GREASE COMPOSITION FOR HUB UNIT BEARING EQUIPPED WITH ANGULAR CONTACT BALL BEARING, AND HUB UNIT BEARING

摘要

The invention provides a grease composition for a hub unit bearing employing an angular contact ball bearing, containing (a) as a thickener a mixture of diurea compounds represented by formula (I): R 1 -NHCONH-R 2 -NHCONH-R 1 , formula (II): R 1 -NHCONH-R 2 -NHCONH-R 3 , and formula (III): R 3 -NHCONH-R 2 -NHCONH-R 3 wherein R 1 is cyclohexyl group, R 2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, R 3 is a straight-chain or branched alkyl group having 12 to 20 carbon atoms, and (R 1 /(R 1 +R 3 )) x 100 = 85 to 95 mol%; (b) a base oil; (c) a molybdenum dialkyldithiocarbamate; and (d) a calcium sulfonate. The grease composition of the invention, when used in the hub unit bearing, shows minimum leakage, excellent anti-flaking properties and satisfactory bearing lubrication life.