Abstract: It is an object of the present invention to provide a quench-hardening testing method in which the quench-hardened depth of a quench-hardened layer and the quench-hardening pattern in inner and outer circumferential surfaces of hollow and solid parts can be measured through non-destructive inspection. A quantity of change in size, between before and after quench-hardening, of a hollow or solid member subjected to quench-hardening treatment in at least one of inner and outer circumferential surfaces of the member is measured, and the measured quantity of change is compared with a pre-measured quantity of change in size of a good member or a value obtained by a comparative calculating operation in accordance with a predetermined algorithm on the basis of the measure quantity of change is compared with a predetermined value of the good member to thereby judge the state of quench-hardening.

Abstract: A rolling element of a rolling bearing is made of a continuously cast bearing steel, and the center segregation rate of carbon, C/C.sub.0, of the bearing steel material satisfies a condition, 0.9.ltoreq.C/C.sub.0 .ltoreq.1.1, where C is the concentration of carbon (wt. %) in a center portion and C.sub.0 is the average concentration of carbon (wt. %).

Abstract: One of component parts of an inner race, an outer race and rolling elements of a rolling bearing is composed of a bearing material that is prepared by working a high-speed steel, carburizing or carbonitriding the wrought steel in a temperature range from 800.degree. C. to less than 1200.degree. C. and subsequently hardening and tempering the carburized or carbonitrided steel, the steel composing of 0.2 wt %.ltoreq.C.ltoreq.2.3 wt %, Si.ltoreq.1.0 wt %, Mn.ltoreq.1.0 wt %, 2.0 wt %.ltoreq.Cr.ltoreq.7.0 wt %, 1.5 wt %.ltoreq.W.ltoreq.22.0 wt %, Mo.ltoreq.10.0 wt %, 0.5.ltoreq.V.ltoreq.6.0 wt %, Co.ltoreq.18.0 wt %, the balance Fe and incidental impurities. By carburizing or carbonitriding the steel at low temperatures less than 1,200.degree. C.

Abstract: An object of this invention is to provide a rolling bearing in which, as for the rolling elements, it is unnecessary to employ a high level heat treatment such as carburizing or carbonitriding which requires a long period of time to achieve, and which is sufficiently long in service life even when used with a lubricant containing foreign matters. In a rolling bearing, the amount of residual austenite (.gamma..sub.R vol %) in the surface layer of at least one of the inner and outer races is in a range of 25 to 40 vol %, and the surface hardness (Hv) thereof meets the following condition:-4.7.times.(.gamma..sub.R vol %)+900.ltoreq.Hv.ltoreq.-4.7.times.(.gamma..sub.R vol %)+1000and the hardness of the rolling elements combined with the inner and outer races is higher by H.sub.R C 1 to 2 than that of the one of the inner and outer races.

Abstract: An object of this invention is to provide a rolling bearing which is long enough in serve life even when it is applied with a lubricant mixed with foreign matters, simply by quenching or by carbonitriding it for a short period of time, and which can be formed at a relatively low manufacturing cost. A rolling bearing is formed as follows: The quantities of elements such as C, Si, Mn, Cr and Mo forming a bearing alloy steel, and the quantity of retained austenite are adjusted to be in predetermined ranges, and the steel is quenched and tempered or carbonitrided so that its hardness is in the following range:-2.2.times.(.gamma..sub.R vol %)+810.ltoreq.Hv.ltoreq.-2.2.times.(.gamma..sub.

Abstract: A rolling bearing having bearing rings and rolling members wherein at least one of the bearing rings and the rolling members essentially consists of an alloy steel which contains carbide-forming elements. The bearing rings and the rolling members are subjected to carburizing or carbo-nitriding and then hardening to form a rolling surface layer. The content of retained austenite (.gamma..sub.R vol %) in the rolling surface layer is from 20 to 45% by volume and the hardness (Hv) of the rolling surface layer reinforced by dispersion of fine carbides or carbonitrides with an average grain size of from 0.5 to 1.5 .mu.m with regard to the content of the retained austenite (.gamma..sub.R vol %) is within the range of:-4.7.times.(.gamma..sub.R vol %)+920.ltoreq.Hv.ltoreq.-4.7.times.(.gamma..sub.R vol %)+1020.

Abstract: A rolling bearing, comprising an inner race, an outer race and rolling members which roll therebetween, at least one of the inner and outer races being subjected to carburizing and heating treatment, is characterized in that:the one race comprises a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the residual austenite content on the track surface layer being 20 to 45 vol. % and the rolling members comprise a carbon steel containing 0.7 to 1.1 wt. % of carbon having carbonitriding and heating treatment applied on the surface layer, with the residual austenite content in such surface layer being 20 to 45 vol. % and the carbonitride in such surface being 3 to 15 vol. %.In another form of the bearing, the rolling members may comprise a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the surface layers thereof being subjected to carburizing and heating treatment and having a residual austenite content of 20 to 45 vol. %.

Abstract: A dynamic pressure type bearing comprising an outer cylindrical member made of metal and a thin walled inner cylindrical member made of synthetic resin and joined to the inner periphery of the outer cylindrical member. The inner periphery of the inner cylindrical member is formed with a plurality of grooves for generating dynamic pressure. The thin walled inner cylindrical member is joined to the inner periphery of the outer cylindrical member during the moulding time by a joining means.

Abstract: A rolling bearing has an inner race, an outer race and a roller, at least one of the inner race, outer race and roller being made with an alloy steel consisting of two or more of 0.2 to 1.7% by weight of Mn, 0.2 to 1.2% by weight of Si, 0.2 to 1.7% by weight of Cr, 0.1 to 0.3% by weight of Mo and 0.1 to 1.0% by weight of Ni, 0.4 to 0.7% by weight of C and the balance of Fe, and by subjecting the alloy steel to carburizing hardening to obtain(a) an additional carbon content at the surface portion of 0.35 to 0.6% by weight and(b) a dissolved carbon content at the surface portion of 0.75 to 1.1% by weight, and having:(c) a hardness at the core portion as H.sub.R C of 57 to 64 and(d) a difference in hardness between the surface portion and the core portion within .+-.5 of H.sub.R C.

Abstract: A bearing assembly comprised of a housing, a shaft extending through the housing, a bearing disposed between the housing and the shaft and a seal disposed among the housing, the shaft and the bearing. The seal comprises an annular magnet, a pole piece affixed to the annular magnet and a ferrofluid injected into a gap between the pole piece and the shaft. Thus, a magnetic circuit for retaining the ferrofluid is formed by the seal, the bearing and the pole piece.

Abstract: A plain bearing comprises a metal cylinder as an external member and a resinous cylinder as an internal member, in which the outer surface of the resinous cylinder is firmly engaged and bitten with a concavo-convex portion formed on the inner surface of the metal cylinder. A process for manufacturing the plain bearing comprises producing the metal cylinder, forming the concavo-convex portion on the inner surface of the metal cylinder, combining the concavo-convex portion of the metal cylinder with the resinous cylinder, inserting a core pin into the interior of a combined cylinder of the metal cylinder and the resinous cylinder, squeezing the combined cylinder through a draw die and producing a finished plain bearing.

Abstract: Sealing and bearing means by use of ferrofluid, in which a magnet is utilized effectively in cooperation with grooves engraved on one surface thereof, the grooves having the function for generating the dynamic pressure of the ferrofluid. The ferrofluid is retained in a gap between a rotary shaft and a magnet of cylindrical or disc type enclosing the rotary shaft concentrically. The magnet performs excellent two functions of bearing and sealing respectively.

Abstract: In an assembly of linear feeding means in which a carrying or carriage member is supported on a rod shaped supporting member and these two members can be relatively moved in lengthwise direction, a plurality of recesses each having a shape or arrow head are disposed such that the tip end of each of the arrow head type recesses is directed to either one direction or to the other opposite direction of the relative movement of the assembly.By virtue of this construction, hydrodynamic pressures are directed in both directions as to ensure smooth running of the assembly.

Abstract: This invention relates to sealing and bearing means by use of ferrofluid, in which a magnet is utilized effectively in cooperation with grooves engraved on one surface thereof, the grooves having the function for generating the dynamic pressure of the ferrofluid. The ferrofluid is retained in a gap between a rotary shaft and a magnet of cylindrical or disc type enclosing the rotary shaft concentrically. The magnet performs excellent two functions of bearing and sealing respectively.

Abstract: The invention relates to a process for producing a ferrofluid, and a composition thereof. More particularly, fine particles of the ferromagnetic materials such as magnetite, ferrite, iron, cobalt alloy, etc. are dispersed stably and uniformly in one dispersing medium selected out of an oil group, an ester group or an ether group, whereby a ferrofluid composition having a high magnetizing capacity is produced effectively.

Abstract: Bearing apparatus for gear type power transmission systems comprising a gear casing containing a lubricating oil, gearing for power transmission retained in the casing and a bearing carried in the casing for rotatably supporting the gear shaft employs a seal for the bearing containing a lubricant so that the bearing is lubricated separately and independently of the oil in the casing.

Abstract: The invention relates to a process for producing a ferrofluid, and a composition thereof. More particularly, fine particles of the ferromagnetic materials such as magnetite, ferrite, iron, cobalt alloy, etc. are dispersed stably and uniformly in one dispersing medium selected out of an oil group, an ester group or an ether group, whereby a ferrofluid composition having a high magnetizing capacity is produced effectively.