Hi Howard,

You will get as many answers as there are readers to this.

The only purposeful way to get an answer is to buy C or K track and test them yourself.
However, I might save you some expense by trialling exactly what you want.
I have a C track layout with all the regular track pieces you mention, and I also own a lot of US rolling stock you mention.
These mostly have RP25 (standard NMRA wheel profile) metal wheelsets, and I suspect may be a bit "jumpy"on the switches.
In the next few days, I will trial some trains with a mix of stock, and let you know the result.

Kimball

Hello Howard

Been dealing with the subject for many years.

I'm not re-writing the book, because it ain't no book!

You have given the main answer already : wheel spacing!
If a 2-rail vehicle derails, check the spacing !
You will solve 95 % of the cases by readjusting
All you need is the gauge from Fohrmann and a wheel spacer to do the job :

Fohrmann HO gauge

Fohrmann wheel spacer

It is a small investment but you'll love it.
It will save you money and, above all, aggravation : you'll never again will need to search for "replacement axles" (they are often hard to find for older equipment, if at all...)
It will allow you to return you 2-rail vehicles back to their original setting, should you ever need it ...

Now what about the last 5% of the problems?

They mostly always come from the flanges depth.
The RP 25 /US style or the "Fine scale" profiles can be a problem, but less so if they are already regauged to 13.8 mm .

The good news is that with C-track , they will be very limited, or not there at all!

From my years of living in the US I collected a fair amount of RP25 compatible vehicles, including locos.

They all run on my C-track layout , after some adjustments as described above.

Only in a few locomotive case , did I replace the RP25 wheels with Märklin ones, essentially on some diesel locos .
That however is another ball game requiring often a lathe, a precision wheel press with the proper inserts and the ancillary tooling.

Converting 2 rail/ RP 25 locos to run on Märklin C-track is indeed another subject, but I'll share whatever you'd need when it would ever come to that.
Suffice to say, ** it works** and the only limitation is the minimal radius (R1 is often out, R2 is OK for 90%, and I have a path using only R3 and above on the layout to operate these big machines when needed.

But a UP Turbine operating on a SBB Gotthard style layout is a sight to behold, and well worth the effort!

Cheers

Jacques

There’s a reason Jacques is known as Dr. Eisenbahn ;)

Hello again everyone,

I'm just replying quickly here, to thank everyone together, for your help and advice, instead of thanking everyone separately.

It is good to know from your testing (everyone), many of the 2 rail freight cars can operate well, on Marklin C track switches (turnouts, points).

I know it will be easier to change wheelsets on many European brands (if needed) such as Piko, Trix, Hamo, Brawa, Fleischmann, Roco, Tillig, Liliput, etc. Many offer 3 rail wheelsets, or a compatible Marklin wheelset can be installed.

But none of the freight cars typically used in North America, have 3 rail wheelsets available from the manufacturer (such as Athearn, MDC/Roundhouse, Atlas, Walthers, Bachmann, Life Like 2000, Stewart, Bowser, Broadway Limited, Kato, Mantua/Tyco, Varney, etc).

I know both Marklin and Trix offer locomotives and freight cars for US railroads. Marklin for 3 rail, and Trix for 2 rail, respectively.

I currently only have a few Marklin train pieces. Most of my collection is 2 rail, DC powered trains, those typical in North America. But I will be buying more Marklin trains, because I like them. I like the easier wiring for complicated track work, such as wyes and reverse loops. I like the replaceable parts for the motors (brushes, etc). I like that many Marklin locomotives have metal bodies, and most vintage models are easy to repair, reliable and rugged.

I generally prefer the older Marklin locomotives, from the 1950's until the 1990's, because they had fewer small detail parts, that could break off. And they have AC motors that can be rebuilt. For the time being, I use analog AC power to control my Marklin trains. But I'm considering upgrading them (someday) to digital controls. Doing the 5 pole, DC magnet and digital decoder of my choice. I will probably install decoders that are compatible with MM, MFX and DCC. But I don't know yet, I'm still thinking about that. That is a future project, not important now.

I don't have a layout right now anyway, I only run my trains on the carpet. I rent a small apartment, with little space for a permanent layout.

When I do build a permanent layout in the future, I know it will have all Marklin track. I think I would use only C turnouts, for their more reliable characteristics for train running. With good condition M or K track (just the straights and curves, not turnouts) mixed in. The M track could be used in hidden areas for instance. Most 2 rail DC wheels will operate fine on good condition M track, as long as it is normal straights and curves. I would try to use the Marklin 5200 (437.4 mm radius) curves when using M track.

---

Considering:

I could include a loop of K track (radius of 553.9 mm and larger) with both rails isolated completely, with no turnouts or crossings. That way I can operate all my 2 rail DC locomotives and cars, that don't like the Marklin turnouts. I would build my own feeder tracks, with code 100 nickel silver rail for easy soldering, to keep all 3 rails completely isolated electrically. That way I can control all of my locomotives, both 2 and 3 rail.

Plus I enjoy building the 2 rail freight car kits, (Athearn, etc) and I have a collection (various brands) that I still need to build. I will not be converting my 2 rail locomotives, they will remain 2 rail. I'm assuming they will work fine on Marklin K track, as long as I keep both rails isolated electrically. And only use the regular straights, curves and flex track; and avoiding special K track, such as turnouts and crossings. And like I said, I will custom build my own feeder tracks, to make sure the rails stay isolated for 2 and 3 rail operation.

And yes I'm fully aware and know, I can't put any 3 rail wheels on the track, at the same time, with the 2 rail locomotives. The 3 rail wheels are not isolated. They will short out the track, when I try to operate 2 and 3 rail trains, on the same track, at the same time.

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Or just use regular 2 rail track (Atlas, Peco, whatever), for my 2 rail locomotives, passenger and freight cars.

And keeping the 2 rail and 3 rail track completely separate from each other. It would make some things easier.


I might just use 2 different track types on the same layout (both 3 rail Marklin track) and 2 rail (Atlas, Peco, etc), and keep them separate for the locomotives.

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Another option is using K track, modified to allow both 2 and 3 rail trains, like the ETE MODULE SPECIFICATIONS. I have downloaded their PDF file from their website, so that is a consideration for me also. I know I can use Marklin K track, and modify the turnouts and feeder track, so I can use the same track for 2 and 3 rail trains.

Decisions, decisions!!

Howard

Good shout Minot.
I do not have a DC setup but it’s good to know it could have undesired results. Safety first ;)

I bought some coach sets in the Trix version because I couldn’t locate the Märklin ones. In order to operate my auto barriers I needed non insulated wheel sets, theoretically, according to Märklin, my dealer should have been able to exchange the wheelsets for no charge but this dealer couldn’t.
Each wheelset had one plain and one insulated wheel on each axle originally so I rearranged the wheels so each coach now had two axles with all insulated wheels and two with no insulated ones, adjusting the back to back measurement to suit Märklin standard. The newly created non insulated wheelsets went at each end of the coaches and I don’t recall any problems with M, K or C points/turnouts/switches.
I used conductive paint when converting Hornby Dublo 2 rail locos into three rail ones before changing to Märklin which was successful.
ChrisG