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Two Loco In Tandem Question

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Two Loco In Tandem Question
Posted by 7793 on Saturday, February 7, 2009 7:32 AM

If I wanted to run two Loco's one behind the other, the first one in line would be powered, but would the second one just be a unpowered dummy engine? I mean if you had two powered units would they conflict? In other word would one powered engine pull all the freight cars in a  train or would you really need two powered engines?

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Posted by bsteel4065 on Saturday, February 7, 2009 7:39 AM

That's the beauty of DCC. You can have a double header or a multiple header (the limit is what DCC system you have) as a consist and they are all pulling as they are all powered. So, it's just like the real thing. You can make up consists from any of your addressed locos and then break them down again and use seperately. Again just like the real thing. Adding locos increases the pulling power and so the more the freight cars can be pulled.

Hope that helps.

Barry

 

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Posted by ATLANTIC CENTRAL on Saturday, February 7, 2009 7:50 AM

7793,

Running more than one powered unit together works just fine in DC or DCC. With DC they must be locos that run at similar speeds but as long as they are close, it will work.

In real life, even with modern computers controling the locomotives, one is often pulling harder/softer than the others, this balances itself out and does so with the models as long as they are close in speed to begin with. In days gone by, the real railroads even ran steam and diesel together and did it only by feel and whistle signals from engineer to engineer.

With DCC you can ajust virtually any to locos to run together, but it sometimes takes a far amount of work.

With DC, lets say you buy three Proto 2000 GP7's, you can just put them on the front of your train and let them go, they will run close enough to the same speed to be fine. Mixing brands or types with DC will reqiure a little testing to see how close they are in speed at various throttle settings when uncoupled, but if they are close, put the faster one in front and let them go. And muliple units do give you more pulling power, 2 locos will almost double what you can pull, etc.

Sheldon

 

    

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Posted by blownout cylinder on Saturday, February 7, 2009 7:56 AM

In DCC one can " speed match" them so they will run together more effectively. Most DCC manufacturers have the process explained for each---depending on which one you buy---make in their instructions that you can download. Have fun---

Any argument carried far enough will end up in Semantics--Hartz's law of rhetoric Emerald. Leemer and Southern The route of the Sceptre Express Barry

I just started my blog site...more stuff to come...

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Posted by dehusman on Saturday, February 7, 2009 7:58 AM

In DC you can add engines together in a consist, as many as you like, until you reach the amperage limits of the power pack.  The engines should operate that they all operate in the same direction regardless of which way they are pointed.  So if you  put two powered GP40's on a train back to back they would operate fine even though they are pointed in opposite directions.  With DC the caveat is that different models with different motors and gear trains may operate at different speeds and "fight" each other.

In DCC you can "consist" locomotives so they all operate as one. Different DCC systems may do the mechanics differently and may have some added features.  In each you have to tell the DCC system which way the engines are facing.  So when you made a consist of the two back to back GOP40's you would tell the DCC system the first unit is forwards and the second unit is backwards.  In older DCC systems one unit is lead in a consist so it you run eastbound the consist is forward, but when you run westbound the engines are running "backwards".  In modern NCE systems, when you consist the engines and indicate which one is the "Lead" and which one is the "trail".  After that you dial up which ever engine is leading in the direction you want to go and that becomes the lead engine.  That way during an op session you don't have to keep track of the consist number or lead engine number, you just dial up the engine that is "leading" in the direction you want to go and you have the consist.

Whether you want to use powered or dummy units is up to you.  Dummy units can be harder to find, but are cheaper.  If you have all powered units then you can split them up and run multiple trains  or longer trains if required.  Your choice.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by 7793 on Saturday, February 7, 2009 8:01 AM

Well i was thinking of going with the NCE DCC Power cab. Will that unit have the option to regulate the engines speeds?

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Posted by BRAKIE on Saturday, February 7, 2009 9:23 AM

bsteel4065

That's the beauty of DCC. You can have a double header or a multiple header (the limit is what DCC system you have) as a consist and they are all pulling as they are all powered. So, it's just like the real thing. You can make up consists from any of your addressed locos and then break them down again and use seperately. Again just like the real thing. Adding locos increases the pulling power and so the more the freight cars can be pulled.

Hope that helps.

Barry

 

 

Well first 2,3 or more locomotives can be mu'd in DC as this picture shows.

 That's been done for eons and not a DCC thing.

 

Look in the mirror and you can see the rest of the train is still on the grade while the locomotives start down grade.35 cars total pulled by 3 Athearn GP38-2s and yes the train was still moving when I snap the picture.

Larry

Conductor.

Summerset Ry.


"Stay Alert, Don't get hurt  Safety First!"

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Posted by selector on Saturday, February 7, 2009 10:16 AM

I believe what everyone is saying so far, regardless of their preferred way of operating, is true.  However, if you have, as I have, a mixed bag of engines, say a Pennsy J1 2-10-4, and you wanted to get a Mountain 4-8-2 on the back as a pusher, but the Mountain was geared differently and motored differently due to its being from another manufacturer, but still Pennsy, you would have a dickens of a time getting them matched in DC.  Not so in DCC.  Also, in DCC, you can run a double A set of F-7's tail to tail, but you can't do that without the engine having an internal reversing switch in DC.  Also, if the two A sets were from different manufacturers, you might have the same problem with speed matching even if you could reverse the rear unit.  Not so with DCC.

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Posted by selector on Saturday, February 7, 2009 10:20 AM

7793
NCE DCC Power cab. Will that unit have the option to regulate the engines speeds?

Yes, it will regulate engine speeds, but I'm not sure if that system has the capability to do it in address 00 if you mean using DC engines.  Otherwise, each engine will need a $13 decoder in order for the NCE system, or any system for that matter, to control the engine's speed.

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Posted by ATLANTIC CENTRAL on Saturday, February 7, 2009 12:03 PM

selector,

Two DC F7's, tail to tail, with both run in the same direction on DC, no modifications or switches needed. DC locos don't know front from back, they only know right rail positive goes forward. So lets say, as you look at them from the side, the rail closest to you is plus, both locos will move to right, regardless of which direction their cabs are facing on the track.

This is basic stuff, if your not familar with it, you may want to leave it those who are.

Sheldon

 

    

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Posted by cuyama on Saturday, February 7, 2009 1:27 PM

ATLANTIC CENTRAL

Two DC F7's, tail to tail, with both run in the same direction on DC, no modifications or switches needed. DC locos don't know front from back, they only know right rail positive goes forward.

Yes, that's the standard, but it's not been true for every DC locomotive ever built. I have seen the odd exception. No need to be snippy.

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Posted by cuyama on Saturday, February 7, 2009 1:29 PM

7793

Well i was thinking of going with the NCE DCC Power cab. Will that unit have the option to regulate the engines speeds?

Yes, with decoder-equipped engines.

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Posted by BigRusty on Saturday, February 7, 2009 2:09 PM

Long ago, in my first HO layout I Mued Athearn PAs AA and Varney FTs ABBA. After much trial I solved the speed differance by placing all four engines on the same track separated by 12 inches. I then operated them at normal train speed. I put the fastest engine at the back and the slowest at the front. This gave the front engines the same help that they would receive from a pusher. Even though there were 32 wheels powered operation was sometimes jerky.

 I solved the problem by wiring all four twogether using hook and eye connections between each. They not only ran more smoothly but could pull 100 car freight trains on level track effortlessly at freight train speed.

Seeing the benfit of the through wiring I wired multicar Reading and Pennsy MU units together. Not only did they run more smoothly, the lights didn't flicker anymore. 

 

Modeling the New Haven Railroad in the transition era
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Posted by ATLANTIC CENTRAL on Saturday, February 7, 2009 2:13 PM

Sorry to have been snippy, I thought that was a polite sugestion. Way more polite than some have been to me in the short time I have been on this forum.

My apologies to selector.

Sheldon

    

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Posted by selector on Saturday, February 7, 2009 2:20 PM

Shoot!  I did get that wrong...I am sorry.  I normally have a better grasp of it than I displayed there.  Thanks for pointing it out, Sheldon.  Somehow I drifted away from the premise of getting them to approach when nose to nose. Why I worked with the tail to tail example I do not know. Blush

Brain fart?

-Crandell

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Posted by corsiar on Tuesday, July 23, 2019 6:47 PM

How are two or more locomotives coupled together on a DC layout without manually pushing them together?

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Posted by ATLANTIC CENTRAL on Tuesday, July 23, 2019 7:42 PM

corsiar

How are two or more locomotives coupled together on a DC layout without manually pushing them together?

 

You do realize this thread is 10 years old?

Some DC modelers have special kill sections in their engine terminals to allow one loco to pull right up to another.

Short of that, you don't, you push them together.

Sheldon

    

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Posted by kasskaboose on Tuesday, July 23, 2019 8:43 PM

Ah, I didn't know about the date until you pointed it out.  It was an interesting thread to read.  The topic is something I plan to consider.

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Posted by BigDaddy on Tuesday, July 23, 2019 9:03 PM

kasskaboose
Ah, I didn't know about the date until you pointed it out.

Newbies seem to glom on to the old threads, but it happens to a lot of us every now and then.

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by Redvdub1 on Friday, July 26, 2019 1:17 PM

I'll bet my answer will generate some controversey but you asked.  Old timers (before DCC) know that you can run multiple engines together AS LONG AS ALL THE DRIVERs ARE rotating and you do not have to do any "speed matching".  Without any train loading one engine will be pulling the other one (or other ones).  As you load up the consist there will be a point (generally 3-5 normally weighted cars) where both engines (or all the engines) will be sharing the load and none of the engines will be acting as a load...and off you go.  This doesn't mean  the engines will be sharing the load equally, but they will interact with each other according to their operating characteristic.  And off  you go. 

IMHO speed matching is not necessary...ever.  In the extreme case of a consist with a very "weak" engine (say an almost dead magnet) you will get bucking effects and you may think that speed matching the "strong" engine/s to the "very weak"engine solves your bucking problem.  But the downside of this scenario is that you have essentially degraded the "good"operating characteristic of the "strong" engine to that of the "very weak" engine.  

 

To determine the critical load where both engines are "pulling" put both locomotives on the layout.  Load up the faster loco with cars until the speeds match.  That is the critical loading point.  With reasonably similar engines the CLP would be 3-5 normally weighted cars.  

Happy consisting.  

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Posted by doctorwayne on Saturday, July 27, 2019 7:37 PM

If two (or more) locomotives are actually needed to move the train, having similar current draw on each for starting is more important than speed matching.
Most of my trains are doubleheaded, and often require pushers, too, due to the many severe grades and curves, and they even-out, speed-wise, very nicely.  Train lengths might range from two or three passenger cars, to in excess of 70 freight cars.  Operation is with DC-powered steam locos.

This train, about 45 cars in length, needs only one 2-8-0 to move it down this 2.8% grade.... 

Were it travelling uphill, there'd be three or four locomotives required, and no issues with speed differences.

Wayne

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Posted by richg1998 on Wednesday, July 31, 2019 8:20 PM

I have two HO Bachmann 44 single motor with LokSound 3.5. I run together. Same address and CV's. Did about ten years ago. Minor frame cutting to fit speaker baffle. Speaker and baffle up in one end of shell. All wiring and old electronic ripped out. Kept light bulbs.

Union Freight RR in Boston use to do that to haul 14 to 20 freight between North and South Station many years ago. Article in MR, 2001.

There is also an article on how to DCC a two motor 44 ton. I have done that. Gears can be a problem with NWSL out of business.

I also have a VO-1000 with Tsunami.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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