An apparatus for mechanically locking and unlocking a passenger access door panel on a railway vehicle which includes a locking lever arm, one end of which is pivotally secured to a movable door panel and having a roller secured at the opposite end, and having a biasing means to pivotally bias the roller against a locking support structure secured to a structure adjacent to the movable door panel when such door panel is moving into the closed position. The locking support structure has a first rail surface at an inclined angle to the door panel and a second rail surface which is substantially perpendicular to the door panel and is positioned so that the roller on the locking lever arm will roll along the first inclined rail surface when the door panel is moving into the closed position, and such that when the door panel reaches a fully closed position, the roller will move beyond such first inclined rail surface and be biased to move against the perpendicular rail surface to thereby lock the door panel in the fully closed position. The apparatus further includes an unlatching lever assembly that will pivot the locking lever arm and roller away from the perpendicular rail surface in response to automatic controls activated by a door opening mechanism, or in response to a manual controls.