Under power head refers to a particular type of vehicle engine of the railroad. If a multiple unit via powered end cars that can not take passengers, one refers to this as the driving head. Are also called power heads in certain cases locomotives, which are exclusively used in push-pull trains.
Power heads are then typically used when the drive is to be concentrated in separate vehicles at the ends of the train, as opposed to those railcars, where the drive is spread over the whole train. Technically, power heads locomotives with only one ( full ) driver's cab and possibly one side only reduces existing train and draw gear. Zugseitig they often possess a customized transition to subsequent car; This ensures a consistent look and better aerodynamics. Has a trainset only one engine head, then on the other hand is usually a control cars to find; an example is the Deutsche Bahn ICE 2 or ET 4010 of the ÖBB. Examples of an engine head on a push-pull train, the double -decker commuter trains (DPZ ) of the Zurich S-Bahn or the Italian E.464. The difference lies in the fact that the intermediate cars can (ie to trains without control car ) is used as a normal car trailer pulled in trains.
Typical representatives of multiple units with power head, the German ICE 1 and 601 series as well as the Italian ETR 500 The Euro Star and Auto Train in the Euro tunnel are covered with power heads.
Critics claim that the use of power heads combine the disadvantages of railcars and lokbespanntem train. First, there is such a multiple unit used as a railcar only in fixed configurations, which makes it flexible to adapt to a fluctuating demand impossible. (However, these days go sometimes locomotive-hauled trains from maintenance reasons, always in the same association, as in the case of Deutsche Bahn as part of the program RIGA ). On the other hand, the power cars like the locomotives to a high axle load, which necessitates especially at high speeds corresponding equipment of the line. Moreover, is in the power heads no room for seats.
However, power heads can also be useful, such as when in double-deck cars no more space is available for the drive units. The drive noises do not penetrate into the passenger compartment. It is represented in more recent series of TGV, for example, the TGV Duplex, the drive is now completely in the engine head, while in the first series in each case also the first car behind the engine head had a powered bogie.