Abstract: A load supporting frame particularly suited for use as a road trailer is disclosed. The frame comprises a pair of longitudinally extending transversely spaced main beams, a plurality of central transverse members extending between said main beams and a plurality of corresponding transverse outboard members outwardly extending from said main beams, and a longitudinally extending side rail secured to the extending ends of said transverse outboard members on each side of the frame. Each of the main beams has a generally I-shaped configuration and comprises a vertically disposed web having an upper edge and a lower edge and removable flanges formed by a pair of angle members along said upper and lower edges. A connector for detachably securing said transverse members defines with the detachable flanges a key and mating keyway whereby the angle members, connectors and transverse members are self-aligning with each other when assembled and secured together.