To obtain a ball-and-roller bearing which exhibits lubricity from the beginning of low-temp. driving and does not cause an abnormal sound even in cold districts by sealing, into the bearing, a lubricating grease prepd. by compounding a base oil with a thickener under specified conditions.
A lubricating grease is prepd. by compounding a base oil (e.g. a mineral oil, a synthetic hydrocarbon oil, or a polyol ester oil) with a soap-base or nonsoap-base thickener (e.g. a lithium soap, a lithium complex soap, or a fluroresin) and other additives while controlling the amt. and type of the thickener and the cooling rate in the production so that the resultant grease has an unworked penetration (JIS K2220) at -20°C of 190-290 and a worked penetration (JIS K2220) at 25°C of 220-310. For instance, 100 pts.wt. base oil comprising a mixture of a synthetic hydrocarbon (oil) and an ester-base synthetic oil is compounded with 12 pts.wt. aliph. urea compd. as the thickener together with an antioxidant, an extreme-pressure additive, etc., to give a grease having an unworked penetration at -20°C of 190.
AKAMATSU YOSHINOBU