Electric train heating with diesel locomotives

With the replacement of steam locomotives by diesel and electric tractors, it was natural to look to electrical energy as a heat source for passenger trains. When substantial parts of the main lines were electrified at 25 kV, the opportunity to change from steam heating to electric heating was taken. To maintain compatibility between electric and diesel locomotives some of the latter were required to be capable of providing a power source for electric train heating. The train-heating-supply systems which became standard are discussed, together with the various means of providing these supplies from a diesel locomotive. As an example of the method generally adopted for British railways, the train-heating installation on one particular type of locomotive is described in some detail, together with some of the practical problems encountered and the solutions adopted to overcome these. As a more recent example, the heating system fitted to British Rail's new high-speed train is discussed. In conclusion, the paper attempts to indicate likely directions for future developments.