diameter cylindrical section.

A backing ring assembly is for a railcar axle assembly including a shaft with a central axis and a bearing mounted on the shaft. An annular backing ring is disposeable upon the shaft between the bearing and a shaft enlarged section and has a central axis, an inner surface extending about the axis and defining a central bore for receiving the shaft and a retention surface facing away from the shaft enlarged section when the backing ring is disposed upon the shaft. A retainer includes an annular body, disposeable about the shaft enlarged section and having an inner surface sized to frictionally engage with the shaft enlarged section cylindrical surface, and at least one coupler connected with the annular body. The coupler(s) engage with the ring retention surface to releasably connect the retainer annular body with the backing ring to retain the ring at a fixed position on the shaft.

A bearing system that accepts a journal of a roll includes a housing defining a cavity and having a forward wall that defines an opening into the cavity, the opening configured to accept the journal through the opening and into the cavity. A sleeve is positioned within the cavity of the housing, the sleeve configured to surround the end of the journal. A first seal is positioned within the cavity of the housing adjacent to the forward wall of the housing, the first seal having an engagement surface. A second seal is positioned within the cavity of the housing and operably connected to the sleeve, the second seal having an engagement surface in contact with the engagement surface of the first seal.

The protective cover having a cup shape is mounted to an outer ring of a bearing so as to seal an inward-side end portion of the bearing. A protective cover includes: a disc part made of a synthetic resin; and a sensor holder part that is made of the synthetic resin and protrudes inward from the disc part. The disc part is provided with a separation wall which separates the magnetic encoder and the magnetic sensor from each other. The separation wall has a surface facing the magnetic encoder and a surface facing the magnetic sensor, and one of the surfaces has a mark of a gas drainage pin of an injection molding die.

A hub unit includes: a bearing section including an outer ring, an inner ring disposed coaxially with and inside the outer ring, rolling elements disposed in a bearing inner space, and a sealing member sealing the bearing inner space at an end on a vehicle inner side; a hub ring including a body portion, and a wheel mounting flange portion on which a wheel is to be mounted; and a covering member protecting the bearing section from a foreign substance. The covering member is fixed to rotate integrally with the hub ring and the inner ring, and covers an end on the vehicle inner side of the bearing section. A part of the covering member opposing to an end surface on the vehicle inner side of the outer ring is not parallel to the end surface.

A nut is used with being fixed to a sensor cap. The sensor cap is attached to an outer ring of a bearing in a wheel bearing device of an automobile. The sensor cap includes a sensor holder for holding a magnetic sensor. The nut is made of steel, and has a screw portion in which a bolt is screwed to attach the magnetic sensor to the sensor cap. A surface of the nut is coated with a zinc-nickel alloy plating layer with a nickel eutectic ratio of 8 to 18%.

A bearing device for a vehicle wheel that is capable of maintaining the sealability of a protective cover by preventing a seal member of the protective cover from being damaged without performing any complex machining. The bearing device for vehicle wheel (1) is provided with: a cylindrical sensor holder (11) that is fitted outside the protective cover (9), wherein in the outer ring (2), a protective cover fitting part (13A) to which the protective cover (9) is fitted, a seal part (13B) with which the seal member (10) of the protective cover (9) is brought into contact, and a sensor holder fitting part (13C) to which the sensor holder (11) is fitted are formed, the inner diameter of the seal part (13B) is equal to that of the sensor holder fitting part (13C), and the seal part (13B) and the sensor holder fitting part (13C) are adjacent to each other.

A sealing assembly for a rolling-element bearing includes a first seal element and a second seal element, the first seal element including a first support member mounted on a first bearing ring, a first seal body extending radially from the first support member and having an oblique side surface, and at least one first seal lip extending radially from the first seal body to the second ring to form a first seal and the second seal element including a second support portion mounted on the second ring, a second seal body projecting from the second support portion and at least one second seal lip extending from the second seal body to the oblique side surface to form a second seal. A buffer member extends from the first seal element toward the second seal element and has first and second radially spaced annular ribs that extend toward the second seal element.