A vacuum pump comprises: a ball bearing which supports a rotor; a holding section which elastically holds an outer ring of the ball bearing; and a grease which is filled between the outer ring and the holding section, the grease having a consistency of NLGI No. 1.5 or less.

A rolling bearing that can prevent peeling on a surface of an iron-based metal member by hydrogen brittleness even under a severe environment is provided. The rolling bearing 1 has plural bearing elements formed of an iron-based metal, and a lubricant composition 7 that lubricates metal contact surfaces of the respective bearing elements, the lubricant composition 7 is a grease containing a base oil and alkanolamine and being free of alkali metal salts and alkaline earth metal salts of inorganic acids, the base oil is at least one oil selected from alkyl diphenyl ether oils, poly-α-olefin oils and ester oils, and the alkanolamine is contained by 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the base oil and a thickener.

To provide a grease composition for a tapered roller bearing having superior bearing lifetime under a condition of high temperature and a condition of high load, and a tapered roller bearing in which the grease composition for the tapered roller bearing is filled. A tapered roller bearing 11 includes an inner ring 12 having a raceway surface 12a, an outer ring 13 having a raceway surface 13a and a plurality of tapered rollers 14, and a flange part of the inner ring 12 gets into sliding contact with the tapered rollers 14. Grease 16 is filled around the tapered rollers 14. The grease 16 includes a base oil, a thickener and an additive. A frequency in which a storage modulus, which varies depending on frequency, of the grease 16 becomes minimum is equal to 7 Hz or more.

The present invention addresses a problem of providing a grease composition containing a urea-based thickener and capable of appropriately maintaining the kinematic friction force in lubrication parts. The grease composition contains a base oil (A) and a urea-based thickener (B), wherein the base oil (A) has a kinematic viscosity at 40° C. of 100 mm.sup.2/s or more, and the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.

The rolling bearing of the present invention is lubricated with a lubricant composition which contains a fatty acid metal salt, a metal dithiocarbamate, a phosphorous-type additive, and a basic additive, and which has a total acid value of 3.7 mgKOH/g or more. The rolling bearing makes it possible to further improve anti-fretting performance, and to reduce a decrease in fretting resistance even when used under the circumstance that fluorine-type grease penetrates into the bearing using urea-type grease.

The present invention addresses a problem of providing a grease composition containing a urea-based thickener and capable of appropriately maintaining the kinematic friction force in lubrication parts. The grease composition contains a base oil (A) and a urea-based thickener (B), wherein the base oil (A) has a kinematic viscosity at 40° C. of 100 mm.sup.2/s or more, and the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.

A grease composition for a tapered roller bearing comprising: (a) at least one compound selected from the group consisting of metallic salts each having a metallic group having a valence of 2 as an additive; (b) a base oil containing a synthetic oil having a viscosity index of 110 or more and a pour point of −35° C. or less in an amount of 40% or more of the entire base oil; (c) a thickener; and (d) an antioxidant.

One aspect of the disclosure relates to a sliding member. The sliding member includes: a first sliding portion having a first lubricant placed between first parts of a first friction sliding mechanism; and a second sliding portion having a second lubricant placed between second parts of a second friction sliding mechanism. The first sliding portion has a lubricant feed port from which the first lubricant is fed, and the second sliding portion has no lubricant feed port from which the second lubricant is fed. The first lubricant contains base oil and an additive. The second lubricant contains base oil and an additive containing conductive carbon. The second lubricant contains a relatively larger amount of conductive carbon than the first lubricant.

One aspect of the disclosure relates to a sliding member. The sliding member includes: a first sliding portion having a first lubricant placed between first parts of a first friction sliding mechanism; a second sliding portion having a second lubricant placed between second parts of a second friction sliding mechanism; and a third sliding portion having a third lubricant placed between third parts of a third friction sliding mechanism. The first sliding portion is in contact with the third lubricant, and the second sliding portion is not in contact with the third lubricant. The second lubricant contains an additive containing conductive carbon, and the third lubricant contains no conductive carbon. The second lubricant contains a relatively larger amount of the conductive carbon than the first lubricant.

Disclosed is a monitoring method for monitoring the film thickness of a lubricant within a lubricated bearing, the bearing having an inner ring, an outer ring and rolling elements being arranged between the inner ring and the outer ring/ The monitoring method comprises a capacitance measuring step for measuring the total capacitance of the bearing; a first calculation step for determining a film thickness of the lubricant based on the measured capacitance of the bearing and for determining whether the lubrication condition is fully flooded or starved, and when the lubrication condition is fully flooded, a second calculation step for correcting the film thickness determined in the first calculation step.