Abstract: A self-sustaining solenoid which is adapted so that when applying an operating current to a coil, a moving iron core disposed in the coil is attracted into contact with a fixed receiver. A magnetic yoke is provided to extend between the fixed receiver and the end portion of the moving iron core projecting out of the coil, and a permanent magnet is disposed on the magnetic yoke at least at one end in the direction of movement of the moving iron core. When the moving iron core is held in contact with the fixed receiver, magnetic fluxes emanating from the permanent magnet mostly pass through the moving iron core, the fixed receiver and the magnetic yoke, and even if the operating current is cut off, the moving iron core is retained in contact with the fixed receiver.

Abstract: By applying an operating current to an operating coil, a moving iron core disposed in the operating coil is attracted deeply thereinto to butt against a fixed receiver. By applying a return current to a return coil, the moving iron core is pulled away from the fixed receiver. At least one of the moving iron core and the fixed receiver is divided into two parts in the direction of travel of the permanent magnet and a permanent magnet is sandwiched between the two parts to couple them together. The permanent magnet is magnetized by an operating magnetic field set up by the operating current and demagnetized by the return current.