The 'Where Did the Caboose Cars Go?' thread reminded me of a question I have: When and why is an engine added to the middle of a train?

I grew up on the south side of Chicago near the steel mills and sat for lots of freight trains. But, I don't recall those trains ever having engines anywhere except at the front of the train.

While I don't see so many freight trains these days, but it seems that a lot of them have an engine in the middle in addition to those at the front.

Is this a newer development?

What purpose does having an engine in the middle of the train serve?

Could it be that the train will break into two further down the line? Just my WAG.

Probably being used as a pusher or puller in long trains or where big grades are encountered...

quote:

Originally posted by goingbroke:
Probably being used as a pusher or puller in long trains or where big grades are encountered...

I'm not sure that's it. A train is not going to encounter much elevation change in the Chicago area.

Another possibility is that that engine needed to be moved from A to B and that's where it wound up in the consist.

quote:

Originally posted by goingbroke:
Probably being used as a pusher or puller in long trains or where big grades are encountered...

This is your answer. As train length grows over say 10k feet, you need more power and needs it separated out in order to overcome topography. Realize there's not much around Chicago, but going west you start to see more hills. For example on long trains you may have the head end portion of the train going down a hill with engine brakes applied, while the rear portion is still struggling up the back side under throttle. This is why you see the rear unit (DP - distributed power) on so many trains these days. The mid-train DP is just an extension of the rear DP. Also, because of radio communications limitations, the mid-train DP is often used as a repeater for communications between the controlling head end units, and the remote engines on the rear.

quote:

Originally posted by CoolRich59:
The 'Where Did the Caboose Cars Go?' thread reminded me of a question I have: When and why is an engine added to the middle of a train?

I grew up on the south side of Chicago near the steel mills and sat for lots of freight trains. But, I don't recall those trains ever having engines anywhere except at the front of the train.

While I don't see so many freight trains these days, but it seems that a lot of them have an engine in the middle in addition to those at the front.

Is this a newer development?

What purpose does having an engine in the middle of the train serve?

I'm going to guess that the trains you're seeing this on are either unit trains of say coal/ore or more likely entirely made up of intermodal cars (shipping containers)?

You also see a pusher on long coal trains. (Oops...SigM4 already mentioned them)...Another thing people may have seen with a unit in the middle of the consist but are also absent today, were the "radio cars" attached to the pusher engine...theses looked like a very large box car without side doors. They contained the radio equipment that linked the lead locomotive to the pusher locomotive so they all worked in unison with the lead. Now days, they have been eliminated as each road locomotive now has the built in technology to talk to one another without the added radio car.

What ever happened to the term "helper"?

quote:

Originally posted by rburg:
What ever happened to the term "helper"?

Back in the day we called them "slave units"...that term wouldn't fly today. I've heard them referred to as "helpers" too.

It would be less stress on the coupler's. Each standard box car is rated at 134 tons so a 100 car train is pulling a lot of weight when loaded.

With a train in the middle, it can pull and push to give better control and less stress especially going around sharp bends and also safer stopping distances.

Guessing this is the answer to making the trains longer without pulling a boxcar in half.

quote:

Originally posted by goingbroke:
Probably being used as a pusher or puller in long trains or where big grades are encountered...

Thanks guys. I appreciate the responses. The trains I see around here are usually full of the "stacked" containers.

goingbroke: sorry I jumped the gun on your comment and just focused on the elevation part.

quote:

Originally posted by Bisleyblackhawk:

quote:

Originally posted by rburg:
What ever happened to the term "helper"?

Back in the day we called them "slave units"...that term wouldn't fly today. I've heard them referred to as "helpers" too.

And see, I’ve only ever known a helper (or helper set) to mean a set of locomotives that attach to the rear of the train specifically to help the train over a particularly steep grade. Usually staged to help each train that traverses the route. In a typical shift a helper set will help shove numerous trains over a hill such as Cajon in SoCal.

quote:

Originally posted by CoolRich59:
[The trains I see around here are usually full of the "stacked" containers.

CR, as an aside I spent all last week in Chicago on business at a conference between all the rail carriers in the Chicago area. If you’re at all interested in trains the Belt Railway yard just south of Midway airport is a neat place to put eyes on.

I'm happy to say that I'm old enough to have stood trackside in Colfax, CA on the Southern Pacific main, watching the loooooong trains of recently iced Pacific Fruit Express reefers out of Roseville icing tracks, eastbound for the summit.

On a good day, there would be one or two AC class 4-8-8-2 Cab Forwards on the head end, one cut in the middle of the consist, and another pushing at the rear!

That would have been in the late 1940s, early 50s... That pretty much defined "power in motion" to me as a kid!

Edited to correct wheel arrangement: 4-8-8-2!

This message has been edited. Last edited by: dsmack,

quote:

Originally posted by dsmack:
I'm happy to say that I'm old enough to have stood trackside in Colfax, CA on the Southern Pacific main, watching the loooooong trains of recently iced Pacific Fruit Express reefers out of Roseville icing tracks, eastbound for the summit.

On a good day, there would be one or two AC class 4-8-8-4 Cab Forwards on the head end, one cut in the middle of the consist, and another pushing at the rear!

That would have been in the late 1940s, early 50s... That pretty much defined "power in motion" to me as a kid!

That would define "power in motion" to anyone who would know how much skill it would take to do that with steam power ...engineers had to know their stuff!

This has been one of my favorite paintings showing a "helper" or "pusher" on the end of a passenger train on Saluda Grade in NC...

I’d like to help you, but I lost interest in trains right after one ran over my BB gun.

Control of slave units has improved to the point that you now see pushers routinely, not just as grade helpers. As stated, it reduces coupler strain on the lead locomotives, and I’d think also it would reduce gauge strain on the track.

Helper, UT (near Price) is a town so named because it was founded solely for the purpose of supplying pusher engines to the coal trains over Soldier Summit.