A rotary machine (1) in the form of an expander is shown. The Expander Induces a housing (5) having a cavity (9), inlet and outlet ducts (11, 12) communicating with the cavity (9), a rotor (2) having a rotor axis (A), a number of vanes (15a, 15b, 15c) movably received in respective grooves (18) in the rotor (2) and articulately connected about an axis (C) to one end of a control arm (14a, 14b, 14c) and in the other end rotatable supported in a fixed shaft (24) extending centrally through the cavity (9) in the housing (5), and at least one working chamber (9a) which is part of the cavity (9), The housing (5) includes an internally cylindrical intermediate part (5c), which part interact with the rotor (2) and the vanes (15a, 15b, 15c). The rotor (2) forms a reel configuration having respective radially extending flange portions (2a′, 2b′) which are rotatable together with the vanes, and against which the respective end surfaces of the vanes act.