A bottom discharge hopper includes an elongated rectangular discharge opening closable by two discharge doors hinged along their outer edges to the hopper so that the doors are biased to an open position. Each door includes control means comprising a biasing member pivotally mounted to the hopper which biases a runner at each end of the door along a runner track on the door towards a position corresponding to the closed position of the door, the runners being located substantially directly below the pivot of the biasing member in this closed position.
