Abstract: The proposed positive-displacement sphere-shaped rotor machine is intended for use as an engine, a pump or a compressor and comprises a casing consisting of two parts 1 and 2, in the spherical cavity of the casing three rotors 4, 5 and 6 being disposed, the central disk rotor 4 being connected from each side by means of a diametrical hinge with sector rotors 5 and 6. The rotors 4, 5 and 6 define four chambers 9, 10, 11 and 12. The chamber-forming radial surfaces of the rotors 4, 5 and 6 have a radius form. Inlet-outlet ducts 15, 16, 17 and 18 are disposed in the zone of overlapping by the sector rotors at the moment of changeover of the cycles in the chambers, the ducts having a nozzle portion and a tangential tilt. The diametrical hinge has two secured semi-axles 21 and 22, whose journals enter into spherical meniscus 25; the second diametrical hinge 5 has a non-split cylindrical axle.