Abstract: An electric actuator includes an input member that is rotationally driven by the electric motor and includes a first rotation stop part on an inner periphery, an output member that includes a second rotation stop part engageable with the first rotation stop part, and a first screw part on an outer periphery, and a linear motion member that includes a second screw part engageable with the first screw part. Both the screw mechanism and the rotation-stop mechanism are formed on the outer periphery of the output member. Therefore, in the electric actuator, the radial and axial dimensions are shortened.

Abstract: An electric brake actuator including a retracting torque applying mechanism that applies a retracting torque to a rotational shaft and including: a torsion spring; a stator including a first retaining portion retaining one end portion of the torsion spring; a rotor including a second retaining portion retaining the other end portion of the torsion spring and configured to be rotated relative to the stator so as to twist the torsion spring; and a clutch mechanism configured to selectively establish a clutch ON state and a clutch OFF state, wherein a first retaining portion prohibits the one end portion from being displaced in a forward rotational direction and includes a biasing member that biases the one end portion in the forward rotational direction, the first retaining portion being configured to allow the one end portion to be displaced in a reverse rotational direction against a biasing force of the biasing member.

Abstract: An electric brake actuator including a retracting torque applying mechanism that applies a retracting torque to a rotational shaft and including: a torsion spring; a stator including a first retaining portion retaining one end portion of the torsion spring; a rotor including a second retaining portion retaining the other end portion of the torsion spring and configured to be rotated relative to the stator so as to twist the torsion spring; and a clutch mechanism configured to selectively establish a clutch ON state and a clutch OFF state, wherein a first retaining portion prohibits the one end portion from being displaced in a forward rotational direction and includes a biasing member that biases the one end portion in the forward rotational direction, the first retaining portion being configured to allow the one end portion to be displaced in a reverse rotational direction against a biasing force of the biasing member.

Abstract: An electrically operated brake device includes an electric motor pressing friction member against a rotating member, and a returning mechanism moving the friction member in a direction away from the rotating member when the electric motor is not energized. The returning mechanism includes a spiral spring and a housing. The spiral spring includes a restraint section. The housing includes a holding surface. When the electric motor is rotated in a forward direction, the restraint section presses the holding surface, and the spiral spring gives a returning torque in a reverse direction. When the returning torque exceeds a predetermined torque, the restraint section slips out of the holding surface. The holding surface is inclined with respect to a normal line surface including a contact part between the restraint section and the holding surface and an axis line of the rotating shaft.