Got my little prototyping machines up and running.

[Lemosteam]

Sight unseen, if I can do four wheels I can do eight.  Although, running in multiples one truck each may do it so they are each self powered.  Or maybe eight wheels on one or two and a dummy.  Also, if this works at all there will be plenty of room for added weight for traction.  At least I think so.

This is what I was thinking, two driven trucks, room for weight and electronics, the body becomes the chassis that the trucks pivot in, RP truck sideframes, and you have a combination for about anything on the rails.

[narrowminded]

That might also make it ideal for the Chicago el car (6200s, IIRC) resin bodies I have around here somewhere.  A Tomix chassis can be wedged in, but I would think your tiny drive might be the ideal answer, and with a little effort on my part, could get the exact truck centers and preserve at least part of the interior and underbody details.

That's actually one of my main goals with the PCC.  Turning radius and a believable interior, lit up like a Christmas tree!

(Keeping it seasonal.)

[sd45elect2000]

Speaking of Chicago, I still need to power these also.

[narrowminded]

This is what I was thinking, two driven trucks, room for weight and electronics, the body becomes the chassis that the trucks pivot in, RP truck sideframes, and you have a combination for about anything on the rails.

In my versions this far and with a coal mine loco driving the design, therefore chassis height and keeping every last fraction of a gram that I can, the width can be trouble on some body designs, especially in Z.  But I've got two and even three or four different solutions for that in the works.  One is just plain old lower (and a little narrower) and then various options where I can give up height for width.  And even one more that would be getting into Speeder territory that would be slow and not a very strong puller, just like a Speeder.   I've already done a little performance testing on that concept and it seems viable.  What's helpful is that most of those I've glanced at where width might be trouble, height usually is not.  And in N it just gets easier as there's more room.

[C855B]

This is what I was thinking, two driven trucks, room for weight and electronics, the body becomes the chassis that the trucks pivot in, RP truck sideframes, and you have a combination for about anything on the rails.

My thought exactly. If this is approached as a configurable power truck capable of 4, 6 or 8 wheels with adjustable axle spacing, combined with RP (or small-production injection), it would be possible to redefine the product universe. Not a bad idea given the production roadblocks starting to appear with split-frame manufacturing. There is at least one supplier of a power truck product for HO - Hollywood Foundry, in Australia - but it is strictly custom machining and would be cost-prohibitive for production, plus they use "standard" size Mashima motors which are already a tough fit in N scale hood units.

[narrowminded]

My thought exactly. If this is approached as a configurable power truck capable of 4, 6 or 8 wheels with adjustable axle spacing, ...

That's already been entertained and I think it is doable.  From my experience this far, plastic is not an option as it's not heavy enough in these small units to be made to run reliably but my laminated chassis halves would lend themselves to this.  I entertained making two halves (lengthwise), one long and one short.  You could select two shorts for one length, a long and a short for another, and then two longs for a third length.  You could also stack them in multiple axles, mix and match, have driven axles or skip one.  Alignment holes through would accept pins to hold them aligned.  There could also be spacers or if the weight was enough without spacers you might just space by leaving a gap between sections.  The motor bore could be through all parts and then placed where most convenient. A pin of the motor bore size could be placed in any unused portions of the bore over the chosen length... or not.  It's flexible that way.    And with all of that, the first call will be, "That thing will do just what I need but could you make the layshaft lower by another .01" because this one......"   I'm kidding of course but that request will come, too... of course.

One thing that happens is tolerance for all of those parts becomes VERY important with one having to fit the next and in metal.  It also could be a little more costly than might appear but it would give flexibility of design for one off efforts that would be prohibitive to purpose build from scratch.  I haven't thought much more about that lately as I have to finish what I've started, but it will be a logical thing to revisit once I have some of these things moved along.   

[nkalanaga]

For my Nn3 purposes, a self-powered RSD truck would be fine.  I can just as easily remove the mechanism from my units and build a floor as to swap trucks.

[nkalanaga]

My question about narrow gauge Alco trucks was basically a "wish I could have them" type.  On the serious side, there is a mechanism I'd love to see, and it's exactly the kind you've been working on.

D&RGW #50, acquired from the Sumpter Valley, was (is?) a 1937, siderod drive, Davenport.  A body kit is available from Republic Locomotive works, designed to use a Marklin mechanism.  I have four of them, and they run quite well, for a small 4 wheeled locomotive.  However, installing the rods on an outside frame locomotive requires changing the axles, which is a real pain on Marklin mechanisms.  So, Marshall includes optional roller bearing plugs for the axle holes.  I used those.

With a cast metal body, weight isn't an issue, and if you could make a mechanism that would fit the body, it could be sold in four versions, simply by changing the axle lengths:

Narrow gauge, no rods.  That's an easy one, just use flush axle ends.

Narrow gauge, with rods.  The kit includes the counterweights, so with longer axles, it would be easy to add the rods.

Standard gauge, inside frame, no rods.  A little harder for the modeler, because the frames would have to be removed from the body casting.  But that isn't hard to do, and they'd have a nice "critter" for any industry, good for any time in the last 80+ years.

Standard gauge, with rods.  Again, it would need extended axles, but the counterweights would be glued against the outside of the wheels. 

The wheels could be the same, with only the axle lengths changed, although you might need spacers, brass tubing maybe, to keep the standard gauge wheels centered.

One mechanism, two gauges, four styles, and multiple eras.  I'm sure Marshall could give you the dimensions, and he'd probably be happy to have an alternative to the Marklin mechanisms.

[Chris333]

If you go to the Nn3 Yahoo group and then "files" there is one called SVRY101 that is a blueprint of their Davenport.

[narrowminded]

My question about narrow gauge Alco trucks was basically a "wish I could have them" type.  On the serious side, there is a mechanism I'd love to see, and it's exactly the kind you've been working on.

D&RGW #50, acquired from the Sumpter Valley, was (is?) a 1937, siderod drive, Davenport.  A body kit is available from Republic Locomotive works, designed to use a Marklin mechanism.  I have four of them, and they run quite well, for a small 4 wheeled locomotive.  However, installing the rods on an outside frame locomotive requires changing the axles, which is a real pain on Marklin mechanisms.  So, Marshall includes optional roller bearing plugs for the axle holes.  I used those.

With a cast metal body, weight isn't an issue, and if you could make a mechanism that would fit the body, it could be sold in four versions, simply by changing the axle lengths:

Narrow gauge, no rods.  That's an easy one, just use flush axle ends.

Narrow gauge, with rods.  The kit includes the counterweights, so with longer axles, it would be easy to add the rods.

Standard gauge, inside frame, no rods.  A little harder for the modeler, because the frames would have to be removed from the body casting.  But that isn't hard to do, and they'd have a nice "critter" for any industry, good for any time in the last 80+ years.

Standard gauge, with rods.  Again, it would need extended axles, but the counterweights would be glued against the outside of the wheels. 

The wheels could be the same, with only the axle lengths changed, although you might need spacers, brass tubing maybe, to keep the standard gauge wheels centered.

One mechanism, two gauges, four styles, and multiple eras.  I'm sure Marshall could give you the dimensions, and he'd probably be happy to have an alternative to the Marklin mechanisms.

That sounds like a doable, too.  And I think I could make the wheels accept stubs for outside drive rods.  As they are, the wheels are machined nickel silver as a one piece wheel and axle stub inserted into the drive gear with a stop in the gear center to maintain isolation as well as set the gauge.  I have already run that prototype from the above test video on N track by simply swapping the wheels out. Took about a minute.   The gauge is set by the axle length and the gear is common to both. 

In this case the N wheel diameters are the same as the Z (Nn3) but the flange profiles and tread width are different per RP-25 standards.  I do have to finish what I started though but as things come together it will settle down and I can probably introduce variations pretty quickly.  I'm still making final selections on many of the details.  I've tested quite a variety of methods and variations for things like wheel pickup and now it's time to choose one... or two.   When that's done, then the tooling to make them more than one at a time.  But with each of these details completed and tooled, each variant gets that detail plugged in to the design, key stroke and it's done.  No reinventing, tooling (for at least the common bits) or testing needed as it's a known and proven component.  At least that's the plan. 

[narrowminded]

And while I'm here, especially for Peteski and Lemosteam, I did a little switch testing this evening with the couple of small Rokuhan switches I have and while I'm not ready to promise just yet, it's looking like some big promises WILL be able to be made and backed up.   I wasn't sure because I hadn't actually tested this exact configuration yet but experience kinda thought it would be pretty good.  I'm pretty excited about that.  I'll know better soon and when I get a chance will make a little video of that.

Today's work just underscored how productive I can be with the tools at my fingertips.  Things are finally moving in serious leaps and I'm HAPPY!

[VonRyan]

When can I sign up to beta-test some of these chassis?

I'm thinking one of these might be a better option for powering an eventual 3D-printed model of the County Donegal Joint Railway Committee locomotive No.11 "Phoenix".

https://thewandererphotos.smugmug.com/RailtoursPreservedRailways/2012/UFTM-190212/i-5rZpXZ9

[peteski]

And while I'm here, especially for Peteski and Lemosteam, I did a little switch testing this evening with the couple of small Rokuhan switches I have and while I'm not ready to promise just yet, it's looking like some big promises WILL be able to be made and backed up.

Nice! Any time a tiny 4-wheel power chassis can reliably go through commercially-made turnouts is a very good news.

[narrowminded]

When can I sign up to beta-test some of these chassis?

I betta' test 'em pretty good myself before I starts ship'n 'em out.   

[nkalanaga]

From personal experience, both Marklin and MT Z wheelsets work fine on N RP-25 track, and every N wheelset I've tried worked on Marklin track, unless the flanges were too deep for the frogs.