Patent ID: 7083031

Claim:
A power transmitting apparatus comprising: an input member and an output member rotatably arranged within a single case to be secured on a stationary member, the power of the input member can be transmitted to the output member or cut off therefrom by appropriately carrying out connection/cut-off between the input and output members; the power transmitting apparatus comprises: an electromagnet secured on the case and generating magnetic flux when energized; an electromagnetic clutch including a rotor for transmitting the magnetic flux, an armature attracted onto the rotor by the magnetic flux transmitted through the rotor, and a return spring arranged between the rotor and the armature and usually axially urging the armature in a direction away from the rotor to create a clearance therebetween when the electromagnet is not energized; a boosting mechanism for converting a torque of the input member to an axial thrusting force when the armature of the electromagnetic clutch is attracted onto the rotor; and a main clutch for connecting the input member and the output member via the thrusting force generated by the boosting mechanism and for transmitting the torque of the input member to the output member so that the reaction force of the thrusting force generated by the boosting mechanism can be used as the fastening force of the electromagnetic clutch.