Abstract: The object of the invention of developing a rotary piston machine, which is to be embodied as a prime mover or as a work machine consisting of two piston mounts rotatably mounted on an axle and being capable of performing a relative movement, wherein they are connected to a straight-line thrust crank mechanism, which serves to generate a relative movement, which causes a conversion of a uniform movement into an non-uniform straight-line movement of the piston mount, was solved in that a center axle of each piston liner stands at right angles on a diameter of a piston mount and in that each piston mount comprising elliptical gearwheels, which are turned relative to one another by 90° and the gearwheels, as mating gears being turned relative thereto by 90°, are fixedly connected to an output, wherein they are rotatably mounted on the axle in the point of intersection of the smallest and of the greatest diameter, on the one hand, and are connected to the output shaft on the other hand, and the working pistons in