Hi,

I’m looking to convert a GP9 or 7 or any other transition era North American two rail DC loco to three rail Märklin.

Has anyone got experience on what manufacturer / model would most likely end up with a good result? Things to consider are wheel profile and bogie suitability for mounting the pickup shoe.

Electronics is not a problem.

BR,
Eino

Hello Eino, all,

For inspiration you could read this topic:
https://www.marklin-user...s-to-3-rail-power-pickup

As stated in that topic, think before you start because in my case it was a lot of work and expirimenting.

In case you try to convert a 2-rail model, good luck and succes and please, show us the result.

Tony.

Hi,

Have you looked at Alsterstreek's posts? I remember that he once showed some of his US conversions.

Carim

Also look at some posts by Jvuye, including,
https://www.marklin-user...stock-on-Marklin-M-track
I have not seen any posts by Jvuye for a long time. I hope he is OK

I still see his biking posts on Facebook

Regards

Mike C

There's some information on DC wheelsets in one of my old posts that might help you.

https://www.marklin-user...elsets-and-Marklin-track

In my very, very limited experience changing the spacing has been successful for everything except passing through the one double slip switch on my layout. Here the sharper flanges of the DC wheelsets (all ROCO items in my case) sometimes catch on the tips of the small double slip switch blades. Not often, but often enough to spoil otherwise trouble-free running and for me to order a full set of the correct AC wheelsets - which are supposed to arrive tomorrow.

Excelent! I ordered that tool and also a pull of device!

Thanks!

-Eino

I would go for wagons/coaches that already have a pick up shoe, i.e. wagons that you put at the end of the train with red lights. The decoder has to be mounted on the locomotive itself, obviously. Wagons like Marklin's 4411
Both loco and coach/wagon need to have NEM coupler pockets for you to be able to insert current conducting couplers
Mainly, install the decoder and instead of attaching each of the decoder cables to the left and right bogie, one goes to the coupler 😊

Hi!

He's a part 2 video of progress with this project:



A few problems I'm hoping that you guys can give good ideas:

1. Pickup clearance. Technically everything works now, but the loco could be lifted just 0,5 to 1 mm so that the wheels would provide better tractive power when going over a turnout. Also on those occasions, theres a dragging noise.

I'm thinking of adding traction tires. I guess those could elevate the loco by "point-some millimeters". The issue is only at the front end where the pickup shoe is... But how do I get the grooves to the wheels though?

2. Wheels are eccentric.

I'm quite sure this is because of the bearing bushes are made for the 2,3mm axels instead of the Märklin 2 mm axel. The tolerance apparently grew enough to make the wheels roll in un wanted manner.

It may also be that the cog wheel is eccentric compared to the axel, but when installing, it felt to fit quite good. No traction though as with the 2,3 mm DC axel, but I solved that with super glue. The cog wheels were not wobbly at all, just not tight. That is the reason I think the bearing bushes are the issue.

Now the bearing bush is a dead simple component. A brass square with a hole in it. I could most likely call a machine shop nearby and ask if they would make me suitable bearing bushes with smaller holes. But I'm not sure what the size of the hole would be? 2,05 or 2,1 mm? I can't measure the current holes since they are so small that my measure does not fit.

While at it, what if I'd order custom bearing bushes and have then me rectangle instead of square? They could be 0,5mm taller than wider and that 0,5mm would then add to the elevation... Do you think that the cogs would still work as expected?

Thanks!

-Eino

Just an update!

Been working with two locos now, the Athearn GP40-2 above and also Proto 2000 GP9.

Both share the same bogies, wheels, gears and bushings.

With the GP9 I discovered that there is no reason to unpower the other axle on the pickup shoe bogie. The pickup shoe can be installed in the middle so that the knuckles at the ends will go over the ends and work like a magic. And they must, because othervise the depth will not be enough. This job involves a hobby knife, a little piece of sheet styrene (to make a floor for the pickup shoe) and superglue. And of course the pucnup shoe. Choose 206370 for the extra flatness. It’s about an hour of job to do it…. Maybe more on the first time around.

Look for a model that has a bogie that looks like this:



With this discovery I came to realize that the DC wheels do not need to be changed to Märklin wheels. Changing to Märklin wheels made the GP40-2 axles eccentric, which led to bangging/rattling running noise. The GP9 runs very well on C track with the DC wheels and does negotiate all turnouts and R1 curves. Also on straight K track. I’m going to change back the DC wheels to the GP40-2. Just make sure to narrow the inner flange distance to 13,8 - 13,9mm. It’s important!

Also these things have massive tractive power as they are so heavy. With four axles at least. Three ain’t quite enough. So no traction tires required.

I’ll be making more videos when my Loksounds 5s and 21 MTC boards arrive.

-Eino

Hi guys,

I'm gonna make a last part of the "how to" series soon, but meanwhile, enjoy this work in progress SD45 Athearn blue box running on Märklin:

All six axles are powered. Original DC wheels, but with ~13,8 - ~13,9mm inner flange width. A long Märklin pickup shoe, not sure which part number, but I think it's the longest available and of course Loksound 5.

Thanks!

-Eino