Patent ID: 8678152

Claim:
An electromagnetic clutch, comprising: a rotatable member including, a first member rotatable around an axis, and a rotor rotatable together with the first member, the rotor including a clutch friction surface and a brake friction surface; a second member disposed coaxially and slidably around an outer periphery of the first member, wherein the second member drives the rotatable member to rotate around the axis; an armature fixed to the second member so as to be displaceable in a direction of the axis, the armature facing the rotor; a coil that presses the armature against the clutch friction surface of the rotor when the coil is supplied with electricity, and that releases the armature from the clutch friction surface of the rotor when the coil is not supplied with electricity; a brake device that continuously applies a brake torque to the rotatable member, the brake device including i) a coil spring with a base end of the coil spring supported on a stationary member side either directly or through a support member, and ii) a brake element positioned on a tip end side of the coil spring, the brake element being put in elastic contact with the brake friction surface of the rotor in an axial direction of the second member; and a restriction mechanism provided between a part of the brake element and an extension part of the stationary member side extending in the axial direction, the restriction mechanism configured to permit relative displacements in the axial direction but restrain relative displacements in the rotating direction, of the part of the brake element, wherein the brake torque applied by the brake device is not less than a slip torque generated between the second member and the first member and less than a driving torque applied by the second member.