Abstract: A composite roll bearing (1), comprising an outer ring (2) and an annular inner ring (3) of groove shape in cross section having first, second, and third receiving surfaces (3a, 3b, 3c) facing the both end face inner peripheral portions (2a, 2b) and the circular inner peripheral surface (2c) of the outer ring (2) at specified intervals. A plurality of rollers (4) for thrust bearing are installed between one end face portion (2a) of the outer ring (2) and the first receiving surface (3a) of the inner ring (3) and between the other end face (2b) of the outer ring (2) and the second receiving surface (3b) of the inner ring (3). A plurality of rollers (5) for radial bearing are installed between the circular inner peripheral surface (2c) of the outer ring (2) and the third receiving surface (3c) of the inner ring (3). The rollers (5) are restricted to move in a thrust direction by retainer portions (8a, 8a) formed at the inner ends of retainers (6, 7) for the rollers (4) for thrust bearing.

Abstract: A composite roll bearing (1), comprising an outer ring (2) and an annular inner ring (3) of groove shape in cross section having first, second, and third receiving surfaces (3a, 3b, 3c) facing the both end face inner peripheral portions (2a, 2b) and the circular inner peripheral surface (2c) of the outer ring (2) at specified intervals. A plurality of rollers (4) for thrust bearing are installed between one end face portion (2a) of the outer ring (2) and the first receiving surface (3a) of the inner ring (3) and between the other end face (2b) of the outer ring (2) and the second receiving surface (3b) of the inner ring (3). A plurality of rollers (5) for radial bearing are installed between the circular inner peripheral surface (2c) of the outer ring (2) and the third receiving surface (3c) of the inner ring (3). The rollers (5) are restricted to move in a thrust direction by retainer portions (8a, 8a) formed at the inner ends of retainers (6, 7) for the rollers (4) for thrust bearing.

Abstract: A 4-point contact ball bearing includes four ring-shaped contact surfaces for forming a ring-shaped raceway between them, each ring-shaped contact surface has a sectional profile defined by a concave curve when cut along a plane including a central axis of rotation of each ball and a central axis of rotation of the ring-shaped raceway. The concave curve is shaped so that it circumscribes the balls and that a curvature thereof is largest at a ball-contact point and is gradually decreased moving away from the ball-contact point. By defining such raceway surfaces, fluctuations in the contact points between the balls and the raceway surfaces due to machining errors can be suppressed, rotational slipping of the balls can be reduced, and differential slip between the balls and the raceway surfaces can also be reduced.

Abstract: A 4-point contact ball bearing includes four ring-shaped contact surfaces for forming a ring-shaped raceway between them. Each ring-shaped contact surface has a sectional profile defined by a concave curve when cut along a plane including a central axis of rotation of each ball and a central axis of rotation of the ring-shaped raceway. The concave curve is shaped so that it circumscribes the balls and that a radius of curvature thereof is largest at a ball-contact point and is gradually decreased moving away from the ball-contact point. By defining such raceway surfaces, fluctuations in the contact points between the balls and the raceway surfaces due to machining errors can be suppressed, rotational slipping of the balls can be reduced, and differential slip between the balls and the raceway surfaces can also be reduced.

Abstract: A planetary gear device (20) comprises a front-stage side planetary gear mechanism (21) and a rear-stage side planetary gear mechanism (23). The rear-stage side planetary gear mechanism (23) comprises an internal gear (25), a carrier (29) rotatably supported by a pair of main guide bearings (26,27) disposed on both sides of the internal gear (25), a plurality of planetary gears (31) rotatably supported on a plurality of planetary shafts (30) extending between a pair of carrier parts (28A,28B) of the carrier (29), a sun gear (33) formed on an outer circumferential surface of a pinion shaft extending in a direction of a device axial line (20a) to pass through the carrier (29), and an output shaft (34) connected to the carrier (29) and extending in the direction of the device axial line (20a).

Abstract: A flexible meshing type gear drive 1 has a rigid internal gear 2 and a flexible external gear 3 whose tooth profiles are defined as follows. First, initial tooth profiles of these gears 2, 3 are defined as in the case that the tooth number of the rigid internal gear is 102 and that of the flexible external gear is 100. The initial tooth profile is adopted as it is for that of the rigid internal gear 2. While, the actual tooth profile of the flexible external gear 3 is determined by thinning out one tooth at every one tooth from the external teeth 34-1, 2, 3, . . . of the initial tooth profile to form tooth bottom portions connecting the respective remaining external teeth 34-1, 3, 5, . . . .