Abstract: A helical down-hole machine comprises a plurality of sections, each such section having a helical rotor and a helical stator arranged with a preselected eccentricity to form cavities of variable volume for the passage of fluid therethrough and positioned axially in series. The identical elements of these sections, rotors or stators, are rigidly interconnected. The rigid connection of at least one of these identical elements of said sections is detachable by frictionally jointing a projection provided at the end of one such element and a recess provided at the end of the adjacent element to be secured against relative angular and axial displacements in the process of rotation.