PURPOSE: To operate a vane motor with a little quantity of gas by a method wherein an output shaft of the vane motor and an input shaft of a vane pump are connected to synchronization and rotation, and a discharge port of the vane pump and an air feed port of the vane motor are coupled through a heater.

CONSTITUTION: An output shaft of a vane motor 1 and an input shaft of a vane pump 2 are connected to synchronous rotation, an exhaust pipe 5 is connected to an exhaust port 4 of the vane pump 2 and a heater 6 is mounted thereto, and further the heater 6 and an air feed port 8 of the vane motor 1 are coupled through an air pipe 7. Thus, a rotodynamic power of the vane motor 1 is partly transferred to the vane pump 2, a gas discharged by the vane pump 2 is heated and sent to the vane motor 1 to serve as a power source for the motor. The rotodynamic power of the vane motor 1 is thus obtainable through utilizing comparatively a little quantity of low-pressure gas.