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With command control, setting up a DPU operation is quite easy, and it works well, at least if the engines run at the same speed. I did it a while ago as a test. I had my ATSF B40-8W pulling the train, with my BNSF GP35 pushing from the rear. The train was not that long, but it worked very well.
Interesting video. I've never tried it, because my layout is small and doesn't have any grades. I would like to have seen in the video, an engine on the point of course, then one at mid-train, then one on the tail end. I'm wondering if that arrangement would have been even smoother. 
Managed this running conventional control.😊 Was a little tricky getting the engines both running forward though.
@Yellowstone Special posted:Interesting video. I've never tried it, because my layout is small and doesn't have any grades. I would like to have seen in the video, an engine on the point of course, then one at mid-train, then one on the tail end. I'm wondering if that arrangement would have been even smoother.
For what it's worth, in the world of real railroading, long standing computer simulations along with extensive over the road testing (with instrumented test cars), have showed that the ideal placement of the DPU "helper" is about 2/3 of the way back in the train. That said, on most, if not all, unit coal trains and/or oil tank trains, placing units "mid-train" was/is NOT operationally practical, especially when auto-flood-loading moving coal trains at the mines, the mine operators could not seem to shut off the coal dropping out of the loading chutes. Thus, coal was being dropped onto/into the "mid-train" DPU! As a result, the coal mines made the railroads (both BN/BNSF and UP) stop the use of "mid-train" units, and only use DPUs at front and rear.
Now, both BNSF and UP seem to use DPU placements at "mid-train" as well as on the rear.
Great post Dan, very informative. Do it some more please.
I don't know how DPUs work. I mean I don't if they are controlled individually by the engineer, or do they just respond to the same control settings as the unit engineer is running.
If they are controlled individually, doing it on a model would be more of a challenge.
As it is either with DCC conventionl DC, they locos have to run at the same speeds if using only one controller. I run a lot of 2 unit diesels sets both powered. I did this with conventional DC and I do it now with DCC Directional control is not a problem with straight DC by the way. My rule of thumb is to make these sets up using units that have the same mechanisms and motors. That way they should run the same. I have no problems doing this. With DCC, I know you can do more custom speed matching. However in the early diesel era, the RRs tended to keep like units together and not mix and match.
If want to really have some fun try running the two units separately - with two operators. I had a late friend who built a helper grade into his layout based on 1928 operations. He designed the grade by increasing it and testing it until a 15-18 car train stalled on the grade. That way you had to use a helper. We ran it with two operators and the helper loco was at the rear. It took a little getting used to but was not too bad. The whistle signals were the two guys talking back and forth and telling one another to start. if two skilled operators did it, you would see the slack moving in and out about 2/3 way along the train one the grade. In the front the couplers would stretched, and in the rear, the couplers would be tight as they were pushed. The point where this changed would move back and forth among 2-3 cars.
@Jack Petrof posted:Managed this running conventional control.😊 Was a little tricky getting the engines both running forward though.
And with Super-O!!!! 
Love it!
Just stick a dummy back there where it should be according to HW's post; problem solved!
Running a DPU setup with DCS is easy. Check out the video below. Full disclosure: This is in 3 rail, and not all the engines are powered units. Each block of engines has at least one powered unit and one dummy.
Chris
LVHR
Sure we can, here's 115 cars pulled by two PRR U-Boats, one is in the middle of the consist. This worked out better than both locomotives in the lead as it reduced the strain on couplers. 115 cars are a HEAVY pull, even if they're light cars, which not all of them are.
Our club runs DPUs with TMCC or Legacy or DCS often, being careful to use engines that are from the same manufacturer and entered as middle units when creating the multiple unit consist (See how I avoided Lionel's "lash-up"). We recently ran 60 ft. long trains this way without any problem. Viewers are amazed when they see and hear the mid-train DPU working hard. As an alternative, just place a non-powered unit in the train. At least it looks the part....
ET
@gunrunnerjohn posted:Sure we can, here's 115 cars pulled by two PRR U-Boats, one is in the middle of the consist. This worked out better than both locomotives in the lead as it reduced the strain on couplers. 115 cars are a HEAVY pull, even if they're light cars, which not all of them are.
Whose layout is this? A club? Never seen such a large O gauge consist before.
@prrjim posted:I don't know how DPUs work. I mean I don't if they are controlled individually by the engineer, or do they just respond to the same control settings as the unit engineer is running.
From my reading, both options (synchronous and non-synchronous) are available. A very long train might be braking downhill on the front but still pulling up a hill at the back. When the locomotives are independently controlled, they put up the "fence" on the display for remote control of the DPU units. It must require a lot of skill and familiarity with the terrain to manage a train with DPU.
@PRRMP54 posted:Just stick a dummy back there where it should be according to HW's post; problem solved!
Except,,,,,,,,,,,,a "dummy" adds additional weight to a train, and still provides no assistance when ascending a steep grade. Thus, it may "look good", but provides no assistance.
We've done this with some huge consists. My advice is no rubber tires except on the leading units. The ones mid train or at the back should slip when they need to.
@MichRR714 posted:We've done this with some huge consists. My advice is no rubber tires except on the leading units. The ones mid train or at the back should slip when they need to.
Good advice... although I think most "2 rail scale" diesels don't have "rubber tires"... 😉... thankfully.
Mark in Oregon
GunrunnerJohn, that is pretty cool. If I could only access more real estate for my trains I would try a protypical sized train with 72" curves. Alas I am forced to use 36" dia. curves. Love seeing long trains!
@Jack Petrof posted:GunrunnerJohn, that is pretty cool. If I could only access more real estate for my trains I would try a protypical sized train with 72" curves. Alas I am forced to use 36" dia. curves. Love seeing long trains!
On my home layout, I'm more limited, though I have managed to run some decent consists at home.
My friend Clem asked me to post this to add to the conversation.
@gunrunnerjohn posted:Sure we can, here's 115 cars pulled by two PRR U-Boats, one is in the middle of the consist. This worked out better than both locomotives in the lead as it reduced the strain on couplers. 115 cars are a HEAVY pull, even if they're light cars, which not all of them are.
John:
Looks like the same train going both ways at the crossing. Great video.
Pat
@irish rifle posted:John:
Looks like the same train going both ways at the crossing. Great video.
Pat
It was indeed, it went around the workshop loop and back out on the other side of the mainline. The mainline there is around three scale miles or a little more, one day I have to measure it with an MTH locomotive.
I had a 62 car consist that was pulled by two MTH Diesel in the front and one about two thirds back. Looked great till it got almost to where it started. The DPU near the rear stalled while train was in a horseshoe turn. Yep! It Straight Lined! What a mess. Haven't done it since as I don't like problems in that area. YEP Again. Murphy's Law. If it is going to happen it will happen in the worse most non accessible area!
Need more reliable motive power Curtis. 
@gunrunnerjohn posted:Need more reliable motive power Curtis.
Not a motive power problem. It was a track switch that cause the power to drop to the DPU locomotive. If I had been running two DPU's together never would have happened. But still, You best have accessible track because sooner or later MURPHY will raise his head when you least expect it. LOL And don't even suggest that a Lionel would not do it. I have had them stop with NO apparent reasoning.
Having had a 50 car freight stuck in a long tunnel and carefully taking the cars out one at a time and crawling out with each car, I hear you! 
Lionel would never do this. 
OK, the devil made me say it, I'm not in total control! 
My experience running MTH engines in DCS is that some run slightly faster/slower than others despite showing the same speed. That is why the DCS manual recommends that you run them individually on the same track separately to ensure that they stay the same distance apart before you program them into a lash-up. I imagine if you run them in a lash-up with the lead engine and the DPU running at slightly different speeds with a series of cars ahead/behind you as asking for a derailment.
I try and run them in at least a pair. Having 2 or more engines in groups smooths out any hiccups.
When run as a consist, the engines help each other. They behave differently. They act as a team.
I run 2 rail with small flanges. The engines will take up slack or loosen as needed. If they hit a dead spot in the layout, they act up. So grouping them helps overcome these trouble areas.
mid train helper:
G scale outback with 3 (distributed) engines
4 diesels. 2 front, and 2 mid train up and over the 2 % hill climb in corner of yard
@CBS072 posted:Old video of DPU train BUT the DPU's are not powered just ERR dummy broads and sound.
"...broads..."(?) 🤔
Mark in Oregon
Before I decided to (mostly) abandon steam, my standard coal train was two MTH Decs at the point, 18 cars, and an MTH Mike at the rear. All three were running DCS.
I very rarely had problems. If I did they were usually solved by cleaning the locos wheels. What was impressive to me, was that as the train worked its way up my 1.8% grade, the coupler gap between the 9th and 10th car continually expanded and contracted a bit. Indicating the speed control among the three locos was pretty well balanced
Note this is a two rail
Hi All,
Some 20+ years ago on Dan Pence's RR, Dan ran a mid-train helper with a bunch (I don't remember the exact number) of hoppers up the hill. The train ran flawlessly. I was impressed. O Scale with Overland engines.
Just a few years ago on an HO RR, I ran a helper on the rear of the train up the PRR Horseshoe Curve. No big deal if you watch the coupler slack mid-train.
NOTE TO DAN: Remove the bullet noise at the beginning of the video. No, I am not against the 2nd Amendment. But, our computer is in the room next to our bedroom and sometimes I use the computer late at night. The bullet sound would have wakened my wife and then I would be in a world of hurt.
Ed
@Strummer posted:"...broads..."(?) 🤔
Mark in Oregon
Hey, I did not use my spell check on my phone just this one time. I only made "A's" in recess/play ground activities in school.
I did do good on some spelling words like - train, railroad, track, Lionel, engine, boxcar, flatcar, etc. Other words not so much.
Used to do it at the club. Pretty easy with DCS because of the cruise control, but doable with TMCC or DCC.
I run a pusher on coal trains most of the time these days. It is easy to do with DCC. Speedmap any engine from any manufacturer and they should work together just fine. It is interesting to watch the slack change when the train goes up and down the hill.
Super simple to DPU with DCC, here's a short clip from 2011 Rock Island Trainfest with four Overlands on the head end and a lone Atlas SD40 bringing up the rear on a stack train.
John
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