A power transmission apparatus a centrifugal clutch including a holder and a press. The holder and the press are each circumferentially provided with protrusions fitted and attached to cut-outs of a clutch housing. The holder is an integrated assembly into which a mass that is being held is integrated. The integrated assembly and the press are non-connected separate components and are independently movable toward or away from each other.

A power transmission apparatus a centrifugal clutch including a holder and a press. The holder and the press are each circumferentially provided with protrusions fitted and attached to cut-outs of a clutch housing. The holder is an integrated assembly into which a mass that is being held is integrated. The integrated assembly and the press are non-connected separate components and are independently movable toward or away from each other.

In a power transmission apparatus, a centrifugal clutch includes a holder, a press, a first spherical 14bodv that is partially protruded from a first opening and in contact with a rolling contact surface of the press so as to be rollable thereon, and a second spherical body that is partially protruded from a second opening and in contact with a rolling contact surface of the holder so as to be rollable thereon. A through hole has a tapered shape from the first opening to the second opening. Disconnection of the first spherical body is prevented by an outer peripheral edge of one of the first opening and the second opening that has a smaller diameter.

During movement of a mass of a centrifugal clutch a radially inner position to a radially outer position and a resulting increase in torque transmitted from an input gear to an output shaft, a power transmission apparatus includes a first torque region where the apparatus restricts operation of a pressing assist cam and a second torque region where the apparatus allows operation of the pressing assist cam.

In a vehicle drive transmission device, a transmission includes an intermesh first engagement device, a frictional second engagement device, a first drive device configured to drive the first engagement device, and a second drive device configured to drive the second engagement device. The first drive device includes a first shift drum, a first cam mechanism configured to convert rotational motion of the first shift drum into linear motion, and a first transmission mechanism configured to perform the linear motion. The second drive device includes a second shift drum, a second cam mechanism configured to convert rotational motion of the second shift drum into linear motion, and a second transmission mechanism configured to perform the linear motion. The first shift drum and the second shift drum are connected so as to rotate integrally with each other via a drive shaft. A drum drive source is provided to drive the drive shaft.

In a vehicle drive transmission device, a transmission includes an intermesh first engagement device, a frictional second engagement device, a first drive device configured to drive the first engagement device, and a second drive device configured to drive the second engagement device. The first drive device includes a first shift drum, a first cam mechanism configured to convert rotational motion of the first shift drum into linear motion, and a first transmission mechanism configured to perform the linear motion. The second drive device includes a second shift drum, a second cam mechanism configured to convert rotational motion of the second shift drum into linear motion, and a second transmission mechanism configured to perform the linear motion. The first shift drum and the second shift drum are connected so as to rotate integrally with each other via a drive shaft. A drum drive source is provided to drive the drive shaft.

In a power transmission apparatus, an auxiliary clutch plate different in diameter from driving and driven clutch plates located in a clutch housing. When the driving and driven clutch plates are pressed against each other, the auxiliary clutch plate is pressed to enable transmission of a driving force of an engine to a driving wheel. When a pressing force exerted on the driving and driven clutch plates is released, a pressing force exerted on the auxiliary clutch plate is released to cut off transmission of the driving force of the engine to the driving wheel.

In a power transmission apparatus, an auxiliary clutch plate different in diameter from driving and driven clutch plates located in a clutch housing. When the driving and driven clutch plates are pressed against each other, the auxiliary clutch plate is pressed to enable transmission of a driving force of an engine to a driving wheel. When a pressing force exerted on the driving and driven clutch plates is released, a pressing force exerted on the auxiliary clutch plate is released to cut off transmission of the driving force of the engine to the driving wheel.

In a power transmission apparatus, a centrifugal clutch includes a holder, a press, a first spherical body that is partially protruded from a first opening and in contact with a rolling contact surface of the press so as to be rollable thereon, and a second spherical body that is partially protruded from a second opening and in contact with a rolling contact surface of the holder so as to be rollable thereon. A through hole has a tapered shape from the first opening to the second opening. Disconnection of the first spherical body is prevented by an outer peripheral edge of one of the first opening and the second opening that has a smaller diameter.

In a power transmission apparatus, a centrifugal clutch includes a holder, a press, a first spherical body that is partially protruded from a first opening and in contact with a rolling contact surface of the press so as to be rollable thereon, and a second spherical body that is partially protruded from a second opening and in contact with a rolling contact surface of the holder so as to be rollable thereon. A through hole has a tapered shape from the first opening to the second opening. Disconnection of the first spherical body is prevented by an outer peripheral edge of one of the first opening and the second opening that has a smaller diameter.