Abstract: In a rotary device with a rotating cylinder barrel of the kind having a plurality of pistons partially engaged in cylinders formed in the cylinder barrel and the axes of which are spaced around the axis of the cylinder barrel, the pistons are displaced in their cylinders by an oblique plate against which there rest shoes carrying spherical heads which are engaged in spherical seatings terminating the pistons. Each piston is rigidly connected to a supporting element which transmits to a skirt, rigidly connected to the cylinder barrel, the radial component of the reaction exerted by the plate on the piston.