How to Trick Athearn Trucks

At some point in most projects you have to draw a line in the sand - you just have to say that the "insanity stops here". I will not scratch build the NBW castings or draw the brass wire to the proper diameter. It’s as bad as the rivet counter guys on some days. I drew the line at the trucks with the on going saga of the U6b’s. I was not going to design a gear train and create the gearboxes etc., etc. What you see in the first picture is all the stuff that $47.92 will buy. I purchased it from Athearn to alleviate that problem for this project; at least partially, including a box full of Styrofoam peanuts. There were, however, some problems.

It was delivered from Athearn/Horizon Hobby for twice the shipping cost. The roller bearing caps are in the bottom bag. The big bag contains 12 worm gear caps (the minimum order)

A three axle truck for a four axle locomotive isn’t going to work. The wheels are too small.  The mounting system is wrong.  The side frames are not useable but lucky for me all this is easily fixable and I get a solid reliable gearbox and axle set in the bargain.

For those of you who don’t know, Athearn got sucked up by Horizon Hobbies and they moved some portion of their operation from Long Beach, California to Long Beach, California!! Or so they said. The customer service people who I deal with suddenly acquired a distinctive accent, and the spelling went south in our e-mail communications. They are very helpful and eager to please but sent me a set of roller bearing caps in HO that I neither ordered nor wanted. Ordinarily I would have commended them for their attention to detail but I specifically told them several times that this was for an “O” scale model. Their shipping charges also doubled during this transaction even though the postage on the box was only half what they charged me. Not good. The quality of the parts is excellent so I don’t feel too bad about all of the above except I have the sneaky feeling someone in Long Beach lost their job during this “move”... maybe it was Long Beach, China?

The fixable stuff is pretty easy. The side frames just pry off with a small screwdriver. If you want to keep or trade them be careful, otherwise just hack away at ‘em because this project doesn’t need them. Next, the plastic clips.  One on the bottom, two on the upper ends and one on the top. The new design Athearn trucks have these plastic clips and a slightly different design requiring a little different approach to the attachment of the center pin. Pop them off with a small screwdriver and be careful because they will “pop” off and be gone if you aren’t easy here. You will need them to reassemble the truck. You should be able to take the whole thing apart now, including the wheel sets with their little bronze bearings and the gear train. If you are building an “O” scale model you will no doubt want to change out the wheels because the ones supplied measure out at about 24 inches. Too small for even the smallest GE industrial switchers like a 44 tonner. NWSL has replacement wheels that drop right in to Athearn units. Actually they push in/press fit. The ones I bought are 30 inches in diameter. A little shy of actual requirements but pretty close. They are dramatically larger than the Athearn supplied wheels. To have the exact wheel diameter made there was a set up fee that was more than I wanted to pay at the time but if the discrepancy bothers, you might want to look into it. They are really nice folks to work with. And now is the time to consider Proto 48 standards for the wheels. I don’t think I’m schizophrenic. It’s a matter of controlling things I can and ignoring things I can’t. When I finally do go back to NWSL I will order Proto 48 wheel contours and find out what happens.

The part I bought was NWSL# 37896-4, On30 30”/110 3/32” ½ axle inside frame Athearn Pkg of 8.  (Enough to do two trucks)  $14.95 plus shipping, $5.95, fair enough.

Comparison of the NWSL On30 30” wheel set and the as delivered Athearn SD40 HO scale wheel set.

The four axle problem with a three axle truck is solved by taking the middle axle out and its associated drive gear. If you need a three axle truck, it is worth investigating the possibilities. You might want to think about how much space is in there to fit traction motors, assuming you care about the logic of the thing. If you stick to a two axle truck don’t just twist the wheels off and leave the gear in place. They will jamb the works. Don’t ask how I know.

For the U6 project I am doing something a little different. This pair of engines is going to be operated together permanently. They will be coupled with a draw bar and used as power for a unit train hauling salt hoppers from the mine to an unloading facility. I don’t need too much tractive effort but I do need internal space to fit electronics and speakers for the sound systems plus all the inside detail that is going into both units. Therefore the “B” unit is only going to have one truck powered to gain the extra needed space. I know it sounds odd for an “O” scale model to be restricted this way but it is a small prototype and narrow gauge at that and not much larger, really, than an HO model. This requires two different modifications to the stock Athearn trucks as I’ll note a little later.

The top clip is modified by drilling a hole in it 1/8” in diameter. I use a number of smaller drills to work my way up to the final finished size. In my particular instance the hole was 5/16” from the front face of the gear tower. It might be different for your mounting design. I used a pair of dividers to mark the location on the clip. I then cut a piece of 1/8” diameter styrene rod about 3/16” long and glued it into the hole so that it was flush with the underside of the clip.  I used CA adhesive for this. If it protrudes below the under surface it will interfere with the gear train. Later, when I mount it in the locomotive underframe I’ll trim the styrene rod flush with the bolster top. All of the trucks get this modification. The unpowered truck, in addition, gets all the gears removed from the gear box and, of course, you will not install the worm shaft and gear to the top of the gear box either. You will, however, install the worm shaft cover as that is also the truck retainer clip that holds the whole truck assembly onto the underframe. Don’t take the gear thing too seriously as the gears on the axles must remain in place as they hold the wheels on!! Those gears won’t be meshed with any others though. The point of this is we’re trying to reduce drag and let this unpowered truck roll freely.

Measuring the distance for the pivot pin location.

You now have a drive system that will work when you couple it up to a motor and flywheel with u-joints and drive shafts.  These are cheap and available from a number of sources. Or not so cheap, if you so desire. 

You now have a drive system that will work when you couple it up to a motor and flywheel with u-joints and drive shafts.  These are cheap and available from a number of sources. Or not so cheap, if you so desire. 

More Power Scotty!

Something has to be done with the metal tabs that have the power lead wires soldered to them. In my installation they are in the way of the underframe and won’t allow the truck to pivot. I cut the plastic gear box away from that portion around the tab that would allow it to be bent over and clear the underframe. The photo shows how that was done. Hopefully, snaking the wire back up into the engine compartment will allow it pass as a traction motor cable. This new power truck design makes wiring everything much simpler. The old Athearn truck required a new bronze wiper pick up and separate wiring harness due to the modifications of the old style that had to be done in order to fit my scheme. 

The small plastic tab directly below the metal prong to which the power wire is soldered must be removed in order to allow the power wire prong to be bent over to clear the under frame. An easy cut with a single edge razor or #11 Xacto blade. 

Now Comes the Misdirection

All good magic tricks use misdirection. And while we have been hacking away at the innards of Athearn’s good works the trick won’t be satisfactory until the illusion is complete. We need sideframes and accoutrements. How you want to accomplish that and how far you want to go with the extra detail is up to you. A few hints are in order though.

As mentioned in the last installment material selection is important. If you are building one engine and you don’t have resin casting materials you might want to go with brass unless you are modeling a cast sideframe. Making a master and casting is probably the only real solution unless you want to try 3D printing. Maybe combine 3D printing and casting.  I’m still working on my CAD skills so can’t report to you on how the 3D thing works yet.

On the left is the completed “dummy” truck. Note there is no gear showing at the top of the gear tower. The power tabs have been bent over to clear the under frame. The right truck is a power truck still in the process of conversion. The brass channels are CA’d to the metal side pieces that are riveted to the plastic gear boxes after being scraped of their finish with a razor blade and cleaned with alcohol. They are the sideframe mounts.

Completed sideframe assembly with sander piping and brake cylinder but unpainted or weathered.

Don’t forget details like sander lines and brackets as well as truck cut out cocks and brake cylinders and rigging where it shows. These details can run into money and you can add them later but often once passed by, are forgotten.  If possible, do them while you have these sub assemblies handy to work on.

Another Possibility, 
Tricking the Whole Thing!

I have a project rattling around the back of my mind that would be based on the entire Athearn SD40 chassis and drive train. It would be a six axle locomotive resembling the DL535 Alco’s that ran on the White Pass and Yukon.  I think I could justify the traction motor problem by claiming there were only two per truck and the middle axle was unpowered, there, only to spread the weight that might be a problem on light rail narrow gauge lines. Which would also justify the equal axle spacing as the traction motors would hang facing inwards in such an arrangement.  There would be noticeably less work to do if you started with an entire powered chassis and I think I could manage the cost problem a little better. For instance, I think purchasing the entire powered chassis is cheaper than buying just the trucks and all the covers etc. that you need to get them to function with another motor and drive train. If the chassis really turns out to be too short, there is probably no good reason it can’t be lengthened enough to fit what I need to make things look right. Just planting seeds for future harvest.