Abstract: A railway hopper car has longitudinally spaced hoppers on both sides of a center sill. The hoppers have door assemblies which may be opened and closed by a door operating mechanism. The door operating mechanism includes a pneumatic cylinder which rotates a lever to move an operating rod longitudinally within the center sill. Door operating levers are rotatably supported on the railway car and pivotally connected to the operating rod to be rotated when it moves. The door operating levers are pivotally connected with struts connected with the door on the hoppers. The mechanism is configured so that all forces are substantially coplanar in a vertical plane passing through the centerline of the center sill to reduce lateral twisting forces in the mechanism. Adjustment of the length of the strut is provided for positioning of the door operating levers during assembly.