Method and apparatus for detecting and signalling derailment conditions in a railway vehicle

An apparatus for detecting and signalling a derailment condition of a railway vehicle wheel, the apparatus comprising:

• vibration sensor means (3), associated with at least a wheel (1) of a railway vehicle, for generating a vibration impulsive signal (V) indicative of the vibration of the wheel;
• and
• processing means for:
• receiving the vibration signal (V);
• generating, based on the vibration signal (V), an impulsive surveillance signal (S);
• comparing the instant value of the surveillance signal (S) with a reference threshold value (T);
• and
• automatically generating an alarm signal (A) when the instant value of the surveillance signal (S) reaches or exceeds said reference threshold value (T);
• characterised in that said processing means comprise means for increasing the instant value of the surveillance signal (S) in a manner correlated to the amplitude of each vibration impulse (I) and decreasing said instant value in accordance with a predetermined law after each vibration impulse.