Grain storage tank for an agricultural harvester

An agricultural harvesting machine, comprising:

• a wheeled main frame;
• means for collecting and processing crop material from a field;
• a storage tank affixed to said main frame for storing therein said processed crop material;
• extension means associated with said storage tank and comprising a first pair of mutually opposed panels and a second pair of mutually opposed panels, said first and said second pair of panels being movable between a lower, inoperative position and a higher, operative position in which said panels substantially increase the effective volume of said storage tank, the movement of the second pair being controllable by the movement of the first pair and said panels of said first and second pairs are provided with locking means for keeping all panels in their operative position, said locking means being disposed to become engaged and to secure the panels in their operative position when said first pair of panels moves the second pair of panels to their operative position, the panels of said first and second pair are hingeably connected by their lower edges to a quadrangular opening of said grain tank;
• and the panels of said first pair have members disposed for engaging the inner surface of the panels of the second during the movement between said operative and said inoperative positions, said panels of said second pair are provided with means for keeping said members in engagement with said inner surface during the movement between said operative and said inoperative positions, wherein:
• said members are constituted by rollers which are mounted for rotation adjacent corners of said panels of said first pair;
• and
• said keeping means are constituted by profiles which are affixed to said inner surface along the path of said rollers.