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I recently was able to acquire this vintage Walthers Heavy Mikado.  It has the Walthers Poly-Drive which I realize is a challenge to get to operate well, but after seeing a YouTube video of one on a 4-8-4 locomotive I figured I'd take the chance.  I'm not sure on the date, but it is a cast shell.  I'm guessing 1940's, but I'm sure there are many experts here who would know better than I would.  More photos when I have a chance to get it apart and inspect the drive system.

My plans are to strip it and detail it for an early CNJ Mikado.  The major changes will be putting a Hodges trailing truck on the rear and putting 4-wheel trucks on the tender.  The other details will mostly be brass castings.  Off course I want to get it running first, but I'm thrilled to add this bit of history to my collection.



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Last edited by GG1 4877
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Thanks for sharing Jonathan!  Can't wait to see more of the drive system, operation, and how your build turns out.  To my eye this looks like a USRA Heavy.  Did the CNJ's Mikes (aka MacArthurs) have a "peaked" boiler like this model?  (Forgive me if I'm using the wrong terminology.  I'm referring to the pronounced slope of the boiler between the sand dome and the steam dome.)

@Ted S posted:

Thanks for sharing Jonathan!  Can't wait to see more of the drive system, operation, and how your build turns out.  To my eye this looks like a USRA Heavy.  Did the CNJ's Mikes (aka MacArthurs) have a "peaked" boiler like this model?  (Forgive me if I'm using the wrong terminology.  I'm referring to the pronounced slope of the boiler between the sand dome and the steam dome.)

The original 10 CNJ Mikados were by the USRA in 1918 as class M-1.  They were built by Alco.  CNJ would go on to add another 76 Mikados to the roster between 1920 and 1925 all based on the USRA design with some differences.  The additional 76 had the wide Wooten firebox and a feedwater heater not present on the USRA provided ones.  Even so, all 86 were eventually reclassified as class M-63. 

As a result, this will make a great candidate with a little work to turn into one of those M-1 class locomotives.  While these were all scrapped by 1949 with the exception of 4 that went to the Pittsburgh & West Virginia in 1947, I am always willing to bend the time frame of when these operated to fit my 2 rail modeling interests.  The last of the CNJ Mikados did not get scrapped until 1955, so at least the class fits into my roughly 1950-1960 timeframe.  Granted that is a huge gap based on the changes that occurred on both the CNJ and the PRR during those years!

As to the model, I enjoy these vintage locomotives when I can find them, and the price seems about right.  Dennis - I thought that you might be one of the people watching this! 

Before bidding I read on this forum some old posts on the Walthers Poly-Drive and how challenging it is to work on.  However, what ultimately sold me was that YouTube video of one running.

YouTube Video of Walthers Poly-Drive

I am finally getting around to working on this project.  First order of business was to get it running which is something my  81year old father enjoyed doing on my behalf.  He disassembled the locomotive and got it running.  Today, I am out on my back patio removing the many layers of paint this locomotive has received over the years.  It has been quite the task.  Paint remover and a toothbrush has been slow at best.  I am going to get some wire brushes as a little etching will allow it to take paint much better anyway.  Just working through the tender today.

In the meantime, some photos of the poly drive and just how complex this really is.  I can see why Walthers went away from this, but at the same time it is some solid engineering to have all axles powered.



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Last edited by GG1 4877

Some actual progress on this project from yesterday and after work this evening.  Much like K4s 1361's current rebuild, I started with the tender.  Lots of layers of paint to remove that was more work than I even anticipated yesterday.  I found the wire brushes online that did a nice job of taking the paint off after a liberal application of paint remover.  Doing the locomotive might be a more delicate operation though.  We will see.  I got enough paint off the tender that I'm comfortable reworking a few details and repainting it.

The first surprise was that the sides and the top are tin, while the ends and the frame are cast brass.  Fairly typical of the era, just an interesting discovery once the paint came off.  The rear pilot came off during cleaning, which helped overall.  The Monarch coupler is operational, but a little touchy.  It doesn't take much pressure on the cut lever to spring the knuckle loose.

One item to replace is the trucks.  I want to use the trucks found in this image.  What is the name of these trucks?  They appear similar to Bettendorf trucks with leaf springs.  I see the Williams brass truck side frames are close, but they aren't as detailed as I'd like.






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Last edited by GG1 4877

What was the supposed advantage of Poly Drive? The drivers on a model engine are already connected by rods (as on a real steam locomotive) so they are all driven, even without the added complexity of  a gearbox on each axle. It seems to me trying to get both the rods (quartering) and the gears in synch would be a difficult job, without any real improvement in tractive effort or running quality.

My guess and it is a guess only, is that the idea was to provide extra torque to the locomotive that you might not have with a traditional setup.  With every axle powered by a single drive shaft it is a lot like a tank drive that is common in most 2 rail diesel locomotives.  I would also surmise that slippage is little less likely.  I'll find out more when I eventually get a place to run it. 

I would agree that the complexity of this system is questionable and is likely the reason it didn't last. According to the TCA Western website, Lionel borrowed this idea for the #726 Berkshire, but did not repeat it.

Yes, have read the same accounts and the interaction between the rods and individual axle drives apparently could send the process way off course with the slightest error(s) in rod and pin alignment, driver quartering etc.. I truly admire those here who can suss out all the issues with building up a conventional straight locomotive drive from a kit, as I have real no experience with the concept, other than disassembly and re-assembly.

To me the Poly Drive is something of a different order of magnitude re complexity,  Jonathan's project here is Fascinating.

@PRRMP54 posted:

Please post a photo of the bottom side of the locomotive. I have never seen the bottom before, just many of the top. TIA


Here is a photo per your request.  I was busy stripping paint off the boiler today.  Most relaxing day I've had all year.  In the meantime, I will be busy reattaching several detail parts that came off in the process of scrubbing paint off the boiler.  Saving the results of that for a future post.



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Got the boiler and the cab stripped today along with the detail parts that came loose during my cleaning of the castings.  It is amazing how removing several layers of paint brings out the detail.  My next task is to start soldering everything back together.  One thing that stood out when I received this locomotive was how many pieces were loose to start.  A great opportunity to put it back together in a more robust manner.

Now that the paint is off this, I have a question of the vintage for the experts out there.  The boiler appears to be aluminum while the cab and firebox are sheet metal / tin.   The details are of course brass. 



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Did you check the boiler with a magnet? I would think that Al would be somewhat hard to work for the average hobbyist, at least without some of the special materials needed. As an example of non-aluminum construction, I offer my box motor built by Bill Robbins many years ago to demonstrate at clinics how he built his cars:


The other side:


As one can see, it is built out of old oil cans. And here are two of his creations using the above method:


The box motor is mine and the combine belongs to a friend.


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Last edited by PRRMP54

I believe the Walthers drivers were mounted on splined axles, which pretty much guaranteed accurate quartering.  Since the axles were powered by a common drive shaft, I'm also guessing that the rods could have a lot more "slop" than usual without fear of binding.  This would have the added benefit of allowing the loco to negotiate tighter curves (if the center drivers were flangeless.)

Using spur gears to connect the motor to the lower layshaft makes it easy to customize the gear ratio for various applications.  And burying that layshaft down in the frame means that it's out of sight, no bulky gearbox spoiling the "daylight" under the boiler.  Sunset 3rd Rail's modern "quiet drive" has a similar architecture, but uses only one gearbox, and powers the other axles conventionally through the rods.

When Lionel borrowed this design for mass-production they made a couple of changes.  Only the end axles were powered, AND they used high-ratio, back drivable worm gears which perhaps better tolerated any difference in the timing of thrust from the axle gear vs. the rods.  It was complex and pretty noisy too.  My guess is the bean-counters forced a redesign after the first year because the double-worm drive cost more to make and took longer to assemble.

Thanks for sharing Jonathan, can't wait to see it run!

Last edited by Ted S

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