A rolling device is provided which employs a lubricating
grease composition which considerably diminishes irregular friction fluctuations occurring on rolling / sliding friction surfaces, shows stable low-torque characteristics in a wide temperature range, can retain a sufficient
oil film even at high temperatures, has along life, and contains a novel thickener. Also provided is an
electric power steering apparatus employing the rolling device.The rolling device is characterized by employing a lubricating
grease composition comprising: a thickener which is a mixed thickener comprising a mixture of (a) one or more diurea compounds which are one or more aliphatic diurea compounds having an average molecular weight of 500-750 in which 10-70% by mole of the linear
hydrocarbon groups are unsaturated components, the aliphatic diurea compounds having been produced using as a
raw material one or more primary amines having a total amine value in the range of 200-400, (b) at least one
fatty acid metal salt, and (c) at least one
amide compound selected from the group consisting of aliphatic amides and aliphatic bisamides represented by formulae (I) and (II):R1CONH2 (I)R1CONHR2NHCOR1 (II)(wherein R1 represents a saturated or unsaturated
alkyl group having 15-17 carbon atoms and R2 represents a
methylene group or an
ethylene group), the proportions of (a) and of (b) and (c) satisfying the relationship:a / (b+c)=0.2−10provided that(1) the proportion of ingredient (a) is 1-10,(2) the proportion of ingredient (b) is 0.5-2.5, and(3) the proportion of ingredient (c) is 0.5-2.5,the amount of the thickener being 2-30% by weight, based on the whole composition;(d) a
base oil which is a lube
base oil having a
pour point of −25° C. or lower and comprising a synthetic
hydrocarbon oil as the main component; and (e) an additive which is a mixture comprising an organomolybdenum complex, an
organozinc compound of a dithiocarbamic acid, and an
organozinc compound of
dithiophosphoric acid, the amount of the additive being 1-7% by weight, based on the whole composition.