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Extending the AHM Civil War Era 4-4-0

Making a readily available but too-early model into a creditable 1880's Locomotive

By Craig Bisgeier

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For a while now I've had a bunch of old Rivarossi / AHM 4-4-0 'Reno' type locomotives in my project cabinet. I bought them very early on when I moved to modeling the 19th century, and discovered two unfortunate things about them after I had bought them: The flanges on the wheels are too big to run with code 70 handlaid rail, and the loco designs themselves are circa 1860 - 1870, too small for the 1890's. As a result, these models have languished in a cabinet for years with the hope that someday I would be able to do something with them.

Well, someday showed up very recently. I have known for some time that there were plenty of locomotives along the general style of the Reno in the 1890's, they were just longer. The photo history shows before boilers got thicker, they got longer to increase the steam generated. Why? I don't really know - I figure it was just easier to extend the boilers and frames they were already making instead of re-tooling and re-engineering for larger boilers. Point is, there are plenty of these long-boiler 1880's engines around in the books, and I find it amazing that there are no models of them available.

Well, making the AHM 4-4-0 'Reno' model longer would be fairly simple, I thought - Just cobble together parts from two identical boilers and voila - done! Well, obviously it isn't quite that easy, but I thought it was worth giving a try. Since I had a free evening I pulled a couple of identical locos out of the cabinet and got to work on them. I was a bit nervous about pulling these models apart, but I figured what the hell, if I didn't do this I would never use them at all. So who cared if I messed them up - nothing ventured, nothing gained.

First, I disassembled the locomotives. It was interesting to see how these tender-drive locos are built, as I had never opened one up before. The top of the boiler and cab come off easily once you take out the screw in the front that holds the smokestack, smokebox, pilot and steam chest together. I popped two retaining clips inside the back cab windows, and the boiler top lifted right off. Next I removed two screws in the bottom, which takes the lead truck mounting and the bottom drive train cover, revealing the axles and power pickups. It's no wonder these locos run balky - they obviously have issues with power pickup. The spring loaded barrel shaped wipers have to touch the metal drive train cover to transmit power to the motor (decoder), and it seems a less than reliable way to connect them. I will probably add a track wiper to sit between the drivers when I put it back together again to improve reliability.

On top of the mechanism, two screws hold on the weight. Taking them out and removing the weight uncovers the driveshaft and worm gear. I pulled out all of the hardware inside including a sort-of T nut that holds the drive train cover plate to the bottom, and washed all the dried old grease out of the plastic loco frame. I discovered that the section between the drivers had a crack (seems like all the frames do), which I repaired with some Plastruct Bondene and a clamp to hold the side together.

I put the frame aside after that and picked up the tops of the boilers. I chose one loco to be the donor model and one to be the master. I whipped out my razor saw and cut the smokebox off the master boiler, leaving the boiler band. I also cut off the smokebox and first course of the boiler on the donor, also keeping the band. A bit of time sanding and filing let me match up the two boiler parts, and I glued them together with Bondene. I was reasonably happy with the way it looked so far, it had the right look of an extended boiler locomotive already.

Back to the donor model. The underside of the boiler course behind the smokebox is actually mounted to the lower half of the model, which also includes the frame. I carefully cut away the boiler section I needed from the donor model frame and glued it onto the master boiler to fill the gaping hole that was left. A little careful trimming and it fit well. As I was trying to carve off the cast-on piping to the air pumps, it occurred to me that the Housatonic's locos generally did not have running boards. So I set about cutting them off and filing / sanding them off the master frame. This wasn't as easy as it looked, and ended up taking hours instead of minutes as I had expected.

I also had hoped to be able to cast this boiler after modifying it, saving a lot of effort on making more conversions like this, but I think it will be too complicated to make a mold of. I will continue to see if I can do something to make it work but at this point it doesn't look too good. There will have to have to be a lot of hand-work to re-create the job. However, I am now thinking that a casting could be made of just the smokebox and first boiler course, which could simply be glued to a loco shell with the smokebox cut off, and eliminate the need for a second donor model. I will investigate this idea further and see if it might be workable.

Back to the donor frame, where I cut off the steam chest and cylinders, keeping as much of the frame rails attached to them as I could. I attached the donor steam chest to the master boiler temporarily using the long screw and smokestack to see where I would need to cut the frame rails on the master model. There wasn't much overlap, so I ended up cutting the frame rails on the master as long as I could. And that was enough, fortunately, to meet the two parts without a splice.

From here I turned to the lead truck assembly. There is a pivoting metal connecting bar that attaches the truck to the frame, which was now too short. I cut off most of the bar from the donor model with a cutoff wheel, and ground off the spring retaining tab on the bar from the master model. I cleaned the surfaces with a file down to bare metal, and soldered one bar on top of the other to extend it from the frame mounting point to where the truck would sit under the cylinders. I had to use a high-wattage soldering gun to do this, but it worked well. Better than epoxy because the attachment is adjustable to fine tune the placement after the boiler and frame are re-united.

Before I quit for the night, I reassembled what I could of the loco and had a look at it - and I was a little dissapointed to find that it now looked a little bit too long. No big deal, really - I'll separate the boiler again and cut about an eighth of an inch out of the first boiler course, and that should get it where I want it to be. That will also help me really get the frame rails to mate up properly, and I will have to adjust the connecting bar to the lead truck too - but I think it will make for a better looking engine in the long run. A spring may be necessary to keep the nose of the now front-heavy loco from drooping, I'll have to see.

That was it for the first night. A few nights later I had a chance to work on the model again, and I started with shortening the boiler a bit. I took out that eighth inch and glued the boiler back together again. The joint came out even better this time, I was happy about that. But I also had to shorten the frame too, and this time that didn't work as well. No big deal, I can reinforce that with strip styrene later and it won't be noticed at all.

I moved on from there to the main rods of the locomotive. I considered trying to cut new ones out of some tin sheet I have, but worried because I didn't have the special rivet that makes up the 'crosshead' on this loco. So instead I took the rods off both of my locos and tried to splice together one longer set of rods out of the two. I first cut the crank pin hole off one set, leaving the rod with the crosshead rivet as long as possible. Then I measured what the distance should have been from the crankpin to the crosshead guides, subtracted the length of the part I'd already cut, and cut the second set of rods with the crank pin holes to that length.

I got some of the tin sheet out and made a small splice plate from it, and tinned it with solder. Then I built a simple jig on a block of wood with some track spikes to hold the two rod pieces in alignment while I soldered them together. Again I had to use a heavy duty soldering gun to get enough heat for a good joint. It took a bit of doing but I finally got the rods back together (had to use a really heavy-duty soldering gun to do it). After a bit of filing to clean up the edges, I put the rods back on the loco and put it back together - to find somehow I had messed up the calculation and gotten the rod length too short by about .15-.20". Now everyone including myself knows I can't add my way out of a paper bag, let alone subtract. So I should have, and did, expect this. After several choice words I took a pair of pliers to the crosshead guides and bent them back a bit so the rods would fit in them, just for testing purposes. The loco rolled back and forth well without any binding, once I'd tweaked the guides a bit. Later, I'll make up those new rods from the tin sheet after all, and solder the crosshead rivet to them. And I'll use the other guide from the donor loco instead. For now, it worked.

I now had the mechanics together enough to try the kitbashed engine out! I stole a DCC equipped tender from another AHM 4-4-0 loco I've had on the layout for a while, and reassembled the loco with the power pickups, drive train and boiler weight installed. I was really glad to see the weight was still centered above the drivers and the model did not nose-dive from the extension. I hooked up the driveshaft between the tender and loco and connected the drawbar, and it was off to the layout. I dialed up the DCC address, and voila! She moves! not real well, but I believe that was mostly due to poor pickup and no break-in time, and actually it got better as I ran it back and forth. Bouncing along over the spike heads didn't help either. But it ran back and forth pretty well, all things considered. Even the lead truck tracked surprisingly well, maybe because of the additional weight of the bar connecting it to the loco.

After I stopped running it, I put it next to some of my Spectrum locomotives, which are more in keeping with my 1890's period. Well, what a difference a half-inch makes. This loco maintains its Victorian look, but it no longer looks like an antique next to them. The extra length really brings the model forth 10-20 years or more, and it looks like a mature engine for its time, but not past its prime. In fact completing the backdating on the Spectrum locos (which out of the box are closer to 1900-1905) will help make this engine look even more correct to the period.

The next step was to find a way to turn down the flanges on the drivers to allow the loco to operate on my code 70 handlaid track.  Discussing it with a friend of mine, he said why not just pop one of the wheels off the axle, chuck the axle with the remaining wheel into a power drill and lightly hold a file to the spinning wheel to file the flanges down?  I had figured this was too crude, but what the heck - I didn't have a $1000 machinist's lathe, so it was worth a try.  I got out my Northwest Short Line Puller II and used it to push one of the drivers off the axle.  I then did as described above, and after a minute or so of light filing the flange matched the NMRA gauge.  I did the same with the other three wheels (except I pressed too hard on one of them and wrecked the hub, so I replaced it with a driver from the donor engine.

I replaced the drivers back onto the axles by tapping them gently with a hammer.  I was able to quarter them pretty well by eye, lining up the spokes in each side by eye.  I got it right on the first try!  I re-assembled the engine and put it back on the layout again to try it out - and I was really surprised to see it actually working!  And boy it looks pretty good.  I took a couple of photos in its current condition, I hope you'll agree that it had pretty good lines for an early 1880's locomotive.  Not perfect, but pretty good. 

The next step will be to strip it down once more and file, sand and paint it up as an early Housatonic Railroad locomotive by Rogers Locomotive Works.  I'm really excited about how this project is coming out, and I can't wait to do some more of them soon.  Lord knows I can use the locomotives on the layout.

A view of the nearly completed AHM 4-4-0 extended locomotive kitbash by Craig Bisgeier

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