Ntn Corporation

Kyodo Yushi Co., Ltd.

Kenta Sakaguchi

Yutaka Imai

Ryo Aida

A grease composition for a rolling bearing for a motor to support a rotor of the motor, containing a pentaerythritol ester base oil with a kinematic viscosity at 40&#xb0; C. of 20 to 55 mm/s; 7 to 13 mass % of a diurea thickener represented by formula (A) where each R group is defined; and a rust inhibitor mixture selected from the group consisting of polyol ester type rust inhibitors and organic sulfonate type rust inhibitors. The grease composition can prevent a peculiar noise from being produced at low temperatures, satisfy the low torque performance over a wide temperature range, extend the bearing lubrication life even under the circumstances of high temperature, and exhibit excellent rust inhibiting effect on varnish. 

Grease composition and grease-packed rolling bearing

A rolling bearing includes a plurality of rolling elements disposed between an inner race and an outer race and a retainer retaining the rolling elements. Lubricating grease is sealed in the bearing in an amount of not less than 20% of an entire spatial volume of an interior of the rolling bearing and not more than 80% of a stationary spatial volume of the interior of the rolling bearing. The lubricating grease includes a base oil having a dynamic viscosity at 40&#xb0; C. of 13-73 cSt, and a thickening agent of aromatic urea family. The entire spatial volume is an entire interior volume of the bearing minus a total volume of the rolling elements and the retainer, and the stationary spatial volume is a portion of the entire spatial volume where neither the rolling elements nor the retainer passes while the bearing is rotating.

Rolling bearing for alternator

A retainer for a ball bearing and a ball bearing have reduced torque even in grease lubrication. The retainer includes a retainer body which has an annular shape and has recesses formed in one axial end surface thereof along a peripheral direction at predetermined pitches and a pair of claw portions provided to protrude from opening ends of each of the recesses, the opening ends being opposed to each other in the peripheral direction. Each of the recesses and the pair of claw portions form a pocket in which a ball is received. A pocket has a PCD which is set smaller than a PCD of the ball to be received in the pocket.

Ball bearing with retainer

A grease-sealed rolling bearing with a rotary outer race is provided of which the lubricating grease has a long life, and which produces less cold-time noise and can effectively prevent leakage of grease. In an outer-race-rotating type of rolling bearing A for use e.g. as a pulley bearing, lubricating grease G is sealed which contains a base oil having a dynamic viscosity at 40&#xb0; C. of 13 to 73 cSt and which is thickened with a thickening agent of urea family so that the grease is present in an amount of not less than 20% of the entire spatial volume of the interior of the rolling bearing, and not more than 80% of the stationary spatial volume of the interior of the rolling bearing.

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Iwata, Japan

Kenta Sakaguchi