Danish State Railways Push-Pull Operation by Diesel and Electric Locomotives with Three-Phase Drive

Abstract

In 1973 the Danish State Railways (DSB) began regular push-pull train operations with diesel-electric locomotives on the east coast line between Copenhagen and Elsinore. The internal train control system was based on transmission via a two-wire transmission line extending through the train. The transmission of information through the train between a driving-trailer coach and one or two locomotives, was accomplished by a digital technique. The push-pull service was gradually extended and now comprises all lines on Zealand. In 1981 the new diesel-electric locomotives (class ME) with three-phase drive was put into push-pull service and 37 M E locomotives now perform the main part of the service (an average of 210000 km per locomotive per annum). The reasons for choosing three-phase locomotives, the experience gained with push-pull service, as well as the maintenance system and costs of maintaining three-phase drive locomotives in comparison with conventional diesel-electric locomotives are described. DSB is carrying out electrification (25 kV, 50 Hz) of all lines east of the Great Belt. The push-pull service with electric three-phase drive locomotives (class EA) commenced in March 1986. The advantages of choosing three-phase drive in connection with the introduction of electrification with a 25 kV, 50 Hz system are discussed. Class EA locomotives are equipped with a new generation of internal train control system based on a time multiplex system, which is able to transmit more information between locomotive and driving-trailer coach than the old system. Present experience regarding the push-pull service with class EA locomotives and the time multiplex control system is also described.