2 trains on 1 track

[smarmaro]

whats the easiest and best way to run 2 tains on 1 track, my layout has about 100ft of track with no switches right now, any help with this. any website references

thanks

stephen

[lionelsoni]

Well, you could get a TMCC or DCS setup.  I'll leave it to the proponents of those systems to say how easy they are to use.  Instead, I'll describe the oddball scheme that I use (in a simplified form).

Install a rectifier diode in each of your two locomotives, between the pickup and everything else.  Make the two diodes point in opposite directions between the two locomotives.  Put a 5000 microfarad electrolytic capacitor in parallel with all the locomotive circuitry downstream of the rectifier.

Use a single transformer, preferably one with a fairly high output voltage, like a type Z.  Connect two Lionel rheostats, each with a rectifier diode in series with it, in parallel and put that combination in series with the single transformer output, turned up all the way.  Control the two trains with the rheostats.

Any whistles or horns will sound continuously with this scheme; so you'll have to disable them.

[dwiemer]

If you look in the pages of CTT, one of the advertisers has a relay set up that they sell for doing just that, run 2 trains on one track.  Not sure what all is involved, but It probably requires blocks.  With this configuration, you would be able to run any locomotives without alteration. 

Dennis

[lionelsoni]

Stephen, are you looking for continuous independent control of the two trains, which my answer aimed at, or automatic collision prevention, which I think is Dennis's line of thinking?

[overall]

Here is what I do;

I have one TMCC locomotive with the odysse speed control and one TMCC locomotive without. I set the one with odysse at a comfortable speed then I control the speed of the other engine, not allowing it to get too close to the first train. It works well.

George

[jonadel]

I use DCS and on my longest run I have three trains on the same track and it works fine, two is easier and then you can just bounce back & forth with independent control by hitting a soft button.  Not difficult at all. 

[mickey4479]

All 5 of my Lionel locos are TMCC and I often run 2 on one track about half the loop apart and a 3rd loco on an inner loop with no problems.

[Wes Whitmore]

Some variation of this might work.  It uses an MTH ITAD, which is around $20.  They make two kinds, one that attaches to realtrax, and one standalone unit that works with any kind of track.  I remove the infrared tigger wire, which converts it into a reliable ground throw activated device (maybe call it a GAD?) 

There are two isolated areas on the loop.  One has an isolated ground rail, and one has an isolated center rail.  The ground rail in section A trips the ITAD.  The B section with the isolated center rail has a lower voltage present all of the time (Either a ZW, or a bridge-rectifier strip if you only want to use one transformer - Thanks Lionelsoni on that tip).  The ITAD applies a higher voltage on top of the lower voltage and the train takes off.  I set the lower voltage so that the train sits there and smokes and sounds, but doesn't move.  You could turn it off, as well, or just don't hook anything up to section B at all.  I keep it at about 6 volts so MTH trains idle.  Set the timer circuit that holds the relay closed until the train clears the B siding.  There is a little screw in the ITAD that varies the time it's closed.  The the voltage lowers waiting on the next train.

The ITAD lets you choose what you send out the tripped relay by flipping a switch.  You can use track power to power the ITAD and send that same power out the tripped relay output, or you can feed an aux supply and send that out.  If you want to power the ITAD relay with accessory power, then feed the aux power with the higher voltage.  I went the easier way here and powered the ITAD with the higher voltage out (or just track power).  It all works the same since the relay seems to work with very little voltage, so you don't need that constant 18+VAC to make this work.

Lastly, I put in a bypass switch so you can bypass the ITAD when you don't want the circuit to work anymore.  It keeps the relay from tripping every time around.  You can bypass it if trains are pretty much equal speeds and you really don't need one to stop to "reset" the pace.  This requires you to watch the layout though.

Good luck,

Wes

 

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[lionelsoni]

Wes, connecting two transformer outputs together like that is asking for trouble.  I can't say what will happen with a modern "transformer"; but with any earlier real transformer, you will get high currents and possibly a fire.  The circuit breaker will not trip.  Bypassing a voltage-dropping element like a rectifier string or a rheostat is the only way I would try it.

This is similar to a scheme that I have described several times, including quite recently, except that, by isolating both outside rails in the stop block, you can eliminate the need for the relay.  Either way, it is very easy to add a signal to the stop block.

I asked Stephen whether he is looking for continuous independent control of the two trains, which my earlier answer aimed at, or automatic collision prevention, which is what your proposal does.  He hasn't answered and may not be following this topic any more.

[Wes Whitmore]

Bob,

I do take your advice to heart.  I thought that the ZW transformer throttles shared the same internal power supply, so both outputs were in sync, and safe.  Maybe it was the Z4000 that was that way?  Regardless, if neither are, then I won't recommend it.  The rectifier string is what I use, and it works well. 

I could use some clarification on both outsides rails in the stop block and eleminating the relay.  How would I I apply a low parking voltage continuously to keep the MTH engines running (say 6 volts), and then add the release voltage (12 volts or so) on top of the low voltage without the relay?  I don't want to just cut power to the train in the stop section.  I also want to shut release power off and return to stop voltage. I don't need a signal.

Steven, your missing out on some good stuff!
Wes

[ADCX Rob]

lionelsoni

Wes, connecting two transformer outputs together like that is asking for trouble.  I can't say what will happen with a modern "transformer"...

 

Bob, "backfeeding" a triac with an output from another in-phase source(like the channels on a ZW controller, or two CW-80's, or two PM-1 PowerMasters) cause no harm & no foul.  The load is transferred to the triac set to the higher output until it's power setting is reached, and then the load is shared(pro-rated).

Of course, doing so with a postwar ZW(like A-D handles) or KW(A-B handles) causes an internal short not protected by any circuit breaker - imagine having the A handle set to both ~19 volts & ~6 volts simultaneously... that's a 13 volt 15+ amp short across the secondaries!

According to the sidebar narrative  in the December CTT, page 51, Steve Garofalo uses the ZW "A" post for the ascending part of the main line & the "B" post to control the down side of his 1957 "Catalog" layout re-creation.  This is of course how Lionel(Kindler) recommended it to be done back then!

Rob

[ADCX Rob]

Wes Whitmore

Bob,

I do take your advice to heart.  I thought that the ZW transformer throttles shared the same internal power supply...

 

This is actually the problem... see above.  If the outputs are from different, but phased transformers, the potential is still there but the transformers would likely be protected by breakers.  They would not be as likely to be subjected physical damage to the secondaries from arcing or burning.

Rob

[lionelsoni]

Rob, I understand and agree in principle with what you're saying about the CW-80 and Powermaster.  But, not owning nor having any experience with them, I am reluctant to advise using them that way.  I would want to be sure that there were not some quirk in the design that would bite me.  Since I have no interest in using those models, I will leave it to you and others to check them out.

The new ZW is, I think, more problematic.  I have been told that it synthesizes a sine wave.  Without knowing at all what technique Lionel uses, I wouldn't even go so far as to say that connecting outputs would be okay in principle (although it might be).

Wes, to get the "parking" voltage, all you need to do is bridge the control rail to the common outside rail with the same voltage-dropping element(s) that you would use with the relay.  The stopped train is supplied with its return current path through the axles of the train over the control rail.  The voltage-dropping element(s) simply provide a partial path for that current when the moving train is on the control rail.

[Wes Whitmore]

Bob, does this mean both trains will have to stop in the stop section?  That was the good part about the variable timed release of the relay in the ITAD.  I could time it so that the stop section kept the high voltage long enough that the trigger train also passed through it, then dropped back down to idle voltage.  I'm sure you could probably design something simple that works as well or better...

Wes

[lionelsoni]

Yes, both of them would stop.  The way I did it, I put the control rail just a train length before the stop block.  I have posted elsewhere a warning that the locomotives' couplers should be insulated to prevent current from flowing through the metal knuckle springs. 

[ttt]

I think that you should probably install TMCC or Legacy.

[lionelsoni]

TMCC won't keep the trains from running into each other.  The various stop-block schemes won't allow independent control of the trains.  Which way to go depends on what he is (you are) trying to accomplish.

[smarmaro]

hi all, thanks for the input. what im really lloking for is the easiest way to run my trains in coventional mode at  the same time on the same track.  may be insulated sections with seperate transformers attached to each section will work.

stephen

 

[lionelsoni]

Conventional operation does not include separate control of two trains on the same track.  I would advise against "insulated sections with seperate transformers attached to each section".  There is danger of fire and of damage to wiring, transformers, and locomotive electronics.

I believe that your choices are, on the one hand, TMCC, DCS, DCC, or a homemade scheme for independent control of the trains or, on the other hand, one of various schemes that automatically stops or retards one or the other train while they run continuously from a single transformer.  Which of those is closer to what you're thinking about?

 

 

 

 

 

 

 

 

 

 

[smarmaro]

will TMCC, DCS or DCC work for my postwar and modern era lionel engines and what about my k-line engines

stephen

[jkerklo]

 

Take a look at this website:

 ATX

It works well with conventional engines without any modification.  It just needs two "stop" track blocks to run two trains.  

 

 

 

[George Thill]

Hi Bob, I have two questions about this "scheme". Why the capacitor? And will this work with the two throttles of an "R" transformer?

 

Thanks!

[alank]

If you are running the likes of postwar trains you could operate 2 trains with one transformer in this manner.

One engine would be controlled by the direction handle in normal manner.   The second engine can be controlled via the whistle option.   Instead of the relay in the tender controlling  the whistle, rewire its output as a control of the e-unit of the second locomotive.

[bobhwalker]

The October 2007 issue of CTT included an article I wrote describing a simple system for running two trains on a single loop.