Detonator (railway)

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A railway detonator (also called a torpedo) is a device used to make a loud sound as a warning signal to train drivers. The detonator is the size of a large coin with two lead straps, one on either side. The detonator is placed on the top of the rail and the straps are used to secure it so that it does not fall off. As the first wheel of the train passes over the detonator, the detonator explodes, making a loud bang. In the United States, detonators were known as Torpedoes.

Typical uses of detonators include:

• providing a warning in dense fog, when signals are invisible;
• warning of a train stopped on the line ahead (the guard of the train is responsible for placing detonators at predetermined distances behind);
• warning of permanent way works ahead, which would not be covered by signals
• as in the Ais Gill rail crash, when the signaller believes that the train driver is ignoring the signals.

[edit] Detonator placer

Many mechanical signal boxes in the UK were fitted with detonator placers, which were controlled from levers in the signalbox, one for each running line. The detonator placers were fed from a cartridge holding a number of detonators. It is not known if the detonator is replaced in the cartridge if it is no longer needed.

[edit] Wrong side failure

To guard against a detonator failing to explode so that the warning is not given, detonators are usually placed in pairs.

[edit] External links

• Detonator use images