Provided is a steel for carbonitrided bearing which excels in hardenability and also excels in toughness, wear resistance, and surface-originated flaking life after quenching and tempering. A steel for carbonitrided bearing of the present embodiment has a chemical composition containing, in mass %, C: 0.22 to 0.45%, Si: not more than 0.50%, Mn: 0.40 to 1.50%, P: not more than 0.015%, S: not more than 0.005%, Cr: 0.30 to 2.0%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.10%, N: not more than 0.030%, and O: not more than 0.0015%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2).
1.20<0.4Cr+0.4Mo+4.5V<2.60(1)
2.7C+0.4Si+Mn+0.8Cr+Mo+V>2.20(2)

A bearing assembly including a chamber provided with a rolling bearing supporting a rotary shaft with respect to a fixed housing. The rolling bearing has a first ring and a second ring in relative rotation one each other, at least one row of rolling elements being arranged between the rings. The chamber having Ethanol in liquid and/or gaseous state. The rings are coated with diamond-like carbon (DLC) material.

A reduction gear includes an external gear, an internal gear which meshes with the external gear, a first member which synchronizes with a rotation of the external gear, a second member which synchronizes with a rotation of the internal gear, and a main bearing which is disposed between the first member and the second member, in which one of the first member and the second member is connected to a driven member and the other is fixed to an external member, and the first member, the second member, and the main bearing are formed of a material having a larger Young's modulus and larger specific gravity than those of a material constituting the external gear and the internal gear.

When a plurality of outer rings (R) are sequentially and inductively heated to a target temperature by energizing a heating coil (2) elongated more than each of the plurality of outer rings (R), which are made of steel and retained coaxially by a retaining unit (3), while relatively moving the outer rings (R) and the heating coil (2) in an axial direction, an output of the heating coil (2) is varied in consideration of the number of outer rings (R) present in an opposing region of the heating coil (2).

A rolling bearing providing a first ring and a second ring in relative rotation one each other, and at least one row of rolling elements being arranged between the said rings. At least one the rings is made by metal injection molding process including the successive steps of mixing a metal powder with a thermoplastic binder, forming a part by injection of the mixed powder in a closed die, debinding such a formed part in a furnace, sintering to densify the part, and quenching to set a ring hardness, to improve wear resistance and fatigue life.

In one aspect of the present invention, a method for manufacturing a bearing component includes: a preparation step of preparing a ring-shaped member of steel having a radially inner surface, a radially outer surface, and a thickness which is a distance between the radially inner surface and the radially outer surface; and a heat treatment step of performing a heat treatment to locally heat one of the radially inner surface and the radially outer surface to a heat treatment temperature and subsequently cool the one of the radially inner surface and the radially outer surface, the method satisfying S930/(0.3477 W.sup.21.594 W0.804), where S represents an average temperature increasing rate (unit: C./sec) applied when the surface is heated and W represents the thickness (unit: mm).

A carburisable steel alloy suitable for bearing components comprising, in percent by weight: C 0.05-0.5 wt. % Cr 2.5-5.0 wt. %, Mo 4-6 wt. %, W 2-4.5 wt. %, V 1-3 wt. %, Ni 2-4 wt. %, Co 2-8 wt. %, optionally one or more of the following elements: Nb 0-2 wt. % N 0-0.5 wt. % Si 0-0.7 wt. %, Mn 0-0.7 wt. %, Al 0-0.1 5 wt. %, wherein the combined amount of Nb+V is within the range 1-3.5 wt. %, the combined amount of C+N is within the range 0.05-0.5 wt. %, the balance being Fe and unavoidable impurities.

In a heat treatment method for obtaining a bearing ring for an annular roller bearing whose thickness changes in an axial direction, the heat treatment method includes (A) applying a quenching process to a work which is annular, made of high carbon chromium bearing steel, and having a thickness changing in an axial direction, (B) applying a tempering process to the work which is quenched to entirely soak the work in cooling liquid and inductively heat the work in a state that the work is soaked in the cooling liquid, and (C) applying a finishing process to the work which is tempered.

A bearing system for a rotating vertical shaft includes a first ball bearing, having a first pitch diameter and a first axial stiffness and a second ball bearing having a second pitch diameter and a second axial stiffness. The first ball bearing is a deep groove Conrad bearing. The second ball bearing is an angular contact bearing. The first and second ball bearings are coaxial, secured to one another and rotatable together. The first pitch diameter is at least 1.5 times greater than the second pitch diameter. The bearing system has an axial stiffness ratio defined by the first axial stiffness divided by the second axial stiffness. The axial stiffness ratio is based on an axial preload force applied to the second outer ring such that an operating torque of the bearing system is within a predetermined range at temperatures from minus 40 to positive 85 degrees Celsius.

Provided is a carbonitrided bearing part which has high hardenability and toughness, and is excellent in wear resistance and surface-originated flaking life. A carbonitrided bearing part of the present embodiment has a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: not more than 0.50%, Mn: 0.40 to 1.50%, P: not more than 0.015%, S: not more than 0.005%, Cr: 0.30 to 2.0%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.10%, N: not more than 0.030%, and O: not more than 0.0015%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2). At surface, C concentration is 0.7 to 1.2%, N concentration is 0.15 to 0.6%, and Rockwell hardness HRC is 58 to 65.
1.20<0.4Cr+0.4Mo+4.5V<2.60(1)
2.7C+0.4Si+Mn+0.8Cr+Mo+V>2.20(2)