Abstract: A turbine or pump having a housing receiving a rotor journaled therefrom by a central shaft with the housing including a tangential inlet and a tangential outlet extending in opposed directions with the rotor including a central partition in the housing and curved blades on each side of the partition. The partition is provided with a central opening which communicates the inlet side of the partition with the outlet side thereof whereby fluid passes radially inwardly in engagement with the blades on the rotor to the radial central portion of the partition adjacent the shaft and then makes a U-turn and moves radially outwardly of the partition in relation to the blades for discharge.