Diesel Engine Type

Discussion in 'Getting Started' started by Bob Collins, May 8, 2002.

  1. Bob Collins

    Bob Collins Active Member

    The UPRR runs/ran a diesel type I believe they called the "Centennial". Can someone tell me the actual engine type please.


  2. Catt

    Catt Guest

    The Centennial I believe is a DD40.Basically a pair of GP40s on one frame and in one car body.
  3. K.V.Div

    K.V.Div Member

    The Centennial is also known as the DD-A-40X, which means that it rides on "D Trucks" (4 axles, 8 wheels per truck) which gives it 16 wheels.
    "A" means that it has a cab, unlike the earlier DD 35 which was a cabless booster and, as Catt said, it was two GP40's mounted on a very long frame and was rated at 6600 horsepower.

  4. Bob Collins

    Bob Collins Active Member

    CATT and Terry;

    Thanks very much. I appreciate it. I think someone makes a model of it because I recall that you have to have minimum 22" radius curves or soimething like that to run it. I can see why with trucks of that size and basically a double length loco.

    Again, many thanks.

  5. Vic

    Vic Active Member

    Bob, At one time Athearn made an HO model of the DD-40. You could get it in a single motor or dual motor version. Don't know if they still make it but every once in a while I'll see one for sale at a trainshow or swapmeet.
  6. justind

    justind Member

    Does anyone have a picture of one that they could post, I would be interested in seeing it. Thanks,
  7. roryglasgow

    roryglasgow Active Member

    According to a web site I found, the "Centennial" was Union Pacific's #6936, a DD40AX. Here are some links with pictures:

    http://www.trainweb.org/jlsrr/pictures/full-scale/portola/assorted/portola assorted.htm

    Bachmann shows both N-scale and HO-scale models of the DD40AX (although not #6936) in their online catalog. Below are links to pictures of the models. It looks like someone vandalized the N-scale pic! The HO-scale model is in their Spectrum series.

  8. BDC

    BDC Member

    The Centennial was made just for the Union Pacific. It was similar to the DD35, which was essentially to GP35s welded together. The Southern Pacific owned some DD35s, including B units.

    UP 6936 is the last surviving centennial of the fleet UP has made to celebrate their 100th year of operation. EMD made 43 of them and now only one is left, pulling passenger trains and other special events.

    Attached Files:

  9. BDC

    BDC Member

    Bachmann is the only N scale maker apart from the Brass importers. Not sure about anything done in HO, although I have seen locos sitting is store displays.

    Above photo was UP 6900 - the first.
    Below is UP 6900 at the unveiling of the model.

    Attached Files:

  10. BDC

    BDC Member

    Some of the DD40s were placed in storage at Las Vegas circa 1975-1985 for any Horsepower problems that UP had. They were brought out occasionally but were eventually scrapped.

    UP 6941 and 6935 at the end of their useful lives waiting for the end.

    Attached Files:

  11. BDC

    BDC Member

    Some of the DD40s were lucky enough to be retired and placed on display. I'm not sure of the exact number but I believe either 12 or 13 are on display.

    UP 6901 on permanent display

    Attached Files:

  12. BDC

    BDC Member

    UP 6916 on display at UP's Wyoming home. UP 26 is a Gas-turbine locomotive.

    Attached Files:

  13. justind

    justind Member

    Wow, pretty cool...due to their size I would have expected them to have a longer serviceable life span...but maybe the size only contributed to their demise. Simply too much upkeep on a loco that size, especially if smaller ones can out perfrom her. Still a beautiful loco, and one I would like to run, but couldn't on my 18" radius.
  14. BDC

    BDC Member

    The Centennials were BIG units. UP 6929 shows off it's size somewhere in the US. I believe they are the largest diesel locomotive built, even larger than the SD90.

    Attached Files:

  15. rockislandmike

    rockislandmike Active Member

    IMHO I think even 22" would be tight for those puppies. No proof of that, of course, but just a feeling.
  16. BDC

    BDC Member

    Sometimes one Centennial wasn't enough. Lashups of 2 or 3 DD40s were not uncommon. UP 6904 leads a sister unit with a mixed consist of freight.

    Attached Files:

  17. rockislandmike

    rockislandmike Active Member

    Does anyone know what its length is in comparison to the Big Boy ???
  18. BDC

    BDC Member

    Just for reference, this is a DD35B, SP 9902. A cabless booster designed to provide a lot of Horsepower when needed.

    Sorry about the number of posts, but the DD40 is one of my favorites!

    Attached Files:

  19. Bob Collins

    Bob Collins Active Member

    So do I understand correctly that the SP DD35 is a cabless version of the DD40? Not knowing the dates on the pix posted I wanted to ask if the DD40 is still operational on the UP?

    Itoo have taken a liking to this engine, but it raises a question too. If there is a model that has two engines will I need two decoders to use DCC?

    Thanks again for all the great info.

  20. 60103

    60103 Pooh Bah

    Bob: you shouldn't need 2 decoders for twin motors but you will want to check the amperage capacity.

    I seem to remember that the Athearn model was released before the prototype. The model was a DD40 and the UP bought DDA40. Some detail differences but I don't remember what.

    DD35B would be a different loco, based on SD35 instead of SD40? The ~B indicates a cabless powered unit.

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