Abstract: At least one pair of first pockets (12A, 12D) are formed in the inner peripheral surface of a housing (1). The first pockets (12A, 12D) are arranged away from each other in a circumferential direction of the housing (1). Planetary gears (3A, 3B) meshed with one pair of side gears (2A, 2B) are rotatably received in the first pockets (12A, 12D), respectively. Second pockets 12B, 12C are formed in the inner peripheral surface of the housing (1) between the first pockets (12A, 12D). Transfer gears (4A, 4B) are rotatably received respectively in the second pockets (12B, 12C). The transfer gears (4A, 4B) are in meshing engagement with the planetary gears (3A, 3B) respectively, and also in meshing engagement with each other.

Abstract: In order to rotationally drive a gear material (3) when the gear material (3) is gear machined using a hob (not shown), a drive hole (34) having a circular configuration in section and extending on an axis L of the gear material (3) is formed in an end face (3e) of the gear material (3) and a shaft member (4) having a polygonal configuration is employed. The distance from an axis of this shaft body (4) to each angular portion (4a) is larger than the radius of the drive hole (34). The distance from the axis of the shaft member (4) to each side portion (4b) of the shaft member (4) is smaller than the radius of the drive hole (34). The shaft member (4) is fitted, under pressure, in the drive hole (34) and the gear member (3) is rotationally driven through this shaft member (4).

Abstract: A support perpendicular to a rotational axis of a housing is secured to one of one of first side gears. One pair of second planet gears are rotatably mounted on the support shaft. The one pair of second planet gears are meshed with one pair of second side gears. A second and a third output shaft are connected respectively to the one pair of second side gears. A first output shaft is connected to the other first side gear.

Abstract: In a disclosed center differential, a front sun gear and a rear sun gear are received within a housing such that they are coaxial with a rotational axis of the housing. The pair of sun gears have helical teeth respectively. The helical teeth of the rear sun gear is helically twisted in a direction for generating a force for urging the rear sun gear toward a rear end wall of the housing when the vehicle makes a turn in its coast driving mode. A front friction generating mechanism is interposed between the front end wall of the housing and the front sun gear, and a rear friction generating mechanism is interposed between the rear end wall of the housing and the rear sun gear. A friction torque transmitted between the housing and the rear sun gear through the rear friction generating mechanism when the vehicle makes a turn in its coast driving mode is larger than a friction torque transmitted between the housing and the front sun gear through the front friction generating mechanism.

Abstract: In a differential gear system disclosed, a pair of sun gears and a plurality of pairs of planetary gears are received in a housing. The pair of sun gears are coaxial with a rotational axis of the housing. End portions of a pair of drive shafts extending through a pair of end walls of the housing are spline-engaged respectively with the pair of sun gears. The pair of sun gears have helical teeth, respectively. Each pair of intermeshing planetary gears are meshed respectively with the helical teeth of the pair of sun gears, respectively. A plurality of washers are interposed between the pair of sun gears. The plurality of washers have first washers and second washers, respectively, which first and second washers are alternately arranged. The first washers are engaged with end portions of reduced diameters of the sun gears such that the first washers are capable of moving axially but incapable of rotation.