A tool holder of a machine tool, in which the machine tool includes a spindle head and a spindle supported by the spindle head, includes: a shank portion attached to the spindle; a rotary portion integrally provided to the shank portion and to which a welding tool (processing tool) used for friction stir welding is attachable; a bearing mechanism (bearing) supporting the rotary portion so that the rotary portion is rotatable; and a bearing holder holding the bearing mechanism, in which the bearing holder is disposed facing the spindle head and is capable of transmitting a load applied to the bearing mechanism to the spindle head.

In one aspect, a dual pitch bearing configuration for coupling a rotor blade to a hub of a wind turbine. The dual pitch bearing configuration including a first pitch bearing and at least one additional pitch bearing disposed axially a distance L.sub.B from the first pitch bearing. The dual pitch bearing configuration further including one or more spacers disposed between the first pitch bearing and the at least one additional pitch bearing and extending the distance L.sub.B. The dual pitch bearing disposed radially within one of a blade root of the rotor blade, a hub extension or a bearing housing and coupled thereto. The dual pitch bearing configuration minimizing moment loading on the first pitch bearing and the at least one additional pitch bearing. A wind turbine including the dual pitch bearing configuration is further disclosed.

A rolling bearing apparatus includes a bearing portion and a lubrication unit. The lubrication unit is provided adjacently to an annular space in an axial direction. The annular space is formed between an inner ring and an outer ring, and the lubrication unit has a tank storing lubricant that is supplied to the annular space. The tank has an outer wall on a radially outer side, and a space formed on a radially inner side of the outer wall is a storage portion for storing the lubricant. An oil supply hole that is used to refill the storage portion with the lubricant is provided passing through the outer wall. The oil supply hole is open to the radially outer side.

A cage segment for a rolling-element bearing having a plurality of rolling elements includes at least one bridge and first and second plates extending from axial ends of the bridge, sides of the bridge being configured to guide rolling elements. Radially inner or outer edges of each of the bridges include at least one axial channel having channel walls projecting radially and circumferentially from the radial inner or outer edge.

A rolling bearing includes an inner ring having an outer surface, an outer ring having an inner surface, a plurality of rolling elements rotatably disposed between the inner ring and the outer ring, and a retainer for retaining the rolling elements. The retainer is made of a resin material and is positioned with respect to the inner surface of the outer ring or the outer surface of the inner ring. The retainer includes a pair of annular portions axially arranged in parallel and a columnar portion coupling the annular portions. Then, the rolling bearing satisfies the following expression: .[.AI=LH.sup.3/dm≥0.025.]. .Iadd.LH.sup.3/dm.sup.2≥0.025 mm.sup.2 .Iaddend.in which H is a radial length of a section of the annular portion, L is an axial length of the same, and dm is PCD of the rolling element.

A method for preloading a bearing includes releasably, threadably, and directly attaching an attaching member to a circumferential outside surface of an exposed end of a threaded shaft of an axle or spindle. A frame is axially separated from, and coupled to, the attaching member. A plurality of extensions extends from the frame axially past the attaching member toward the wheel hub assembly. An adjustment mechanism moves the frame and the plurality of extensions axially towards the wheel hub assembly to contact the wheel hub assembly and/or the bearing to apply a preload to the bearing within the wheel hub assembly.

A multi-part adjusting element is proposed, which makes possible a very precise adjustment of a shaft bearing.

A caster hub is provided that includes a housing having a wall with internal and external surfaces and an axial bore defined by the wall. First and second bearings are disposed coaxially in the bore of the housing. Each bearing has a cylindrical inner race and a cylindrical outer race, with the races separated by rolling elements, and the races defining interior and exterior radial end faces of the bearings. A seat is disposed in the bore that is connected to the internal surface of the wall between the first and second bearings. The seat is engageable with the outer races of the bearings at the confronting interior end faces of the bearings. An inner spacer is disposed in the bore between the first and second bearings, the inner spacer being engageable with the inner races of the bearings at the confronting interior end faces of the bearings.

Only an outer spacer (33) is cooled by an outer spacer cooling structure, thereby causing a temperature difference between an inner spacer (32) and the outer spacer (33). According to this temperature difference, an inner ring (37) of a bearing (31) is displaced relatively to an outer ring (38) in a direction in which a preload inside the bearing (31) decreases.

A bearing housing is configured as an end-side cover for a nacelle of a fluid-flow power plant and includes a cylindrical section having an interior and a bearing unit in the interior. The bearing unit includes at least one rolling-element bearing having an inner ring and an outer ring rotatably disposed with respect to each other about a bearing rotational axis and a plurality of rolling elements between the rings. A pressure line of the bearing intersects the bearing rotational axis at a first angle. An angled section of the housing extends from the cylindrical section of the housing at a second angle that is related to, and preferably substantially equal to, the first angle.