With the question posted, I'll add my idea separately.

This is specifically for a tender truck, so I want it to be able to collect current through all wheels.  For that reason, I would get NWSL to custom make a set of wheels on half shouldered axles.  The shoulder would fit into a simple, easy to make hole in the side frame and serve as both bearing and electrical wiper, and the half axles would be inserted into styrene tubing to keep the two sides insulated.  So far, I have a simple way to collect power with a minimum of drag.

The side frames would be soldered up from brass .010"x.030" strip.  If I can find .015"x.030" strip, I could use that for the (usually heavier) top bar.  I might also see if I can find .040" instead of .030", but I think either one would work.  The journals would be square brass tube, with round tube to fit over the axles soldered inside.  The center posts and bolster would be a section of rectangular brass tube, with dummy leaf springs inside.  I'd have to make a clamping jig to hold everything while soldering, of course, probably out of wood.

I'd probably make the journal box lids out of styrene, and glue them on with epoxy or super glue.

The bolster would be plastic, to insulate the side frames form each other.  I'm thinking that a square styrene tube would be the simplest bolster, and could be easily built up or cut down to suit a given model.

I'm still working on the attachment between the bolster and side frames.  One idea would be to leave the springs out of the side frames, but solder a plate in behind them.  I might even just use a piece of rectangular tube with a side cut off, or brass channel, to form both the plate and posts.  A hole in the plate would admit a screw into the bolster, allowing the side frame the freedom to rotate.  A dummy spring could be glued or otherwise put in place over the screw head.

I think that the hardest part of the whole process would be making an accurate assembly jig.  Once that's done, in theory everything ought to more or less fall into place, I would think.  I think....  As I said, I'm completely off my rocker.

Tahoe Model Works has a couple of very nice HO scale arch bar trucks available. One follows an AC&F prototype. These show up in many AC&F builders images. They may have been the final progression of arch bar construction and design. Here's an image:

http://www.caboosehobbies.com/catalog/images/catalog/8126/8126203.jpg

They also have an arch bar with a five-foot wheelbase. This was used under some early Union Tank Line tank cars and short ventilated box cars like those rostered by the Atlantic Coast Line. Some cabooses had similar trucks but were equipped with a leaf spring package. I can't find an online image right now but with a shorter wheelbase these have a more pronounced angle on the metal chord that runs across the top of the truck.

I've been using several Tahoe trucks on my 1926 era equipment and find few other products that equal the detail and engineering quality.

As for building your own, that would be an interesting exercise. I'm certain it can be done, but the numbers needed to equip a fleet could be staggering. Even if you are only considering specific applications for locomotives. A problem with the prototype arch bar trucks was the number of parts and bolts that constantly needed to be checked and tightened. Even using our current crop of 21st century adhesives, I can still see this as a long term problem if building your own for an operating fleet. Developing an easy to fit spring package to alter the appearance of a commercial offering may be easier to do to equip a number of tenders and cabooses.

I look forward to your reports on this modeling aspect.

Eric

I think that the only way to actually build a truck the way you want it is to start with a lathe or mill and build your own wheels and axles from scratch.

Does Northwest Shortline even do custom wheel sets?

They used to, so I assume they still do.  I had a set of HOn3 wheels, axles and bearing made up, and remember the cost being quite reasonable.  I don't think they make a half axle with a shouldered end as part of their regular stock, so that might cost more.  If I were to tackle the job, I assume I'd want to order as many wheels as I might ever need.

... scatchbuilding trucks will be a lot easier because insulation is not necessary..

scatchbuilding trucks will be a lot easier because insulation is not necessary..

..But only for those few who have an RC layout, and only if they have no power on the rails, and only if they build models which will never run on a track-power layout.

That leaves me out, for a number of reasons.  I find it amusing that there is much the same debate (track power vs. radio control) over on the large scale forums, where battery power is still only barely viable and requires compromises.

"Barely Viable??"

I've seen enough layouts now where it's more than proven to be not just viable, but reliable too.

my problem with the masses is how it's always "Either/Or!"  It's always BLACK versus White. 

I am of the belief that the tracks is the best transmission line for power, but as proven for transmission of information, it has been proven that the rails/wheels have to be absolutely clean to a level that is simply incomprehensible.  DC never saw so much track cleaning as we do now!!

Thus, the Air is the best means of transmitting information.  As long as the decoder has a power source, it will receive 100% of the commands you send, interference being nowhere near what it used to be.

In your case, I do believe you still want your trucks to be rail insulated - that will remain the best setup for all time. 

There's some promising results coming out of the 3D printers - you might want to check out the trucks that are for sale on the Model Shapeway's website.

http://www.shapeways.com/model/95280/swing_motion_truck___22_7_mm_axles.html?gid=mg

"Barely Viable??"

Yes.  If you run very large steam locos with long haul tenders, or a dedicated consist of diesels, so that you can hide a sufficient battery, I'd call it a viable control method.  If you just want trains to go around, so that you can keep the locomotive coupled to a battery trailer, I'd call it viable.  If you don't mind 8 hours of charging after an hour of running, or keeping a fire extinguisher handy in case of a fire after a quick charge, it works fine.

But what about somebody like me who wants to run small locomotives, and switch a yard, and have trains running for hours sometimes?  You just cannot hide enough battery with today's typical battery technology.  In G scale.  I just cannot imagine how it can be done realistically in HO.  Maybe in the future, as batteries improve and shrink, but right now, it is not viable.

My point is that I cannot call battery power universally viable in any scale - N, HO, G, or full size automobiles.  Battery technology has not advanced enough yet.  I'm sure it will, but right now, it's only suitable for some purposes, not general use.