METHOD AND APPARATUS FOR DETECTING RAILROAD CAR DERAILMENT

A method for detecting the velocity (v) of a railroad car (1) and a vertical acceleration (a) that occurs at the portion of a car body (2) above a spring device (6) of a bogie (3) while the car (1) is running on a track, and also extracting a component of the vertical acceleration (a) in a predetermined frequency range. The method decides that the car (1) has derailed when the absolute value of the vertical acceleration (a) in this frequency range exceeds a predetermined limit vertical acceleration (al) corresponding to a predetermined velocity (v), or when a vertical displacement (d) calculated by double-integrating the vertical acceleration (a) for each predetermined evaluation time (T) is negative and its absolute value is greater than a reference value (dc).