Abstract: A pneumatic outlet is provided in which a discharge conduit is affixed to spaced outlet slope sheets and to outlet end sheets. A valve member is movable vertically in the discharge conduit to assume a fully closed and a plurality of open positions. The extent of valve opening may vary from a closed position on one side of the outlet to a partially or fully open position on the other side, linearly across the outlet. Operating mechanisms for raising and lowering the valve member are provided on opposite sides of the outlet, preferably comprising lift rods which engage the valve member. A plurality of operating mechanisms for raising and lowering the valve member are disclosed including screw jack assemblies and cam and cable assemblies. The operating mechanism preferably includes transverse linkages along the outlet operating the valve member from the opposite side of the outlet from either side of the outlet.