A release unit for a machine tool spindle, in particular motor spindle, for releasing a tool clamp, wherein the release unit comprises at least one adjustment element which can be linearly adjusted along an adjustment path for actuating the tool clamp, which release unit reduces the structural and/or economic complexity. This is achieved according to the invention in that the release unit is constructed as an electric motor which comprises an electromagnetic drive system having a hollow-cylindrical rotor shaft which rotates about a rotation axis, in that the linearly adjustable adjustment element is constructed as a spindle element of a conversion unit for converting the rotation of the electric motor into a linear adjustment and in that the rotor shaft is constructed as a spindle nut of the conversion unit which rotates about the rotation axis.

A matched ball bearing includes four or more rows of angular ball bearings axially aligned, two or more rows of the angular ball bearings with contact angles in a same direction being arranged in a back-to-back combination. The respective angular ball bearings have same inner diameters, respectively. The respective angular ball bearings with contact angles in the same direction have same outer diameters, respectively. The respective angular ball bearings with contact angles in different directions have different outer diameters, respectively. With respect to at least the respective angular ball bearings having the larger outer diameters, the angular ball bearing positioned at an axially outboard side has a ball diameter and a contact angle greater than those of the angular ball bearing positioned at an axially inboard side.

A matched ball bearing includes four or more rows of angular ball bearings axially aligned, two or more rows of the angular ball bearings with contact angles in a same direction being arranged in a back-to-back combination. The respective angular ball bearings have same inner diameters, respectively. The respective angular ball bearings with contact angles in the same direction have same outer diameters, respectively. The respective angular ball bearings with contact angles in different directions have different outer diameters, respectively. With respect to at least the respective angular ball bearings having the larger outer diameters, the angular ball bearing positioned at an axially outboard side has a ball diameter and a contact angle greater than those of the angular ball bearing positioned at an axially inboard side.

A method for diagnosing an abnormality of rolling bearing includes: measuring a vibration of a rotator; performing a frequency analysis on the vibration to calculate a magnitude of a vibration at each frequency; calculating a characteristic frequency as a frequency of a vibration from a specification of the rolling bearing and a rotation speed of the rotator at a vibration measurement in the measuring; calculating a vibration value from which an effect of the rotation speed is removed by dividing a magnitude of a vibration at the characteristic frequency by a value including a base and an exponent, the base being a predetermined physical quantity in a proportional relation with an angular velocity of the rotator at the vibration measurement in the measuring, the exponent being a positive number; calculating an evaluation index based on the vibration value; and determining an existence of an abnormality based on the evaluation index.

A method for diagnosing an abnormality of rolling bearing includes: measuring a vibration of a rotator; performing a frequency analysis on the vibration to calculate a magnitude of a vibration at each frequency; calculating a characteristic frequency as a frequency of a vibration from a specification of the rolling bearing and a rotation speed of the rotator at a vibration measurement in the measuring; calculating a vibration value from which an effect of the rotation speed is removed by dividing a magnitude of a vibration at the characteristic frequency by a value including a base and an exponent, the base being a predetermined physical quantity in a proportional relation with an angular velocity of the rotator at the vibration measurement in the measuring, the exponent being a positive number; calculating an evaluation index based on the vibration value; and determining an existence of an abnormality based on the evaluation index.

A bearing unit configured to support a first component for rotary movement with respect to a second component includes a first bearing having an inner ring and an outer ring and a second bearing having an inner ring and an outer ring and a separator axially disposed between and connecting the outer ring of the first bearing and the outer ring of the second bearing in an interference fit manner or in a friction fit manner to form a preassembled unit. The separator may be annular and have a plastic base body with axial openings in which metal spacers, cylindrical rods, for example, are mounted.

A vehicle spindle and a method of attaching the spindle to a portion of an axle half shaft housing. The spindle has an inner surface, an outer surface, one or more bearing journals on the outer surface of the spindle and a radially protruding portion circumferentially extending from at least a portion of the outer surface of an axially inboard end portion of the spindle. Prior to attaching the spindle to the axle half shaft housing, the one or more bearing journals are ground, a clocking angle for the radially protruding portion of the spindle is determined and the spindle is aligned to the determined clocking angle. Once the spindle is aligned to the determined clocking angle, the axially inboard end portion of the spindle is attached to an axially outboard end portion of the axle half shaft housing using one or more welds.

A vehicle spindle and a method of attaching the spindle to a portion of an axle half shaft housing. The spindle has an inner surface, an outer surface, one or more bearing journals on the outer surface of the spindle and a radially protruding portion circumferentially extending from at least a portion of the outer surface of an axially inboard end portion of the spindle. Prior to attaching the spindle to the axle half shaft housing, the one or more bearing journals are ground, a clocking angle for the radially protruding portion of the spindle is determined and the spindle is aligned to the determined clocking angle. Once the spindle is aligned to the determined clocking angle, the axially inboard end portion of the spindle is attached to an axially outboard end portion of the axle half shaft housing using one or more welds.

A detecting apparatus for detecting displacement of a bearing unit sandwiched between a spindle extending in an axial direction and a spindle seat is provided. The detecting apparatus includes a detector unit and a control unit. The detector unit includes a pair of sensing devices with each sensing device including a sensor that abuts against an end surface of an outer ring of the bearing unit and outputting, based on a sensing of the sensor thereof, a detected signal associated with a displacement of the end surface in the axial direction. The control unit is configured to determine whether the bearing unit is abnormal based on the detected signals.

A magnetic fluid seal includes an outer cylinder member with a heat barrier that internally houses a rotating shaft extending from a housing of a fluid machine and includes an attachment portion to be attached to the housing, magnetic pole members that are disposed around the rotating shaft housed in the outer cylinder member and form a magnetic circuit, and sealing films that are magnetically connected to the magnetic circuit, are respectively disposed between the magnetic pole members and the rotating shaft, are made of magnetic fluids, and are formed in an axial direction.