Patent ID: 7721862

Claim:
A power transmitting apparatus comprising: a clutch housing rotatable together with an input member; a plurality of driving clutch plates mounted on the clutch housing and rotatable together with the clutch housing; a plurality of driven clutch plates alternately arranged between the driving clutch plates and movable between pressure-contact and release positions relative to the driving clutch plates; a clutch member of a substantially cylindrical configuration connected to an output member for rotation about a rotational axis, the driven clutch plates being mounted on the clutch member; a pressure member configured to be moveable so as to press and release the driving clutch plates relative to the driven clutch plates; a pressure-contact assisting cam configured to increase a pressure-contacting force between the driving clutch plates and driven clutch plates when a condition in which a rotational force input to the input member is transmitted to the output member; and a back-torque limiting cam configured to release the connection between the driving clutch plates and the driven clutch plates when the rotation speed of the output member has exceeded that of the input member; wherein at least one cam surface included in at least one of the pressure-contact assisting cam and the back-torque limiting cam is arranged so as to extend along a circumferential edge of the clutch member; and wherein said at least one cam surface is crowned along at least one of an extending direction and a width direction, the extending direction being defined as a direction parallel to the rotational axis, the width direction being defined as a direction which extends from a radially inner portion of the clutch member to a radially outer portion of the clutch member, relative to the rotational axis.