Abstract: It is an object of the present invention to provide a chain transmission device including rolling-type chain guides capable of guiding a chain quietly. In the chain transmission deice including the chain guides in which a plurality of spaced apart rollers for guiding the chain are arranged, distance L (m) between the contact points of a trained portion of the chain is set to satisfy the following inequality: L < 1 2 ? ? ? MAX ? T ? ( 1 ) where ?MAX is the maximum excitation frequency (Hz) from a crank shaft, ? is the mass of the chain per unit length (kg/m), and T is the time-average tension of the chain (N).

Abstract: A cam follower for a rocker arm includes a cylindrical outer ring (11) having an outer circumference surface abutting on a cam, a support shaft (6) to support the outer ring (11), a plurality of rollers (12) arranged in an annular region between the support shaft (6) and the outer ring (11), and a side plate (16) composed of a ring-shaped disk penetrated by the support shaft (6), opposed to an end face (15) of the roller (12), and having an outer diameter Ds smaller than an inner diameter Dr of the outer ring (11). The side plate (16) is arranged at each end of the roller (12), and a relationship Lr<Lk+2t is satisfied in which Lk represents a shaft length of the roller (12), Lr represents a shaft length of the outer ring (11), and t represents a thickness of the side plate (16).

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 steel-made rolling-contact shaft with a joint claw improved in both the rolling contact fatigue life at the raceway and the static fracture strength (torsional strength) at the claw includes a joint claw at one end, and has a portion of the outer cylindrical surface functioning as a raceway of a needle roller qualified as a rolling element of a needle bearing. The joint claw is subjected to tempering by induction heating. A nitrogen-enriched layer is formed at the surface layer of the rolling-contact shaft with a joint claw. The grain size number of austenite grains in the nitrogen-enriched layer exceeds number 10. The hydrogen content of the rolling-contact shaft with a joint claw is not more than 0.5 ppm.

Abstract: A cam follower for a rocker arm includes a cylindrical outer ring (11) having an outer circumference surface abutting on a cam, a support shaft (6) to support the outer ring (11), a plurality of rollers (12) arranged in an annular region between the support shaft (6) and the outer ring (11), and a side plate (16) composed of a ring-shaped disk penetrated by the support shaft (6), opposed to an end face (15) of the roller (12), and having an outer diameter Ds smaller than an inner diameter Dr of the outer ring (11), in which the side plate (16) is arranged at each end of the roller (12), and a relationship Lr<Lk+2t is satisfied in which Lk represents a shaft length of the roller (12), Lr represents a shaft length of the outer ring (11), and t represents a thickness of the side plate (16).

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 steel-made rolling-contact shaft with a joint claw improved in both the rolling contact fatigue life at the raceway and the static fracture strength (torsional strength) at the claw includes a joint claw at one end, and has a portion of the outer cylindrical surface functioning as a raceway of a needle roller qualified as a rolling element of a needle bearing. The joint claw is subjected to tempering by induction heating. A nitrogen-enriched layer is formed at the surface layer of the rolling-contact shaft with a joint claw. The grain size number of austenite grains in the nitrogen-enriched layer exceeds number 10. The hydrogen content of the rolling-contact shaft with ajoint claw is not more than 0.5 ppm.