be operatively connected to the platform assembly by at least two tethers each of which is attached to the platform frame through an outer opening in the opposite outer side of each first end frame and second end frame at a point at or below the first frame apex and second frame apex respectively and the at least two tethers fastened securely within the platform frame for the purpose of raising the platform assembly and any cargo placed on the lifting platform into the portal wherein when the platform assembly is raised to the portal the first frame apex of the first end frame and the second frame apex of the second end frame are drawn and guided into the portal lower entrance by the at least two tethers which extend from the outer sides of the first and second end frames of the platform frame and which thereby inhibit the first and second frame apexes from impacting the lower portal entrance as they are drawn in by the at least two tethers and wherein as the platform assembly advances upward into the portal the first side converging portion and the second side converging portion of each first end frame and second end frame can engage a portion of the lower portal entrance to progressively urge the platform frame into a proper alignment for entering the portal as the platform frame is drawn upwardly into the portal thereby preventing contact between a portal edge and the lifting platform or cargo disposed thereon and within the cargo space the biasing mechanism may be connected to the platform frame and to the closure platform thereby connecting the closure platform.