The online magazine on the history and operation of vintage scale model trains in American OO gauge

Thursday, January 5, 2012

A Pair of Alco Switchers for the Orient

The last completed project of 2011 was this pair of Alco S-2 switchers. These both started life as Model Power HO models, which were based on an AHM model (the “Alco 1000”) that I describe further in this prior article. Also, an older conversion of one of these that I did may be seen here, but it is running with the original AHM drive with the vertical motor, which is an easy OO conversion but not a great drive. It is geared too high and only has four wheel electrical pickup.

Also in that second link above may be seen an SW-1 conversion also based on an AHM/Model Power model with a horizontally mounted motor. It was converted to run with an Athearn power truck, with a key thing to note right away being that both of these models are marketed as HO but have overscale bodies and trucks that from the side especially scale out very well for 1/76. This fact lends them to conversion to run in American OO without a lot of heroic effort.

I wanted to do a pair of these and I am very happy with the end result. The conversion is pretty straightforward. It took two different train shows to locate the models but I found two good examples with the horizontal motor setup. Step one was completely tearing down the models to repaint the frame and body. I used the original motor and the front truck of the Model Power models and modified the drive truck area to accept an Athearn drive truck, selected as it not only is simple to convert to OO but also because it has better gears and picks up power. Using the drive involved opening up the frame area to accept the larger drive truck mechanism (there is plenty of room in the cab to do this easily), making a new mounting bolster out of rectangular plastic tube (glued in the pocket where the original truck mounting was), fitting the drive, and modifying the cab weight to clear the back of the new drive. I also added more weight above the drive truck as there is extra room, leaving the model weighted just a bit heavier than it was from the factory.

The second photo shows the underside of one of the models, giving a clear view of the drive modifications. These I have described in previous articles, with a good description found here. I used the original front truck but modified it so the sideframes would clear the wheelsets (widened out on the original axle) and modified the other sideframes to mount on a ground down remnant of the original Athearn sideframe. Power is picked up from all eight wheels, and the driveline itself uses mostly Athearn parts (a couple shortened) but with the original AHM part that was on the gear tower shifted over to the original motor to make it all work.

The main compromises are the model is a bit narrow over the walkways and the wheelsets are too small in diameter. These defects are not particularly visible and are totally acceptable to me in the context of now I have a pair of models that are closely matched, that run very smoothly at prototypical speeds, and have enough power together to pull a good string of cars. Right now to begin the year I have them running with “modern” cars from the 1980s but they look great with equipment from the 1940s era on up. Plus, if anything goes wrong with the drives I can easily fix them and I only spent something like $60 total on both models! Retro-modeling is easy on the budget.

I would certainly do this conversion again and very likely will at some point, perhaps next time keeping the factory paint job. In particular, the first HO locomotive I ever purchased was the AHM ATSF version of this model; at some point I would like to get one of those set up for OO. But a more likely project will be to create an OO scale Alco RSD-1 (or MRS-1) from these body parts and the drive of an Athearn FM Trainmaster. It is great to get projects done but also great to be thinking ahead to the next one.

Finally, looking ahead for this site, I will have to slow down on posting for probably the next several months. Professionally I hit one of the busiest times of my year. I will try to have something new up every week or two, and trust that regular readers can find much of interest in the site with a bit of digging around.

UPDATE: To make the conversion a bit clearer, this final photo is of the drive with the body removed. Focusing in on the drive specifically, the first plastic part off the motor was originally on the gear tower side of the Model Power drive. The rest of the drive line is Athearn but with parts shortened to make it all fit. Wires are soldered on to the Athearn drive as well to facilitate 8 wheel pick up. Also visible in the photo are the modified weights. The bottom line being this model now runs quite smoothly, the conversion is well worth the effort.


Steve Neubaum said...

Reading this webpage here:

I wonder if, when it says the BL-2 is larger than scale, if it is a candidate for HO conversion to American OO? I thought of the AHM switcher article here as soon as I read that.

John Ericson said... looks visually for OO a bit short and probably not long enough but would have to compare one to a scale drawing to know for sure.

John Ericson said...

Following up on the AHM BL-2, it is HO scale but just a bit chunky on the details, not one to convert to OO.

Craig Owen said...

I'm trying to understand the modification, which looks good.

You changed the powered truck to Athearn to improve the drive and moved the side frames out to look more like 00.

Why did you move the wheels out on the axle? I thought that 00 and H0 are the same wheel spacing?

I think that the body is the right height, but the solebar is a bit low meaning that the roof is about 5mm lower than it should be for 00 scale.

I guess using larger wheels would increase the height slightly, but I think a spacer might be needed between the top of the truck and the chassis.

What do you think? My measurements are on my Model Power Alco 1000. The top of the cab should be 57mm high.

The top of the roof radiator grille should be level with the roof of a Deltic (from photos I've seen).

Once I've converted my model it will be running with BR MK1 coaches so I think that the height is quite important.

Looking forward to hearing your thoughts and recommendations


John Ericson said...

I may create an article to expand on this answer but in short one thing to note is American OO is 19mm gauge, wider than HO. The gauge was corrected to match the scale when the early British models came to the USA. Please check the history links in the sidebar for more, but in short no American prototype models were intentionally made with 1/76 bodies to run on HO gauge track -- but some were produced, inadvertently, by HO makers on the lower end of the price spectrum.

The overall height is a bit low on these models for American OO use. There are a couple dimensional issues when used in OO but the big one visually is the radius of the cab roof which is arched too high. As a result the hood is a bit low too.

Essentially this was a model intended to be put in train sets, not a great scale model. It looks nice in OO and would be a good starting point for a more finely scaled model but would take some effort.

Craig Owen said...

Thanks for the information, it makes more sense now.
I guess to run it on a British OO gauge railway with British outline rolling stock I should keep the bogies and try to increase the diameter of the wheels to lift the whole body slightly. The walkway is slightly too low when put next to British OO vehicles. I think that the sideframes of the trucks need to be moved outwards. On the prototype the axle boxes are level with the battery box but recessed on the model.