Box with collapsible walls designed to stack a corresponding box with lower dimensions

Plastic moulded box with collapsible lateral walls, of the type provided in internal position on top of each transversal wall (2) with a collapsible shelf (5) designed to be spontaneously brought, during the inverse rotations of the corresponding transversal wall (2) with respect to the bottom (4), from an operative position that protrudes on the inside of the box (1) to a non-operative position in which no impediment is generated between the internal side of the transversal wall (2) and the upper side of the bottom (4), characterized by the fact that the shelf (5) is hinged to the top edge (2a) of the transversal wall (2) by means of suitable pivoting means (6, 6a) that allow the shelf (5) to be placed in a perfectly horizontal position by gravity when the transversal wall (2) is maintained in vertical operative position;

• it being provided that the internal side of the two longitudinal walls (3) is provided with symmetrically opposite means (10) designed to interfere, near the end of the rotation of the transversal wall (2) towards the non-operative horizontal position, with the ends (5a) of the shelf (5), thus imposing a forward rotation of approximately 90° on the shelf (5), reaching a perfectly coplanar position with the transversal wall (2).