Grease composition and rolling bearing lubricated by the grease composition

Abstract

It is an object of the invention to provide a grease composition which can improve both the acoustic performance and anti-fretting property of a ball bearing, and a rolling bearing which is lubricated by such a grease composition. As solving means for the above, in a grease composition which essentially comprises a base oil and a thickener, a mixture of a urea compound and lithium soap is blended as the thickener. The content of the urea compound in the thickener is preferably set to 20 to 80 wt %. As the urea compound, an alkyl group- or cyclohexyl group-terminated diurea compound, or, particularly, a diurea compound in which the diisocyanate component is 4,4′-diphenylmethane diisocyanate is preferably used. In a rolling bearing which is lubricated by the grease composition, the acoustic performance is largely improved by a synergistic action of the lithium soap and the urea compound, and simultaneously also the anti-fretting property is enhanced by an action of the urea compound.

Dependencies are inferred from the claim text.