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MORE ON: MARKLIN STEAMERS AND ROKUHAN TURNOUTS

 

After this thread first appeared, I queried the Nn3 Group during one of our semi-monthly Zoom conferences. One of the UK members of that Group encountered issues with some of this Marklin steamers. He did some checking and found the back-to-back wheel dimension on these was "tight". He widened this out to 5.2+mm and had no further problems with them running through Rokuhan turnouts. The NMRA Standard S4.2 lists 5.28mm as back-to-back for Nn3 and 5.44 for Z. Not sure why the difference. I was part of the NMRA Technical Committee that came up with the Nn3 standards in the 1970's, realistically recognizing that for most modelers "Nn3" was only practical utilizing Marklin Z components. I did not participate in the development of the Z standards.
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Tom K. NMRA MMR#101
 

That is very interesting.

What is the best way to make this expansion? I would be wary of popping the wheels off the axels. Also, all those new drive rod assemblies look cool but they are very delicate and don't hold up well to handling much.

On Wednesday, March 30, 2022, 06:59:10 PM EDT, Thomas Knapp <thomasknapp@...> wrote:


After this thread first appeared, I queried the Nn3 Group during one of our semi-monthly Zoom conferences. One of the UK members of that Group encountered issues with some of this Marklin steamers. He did some checking and found the back-to-back wheel dimension on these was "tight". He widened this out to 5.2+mm and had no further problems with them running through Rokuhan turnouts. The NMRA Standard S4.2 lists 5.28mm as back-to-back for Nn3 and 5.44 for Z. Not sure why the difference. I was part of the NMRA Technical Committee that came up with the Nn3 standards in the 1970's, realistically recognizing that for most modelers "Nn3" was only practical utilizing Marklin Z components. I did not participate in the development of the Z standards.
--
Tom K. NMRA MMR#101

 

I'd stay away from this "fix". Not all loco's need this adjustment.

Recently I took a 2-10-0 apart to clean. I broke both sides of the power pickups...bent too many times. I also couldn't re-assemble the 10 wheels. I couldn't figure out the 1/4 turn offset. Broke 3 cogs (pin that connects the wheels). In the end, I paid top doller for an expert repair person to obtain the part and reassemble. Not opening another loco again! I met my match. It's my favorite steam loco.
 

Such one was the first Z-loco I dismounted... (... yes I know, but I was young... ;-) )

The point is: The four cog-wheels between the coupled axles looks same but are not! Have a look at the exploded-draw () No. 20 on the draw has one cog more (or less, I don't remember exactly) as the other three (No. 19). So if you mixed theat four cog-wheels, you have to count the cogs of this pieces.

This principle is true for other steamers too.

Have fun (and "acrobatic" fingers)
Arnim

Am 01.04.22 um 21:01 schrieb Kian Holstead via groups.io:

I'd stay away from this "fix". Not all loco's need this adjustment.
Recently I took a 2-10-0 apart to clean. I broke [...]
 


--
Anthony,
Since converting my first Marklin Mini Club steam locomotive to Nn3 in 1972, I have disassembled and re-assembled dozens (if not hundreds) of Z steam locomotives. Removing the driver assembly and gears is not something to be taken lightly, so my first choice for widening the back-to-back would be to press a tapered shim between the back of the wheel and the chassis to lever the driver out a bit while the driver assembly and all gears are still within the chassis.
Tom K.
 

That's a good idea. I have been experimenting with adding sound decoders to my steam locos and in the process I have inadvertently popped the pin out if the new driver assemblies a few times. I have been able to get them back (usually) in place but it does require many tries, A LOT of patience and a steady hand. Also, some trial and error; put back if it looks right, test on the track and see if it runs smoothly, it will tell you if not, then pop out and try again. So I like the idea of a solution that doesn't require messing with opening the bottom plate or involving the driver assemblies.

On Sunday, April 3, 2022, 05:20:20 PM EDT, Thomas Knapp <thomasknapp@...> wrote:



--
Anthony,
Since converting my first Marklin Mini Club steam locomotive to Nn3 in 1972, I have disassembled and re-assembled dozens (if not hundreds) of Z steam locomotives. Removing the driver assembly and gears is not something to be taken lightly, so my first choice for widening the back-to-back would be to press a tapered shim between the back of the wheel and the chassis to lever the driver out a bit while the driver assembly and all gears are still within the chassis.
Tom K.

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