HO Bachmann Spectrum 44 ton to HOe/HOn3 Oahu Railway GE 47 ton

Discussion in 'Narrow Gauge Model Railroading' started by Canopus, Mar 22, 2006.

  1. lv4142003

    lv4142003 Member

    Did you replace the wheels with larger ones? lv4142003
  2. bertschi

    bertschi New Member

    47-tonner wheels

    I left the original N-scale SD-9 wheels on, since the original plastic center gears on the SD-9 were too small to drill out to fit the axles Bachmann 44 tonner HO wheelsets. The SD-9 axles were really tiny, about 1 mm in diameter. Also there were clearence problems with HO wheels -I would have had to grind awa the plastic center tab that held the SD-9 axles/gears and sideframes to the trucks (sandwich-style). A benefit (if you can stand the non-scale wheel diameter) is that the loco runs slower (closer to prototypical speeds) since the same number of RPMs on the axle causes the smaller wheel rim (*think circumference) to roll a shorter distance than with HO wheels-essentially another "reduction gear".
  3. Canopus

    Canopus Member

    I believe he said that he did not, since it was not noticeable.

    I'm inclined to disagree that it isn't noticeable, but would rather say it doesn't make a huge impact on the appearance of the model. Since the model is mostly accurate, and since the wheels only make up a very small part of the overall model, I'd say it's not an issue unless you absolutely insist on prototypical details.

    What I do question is his statement that the gears were 1mm in diameter! I'd accept maybe 3mm in diameter, I think that's reasonable. But a 1mm diameter gear would require an axle of approximately 0.5mm or smaller.

    It is possible to purchase and fit replacement wheels of a larger diameter, but I'd only be repeating what's already been said by saying that sometimes it isn't practical.

    Of course, scratchbuilding a chassis eliminates any element of compromise, but that takes a lot more skill, effort, and time (considering you have to track down and purchase all the corresponding parts).
  4. bertschi

    bertschi New Member

    Dear Canopus,
    The N scale AXLES were about 1 mm in diameter, and the plastic bearing hubs projecting from the gears were about 3 mm in diameter, which was not much bigger than the Bachmann 44-tonner axles. (The gears were probably more like 4-5 mm in diameter). A look at the underside of a life-like N scale SD-9 shows this clearly.
  5. Canopus

    Canopus Member

    My apologies, I must've misread.

    Out of interest, was this conversion undertaken on the old bachmann 44 tonner, or the newer retooled version?
  6. bertschi

    bertschi New Member

    47 ton dropcab

    Dear Canopus,
    I used the old Bachmann 44-tonner (I did the two 47-ton dropcab conversions in 1999-2000).
  7. lv4142003

    lv4142003 Member

    Canopus, did you finish the 47 tonners ? I haven't been here for a while and wondered if I missed the finish. lv4142003
  8. Canopus

    Canopus Member

    No I didn't, and every time someone brings this thread back or mentions the project it reminds me that I REALLY need to get on with it!

    Since I last posted, I've built my own self contained motor unit, which uses a mashima motor to give power to a single axle. I need to get around to finishing the trucks, because I've also managed to lose one of the truck frames, so I'll have to fabricate one. I still need to build the chassis, and find some wire to do the handrails. But once I've done that the model will be complete.

    I'm currently at the start of a week's holiday, so I should have plenty of time to do some modelling!
  9. Maxxi

    Maxxi New Member

    Hello ,
    where can I find the drawing ? Have some thoughts to build the 47ton in Sn3.
  10. Bill Nelson

    Bill Nelson Well-Known Member

    How did I miss this

    Good work, glad to see some work in this area. I like the looks of this animal. I have been giving some consideration as to weather the same conversion I used on the bachman GE 70 tonner (over in the Hon3 engine shops thread) would work with one of the center cab Ho GE units

    thanks for sharing.

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