Mid-train/end of train helpers?

You need to list the models used.

Each unit is distinct in pulling power and reaction time. 

Andrew

Never tried it with TMCC; but it works great using DCS andPS-2 engines.

Well, right up until one of the engines derails or falters for some reason!

Rod

I have used various TMCC engines and create very interesting trains.  Multi pullers, Mid pullers and back pushers.  Even mixing an SD70ACe with an F3 works.  All of the engines are post year 2004 with Odyssey and TMCC.  Earlier versions, late 1990s, without Odyssey do not sync.

having put any number of cars on the floor trying to get this accomplished, I write with the results. Yes, you can use a pusher(s) (never tried the mid unit(s)). I suggest you start with just a few cars between the engines you choose to use. This will give a quick check on the compatibility of the 2 engines. I really sorry, but all engines are not geared the same, irrespective of maker or boards (yes I know that all TMCC are supposed to be the same..........etc, hold on to that thought). Once you have found the compatible engines, I suggest setting them up as TRAIN whatever number between 2 and 9 you wish. Run the short version of your train around the track and see how it performs-you may have some renegade cars that don't like to pushed and pulled. As you become more comfortable with this operation, add cars, test the train, add more cars, test, then when you decide that absolutely nothing can go wrong, invite a friend over and watch what happens! I assure you that, like children when the phone rings or someone comes to the door, your trains will show their backsides shortly after your guest arrives! 

I successfully operate 2 Lionel Y6's in push pull and sometimes add an A with about 30-40 Weaver 2 bay coal cars (I am a less discerning modeller) with coal loads around the layout.  No, the leading engine does not come close to the rear of the train. I started with an mth Y6 converted to TMCC, which ran quite well, but I didn't like the whistle. Hope this helps!

Just to say and so far as I know, additional, temporary locos at the front of the train

and in the middle of the train are called "helpers"; at the rear of the train they are

properly termed "pushers". 

That would be true back in the days of steam, and then diesels up through the early 1970s. However, with the development of "Loco-Trol" and now with the modern computer/radio remote unit operations, the proper term is DPU, i.e Distributed Power Unit operation. Thus, there can be DPUs a third of the way back in the train, and additional DPUs on the rear of the train. ALL being controlled by ONE Engineer in the lead unit!

Sounds grest if you care running all of them as one "consist".  But there is a variation in DPU use where the engineer can control a DPU set apart from the rest.  I think he or she can bring up a different "window" in order to do that. 

Doesn't matter how you configure the trailing DPUs. They are ALL still controlled by the Engineer on the lead set of power.

You're talking about synchronous mode, in which all consists, both lead and remote, respond identically when the throttle or dynamic brake controller is moved.  in independent motoring mode, the Engineer can "put up a fence" to control the head end consist separately from other consists.

You might think that synchronous mode was a dream come true.  In reality, it has its place, but is not the ticket for heavy undulating territory, nor for descending grades of 2% or more at low speed, where the train will be on the grade for quite a distance.  Other situations in which independent motoring is best include passing through slow orders, entering and departing yards, and other situations where buff and draft forces at low speed are a consideration.

But, getting back to the topic of this thread, paperboy has a good idea, because there are minute variations in the speed at which our model locomotives operate in command control, and his idea is just about the only way to know if two specific locomotives are suitable for helper or pusher operation together.

I've done mid-train units a couple of times, once with a pair of K-Line Mikados in TMCC and once with MTH Milwaukee Road boxcab electrics in DCS. In both cases the locomotives were set up as a 'lash-up" just as if both were at the front of the train. This was on a large club/museum layout with trains of 40-50 cars. It worked just fine. No grades were involved as the main lines on the layout are flat. 

Car weight is crucial for doing this as well. You cant have a couple really lite cars in the mix because they will become a problem (pulled or shoved right off the rails). Try to keep the weights close to NMRA standards. We gotta keep those rear end cars over 45 tons depending on total train tonnage