Abstract: A wind-powered prime mover comprising a pair of elongate, vertically extending, laterally spaced parallel rotors with a plurality of circumferentially spaced radially outwardly projecting circumferentially and longitudinally extending vanes. The rotors are arranged so that the vanes of each rotor projects between adjacent pairs of vanes of the other rotor as the rotors rotate. The rotors are rotatably supported atop a turn-table which turns to dispose the lateral plane on which the axes of the rotors occur at right angle to prevailing wind. Wind directing shrouds are engaged about the lateral outside halves of the rotors and function to direct wind from said outer halves of the rotors laterally inward toward and between the lateral inner halves of the rotors. The windward sides of the shrouds define a wind gate through which wind moves into engagement with the rotors and are pivotally movable to increase and decrease the lateral extent of the wind gate to throttle the wind, as desired.