Abstract: A power transmission device for an astride-riding vehicle is provided, the power transmission device including a torque converter T and a clutch C disposed in series in a transmission route between an engine E and a gear speed change device M. The torque converter T is arranged so that a pump capacity ? is a maximum at a speed ratio e=0, and gradually decreases in response to an increase in the speed ratio e. Linear properties in which both the engine rotational speed and the turbine rotational speed increase substantially linearly in response to an acceleration operation of the engine can therefore be obtained, thereby providing good drivability.

Abstract: A power transmission device for an astride-riding vehicle is provided, the power transmission device including a torque converter T and a clutch C disposed in series in a transmission route between an engine E and a gear speed change device M. The torque converter T is arranged so that a pump capacity &tgr; is a maximum at a speed ratio e=0, and gradually decreases in response to an increase in the speed ratio e. Linear properties in which both the engine rotational speed and the turbine rotational speed increase substantially linearly in response to an acceleration operation of the engine can therefore be obtained, thereby providing good drivability.

Abstract: In a torque converter in which a radial bearing and a one-way clutch are disposed adjacent and concentrically with each other between a hub of a side cover and a turbine shaft extending through the hub, and a hub of an output gear is coupled to an outer end of the turbine shaft, an inner peripheral surface of the hub of the side cover is comprised of a larger-diameter inner peripheral surface portion located on the side of its base end, and a smaller-diameter inner peripheral surface portion located on the side of its tip end and connected to the larger-diameter inner peripheral surface portion through an annular step, and an outer race of the radial bearing fitted to the larger-diameter inner peripheral surface portion is clamped by the annular step and a retaining ring locked to the larger-diameter inner peripheral surface portion.

Abstract: In a torque converter in which a radial bearing and a one-way clutch are disposed adjacent and concentrically with each other between a hub of a side cover and a turbine shaft extending through the hub, and a hub of an output gear is coupled to an outer end of the turbine shaft, an inner peripheral surface of the hub of the side cover is comprised of a larger-diameter inner peripheral surface portion located on the side of its base end, and a smaller-diameter inner peripheral surface portion located on the side of its tip end and connected to the larger-diameter inner peripheral surface portion through an annular step, and an outer race of the radial bearing fitted to the larger-diameter inner peripheral surface portion is clamped by the annular step and a retaining ring locked to the larger-diameter inner peripheral surface portion.

Abstract: An exhaust manifold for an engine includes a manifold body 7 having a plurality of branch pipes and a common collecting chamber integrally connected to the branch pipes and communicating with an exhaust emission control device is divided into an upper half and a lower half at a boundary face extending in a direction of arrangement of the branch pipes. The upper and lower halves are made of steel plates and welded to each other. In the exhaust manifold, a welding mating coupler is formed by outer edges of the upper and lower halves, and a welding stepped superposing coupler is formed by inner edges of the upper and lower halves. Thus, during welding, it is possible to limit the misalignment of the upper and lower halves in a direction along the boundary face and the misalignment of the upper and lower halves in a direction perpendicular to the boundary face by cooperation of the mating coupler and the stepped superposing coupler.