Abstract: An apparatus for opening and closing the discharge doors of a railroad hopper car is described comprising a mounting frame secured to the hopper car forwardly of the discharge door and having a pivot frame pivotally secured thereto which is interconnected to the discharge door by an elongated linkage. A pivot arm is also pivotally secured to the mounting frame and has an air cylinder pivotally secured thereto which is interconnected to the pivot frame. Extension of the hydraulic cylinder causes the pivot frame to pivot with respect to the mounting frame thereby causing the adjustable linkage to open the door. Retraction of the cylinder rod into the cylinder causes the pivot frame to pivot with respect to the mounting frame to cause the adjustable linkage to close the discharge door. When the door is in its closed position, the cylinder rod of the air cylinder is in its retracted position.