A switching mechanism in a star-delta-switch with a rotatable and axially displaceable switch-shaft prevents rotation of the switch-shaft from the off- to the delta-connection position in the direction of rotation from the delta-connection to the off-position in one of the axial positions while axial...http://www.google.fr/patents/US4503412?utm_source=gb-gplus-shareBrevet US4503412 - Star-delta-switch
