The machine has a rotor provided with an arm (16) that comprises two portions (24, 25). The portions of the arm are connected together by a coupling device (27), and an abutment (33) comprises two support portions (35, 36) that are attached to the two portions of the arm, respectively. The support portions respectively comprise two support faces (43, 44) that are tilted with respect to an axis (26). The faces are provided in contact with each other such that a relative immobilization of the two portions of the arm along the axis is enabled in an operational position.
