ATSF Class 3460 4-6-4 Hudson kitbash

alister May 15, 2021

  1. alister

    alister TrainBoard Member

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    Doesn't look like it s far as I can tell.
     
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  2. alister

    alister TrainBoard Member

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    The ATSF 4-6-4, 4-8-4 and 2-10-4 shared design elements, you can see that the 3 types have the same setup. Looking at the 3776 class 4-8-4 a diagram shows the 2 pipes going back into the front of the cab area and travelling down to probably the appliances hung off the bottom of the cab.
     
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  3. BigJake

    BigJake TrainBoard Member

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    What kinds of appliances would need the amount of saturated steam that two pipes like that could deliver?
     
  4. alister

    alister TrainBoard Member

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    The things underneath the cab, or check this reference out "Santa Fe Systems Car and Locomotive Plans". They are copyrighted so I can't publish them.
     
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  5. alister

    alister TrainBoard Member

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    Working on the shell, fixing the walkways and shell irregularities. The styrene insert is a little thin and needs a thinner insert glued on top.

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  6. BigJake

    BigJake TrainBoard Member

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    Alister,

    I appreciate your diligence in protecting the rights of copyright owners.

    Fair Use Doctrine, under which copyrighted material may be used without permission, applies to any of the four following purposes: noncommercial, educational, scientific, or historical. IMHO (I am not an attorney), all four purposes apply here.

    Fair Use does not permit verbatim copying of large portions of text from a copyrighted source, but it does allow summarizing and commentary of such information for any of the purposes listed above.

    Fair use also requires that the amount of information presented, when compared to the entire content covered by the copyright, be such that the value of the copyrighted work is not reduced.

    So, if you were to analyze and provide, the purpose(s), of under cab appliance(s) indicated in the copyrighted source, that may have need for the large amount of steam made available by the large pipes we are discussing, then the copyright would not be violated.

    Even when copyrighted material is used legally without permission, it is strongly recommended that the source be cited with the usage. Besides courtesy, this bolsters the claim that the copyright value is not reduced, but is likely increased, by the usage with citation.
     
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  7. alister

    alister TrainBoard Member

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    I appreciate your comments and you may well be right. I'm not an American and I don't know your laws so I was erring on the side of caution, however I did locate a pdf version - I just need to find it. I'll post the link when I locate it.
     
  8. CarlH

    CarlH TrainBoard Member

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  9. alister

    alister TrainBoard Member

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    Hi Carl,
    Yes that's been bugging me, I have a J class rear truck which might look better. I'll try that and see how it looks. I hadn't looked too closely at the rear truck design and it does look quite different to the 4-8-4 style truck.
     
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  10. BigJake

    BigJake TrainBoard Member

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    Okay, I found the document online. Note, it may not be published with permission, so I am not providing a link. A search engine, given the title, will likely find it for you, along with several sites selling print copies of it (hopefully with permission.)

    The document did not provide any direct information on the purpose of the pipes from the steam dome back to the front of the cab, or on any appliances in/under the cab. However, I noticed that the pipes are not provided on locomotives built up until the late 1920's. They appear only on steam locomotives built in the late '30's and the '40's, which, IINM, coincides with the widespread use of superheated steam piston engines (industrial and locomotive).

    So, I did a little research to refresh my memory from my thermodynamics course in college (~40 years ago), regarding saturated vs superheated steam (and "wet" vs "dry" steam).

    There are many advantages of superheated steam (over saturated steam straight from the boiler), especially for generating mechanical energy via expansion (e.g. in piston or turbine engines). However, heating applications is not one of them, because the heat transfer from the superheated steam is not as great as when saturated steam is condensed, liberating much more heat, without even losing temperature. Thus the return on input heating energy for superheating steam is not as great in heating applications. The heat liberated by condensing saturated steam into water, with no temperature loss, is the most effective heat transfer mechanism of steam systems. Furthermore, the water (still at the boiling temperature at pressure) condensed on the heat exchanger surfaces has significant heat left to efficiently liberate in heating applications. Therefore, it is more likely that the steam pipes headed rearward from the steam dome would be for heating, rather than mechanical functions.

    Note that feedwater heaters (to pre-heat replenishment water for the boiler) were typically employed in/on the smoke box, scavenging heat from firebox exhaust and exhausted steam from the cylinders. I suppose it is possible that these locomotives had feedwater heaters back near the cab, heated with saturated steam. Note that the pipes actually enter an enclosure on top of the boiler, in front of the cab. Perhaps that enclosed a feedwater heat exchanger?

    The only uses I know for steam in/near the cab, would be for
    1. cab heating in cold weather (not likely, given the firebox and back of the boiler is right there),
    2. rear booster truck (would be better powered with superheated steam, but given their limited use, perhaps not worth the expense in plumbing superheated steam all the way from the smokebox back to the rear truck),
    3. firebox stoker (another mechanical use where superheated steam might be preferred)
    4. feedwater injection, for which saturated steam is sufficient, and would waste less energy using it). But I don't think feedwater injectors needed anywhere near the amount of steam those pipes could carry. Note also that steam feedwater injectors typically raised the feedwater temperature from ambient to 200F, not the ~400F temperature of the boiler water.
    5. feedwater heater. There were two reasons to heat feedwater: efficiency, and reducing mechanical stress from injecting cold water into a hot boiler. Generally FW heaters took two forms, closed and open, and were employed in the smokebox, scavenging the waste heat there. Open form actually passed steam into/through the feedwater, heating it. Closed form used a conventional tube heat exchanger, keeping the two systems separate. Most feedwater heaters scavenged waste heat from the smoke box, thus open forms would also mix firebox exhaust gasses and cylinder oil, present in the exhaust steam, into the feedwater, contaminating it and accumulating in the boiler. But if an open form feedwater heater used saturated steam merely to reduce mechanical stress (no efficiency gain), the more efficient open form heater could be a practical design.
    Perhaps the pipes' large appearance is due to insulation around a smaller pipe? Keeping saturated steam from condensing ahead of the feedwater injector might be a valid reason for such insulation. And I suspect the steam flow rate would be rather slow/intermittent, with ample time for cooling and condensing in route to the injector.

    I sure wish my grandfather was still around to tell me all about it!
     
  11. alister

    alister TrainBoard Member

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    WOW that's a master class in steam! Fixed up one side walkway, working on the other side, fixed the cab bulge - roof. Rear cab end will be next. Front of the boiler had some work - a bit more styrene rod to add.

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  12. alister

    alister TrainBoard Member

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    Is this rear truck better than the previous pictures?

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  13. CarlH

    CarlH TrainBoard Member

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    Sorry if I was not clear: I was trying to say that I think the trailing truck of the prototype looks weird.
     
  14. alister

    alister TrainBoard Member

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    Yes I was thinking that too, but I think the one I swapped in is a better match for it, it's still not right but I think that's as close as I'm going to get without 3D printing.
     
  15. BigJake

    BigJake TrainBoard Member

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    I did a little more research on steam superheaters in steam locomotives. Turns out they were in use starting in the 1900's on NA locomotives. So the appearance of the box over the top of the firebox section of the boiler after 1930 is not directly related to the introduction of superheating.
     
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  16. alister

    alister TrainBoard Member

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    A little more work on the walkways, both sides nearly completed.

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  17. alister

    alister TrainBoard Member

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    tidied up the shell a little. Next is fixing the fron boiler cross brace right at the front of the boiler,.

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  18. alister

    alister TrainBoard Member

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    I've become aware that the above shell based on a cut down Bachmann 4-8-4 is not really a shining example of a Santa Fe Hudson so I have rethought this and have decided to make another Hudson but this time it will be a Brass / Plastic hybrid. So I'll end up with 2 Hudsons so that's all good!
    Right now there's 2 parts, I'm using the cab of a Bachmann 4-8-4 and a brass boiler of 15mm in diameter.
    I put it on the test mechanism for fun.

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  19. alister

    alister TrainBoard Member

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    Just to keep everyone off guard here's a streamlined Hudson number 3460 "Blue Goose"or "Bluebird" whichever name you prefer.
    It's a Robert Nunes shell on a Concor Hudson mechanism (Kato). I haven't modified the tender yet so it's an ATSF Burlington Goose :)

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  20. alister

    alister TrainBoard Member

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    The test mechanism now has a new motor, all its gear sets are in and the metal contact strips are attached. I going to need traction tires, hopefully the white box 4-8-4 I have coming from the US has a pair. One of mine didn't. Applying power the thing just sits there spinning its wheels, at least the gears aren't cracked.
     
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