Abstract: An oil pump comprises a rotation shaft having an eccentric part, a needle roller bearing supporting the eccentric part of the rotation shaft, a tappet abutting on the outer ring of the needle roller bearing and arranged in a radial manner, a plunger arranged on the tappet and reciprocated by the rotation of the rotation shaft, and a balancer arranged on both ends of the eccentric part. The balancer has a large diameter part and a small diameter part and when the large diameter part is arranged so as to face the direction opposite to an eccentric direction, the rolling space of a roller can be projected from an axial direction through the balancer.

Abstract: An oil pump comprises a rotation shaft having an eccentric part, a needle roller bearing supporting the eccentric part of the rotation shaft, a tappet abutting on the outer ring of the needle roller bearing and arranged in a radial manner, a plunger arranged on the tappet and reciprocated by the rotation of the rotation shaft, and a balancer arranged on both ends of the eccentric part. The balancer has a large diameter part and a small diameter part and when the large diameter part is arranged so as to face the direction opposite to an eccentric direction, the rolling space of a roller can be projected from an axial direction through the balancer.

Abstract: A pulley with a built-in one-way clutch, the type of which has sprags tilting in a direction to wedge between inner and outer rings while being guided on respective riding lands of a cage by pressing of respective leaf springs, is mounted on an alternator shaft of an alternator to which torque of a crank shaft of a vehicle engine rotating together with slight variations in angular velocity is transmitted through a power transmission belt. In the mounting, a tilting force acting on a contact point at which each sprag contacts the corresponding riding land to tilt the sprag in the wedging direction is set larger than a frictional force between the sprag and the riding land acting on the contact point. According to this setting, the sprag can be tilted in the wedging direction regardless of the frictional force between the sprag and the riding land, thereby eliminating a locking failure within the high engine speed range.

Abstract: The inner circumference 4a2 of the bearing ring 4a is square-shaped, and the outer circumference 4a3 thereof is circular. The shoulder 1a1 of the attaching portion 1a of the scroll member 1 is formed to be square-shaped, corresponding to the inner circumference 4a2 of the bearing ring 4a. When attaching the bearing ring 4a to the attaching portion 1a, the square-shaped inner circumference 4a2 of the bearing ring 4a is fitted to the square-shaped shoulder 1a1 of the attaching portion 1a. Thus, by fitting the inner circumference 4a2 of the bearing ring 4a to the shoulder 1a1 of the attaching portion 1a, the bearing ring 4a is prevented from rotating with respect to the swivel scroll member 1.