Abstract: A door for opening and closing the discharge opening of a hopper is carried y a support suspended from an oblique lateral wall of the hopper by two links pivoted to the support at one end and pivoted to the support at the other end of the links. An actuating and locking mechanism for the door is connected to the support. The support has a generally triangular shape and the two pivotal connections between the links and the support are in the vicinity of two of the corners of the triangle. The door is located in the vicinity of the third corner of the triangle.