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busyEMT
02-04-2004, 02:47 AM
I must ask, as I haven't found the answer elsewhere. What does DPU stand for? Something to do with coal trains maybe?

Ken Carr
02-04-2004, 03:40 AM
This is the what I got from a number of sources: DPU
Stands for Distributed Power Unit, a locomotive set capable of remote-control operation in conjunction with locomotive units at the train's head end. DPUs are placed in the middle or at the rear of heavy trains to help climb steep grades, particularly in the West.

J
02-08-2004, 01:16 AM
Distributed Power Unit is correct. The term differentiates between a radio helper unit (controlled by a lead locomoive) and RCL or "Remote Control Locomotive" controlled by an operator wearing a portable device - generally in switching service. See the following from ESSPEBOY

http://www.railpictures.net/viewphoto.php?id=49050

DPU, sometimes called "slave unit operation" has been around in the US for decades. Early installations often used old "B" units such as an F7B equipped with the radio gear mu'ed to a set of power with standard MU cables / hoses.

A number of SP SD40T-2's were delivered with the remote control equipment installed in an extended nose (almost three feet longer than standard. See:

http://espee.railfan.net/nonindex/sd40t-2_photos/8309_sp-sd40t-2_bob_dengler.jpg

In time, this equipment was found to lose communication in mountainous territory and tunnels and was eventually deactivated. For a time, SP would use it to reduce fuel consumption by locating a "master" locomotive in the lead with a "remote unit" as part of the trailing consist. The units would be set up with the MU cable not installed ahead of the remote unit allowing the trailing unit(s) to be reduced to idle when total horsepower was not needed.