Abstract: A locking mechanism for releasably and positively locking a hinged door of a railroad hopper car in a releasably closed position or condition is disclosed. The locking mechanism for each hinged door on the hopper car includes a lock carried on the hopper car adjacent a discharge opening, a pivotal locking element carried by the discharge door and movable therewith into releasable but positive locking engagement with the lock when the door is swung into a closed position or condition, and a door release mechanism for controllably releasing the locking element from engagement with the lock thereby permitting the discharge door to swing to an open condition or position. When a series of doors are arranged in end-to end relation along a bottom of the car, the door release mechanisms for the discharge doors are operated substantially simultaneously thereby opening substantially an entire bottom of the hopper car.