This invention relates generally to the field of collapsible reusable shipping containers of the type disclosed in my prior U.S. Pat. No. 3,443,737 granted Apr. 13, 1969; and more particularly to an improved sliding door construction which may be incorporated into a vertical wall of such container to impart greater structural rigidity thereto under fluid loads which tend to exert a hydraulic outward pressure against the inner surfaces of the container.
In the container disclosed in the above patent, the door is supported in a through opening in a side wall by a pair of extrusions of generally H-shaped cross section, each of which define opposed recesses engaging a vertically disposed edge of the door opening, and a corresponding vertical edge on the door. While this arrangement does guide the door smoothly during opening and closing movement, the pressure on the edges of the abutting wall is entirely frictional in nature, and when the container is loaded, for example, with a relatively heavy particulate load, resistance to outward deformation of the wall and the door depends almost entirely upon the engagement of the wall at the lower edges thereof with the rigid pallet, and the engagement of the upper edges thereof beneath the rim of the detachable lid. Depending upon the height and thickness of the walls of the container, and the density of the fluid load, this construction has at times proven inadequate. It is, of course, possible to rigidly interconnect the extrusions to the edges of the wall, but since the door edges must remain free to move in order to selectively open the door, this expedient has but limited utility.