A railroad car is equipped with air release means in air flow communication with the car train pipe that is normally provided for connection with the air brake train line of a railroad train. Activators for the air release means are associated with respective sets of wheels, at opposite sides of respective wheel trucks of the car and at a height which will clear the corresponding rails of the railroad track during their travel but in positions to engage such rails upon derailment of any corresponding car wheel for operating the air release means, whereby the brakes of the train will be applied automatically upon any derailment. A novel air release valve with activator is preferably employed at respective opposite sides of respective wheel trucks as the air release means.