Conversion on European layout

Hello Riccardo, The US O-Gauge system is a three rail system. The standard is 60 cycle AC. You are correct, this AC is converted to DC by a rectifier built into the engine. In the older Post-War, or after WW2 engines they did use open frame AC motors, but today almost all engines are produced with DC, flywheel equiped motors.

 

Direction is controld by an electronic device called the E-unit. Please don't ask me why it's called an e-unit. It is a hold over term from the early days of electro-mechanical direction control.

 

The two outside rails are used for return, or (-) and the center rail is used for primary input, or (+). This 3rd rail configuration has become a standard because the second return can be used to drive accessory devices. It also provides a better ground return and allows for a one switch turn around, or loop-back with no special circuits.

 

In the new control systems such as Lionel's Legacy or TMCC and MTH DCS electronic signals are used to control the engine. This is true for not only direction control but also many other features.

 

With the Lionel system  control signal goes out on the outside rails and on the MTH system the control signals travel back and forth between the TIU (Track Interface Unit) and the engine on the center rail. For a more detailed discription you should visit the OGR DCS and Legacy/TMCC sites.

 

In O-Scale DC is used on a two rail system.

 

 

AS for purchasing a Big Boy to take home I would talk to a dealer that deals with MTH. They, or MTH have an exstensive presence in the European market and you will be able to receive service if and when needed.

 

Lionel has customers all over the world as well, but you may have to ship back to the States if you need work done on the product.

 

I hope I have been of some help to you and I wish you a great trip to the US.

Another thing to note, you may already know MTH is making a range of European models. The latest control system, PS3, includes DCC.

Also, a good option for you, when buying American locos, consider second hand locos and older locos with no remote control feature, such as MTH PS1 locos or older brass models, that allow you to install DCC decoders, this will save you a lot of money.

I suggest however, when you are considering a purchase, come here and ask the forum opinion, there are many pitfalls and you can make a mistake, as there are so many things you will need to learn about.

That is correct.  However, some 3-rail track has the external rails connected.

This is only true of MTH engines with the "Proto 3-2" feature and 2-rail engines.  On early MTH 3-rail engines and Lionel engines the wheels are short circuited from side to side.

That will only work on MTH engines with the "Proto 3-2" feature.  However, the wheel flanges are larger on 3-rail engines than on 2-rail engines.  They do conform to NMRA RP25 or NEM 310 standards.  Your easiest conversion to DCC electrically would be an MTH or brass engine made for 2-rail.  These engines require very large curves.  At least 2 meter radius curves.  Do you have curves this large?  If not, you will want an MTH 3-rail engine with the "Proto 3-2" feature.  These engines turn tighter.

You will need a decoder that can handle at least 4 amps continuous.  If you want to run the smoke unit make it 5 amps continuous.

Hi Riccardo, when I said you could use one of the outside rails to control an accessory I was talking about the fact that the outside rails are shorted through the engine on a three rail system.

If you take a section of one of the outside rails and place isolation pins at each end of that section you could use said section as the return of any device that gets it's primary source from the same potential of that of the engines source.

If you have a gate man accessory that gets it's power source from the center rail of the track that the engine is running on and it's return wire is connected to the above mentioned isolated rail then when the engine or any three rail car passes over that section of rail the return will be shorted to that rail through the rolling stock thus providing a return for the Gateman and it will operate as long as there is some device that provides the return path.

 

To convert three rail to two rail you must isolate the only two rails you have for power or there will be a dead short when you apply power and that will not be a good thing.

That is why most HO products use non conductor wheels on one side of each truck assembly.

 

With the MTH product that Dave is speeking of above the engines are designed in a way that makes this conversion as simple as modifying the truck assemblies. I believe that the new MTH engines all come with these kits.

With 2 rail systems you can only get the + from one rail and the - from the other.

Even with two rail AC operation, such as the American flyer S guage line the rails must be isolated. When one side is pluss the other must be negative and never shall the two meet other then through the motor.

An 0-72 engine will most certainly derail if it tries to enter an 0-31 curve. Some 0-72 engines are barely comfortable with 0-72, other models (not the same locomotive) might be able to get through as small as 0-54. The reason is not the size of the flanges (that's for running on round-headed sheet-metal rails) but the lack of them on the center axles--typically only the first and last driver wheels have them.

 

Since you're looking for a Big Boy, it's important to understand that in the US 3-rail market, there are scale-proportioned models, and then there are under-size models intended for people whose layouts are too small for the larger locomotives. Under MTH, these are known as RailKing (or RailKing Imperial with extra detail), and under Lionel, they're known as Lionmaster.

 

The Big Boys marketed under these two product lines will travel through a 0-31 curve, but only because they are about 2/3 the size of a scale-proportioned model, and both sets of drivers pivot under the boiler. On the scale models and the real thing, only the front set pivots (from the end opposite the cylinders), and the rear set is fixed. Lionmaster and Railking articulated steamers have two motors, and scale versions have one large motor.

 

---PCJ

http://www.ebay.com/sch/i.html?_nkw=Big+Boy&_sacat=19145&_odkw=Big+Boy&_osacat=19145

Riccardo,

Somewhere above a statement was made that "the MTH Big Boys run better than the
brass", which is not necessarily true, of course.

Not to criticize MTH; I love their products. But, on eBay, there are available, from time to
time, UP Big Boys (and other large brass steamers) from Williams, marketed 15 - 20
years ago. They were made in both 2- and 3-rail versions, I believe. They are brass,
made in Korea, the detailing is basic but correct, the quality is good and they run
very, very well. They are "conventional" (analogue) locos, running on AC (3-rail) or
DC (2-rail). Easily updated to a "command" system of your choice. They are often
obtainable for $500 or so; I have seen them go for less, in excellent shape. The gear
ratios are good. The same maker also built brass steamers for Weaver (a GN 2-8-8-2,
for example), and these have the same good characteristics as the Williams units. The
3-rail locos will negotiate 72" diameter (36" radius) curves. 

In other words, the loco you seek is available for not a ridiculous amount of money,
even after an upgrade.