Distributed Power - Advantages and Disadvantages

Advantages and Disadvantages

The obvious benefit is reducing drawbar pull on the front cars of a train versus what would be required if all the power exerted were at the head end. On an undulating track profile, a skillful engineer can manipulate the relative power outputs (as well as dynamic and air brake applications) to minimize run-in and run-out of the coupler slack throughout the train."

This reduced drawbar pull will reduce the lateral force between wheel and rail on curves, thus minimizing wear on various components. Lower friction results in fuel savings and/or the capability of running heavier trains.

Another benefit is quicker application of standard air brakes. It can take several seconds for brake-pipe pressure changes initiated by the engineer to propagate to the rear of the train with all braking control at the front on a conventional train. When distributed-power locomotives are directed to set the brakes simultaneously, the desired air pressure change will reach more cars sooner. This is particularly true when the extra power units are in the middle of the train.

The main disadvantage, especially with mid-train units, is the time and track configuration required to add and remove additional locomotive consists. There are costs associated with equipping locomotives with the extra control apparatus. Operationally, loss of the telemetry signals is coped with in various fail-safe manners.