A glass ball has a density of 2.3 to 3.2 g/cm.sup.3, a Young's modulus of 60 to 150 GPa, and an average coefficient of thermal expansion at 50 to 350° C. being 40×10.sup.−7 to 120×10.sup.−7/° C. The glass ball is formed of a glass material including, as represented by mole percentage based on oxides, 30 to 75 mol % of SiO.sub.2, 2 to 30 mol % of Al.sub.2O.sub.3, and 5 to 25 mol % of R.sub.2O, where R is at least one kind selected from Li, Na and K. The glass ball includes a compressive stress layer in a surface thereof.

An assembly with a housing, a bearing, which is received in a bearing bore formed in the housing, and an annular compensation member. The housing and the compensation member are formed of materials having a larger coefficient of linear thermal expansion than a material from which the outer bearing race is formed. The compensation member is fixedly coupled to the housing and mounted about an outer bearing race of the bearing. The compensation member is configured to grow in a radial direction into contact with an inside circumferential surface of the outer bearing race when a temperature of the assembly increases from a first predetermined temperature to a second predetermined temperature.

A main shaft device is attached to a work machine. The main shaft device is provided with a main shaft that supports a tool or a workpiece, and a main shaft motor that causes the main shaft to rotate. The main shaft device is provided with bearings that are rolling bearings which support the main shaft in an inner race, and a housing and a rear housing that secure an outer race of the bearings. The housing and the rear housing are formed of a material having a coefficient of thermal expansion greater than that of the main shaft.

A bearing carrier is provided. The bearing carrier including: a bearing body of a first material having a shaft-receiving aperture and a bridge land with a finger cut to channel fluid pressurized by intermeshing of gears rotatably supported by the bearing carrier into an outlet defined by a housing enveloping the bearing carrier, wherein the bearing body includes a bearing face configured to be in a facing spaced relationship with the gears, wherein the bearing face includes a second material integral with the first material, wherein at least one of the first material and the second material define a portion of the bearing face of the bearing body extending about the shaft-receiving aperture, the portion of the bearing face excluding the bridgeland.

A high-speed shaft assembly includes a shaft of a first material and an outer member of a second material disposed about the shaft, the shaft or outer member being rotatable about an axis. The two materials have substantially different coefficients of thermal expansion such that the shaft and/or the outer member is relatively displaceable along the axis at temperatures over 250 F. and less than 0 F. A bearing inner ring is disposed about the shaft and has an outer race which is a cylindrical surface or an annular groove. A bearing outer ring is disposed about the inner ring and coupled with the outer member. The outer ring has an outer race which is the other one of the cylindrical surface and the groove. A plurality of balls disposed between the races are displaceable axially along the cylindrical race surface during relative displacement of the shaft and outer member.

Techniques are disclosed for systems and methods for nested gimbal assemblies. A gimbal system may include a base, a yoke, and a gimbal assembly rotatably connecting the yoke to the base. The gimbal assembly may include a motor, a bearing, and a ferrofluid seal. The motor may be configured to rotate the yoke relative to the base about a rotational axis. The bearing may be seated within the base and permit rotation of the yoke relative to the base about the rotational axis. The ferrofluid seal may be positioned to seal an interface between the yoke and the base. The motor may be positioned within an inner diameter of the bearing. The bearing may be positioned within an inner diameter of the ferrofluid seal.

A rotor of an inner rotor type motor includes: a circular plate portion rotatably supported about an axis; an eccentric portion provided in the circular plate portion and eccentric with respect to the axis; a peripheral wall portion extending from an outer edge of the circular plate portion; and a permanent magnet held on the peripheral wall portion, wherein a circular plate portion includes a hole portion located radially outward from the eccentric portion, and the peripheral wall portion includes a protruding portion protruding radially inward and being located in a side opposite to the hole portion with respect to the eccentric portion.

The invention relates to an exhaust-gas-driven turbocharger having a hydrodynamic plain bearing having a rotor and a stator, the rotor being rotatable with respect to the stator, the rotor bearing surface being located opposite a counter-surface of the stator in order to generate hydrodynamic pressure in the region of a converging gap. In such a hydrodynamic plain bearing, the application properties can be improved by the fact that the rotor bearing surface and/or the counter-surface constitutes in a section view, in the context of a section along and through the rotation axis, a continuous bearing contour that is constituted from convex or concave curvatures and/or from at least two contour segments that are embodied as straight lines and/or curvatures. The invention also relates to a hydrodynamic plain bearing or bearing arrangement having such a plain bearing.

A bearing unit structure includes a bearing and a bearing holding unit. The bearing rotatably supports a drive shaft. The bearing holding unit is provided to a crankcase so as to hold the bearing. A groove portion is formed on an inner peripheral surface of the bearing holding unit, and the inner peripheral surface faces the bearing. A thermal expansion correction band made of a resin is integrally formed with the bearing holding unit in a state of being embedded into the groove portion.

The invention relates to an exhaust-gas-driven turbocharger having a hydrodynamic plain bearing having a rotor and a stator, the rotor being rotatable with respect to the stator, the rotor bearing surface being located opposite a counter-surface of the stator in order to generate hydrodynamic pressure in the region of a converging gap. In such a hydrodynamic plain bearing, the application properties can be improved by the fact that the rotor bearing surface and/or the counter-surface constitutes in a section view, in the context of a section along and through the rotation axis, a continuous bearing contour that is constituted from convex or concave curvatures and/or from at least two contour segments that are embodied as straight lines and/or curvatures. The invention also relates to a hydrodynamic plain bearing or bearing arrangement having such a plain bearing.