An armature of magnetizable material is mounted within a magnetic housing by means of a pair of Belleville springs so that the armature is movable along the central axis thereof between opposed pole pieces formed in the housing. A radially magnetized permanent magnet is positioned in the housing concentric with the armature and a single actuator coil is positioned in the housing concentric with one of the pole pieces. The armature is held in engagement with one of the pole pieces by the flux of the permanent magnet. When the coil is energized the armature is moved into engagement with the opposite pole piece against the biasing force of the Belleville springs, in which position one valve element is closed and the other valve element is opened. The armature pole faces and the pole pieces within the housing have a configuration such that when the armature is in the coil energized position the magnetic permeance of the armature with respect to each pole piece is substantially equal. Accordingly, when the coil is deenergized approximately half of the permanent magnet flux is diverted away from the opposite pole piece to permit the Belleville springs to return the armature to its initial position.