Abstract: The instant invention relates to a valveless bi-chamber rotary steam engine with turbine effect comprising two sets of rotor blades of which each set of rotor blades rotates around its own eccentric point on a stationary mutual crank shaft within a semicircular engine housing. A drum-type rotor is concentrically mounted within the engine housing thus forming two diametrically opposed radial chambers. The said two sets of rotor blades move through equidistant slots arranged within the drum-type rotor thus varying the space volume of the respective radial chamber where through the introduction of a pressurized medium through diametrically arranged inlet ports the generation of a torque moment is achieved.