Extensible and extractable cargo container

An extensible and retractable cargo container comprising an upper portion, a middle portion and a lower portion engaged with each other together by sleeve joints, wherein:

• said upper portion has a top end face and a bottom end in a form of opening, in said top end face, a number of input holes beings made as material input holes and at the four corners of the bottom end opening, a flange being formed inward projected horizontally;
• said middle portion is sleeve jointed into said upper portion and has openings in both top and bottom ends, at the inner sides of the four corners thereof each forms a square shaped space surrounded by walls, at the top end of said square shaped space and on the outside wall between two adjoining rectangular corners, a horizontal flange being disposed outward to engage on top of the flange of the upper portion, at the bottom end of said square shaped space and on the outside wall between two adjoining rectangular corners, a horizontal flange being also disposed inward;
• and
• said lower portion has opening at top end and recessed four corners to fit the shape of the four corners of the four corners of the middle portion in order to be sleeve jointed into the internal of the middle portion, at the outer walls and on the top of the four corners, a projected flange being formed outward to engaged on the bottom end flange of the middle portion, therein, the bottom end having a bottom plate formed by two pivot connected subplates, at the far ends of these two subplates, each disposed with a pivoted rollers which can move along the slantwise rising grooves on the front and rear side walls of the lower portion.