Abstract: A method of making a rotor of a fluid energy translating device wherein the rotor has an annular passage entirely within the rotor, a plurality of radially extending vane slots intersecting the passage and axial openings intersecting the annular passage. The method comprises forming an annular groove in the periphery of a solid body, closing the open side of the groove to provide the annular passage, forming radial vane slots in the body intersecting the annular passage, and forming axial openings in the body intersecting the annular passage.

Abstract: A variable displacement vane pump is provided in which a pair of rings having oval-shaped inner contours are rotatably mounted in side-by-side relationship. The rings are adapted for relative rotation to each other from a first position wherein the inner contours are in register with each other and a moved position wherein the inner contours are out-of-register, and means are provided for effecting the relative rotation, which include a gear system operatively connected to the rings. A rotor member is mounted for rotation within the rings and is formed with a plurality of circumferentially spaced recesses which extend the entire axial length of the rotor. Each of the recesses carries a pair of vanes in abutting relationship. The vanes are mounted for radial movement in the recesses and are adapted for slidable contact with the inner contours of the rings. The vanes form two side-by-side rows of vanes with each row in tracking relationship with the inner contours of the rings.