A brake device includes: an outer race having a cylindrical inner peripheral surface; at least two brake cams arranged inside the outer race in a circumferential direction, each brake cam having brake surfaces located at both ends in the circumferential direction of a side of the brake cam facing the outer race, each brake surface being contactable with the inner peripheral surface of the outer race; and an output-side rotary member arranged at radially inner sides of the respective brake cams, the output-side rotary member including contact portions contactable with surfaces of the brake cams facing the radially inner sides. Contact points at which the respective contact portions and the respective brake cams are contactable are on an axis-of-rotation side of a both-end reference plane (plane connecting outer ends of the respective brake surfaces located at the both ends of to corresponding brake cam), or on the both-end reference plane.

A reverse-input blocking clutch includes a pressed member having a pressed surface; an input member having an input-side engaging portion; an output member having an output-side engaging portion; an engaging element having a pressing surface, an input-side engaged portion, and an output-side engaged portion and arranged between the pressed surface and the output-side engaging portion with respect to a first direction which is a direction of moving toward or away from the pressed surface; an elastic member that elastically urge the pressing surface toward the pressed surface 7 in the first direction; and a displacement prevention means for preventing relative displacement in the axial direction of the engaging element with respires to the output member.

A reverse-input blocking clutch includes a pressed member having a pressed surface; an input member having an input-side engaging portion; an output member having an output-side engaging portion; an engaging element having a pressing surface, an input-side engaged portion, and an output-side engaged portion and arranged between the pressed surface and the output-side engaging portion with respect to a first direction which is a direction of moving toward or away from the pressed surface; an elastic member that elastically urge the pressing surface toward the pressed surface 7 in the first direction; and a displacement prevention means for preventing relative displacement in the axial direction of the engaging element with respires to the output member.

The invention relates to an actuator comprising a stationary structure and an actuating element that is movable relative to the stationary structure, a device for locking the actuating element in position which is mounted on the stationary structure and has a state for locking and a state for releasing the actuating element. The locking device comprises, successively, a stress limiter and at least one locking element so arranged as to be butting against one surface of the actuating element, in order to oppose a motion of the actuating element in a predetermined direction. The actuator comprises a member for controlling the locking device in the releasing state thereof and a member for resiliently returning the locking device to the locking state thereof.

The invention relates to an actuator comprising a stationary structure and an actuating element that is movable relative to the stationary structure, a device for locking the actuating element in position which is mounted on the stationary structure and has a state for locking and a state for releasing the actuating element. The locking device comprises, successively, a stress limiter and at least one locking element so arranged as to be butting against one surface of the actuating element, in order to oppose a motion of the actuating element in a predetermined direction. The actuator comprises a member for controlling the locking device in the releasing state thereof and a member for resiliently returning the locking device to the locking state thereof.