The purpose of a derailment detector is to stop the train by activahng automatic application of the
brakes or to send a signal to the train driver when its triggering threshhold has been reached following
a wagon derailment. ~
The Jerailment detector cannot prevent derailments. Its presence on a vehicule should never be used
as an excuse for cutting back or compromising on preventive vehicule marntenance.
The pneumatic derailment detector monitors vertical accelerations at wagon-body level and, when its
triggering threshold is reached, opens a large aperture to exhaust the main brake pipe to atmosphere.
The electronic derailment detector does not necessarily cause the main brake pipe of the vehicle
concerned to open. If the train is equipped with a train control-command and diagnosis system, the
detector can transmit an advance warning and derailment signal to the driver.
(The relevant conditions have not yet been defined in this leaflet).
Accelerations occurring in normal service should not trigger the derailment detector.
It is crucial that, in the event of a derailment, the vertical acceleration occurring at the point where the
derailment detector is to be fitted exceeds the triggering threshold of the detector. This applies
irrespective of the load conditions and speed of the wagon.
The derailment detector should be designed to operate on lines that meet the quality standards laid
down in UIC Leaflet 518, Appendix D (QN1-QN3).