A left hopper door and a right hopper door are associated with a hopper of a railroad hopper car that includes an operating beam which is longitudinally moveable within a center sill. A door operating mechanism for such doors includes an operating arm that includes a longitudinal slot, and a fulcrum that is attached to the operating beam. The fulcrum includes a pin that is adapted to slide within the slot of the operating arm. A V-lever is pivotally mounted on the center sill. The V-lever includes a left arm that is attached to the left hopper door and a right arm that is attached to the right hopper door. The right arm of the V-lever also include an intermediate pivot mount to which the operating arm is pivotally attached. An arming assembly is configurable in an armed configuration in which longitudinal movement of the operating beam will cause the left hopper door and the right hopper door to move between opened and closed positions, and in a disarmed configuration in which longitudinal movement of the operating beam will not cause the left hopper door and the right hopper door to move.