CSX Train Today

[mu26aeh]

https://gorail.org/infrastructure/nuts-bolts-why-is-there-an-engine-in-the-middle-of-that-train

[CBQ Fan]

Interesting!

[glakedylan]

yep...basic physics.
I am glad this is being incorporated for the benefits it offers.


sincerely
Gary

[CBQ Fan]

yep...basic physics.
I am glad this is being incorporated for the benefits it offers.


sincerely
Gary

Kind of wild it took this long if the benefits can be realized.

[Maletrain]

Well, this isn't actually a new thing.  The computers connected by radios certainly make it easier to coordinate.  But, if you take a look at the Western Maryland Railway back in the days of steam locomotives, you will see that they put locos at the head end, middle and rear end of some hefty coal drags to get them over some saw-toothed looking elevation changes.  In those days, 5, 7 and even 9 big consolidations, each with their own engineers, coordinated to use the same physical principals without all the modern communication conveniences.

[Hyperion]

Kind of wild it took this long if the benefits can be realized.

Distributed Power technology has been around for over 50 years but it has never been all that... robust, I guess you can say.

Connecting units was slow, a little iffy, and you could never be all that sure that connections would be maintained.   The longer the train, the more substantial the benefits, the more it was worth the trouble.   So it was generally relegated to just the benefits that could be realized from longer trains.

But more recent developments with Locotrol technologies (now called "LXA") in the past couple of years have made it much, much more reliable.   Connecting is easier, quicker, and it it runs a couple different redundant backup systems so reliability of the connection is practically guaranteed.

[Hawghead]

Mid-train DPUs are used for two basic reasons. 

1. You can only put so many helpers on the rear.  To much tractive effort on the rear can shove cars off the rail especially on heavy ascending grades.  So in most cases if you need more than two helpers, they need to go in the middle.  There is a whole section in our special instructions on DPU placement.

2. You can only have a maximum of about 7,500' between the head end controller and the and the DPUs, more than that and you start having communication problems.  This is why you sometimes see "mid train" DPUs with only a handful of cars behind them.

When you see a 1x2 (1 leader, 2 DPUs) chances are one of the DPUs is isolated.  You don't want more DPU tractive effort than head end tractive effort if you can help it, unless of course you like 10,000 ton enemas 

Scott
 

[CBQ Fan]

What I find interesting is applying the practice to small freight trains with only two engines total.