A Hybrid rolling bearing includes an inner raceway and an outer raceway and a plurality of rolling elements arranged therebetween. The outer raceway and the inner raceway are made from bearing steel, having a first surface RMS roughness R.sub.q1. The rolling elements are made from a ceramic material and have second surface RMS roughnesses R.sub.q2,i. At least one of the rolling elements has an increased surface RMS roughness R.sub.q2,N, which is significantly higher than the RMS roughnesses R.sub.q2,i, of the remaining rolling elements. The hybrid rolling bearing can be installed within a refrigerant compressor.

A rolling bearing includes a plurality of balls and two raceway members. The balls and the raceway members have contact surfaces. In at least either of balls and raceway members, a superficial part is formed in a region from the contact surface to a depth of 20 ?m. Of the balls and the raceway members, the member in which a superficial part is formed in the contact surface is made of steel that has been quenched. A raceway surface which is a contact surface of the raceway member is a partial arc in a sectional view that passes a central axis of the rolling bearing and is parallel with the central axis. The diameter of the partial arc is greater than or equal to 1.01 times and less than or equal to 1.08 times the diameter of the ball.

A heat-resistant bearing material may include an austenitic iron matrix alloy having a proportion of sulphur sufficient to achieve a solid lubricating action on bearing surfaces of the heat-resistant bearing material. The iron matrix alloy may have a proportion of carbides to achieve a reduction of wear on bearing surfaces of the heat-resistant bearing material and a proportion of 1 to 6 percentage by weight of at least one alloying element including cobalt, niobium, rhenium, tantalum, vanadium, tungsten, hafnium, yttrium and zirconium. The iron matrix alloy may also include the following alloying elements: carbon, chromium, manganese, silicon, nickel, molybdenum, niobium, tungsten, sulphur, copper, nitrogen and iron.

A bearing part according the present invention includes, as the chemical composition, by mass %, C: 0.95% to 1.10%, Si: 0.10% to 0.70%, Mn: 0.20% to 1.20%, Cr: 0.90% to 1.60%, Al: 0.010% to 0.100%, N: 0.003% to 0.030%, P: 0.025% or less, S: 0.025% or less, O: 0.0010% or less, and optionally Mo: 0.25% or less, B: 0.0050% or less, Cu: 1.0% or less, Ni: 3.0% or less, and Ca: 0.0015% or less, and a remainder including Fe and impurities; metallographic structure includes a retained austenite, a spherical cementite and a martensite; an amount of the retained austenite is 15% to 25%, by volume %; an average grain size of prior-austenite is 8.0 m or less; and a number density of a void having a circle equivalent diameter of 0.02 m to 3.0 m is 2000 mm.sup.2 or less in the metallographic structure.

An automobile vehicle crankshaft including a crankshaft casting of a nodular iron. The crankshaft casting includes multiple main journals coaxially aligned on a common crankshaft casting axis. Multiple crankpin journals are fixedly connected to the main journals by individual webs. Multiple lightening holes have individual ones of the multiple lightening holes integrally formed within individual ones of the crankpin journals during casting. A bubble space is located proximate to a mid-portion of selected ones of the multiple lightening holes of the crankpin journals. The bubble space locally increases a passage size of the selected ones of the multiple lightening holes and reduces a mass of the individual ones of the crankpin journals.

A roughly shaped material for a rolling bearing of the present invention is produced by forging a steel composed of a high-carbon chrome bearing steel containing 0.7 mass % to 1.2 mass % of a carbon, and 0.8 mass % to 1.8 mass % of a chromium to a predetermined shape while heating the steel to a forging temperature in a range of (Ae.sub.1 point+25 C.) to (Ae.sub.1 point+105 C.), cooling a forged article to a temperature of Ae.sub.1 point or lower, and performing an annealing in which the forged article that is obtained is heated to a soaking temperature in a range of (Ae.sub.1 point+25 C.) to (Ae.sub.1 point+85 C.), the forged article is retained for 0.5 hours or longer, and the forged article is cooled down to 700 C. or lower at a cooling rate of 0.30 C./s or slower.

The manufacturing method notably includes a step (110) for sintering steel powder (10), the chemical composition of which includes, in mass percent, 2.3% of carbon, 4.2% of chromium, 7% of molybdenum, 6.5% of tungsten, 10.5% of cobalt and 6.5% of vanadium, so as to obtain a sintered steel (12) and shaping of the sintered steel (12), for forming a bearing ring (18).

A near-eutectoid bearing steel having from 0.7 to 0.9 wt. % carbon, from 0.1 to 0.35 wt. % silicon, from 0.7 to 1.2 wt. % manganese, from 1.0 to 2.0 wt. % chromium, from 0.1 to 0.35 wt. % molybdenum, from 0.2 to 0.6 wt. % nickel, from 0.4 to 1.2 wt. % copper, from 0 to 0.15 wt. % vanadium, from 0 to 0.15 wt. % niobium, from 0 to 0.15 wt. % tantalum, from 0 to 0.2 wt. % cobalt, from 0 to 0.1 wt. % aluminum, from 0 to 0.05 wt. % phosphorous, from 0 to 0.03 wt. % sulphur, from 0 to 0.075 wt. % tin, from 0 to 0.075 wt. % antimony, from 0 to 0.04 wt. % arsenic, from 0 to 0.01 wt. % lead, up to 350 ppm nitrogen, up to 100 ppm oxygen, up to 50 ppm calcium, up to 50 ppm boron, up to 50 ppm titanium, the balance iron, together with any other unavoidable impurities.

A bearing component composed of a chromium-molybdenum-vanadium alloyed tool steel is produced by a process that includes: (i) performing a first preheating within a temperature range of 600-650 C., (ii) performing a second preheating within a temperature range of 850-900 C., (iii) austenitizing in vacuum at 1000-1180 C. for 20-40 min, (iv) gas quenching at a minimum of 4-5 bar overpressure, and (v) tempering by performing either a double temper at 520-560 C. for 1.5-2.5 hours in each temper, or a triple temper at 520-560 C. for 0.5-1.5 hours in each temper. The steel alloy may be composed (in mass percent) of 1.32-1.45 C, 0.32-0.50 Si, 0.26-0.48 Mn, 4.0-4.85 Cr, 3.35-3.55 Mo, 3.55-3.85 V, 0-0.13 W, 0-0.20 Ni, 0-0.15 Cu, 0-0.8 Co, 0-0.03 P, and 0-0.03 S, the balance being iron and unavoidable impurities. Mo may be replaced with W or vice versa in a replacement ratio Mo:W of 1:2.

A refrigeration chiller employs a centrifugal compressor the impellers of which are mounted on a shaft which is itself mounted for rotation using rolling element bearings lubricated only by the refrigerant which constitutes the working fluid of the chiller system. Apparatus is taught for providing liquid refrigerant to (1.) the bearings immediately upon chiller start-up, during chiller operation and during a coastdown period subsequent to shutdown of the chiller and (2.) the drive motor of the chiller's compressor for motor cooling purposes. By use of a variable speed-driven motor to drive the compressor, optimized part load chiller performance is achieved in a chiller which does not require or employ an oil-based lubrication system.