A system for unloading a grain storage tank of a combine harvester includes a conduit that is sized to extend into an interior region of the grain storage tank. The conduit defines an interior space that is sized to receive an auger that is configured to remove the grain from the grain storage tank. The conduit further defines an opening for receiving grain from the interior region of the grain storage tank. A panel is positioned adjacent the opening in the conduit. The panel is movable between a first position in which the panel at least partially conceals the opening to meter the entrance of grain through the opening, and a second position in which the panel does not conceal the opening to freely permit the entrance of grain through the opening and into the conduit.
