Abstract: There is set forth a retractable roof system of a specified arrangement including a first elongated track and a second elongated track, and a beam extending between the first elongated track and the second elongated track. The beam is described as supporting a cover. There is also set forth apparatus for moving the beam in relation to the first elongated track and the second elongated track.

Abstract: A bang-bang servo system controls motors which provide drive for trucks on each end of a fabric support beam structure. A plurality of such truck/beam/fabric units comprise a retractable roof Separation of inner and outer truck guiding tracks/support platforms may be wide and somewhat variable. The radius of curvature of the inner and outer tracks may vary widely over the beam excursion path between open and closed roof conditions. Individual beam motion sequencing and stop position are commanded through a central control unit. These features allow great flexibility and adaptability in application of this invention.