Consisting in the prototype?


F

fast_ian

Member
Hi,

While noodling around I came across the pic attached - That's some *serious* pulling power!.....

Not being a "railfan" (or having any real knowledge of these big guys) I'm a little surprised they put all the power at the front (?)

Or, is there even more power in the middle / at the back of the train? :eek:

I'd have guessed that with "modern" control technology power in the middle and/or at the back would be beneficial?

Cheers,
Ian
 
Lately I've been seeing short trains (25 car trains) with 5 and 6 locomotives on them, especially of other roads (patched Conrail SD60, NS Dash 9s and SD60s, CSX SD60s) rolling through. These locos are pool power, and in some cases, putting them on a train is a way to get them from A to B, where they are needed.

For grain trains, I see 2 or three six axles on the front with a DPU on the rear. Same for double stacks. For coal drags, one or two up front with one or two DPUs in the rear.
 
I know around my me (CN, former WC), they sometimes shuttle Loco's back to somewhere else in a small consist. So you'll see a lot of power on a small train but they won't all be runing either.
 
I've seen MRL put together 5 loco sets of SD45's to help BNSF trains over the passes here in Montana.......that would be added to the 3 to 5 BNSF locos already on the train. So the train in you picture might have added power elsewhere in the consist. In your picture, I'd also guess there's a little "extra" power put on that train due to the snow. Busting drifts takes a lot of extra power.
 
Yep see the same here on the CN ex WC. short freight with 5 locos. then you see a coal Drag with just 2 locos up front.

regarding where they put the locos..
for snow you want them all up front. Last few years they have been putting a rear loco on and sometimes even in the middle. It not only helps with slowing the train but getting it up to speed. Less slack in the train also.
I see the rear units used mostly on longer heavy trains out west.
 
That's a nice picture. Did it say what railway that is?

With regard to mid and end of train power --- Often times above the 49th here in the prairie I see container, grain, and potash trains with 2 large units up front one in the middle and one at the end. These trains are usually a couple miles long running the so-called "flat" prairie, but when you drive along side these tracks there is no flatness about them. They dip and climb and weave through some pretty un-flat terrain. The extra motive power in the middle and ends helps a lot with the train slack and ups and downs of the rolling prairie. Grades are not huge but are long and moving that much weight up hill requires extra power.
 
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Another reason we use distributed power is better braking.
With locos placed throughout the train there's more air available farther down and faster when needed.
 
Hey,

Firstly, thanks for the comments.

Outback said:
That's a nice picture. Did it say what railway that is?
Click to expand...

Apparently, the "Iowa, Chicago & Eastern" and it was taken;

Mason City Sub
Lawler, Iowa, USA
February 04, 2011

[It's actually a "screeners favorite" on railpictures.net right now - Beware however, the site is one *enormous* time sink! ;)]

Anyway, it seems that other than moving them to different locations - ie, unpowered, the prototype does indeed put its power in the middle & at the back. This makes sense to me and leads to the question; is it possible in our models?

OK, I know we can consist many locos in a train, but we have to speed match 'em first. I'm wondering if it would be possible to incorporate strain gauges into some of the couplers - Say, in the cars directly ahead and behind the middle unit and then have a little "electronic magic" fine tune the power in between..... Communicating the data between cars/locos may be "challenging", but strain gauges and their support circuitry are small & cheap. Thoughts?

Cheers,
Ian
 
For narrow gauge ops (i.e. D&RGW) it was common practice when consisting to put the motive power in the middle of the train as well as the head.

As was mentioned it helped with braking, which on steep grades and mountain railroads is a must.

-G-
 
I routinely run 4 -5 loco's on my 120-200 car coal drags at the club. 2 in the front, 1 or 2 in the middle, and 1 or 2 at the end. I have found that if you are not careful where u put the "middle" one you can have a mess. If I am going to run on the "flat" level I put it about 80-90 cars back. On our two "elevated" routes it goes about 70 cars back. I watch the couplers to see what they are doing and adjust from there I usually have good luck. I have a video on my phone that I can't seem to get on here.
 
irocinblue89 said:
I routinely run 4 -5 loco's on my 120-200 car coal drags at the club. 2 in the front, 1 or 2 in the middle, and 1 or 2 at the end. I have found that if you are not careful where u put the "middle" one you can have a mess. If I am going to run on the "flat" level I put it about 80-90 cars back. On our two "elevated" routes it goes about 70 cars back. I watch the couplers to see what they are doing and adjust from there I usually have good luck. I have a video on my phone that I can't seem to get on here.
Click to expand...

Very cool! The part I emphasized is what I'm trying to talk about - Rather than "watching the couplers", lets do it with some electronic magic..... I believe the prototype does basically the same - Measure the load at the couplers and adjust the power accordingly.

I also guess that you *need* those 4-5 locos to move a 200 car drag - This is not "for show", but really needed? [ie, dummy's won't cut it].

Cheers,
Ian
 
For the prototype, such as long coal drags on UP, they put engines in the middle because the coal cars are heavy and if they go up the steep mountain passes, it puts strain on the couplers. Sometimes they run trains that are too heavy for the couplers to stay coupled so they put engines in the middle so that the front engines are exerting force on the first half of the train, and the middle engine(s) exert force on the rear half of the train as well as exerting a bit of force on the front half in the train in the opposite direction to put some slack on the couplers which helps coupler integrity.

Having a source of air in the middle of the train also helps for the air to travel faster throughout the train to improve braking performance.

Some railroads run locals on branchlines or single track main lines without switches for engines to run around or if it is too inconvenient to run around the train, then tacking an engine on the rear end dead in tow, then turning it on when going back and shutting down the front loco, they don't need to run around the train and/or run long hood forward (which may not be the best idea if you have a GE with winged radiators or a locomotive with desktop controls instead of a control stand)
 
often when you see a lot of engines on a train, especially if they are all on the front is that many of them are simply being moved to where they are needed. The engines may be running/idling but technically 'offline' so they aren't contributing anything to pulling. This is usually called a power move and they try to avoid having to do it as much as possible as it is very inefficient. KCS used to have to do it a lot around here, it wasn't unusual to see 7 engines on eastbound trains thru Houston as they typically had a lot more coming to Houston than coming from Houston, so they had a lot of power wind up here with no loads to carry back east/north. Those extra engines were simply added to the next outbound and went along for the ride, running but offline.

There have been some of 25-30 engine moves when the move is to a scrap yard or some other final destination, often these are trains of nothing but engines. I used to see blocks of 7-10 engines when a lot of old GE B/C-23, 30 and 36 engines were going to the Port of Houston for shipment to Brazil.

For normal uses, where all engines are under power and being used, I have been told that 7 is the maximum number than can be used together. That may or may not still be true and there may be exceptions. The image you have is 5 units, and not only is that well within the supposed 7 unit limit, but not that uncommon in some areas alto today they are often split into lead and DPU units.
 
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