A clutch having: a fixed hub, a movable hub, and a plurality of plates interposed to selectively transmit a torque. The clutch has a centrifugal pressure plate assembly having: a mass carrier; a plurality of radially movable mass elements, in which each mass element has a pivot connected to the mass carrier for displacement towards an external position under centrifugal effects; wherein the mass elements are further configured to exert axial thrust on a thrust surface of the centrifugal pressure plate assembly, to bring the movable hub closer to the fixed hub and increase the variable axial load. Each mass element has at least one respective rolling element in contact with the thrust surface. The thrust surface has a profile that is sloped and raised towards the external position.

In a power transmission apparatus, a centrifugal clutch includes a holder, a press, and springs to urge masses from a radially outer position to a radially inner position. The masses are each housed in an associated one of housing portions arranged in a circumferential direction of the holder such that the masses are radially movable. More than one spring is provided in the circumferential direction between an inner peripheral wall surface of each of the housing portions and an associated one of the masses to urge the associated mass from the radially outer position to the radially inner position.

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.

Vehicles that are relatively heavy and/or configured to transport heavy loads may utilize a powertrain comprising an electric machine capable of operating at high speeds and a multispeed transmission to propel the vehicle. An interface module is configured to modulate torque between the electric machine and the multispeed transmission allowing the electric machine to smoothly match speed as the multispeed transmission shifts between gears. The interface module facilitates efficient, predictable, and reliable modulation of torque between an input and an output of the powertrain of the vehicle.

A power transmission device has a back torque transmission cam that brings driving clutch plates 6 and driven clutch plates 7 into press contact with each other. A second clutch member 4b is moved when a rotational force is input to a first clutch member 4a via the output shaft 3. The pressure member 5 is located at a non-actuation position. A torque transmission portion transmits a rotational force transmitted to the second clutch member 4b to the first clutch member 4a not via the back torque transmission cam.

A spring assembly comprises an edge wound wave spring and a shim. The spring comprises a plurality of axially spaced, axially compressible wave-like turns extending between a first end portion and a second end portion. The first end portion comprises a plurality of closely arranged parallel turns. The shim comprises a shim body and at least one mounting lug projecting radially from the shim body. The mounting lug is received between adjacent turns of the first end portion of the edge wound wave spring for retaining the shim to the edge wound wave spring.

A power transmission device has a back torque transmission cam that brings driving clutch plates 6 and driven clutch plates 7 into press contact with each other. This occurs by moving a second clutch member 4b when a rotational force is input to a first clutch member 4a, via the output shaft 3. A pressure member 5 is located at a non-actuation position. A back torque transmission cam can hold abutment between an interlocking member 9 and weight member 8 by moving the second clutch member 4b in a direction of being brought into proximity to the interlocking member 9.

Vehicles that are relatively heavy and/or configured to transport heavy loads may utilize a powertrain comprising an electric machine capable of operating at high speeds and a multispeed transmission to propel the vehicle. An interface module is configured to modulate torque between the electric machine and the multispeed transmission allowing the electric machine to smoothly match speed as the multispeed transmission shifts between gears. The interface module facilitates efficient, predictable, and reliable modulation of torque between an input and an output of the powertrain of the vehicle.