A mechanical assembly includes an inner member, an outer member disposed about the inner member, a bearing inner ring, a bearing outer ring and a plurality of balls disposed between the two rings. The inner member has an outer circumferential surface with an outside diameter, which has a tolerance of greater than +/?0.00125. The outer member has an inner circumferential surface with an inside diameter, which has a tolerance of greater than +/?0.002. The inner ring has an annular groove with an inside diameter and the outer ring has an annular groove with an outside diameter. The balls are disposed within the two grooves and has a diameter sized such that the sum of twice the diameter plus the inside diameter of the inner ring groove is greater than the outside diameter of the outer ring groove, thereby establishing an internal preload in the bearing.

A miniature slider structure having foot portions and a linear slide are provided. The linear slide includes a slider and a slide rail. The slider straddles the slide rail so that the slider can be reciprocated on the slide rail. The slide rail extends in a direction. The slider includes a plate and two opposite foot portions extending downward from the plate. The slider straddles the slide rail through the foot portions. The plate has a mounting surface. Through the polishing process on the mounting surface of the plate, the roughness Ra of the mounting surface is controlled to be in the range of 0.01 microns to 0.1 microns so as to reduce the deformation of the foot portions when the working platform is installed.

This sliding bearing comprises a pair of semicircular half bearings formed into a cylindrical shape by bringing both circumferential ends thereof into contact with each other. The axial width of the half bearings is narrower in both circumferential ends and the circumferential center, and wider in the quarter parts located therebetween. During manufacturing of the half bearings, finishing by cutting processing is first performed on the parts of a flat-plate material which after formation are to become the two axial-direction end faces and the two circumferential-direction end faces of the half bearings, and thereafter, the flat-plate material is deformed into a semicircle.

A mechanical assembly includes an inner member, an outer member disposed about the inner member, a bearing inner ring, a bearing outer ring and a plurality of balls disposed between the two rings. The inner member has an outer circumferential surface with an outside diameter, which has a tolerance of greater than +/0.00125. The outer member has an inner circumferential surface with an inside diameter, which has a tolerance of greater than +/0.002. The inner ring has an annular groove with an inside diameter and the outer ring has an annular groove with an outside diameter. The balls are disposed within the two grooves and has a diameter sized such that the sum of twice the diameter plus the inside diameter of the inner ring groove is greater than the outside diameter of the outer ring groove, thereby establishing an internal preload in the bearing.

A process for manufacturing a hollow roller of a roller bearing including steps of: machining an outer radial cylindrical surface, with a circular cross section centered on a first axis, and machining an inner radial cylindrical surface with a circular cross section centered on a second axis. These two steps are realized on the same lathe. The hollow roller is provided with the outer radial cylindrical surface, with a diameter of at least 5 mm, and the inner radial cylindrical surface. An offset between the first axis and the second axis, measured in the hollow roller between two axial surfaces of the hollow roller, is less than 2 m, and an inclination angle between the first axis and the second axis is less than one minute of angle. The roller bearing comprises amongst others, at least one such hollow roller.

A rotation method includes bringing a conical first cone having a first rotation shaft into contact with a spherical body to be rotated at a first contact point of the spherical body from a first direction along the first rotation shaft and bringing a conical second cone having a second rotation shaft into contact at a second contact point different from the first contact point of the spherical body from the first direction and rotating the spherical body around an axis extending in a direction along a line segment which connects the first contact point and the second contact point to each other while the first cone and the second cone are relatively pressed against the spherical body from the first direction.

The present disclosure provides a processing method for preparing at least one sliding part of a pair of sliding parts, and includes a processing step of forming a shallow groove within a range of depth from 0.05 m to 5 m on a sealing face of the sliding part by irradiating an ultrashort pulse laser to a part of the sealing face where a positive pressure generation groove and a negative pressure generation groove are formed and removing part of a surface of the sealing face, wherein an energy fluence of the ultrashort pulse laser used in the processing step is 0.5 J/(cm.sup.2.Math.pulse) to 7 J/(cm.sup.2.Math.pulse).

A bearing cage or bearing cage segment is disclosed, in particular for a rolling-element bearing, wherein the bearing cage includes a polyetheretherketone (PEEK) base material having a low and medium viscosity, and less than 30%, in particular 15% to 25%, reinforcing material is added to the base material, and the reinforced PEEK material has a shrinkage in the melt-flow direction that falls in the range of 0.4% to 0.6%.

The present disclosure provides a processing method for preparing at least one sliding part of a pair of sliding parts, and includes a processing step of forming a shallow groove within a range of depth from 0.05 m to 5 m on a sealing face of the sliding part by irradiating an ultrashort pulse laser to a part of the sealing face where a positive pressure generation groove and a negative pressure generation groove are formed and removing part of a surface of the sealing face, wherein an energy fluence of the ultrashort pulse laser used in the processing step is 0.5 J/(cm.sup.2.Math.pulse) to 7 J/(cm.sub.2.Math.pulse).

An object of the present invention is to provide a chain guide superior in silence, which includes: a guide base extending in a traveling direction of a chain; a plurality of roller shafts attached to the guide base at an interval along the traveling direction of the chain; and rollers each rotatably supported by one of the roller shafts. The roller has a cylindrical outer circumferential surface for guiding the chain. The outer circumferential surface of the roller has a cylindricity not greater than 20 m.