An energy converter comprising a) a housing which confines a spherical working chamber and in which inlet and outlet openings for a pressurized liquid or gaseous medium are arranged, b) a shaft and two hollow shafts (3a, 3b) receiving the shaft, which hollow shafts (3a, 3b) are mounted rotatably in the housing, wherein their axes of rotation coincide with a diameter of the working chamber, wherein a first of the two hollow shafts is connected to the shaft torque proof and a second of the two hollow shafts is supported rotatably on the shaft, c) two flat rotary pistons (4, 5) which bear sealingly against the inner wall of the housing and have a circular profile, wherein one flat rotary piston is connected torque proof to the shaft and the other flat rotary piston is connected torque proof to the second hollow shaft, d) two toothed gears (6, 7) which are connected to the shaft or to the second hollow shaft via a freewheel clutch, preventing rotation of the toothed gears (6, 7) with respect to the shaft or the second hollow shaft counter to the working direction of rotation, and e) an output toothed gear which meshes with both toothed gears (6, 7), characterized in f) that two inlet openings opposite one another and two outlet openings opposite one another are arranged in the housing, g) that the shaft and the second hollow shaft are each supported in the housing via a freewheel clutch (12, 13), preventing rotation of the shaft or of the second hollow shaft counter to the working direction of rotation, h) that stop bolts are assigned to the two flat rotary pistons (4, 5) which bolts engage at the end of a working cycle of one flat rotary piston (4, 5), with the other flat rotary piston (5, 4) and move the latter across the two inlet openings. a) a housing which confines a spherical working chamber and in which inlet and outlet openings for a pressurized liquid or gaseous medium are arranged, b) a shaft and two hollow shafts (3a, 3b) receiving the shaft, which hollow shafts (3a, 3b) are mounted rotatably in the housing, wherein their axes of rotation coincide with a diameter of the working chamber, wherein a first of the two hollow shafts is connected to the shaft torque proof and a second of the two hollow shafts is supported rotatably on the shaft, c) two flat rotary pistons (4, 5) which bear sealingly against the inner wall of the housing and have a circular profile, wherein one flat rotary piston is connected torque proof to the shaft and the other flat rotary piston is connected torque proof to the second hollow shaft, d) two toothed gears (6, 7) which are connected to the shaft or to the second hollow shaft via a freewheel clutch, preventing rotation of the toothed gears (6, 7) with respect to the shaft or the second hollow shaft counter to the working direction of rotation, and e) an output toothed gear which meshes with both toothed gears (6, 7), characterized in f) that two inlet openings opposite one another and two outlet openings opposite one another are arranged in the housing, g) that the shaft and the second hollow shaft are each supported in the housing via a freewheel clutch (12, 13), preventing rotation of the shaft or of the second hollow shaft counter to the working direction of rotation, h) that stop bolts are assigned to the two flat rotary pistons (4, 5) which bolts engage at the end of a working cycle of one flat rotary piston (4, 5), with the other flat rotary piston (5, 4) and move the latter across the two inlet openings.