Abstract: A rectilinear-motion actuator includes a motor, a reduction gear mechanism coupled with a motor shaft of the motor, and a rectilinear, reciprocative motion mechanism for converting a rotary motion of a last-stage gear of the reduction gear mechanism to a rectilinear, reciprocative motion. The last-stage gear has a pin provided thereon which is offset from its center of rotation. The rectilinear, reciprocative motion mechanism includes a movable plate having a slit and allowing the pin to move within the slit. The slit is arranged orthogonally to the axis of the motor shaft. The longitudinal center of the slit is located on a line in parallel with the motor shaft axis and passing through the center of the last-stage gear. The axis of reciprocative motion of the movable plate is offset from the line passing through the center of the last-stage gear in a direction away from the motor shaft.

Abstract: In a longitudinal motion actuator, one pinion is fixed to a motor output shaft, and a plurality of transmission mechanisms having the same configuration are provided. Each of transmission mechanisms is configured so that both ends of a lead screw to which a gear engaging with the pinion is fixed are rotatably supported by bearings. A movable nut provided with a plurality of threaded holes engaging with thread grooves in the lead screws of the plurality of transmission mechanisms is provided, and when the motor is rotated, the lead screws are rotated in the same direction via the pinion and the gear, by which the movable nut is driven longitudinally.

Abstract: A commutator has such a construction that a flange having an outside diameter larger than the outside diameter of a cylindrical body is provided integrally with the cylindrical body in the vicinity of one end of the cylindrical body; guide grooves formed in a circular arc shape in cross section are provided on the flange at the boundary of the flange to the cylindrical body; engaging pieces passing through the guide grooves are provided on one end of a commutator segment; and engaging pieces are caused to deform plastically to fixedly fit the engaging pieces to the flange.