Shot in the dark: any 3-rail layouts converted to straight DC?

There was an episode of 'I love Toy Trains' sometime last year that featured a layout that was running trains on DC. I am thinking they were pre-war, but I may have my episodes mixed up here? They were conventional anyway. They made it sound very simple to convert, like just adding a bridge rectifier or something? From what was said and what I remember, I am not sure it made sense (to me anyway) as to what they had done?

A lot of early British trains were made to run on DC & I've got a couple of Lima 12v locos converted to 3 rail, will get to convert them to AC.  James

OK, here is a dumb question; if DC power, then why would the center "3rd rail" be needed?  I tend to think 2-Rail SCALE or HO when someone mentions "DC powered", i.e. one outside rail being positive and the other negative.

Hot Water posted:

OK, here is a dumb question; if DC power, then why would the center "3rd rail" be needed?

It's a lot easier to wire a 3 rail layout for running in both directions w/o regard to polarity, and especially when it come to turning a train(think reverse loops).

ADCX Rob posted:

Hot Water posted:

OK, here is a dumb question; if DC power, then why would the center "3rd rail" be needed?

It's a lot easier to wire a 3 rail layout for running in both directions w/o regard to polarity, and especially when it come to turning a train(think reverse loops).

Yes, obviously for AC power, I understand that.  But why would a 3rd rail be needed for DC power, as per the original posters question?

Hot Water posted:

ADCX Rob posted:

Hot Water posted:

OK, here is a dumb question; if DC power, then why would the center "3rd rail" be needed?

It's a lot easier to wire a 3 rail layout for running in both directions w/o regard to polarity, and especially when it come to turning a train(think reverse loops).

Yes, obviously for AC power, I understand that.  But why would a 3rd rail be needed for DC power, as per the original posters question?

The original poster asked about large 3 rail:

I recall articles from the 80s or 90s on large Lionel 3-rail layouts that the owners had converted to DC

And the Choo Choo Barn which is also 3 rail.

And wiring for a DC reverse loop is also easier with 3 rail as ADCX Rob indicated, especially if one runs typical 3 rail equipment on 2 rails, think short circuit, 

Jerry

Hot Water posted:

ADCX Rob posted:

Hot Water posted:

OK, here is a dumb question; if DC power, then why would the center "3rd rail" be needed?

It's a lot easier to wire a 3 rail layout for running in both directions w/o regard to polarity, and especially when it come to turning a train(think reverse loops).

Yes, obviously for AC power, I understand that.  But why would a 3rd rail be needed for DC power, as per the original posters question?

As Rob says, it's easier to skip reverse polarity wiring and have a 3rd rail instead. It doesn't matter if it's AC or DC, the point is the total separation of positive and negative throughout a track layout, and not having the short created by 2-rail equipment running back on a reverse loop. 2-rail AC American Flyer had a reverse loop relay they supplied to flip the polarity of the trackage. http://www.portlines.com/Adobe...0LOOP%20HANDBOOK.pdf

My fuzzy memory recalls something about the DC 3-rail being more operationally reliable than the AC 3-rail, at least until the heavy application of onboard electronics, hence the choice of some operators to convert their Lionel layouts to straight DC. Any thoughts?

Most 3-rail track (all that I am familiar with), has the the 2 outside rails electrically connected together.    So the 3rd rail in the center is needed for the opposite pickup.    Regardless of AC, DC, or some form of digital command control, you need 2 pickups.   

In all 2 rail track, the outside rails are insulatd from each other providing the 2 poles.    In 3 rail mostly, the center rail is used for one pole and the 2 outside for the second pole.   

Many 3 railers with more modern track or with work, use one outside rail for signaling and detection.    It has to be insulated from the other outside rail in these cases and also broken into the signalin blocks.

you could gut a 3-rail engine of all electronics but the dc can motor and hook a dc power supply to the center and outside rails.

actually, I have done this but only temporarily with a weaver rs3.

I have a friend who has gone to straight DC.  Buys burnt out engines, pulls guts out, wire direct to the DC motor.

Somewhat off-point: Unless you plan to re-wheel all your locos and equipment, one could not use typical (almost universal) 3-rail O equipment on 2-rail track (which needn't be DC; could be AC, also). The wheel sets and axles are not insulated, as we all should know... 

Using DC made the electromechanical E-unit stop buzzing. However, I understand that there then sometimes/often ensued an overheating problem with the DC-run E-unit. Not sure about that last point, but it makes some sense.

I have heard, over the years, many discussions about 3-rails, DC and AC, and there is, among many out there, a complete misunderstanding on the point. I am sure that most of you here know better, but 3 rails have nothing to do with AC or DC.

You can send both through either just fine, so long as the equipment is wired for it. "2-Rail TMCC" from Atlas and Weaver is AC, all day long. I've heard so many comments over the years about "Lionel needing 3 rails because it is AC". I even heard that once from an HO guy who is otherwise pretty sharp.

I am already making mental plans to DC my favorite locos when all the electronics go in the future, and cannot be replaced or repaired. Oh, I love it, mostly, but that scale Lionel 2-6-6-2 with the can motor will run just fine on straight DC - no sound, no boards, no cruise, but will still be 3-rail and not dead. Fortunately (well, not really), the boards will outlive me, at this point. 

Worth noting that LionCheif/Plus run on either AC or DC right out of the box.  I think TMCC and Legacy would run equally well but for one problem... the track signal requires AC to broadcast, so there was no reason to insure they would have operated on DC power.  Perhaps one of the folks that knows more about the design of the electronics could confirm or refute this, but I would imagine the very first thing that happens in any locomotive with modern electronics is that the pick-up rollers are connected to a bridge rectifier and the power is converted to DC.  

JGL

Of course, you rip out the old boards and go with DCC.

D500 posted:

Somewhat off-point: Unless you plan to re-wheel all your locos and equipment, one could not use typical (almost universal) 3-rail O equipment on 2-rail track (which needn't be DC; could be AC, also). The wheel sets and axles are not insulated, as we all should know... 

 

The 3-rail is an interesting pre-plastic hangover that lets the non-isolated wheels and old tinplate stuff run with a few layers of cloth and phenol for the hot side. I like being able to run the old stuff, but ay-ay-ay, the E-units! I like to try and operate a little as well as watch them run - old E-units are a pain on that front.

I am slowly DC'ing my small Gilbert Flyer loco collection (more E-unit frustration). I was curious if anybody was doing the same in 3-rail since all the modern locos have the DC cans anyway, and the extra electronics seem to be high-maintenance (going by forum posts on the subject).

Here's some old Flyer converted to DC can motors and DC track power:  

I'm not a fan of complicated electronics, and will probably go straight DC on everything in some form at some future point. It probably won't be long (tomorrow?) before there's a universal after-market package that lets us Bluetooth through our smart phones and get some non-tincan sounds to that wi-fi subwoofer in the room. Then the center rail gets torn out and we're all super-battery powered. 

My original thought was to see if any established 3-rail straight DC layouts are running out there.

One of the other advantages of DC in 3-rail is that open-frame (Pullmor) motors tend to operate smoother and quieter, ditto with (some) operating accessories.

Along the lines of the 'other advantages of DC', my Atlas switch machines seem to do better on DC, I am going to convert them to all DC operation. I also have an old Lionel crossing gate that requires the user to wear ear plugs when operated on AC, it is just about completely silent when using DC.

I have a quick change set up for running trashed locos that I have wired for DC. My post-war stuff will also run on it but they seem to run hotter but that may be more imagining than factual.