Western Railroad Discussion > Multiple engines used

I'm just a lay-person when it comes to trains, although we enjoy a room on the Coast Starlight. I have a question as to how do the multple freight engines hook up to the front engine as far as the SPEED control, especially the engines in the middle and on the end.?
Thanks much -
GG

These are connected via radio signals and computers. Is is called a Distributed Power Unit system.

Posted from Windows Phone OS 7

The engines that are coupled to each other "communicate" electrically. You'll notice a big jumper cable that links each unit with a fat jack on each end -- that's a "multiple-unit" ("MU") cable that transmits power/dynamic-brake/headlight settings between the lead engine and those that follow it.

Other locomotives at the middle or rear of the train are controlled as described by fbe or, in some territories, by an additional ("helper") crew, or a mix of both.



Edited 2 time(s). Last edit at 08/29/14 14:41 by toledopatch.

Engines directly behind the lead are controlled via cables, called Multiple Unit cables (MU) that plug into the ends of the units. They respond directly to the throttle position in the lead engine.

Engines in the middle or on the back end use a process called Distributed Power (DPU). The lead engineer uses separate controls from the regular throttle for this.

The M. U. cable is for electrical connections: throttle, rear headlight, reverser, dynamic brake, etc. Independent air brake application and release as well as air equalizing is taken care of by the small hoses each side of the coupler - duplicate sets so you can turn power and always have a set that faces the ones on the other unit.
For power that is further back in the train as the guys said, it is controlled via radio signals to electrical components that operate the unit as well as the air system. Distributed Power Unit.
Manned helpers are. . . . .manned.
Steam engines running today are sometimes equipped with an electrical control box so that modern diesel locomotives can be operated from the cab of the steam engine. Of course, the engineer operating the steam engine has to have the presence of mind to shut the diesel down if he needs to stop. :)

>I have a question as to how do the multple freight engines hook up to the front engine as far as the SPEED control, especially the engines in the middle and on the end.?

Speed is controlled by the engineer in the lead unit using the throttle and brakes, just like on a freight train. All US locomotives, er rather I should say, all US diesel locomotives will MU with each other, brakes and control (yes, yes, there is still the odd air-throttle Baldwin here and there which are exceptions to this). If you're wondering about the P-42's "cruise control", whenever the lead locomotive isn't equipped with cruise control, it won't function in a trailing one, even of the trailing one is so equipped. Therefore an F-59 leading P-42s means there is no cruise control functionality available in the entire consist until the F-59 is removed.

THANKS SO MUCH TO ALL YOU KNOWLEDGEABLE GUYS, WHO MOST LIKELY ARE ENGINERS. THAT'S A LOT OF HELP TRYING TO EXPLAN TO MY GRANDSON.
SAFE TRAINING AND GOD BLESS -

GG.

I appreciate the info too, as I know little, but want to know more. Thank you!

I'm not an engineer, but I did stay at a Holiday Inn Express last night.

Touche' Toledopatch. good one!