Abstract: A radial piston machine in which a rotor with radial bores is rotatable on a trunnion integral with the machine housing. Pistons, preferably in the form of hollows balls, are respectively located in the bores of the rotor and moved during rotation of the latter along suction and compression strokes by engagement with a displacement ring eccentrically arranged with respect to the rotor axis. Channels in part formed in the trunnion serve for feeding pressure fluid in and out of the machine.