Helper engine goes in reverse.

[Bigfrank2]

I am new to the site and don't know a lot about railroading, so I'll have more questions than answers. Why does the last engine of a multiple engine unit go backwards? Bigfrank2

[Paul of Covington]

    I was looking for something else and noticed that this question had not been answered.    I'm not a railroader, but as I understand your question, you're talking about the set of engines pulling a train.   The term "helper" usually refers to a separate engine or set of engines pushing on the rear of the train or sometimes cut in somewhere in the train that is controlled by an engineer.   If such an engine is remote-controlled by the engineer in the lead unit, it is usually referred to as "distributed power."

   Back to your question:  I think you are asking about the fact that in most cases the last engine has its cab facing backward.   Diesel locomotives run equally well in either direction so for convenience they are set up so that the group, if necessary, can be used to pull another train in the opposite direction without having to turn the locomotives.

[BaltACD]

Manned helpers do normally shove with the long end coupled to the rear of the train they are shoving.  When they get to the end of the helper district they can return to their home low hood forward - easier for the crew to operate.  They don't need to 'see' when they are shoving, that is the responsibility of the crew on the head end of the train.  The do need to 'see' when they are operating back to their origin.

[Overmod]

Bigfrank2

Why does the last engine of a multiple engine unit go backwards?

I think he's talking about a general consist, not just a helper consist.

The idea (as I understand it) is to have 'cabs out' at the ends, so that the consist can be easily run in either direction without turning or wying -- as if it were a large double-cab locomotive.

The alternative (as seen on many unit trains in my area) is to run consists with all the low ends/cabs forward, also known as 'elephant style' -- this allows locomotives to be removed from the consist or simply switched to a trailing position, for example if the lead locomotive control fails, and have a cab immediately available to control the consist properly. 

[BaltACD]

From a dispatching perspective 'back to back' power is the most desired configuration, unless you are dealing with a 'overpowered' premier train where a lead locomotive failure can more easily be overcome by having at least the lead two engines running elephant style.  In either case you have to play with the cards you have been dealt and make the most effective moves possible.

[jeffhergert]

Most of the time, for over the road through trains, it's because that's the way they were facing when the consist was originally made up.

There may be times when there is a requirement, due to lack of turning facilities at the far terminal/end of the run, when an engine needs to be pointed the other way.  One of the runs in my area has that requirement, but it doesn't have to be the last engine in the consist.  It just has to have at least one pointed in the opposite direction.  Trains that don't meet that requirement have to turn at least one trailing engine at the junction with that subdivision.

Jeff