Atlas 2 rail powered trucks

[stevef45]

I cannot locate any good pics of emd 4 axle 2 rail powered trucks from atlas that show the mounting area. I am trying to find how they mount to the frames. Are they an identical mount system to the 6 axle 2 rail trucks? Frames all look similar where the pivot and wire openings are so it has me wondering. But with no good pics i cannot figure this out. Anyone able to help me out?

[big train james]

Generally the 2 axle trucks mount in the same manner as the 3 axle trucks. Motors are mounted to truck gearboxes, which are attached to bolster plates, which are then attached to the frames. This is consistent for nearly all road locos, which have the 2 motor drive design commonly found in most modern O scale products. The anomalies are the switcher trucks (and the AEM-7), which have single motor drives that are essentially clones of the typical HO drive.

Parts diagrams for Blomberg trucks, and for the many frames they fit to, can be found on the Atlas website via the drop-down menu for O scale product.

The following photo shows trucks for GE locos (Master b40-8 to the right of the frame, Trainman u23b above the frame), but the application is the same for the Blombergs. You can see that the bolster plate sizes are different. The frame is for the u23b, and as a Trainman product it has a stamped frame. Most of the Master products will have diecast frames which I can only presume has something to do with the difference in plate size.



If you're doing something with one of the switcher models, I have examples of both here and can supply photos.

Jim

[stevef45]

This helps tremendously. Im basically trying to see if i can use a SD45 frame from atlas with gp40/blomburg trucks mounted under it. How different if any at all will the mounting be. I ended up finding diagrams on their site and it looks possible based on their diagrams.

[big train james]

Be aware that the sd45 is not a native Atlas product, but rather tooling acquired from MTH. It should have the same general style of truck mounting, the 2-motor drive is the standard for 3-rail locos these days and therefor also the standard for 2-rail. However, there may be differences in the particulars between Atlas tooled units and the MTH models. I don't see parts diagrams for the ex-MTH locos on the Atlas site. A shallow dive on the MTH site shows diagrams for the sd45 for electronics only, with diagrams for the models "coming soon". I did find a diagram for an et44 which shows a similar truck block, but it doesn't indicate a bolster plate.  That pretty much exhausts my knowledge of MTH locos, which was very limited to begin with.

I would suggest a call to Atlas parts or perhaps search around a forum like the one associated with O Guage Railroading Magazine .  It's much more 3-rail centric, but that is the largest market for the MTH product.  There's really no difference between the 3-rail and 2-rail trucks other than the power pickups, so one should inform the other.

Jim

[stevef45]

I've been in contact with someone about parts that weren't on the website. So im going to reach out to him to see if he can provide a exploded parts diagram first. It could just end up killing this project if things aren't workable.

[big train james]

I've just re-read this thread and I see that you mention the gp40. It's also ex-MTH tooling so may have more in common with the MTH 3-axle truck block than those for the gp's developed by Atlas.

One other thing to note, the most recent run of sd45's included SP units, which were shipped with GE Adirondack truck sideframes. Atlas has done replacements. Units for other roads appear to be correct on delivery. This may not have any bearing on your project since you are looking to swap to Blombergs, but if you were going to sell unused parts afterward it could have an effect.

Good luck, I hope the project is ultimately feasible.

Jim

[big train james]

I keep coming back to this as I think of other things to consider that wouldn't be an issue for a typical HO bash. A lot of O scale 6-axle locos have the truck pivot points inboard of the prototypical bolster position. This allows for the motor mounting between axles, but it also effectively shortens the wheelbase to allow for operation on tighter than normal curves. You may find that the truck mounting position on the sd45 frame is offset from where you would mount the Blomberg truck, and modifications to the frame may be required to get things in the right places. It doesn't mean it won't work, but don't be surprised if you need to drill or cut new holes.

Jim

[cf7]

Speaking of Atlas 2 rail trucks, I have an Atlas SW8 that I want to convert to 2 rail. I called Atlas and they don’t have the trucks. Any ideas?

[big train james]

Hey Chuck,

There are a couple of options for converting the Atlas sw8 to 2-rail. Which one you choose will depend on a few factors, like how much do you want to spend, how patient are you, are you willing to do swaps and then sell spare parts onward, those sorts of things. Another question is whether you want to do p48 or standard 2-rail.

You didn't mention these other aspects of converting a loco, but you will need to add 2-rail couplers and wipers for power pickup. An optional modification is to change to a 2-rail pilot that doesn't have the gaping hole for the 3-rail coupler. Lastly, I highly recommend removing all factory boards and replacing with the decoder brand of your choice and a new speaker. I'd even remove them if you are sticking with traditional DC.

Options are:

• Wait patiently for a 2-rail version to appear on ebay, purchase it, swap chassis, sell the extra model on ebay for parts.  Right now I'm only seeing high prices on ebay for these models, but eventually somebody will list one for $100.  How long do you want to wait?  Are you willing to eat a little money buying a higher priced model and not getting all your money back out of it on resale?  This option provides for the trucks, pickups, couplers, and 2-rail pilot.  It would still be on you to swap boards for control.
• Order a set of drop-in replacement geared wheelsets from NWSL.  A set will cost you $65, plus shipping.  I believe everything is made to order these days, so they quote a lead time of 2-4 weeks for all items.  This only addresses the wheelsets though, you will still need to come up with pickups.  They also do the same set in p48 if applicable.
• Find somebody, cough, cough, ahem , who has a set of used Atlas 2-rail wheelsets available.  They do show some wear on the treads from use, but otherwise are in fine shape.  Pickups are still an issue.  Said somebody also has at least one set of the NWSL p48 drop-in wheelsets available if you are choosing that route.
• Purchase just the 40" wheels from NWSL, and convert your wheelsets yourself.  Same caveats apply as for above.
• Find somebody that is going to the Chicago March Meet in two months, and have them look out for a suitable donor model while there.  
• Sign up for O Scale Yard Sale on Groups IO, and post a want ad for a donor model or even just the trucks.

As you can see, there are options, but none of them are perfect.  Pickups are a common problem, but that can be solved by 3d printing.  They consist of an engineered plastic mount that press fits/snaps into the gearbox housing, with a length of phosphor bronze wire attached for the contact.  It's a simple part which can easily be reverse-engineered, drawn in 3d cad, and 3d printed in a suitable resin.  There are pickup strips available in etched .008" thick phosphor bronze that will act as the wheel wipers.

The pilots and couplers can also be worked out.  I'm sure couplers could be swapped to Kadees, although I've never done it.  I'm not sure what's there on the frame to mount the Kadees to, so some sort of shim or pad may need to be added.  I also will take a look through my scrap box and see if I have a pair of 2-rail Atlas couplers left over.  I'll check and report back on that this weekend.  For the pilot end sheets, you could always fill them with styrene sheet to narrow the coupler opening, or there is always the possibility of 3d printing a coupler box and end sheet infill part.

If you're going DCC, I feel confident you can fit an ESU Loksound decoder and fairly large Tang Band speaker module in the sw8 hood.  I can discuss that with you if you are interested.

All for now, I'll take a look around this weekend and see what I can find in my stash that might be useful.  Then we should probably take this offline or start a separate thread for it.

Jim

[cf7]

Hey, Jim, I sent you an email.