Abstract: One aspect of the present invention includes rail and carriage assembly combination that provides improved efficient operation. A rail is provided that has an inside surface that includes a straight back surface and an angled front surface. A carriage assembly is provided that includes upper rollers that are canted. Preferably the upper rollers are canted to match the angle of the angled front surface of the rail when a load is applied to the carriage assembly. As to fore/aft loads, the present invention provides a rail and carriage assembly design that causes the upper rollers of the carriage assembly to contact the front inside surface of the rail.