DERAILMENT DETECTOR SYSTEMS FOR CFF/SBB ROLLING STOCK

Following a spate of accidents which were caused by derailments on the CFF/SBB network in 1994 and which had serious consequences for the local population, nature and the environment, the Swiss firm OERLIKON-KNORR Eisenbahntechnick AG set about designing a derailment detetor based on the emergency brake valve that has long proved such an invaluable asset on many different railways. The aim of the device is to minimise the repercussions of derailments. A sprung mass oscillator is used to detect vertical impact on the buffer beam, on which the derailment detectors are fitted between the buffers and the draw hook at both wagon ends. If a limiting value of 7.5 plus or minus 0.5 is exceeded for longer than a given amount of time, the derailment detector's emergency brake valve will be triggered. This will open the main air pipe and thus bring the train to a halt. An indicator on the device will show which of the derailment detectors has been triggered. Once the driver has checked his train and, provided that none of its axles have derailed, the main air pipe can be refilled and the train pursue its journey. Before the train moves, it is however necessary to manually re-set the warning indicator on the device tripped. For passenger trains operating in the higher speed ranges, CFF/SBB is planning to use electronic systems at present under development. (A)