History question regarding Alco PA's

Discussion in 'The Real Thing- North America' started by Herc Driver, Jan 11, 2007.

  1. Herc Driver

    Herc Driver Active Member

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    I haven't been able to find this answer out yet so I'm hoping you guys can fill in the informational gaps.

    Let me keep this in context too...Several PA's are being restored around the country - one specifically will be in the Santa Fe red warbonnet colors for the Smithsonian. So in honor of a great looking diesel, I'm creating an excursion train that would run today (as if the Smithsonian would actually let someone use a museum exhibit) which gives license to do about whatever I want, but I'm curious what amount of total power I need to be somewhat realistic.

    As I've posted pictures of, I'm building the Super Chief using a PA1 instead of the normal F-units. My question is this...in several pictures I noticed that two "A" units would be paired with a "B" unit (the back of the "A" units connecting to the "B" unit). Did passenger trains of the Super Chief type (long haul across various terrain features) pulling 12 or more cars, require tractive/braking power from the extra "A" and "B" units or a power boost to the electrical/HVAC units to service the passengers orboth? (Forgive the ignorance on exactly how a diesel sends its electrical power to each passenger car - I'm assuming it creates then sends the electrical power to power the HVAC units/kitchen/lights via a parallel circuit. But just how much power is required I don't know. I promise to get a good book on just how diesels work...but for now...does anyone know?

    Attached Files:

  2. nachoman

    nachoman Guest

    I think each railroad did things differently. Amtrak had issues with this when they wanted to run cars from different railroads together. Eventually, they converted all cars to HEP (head end power) and the problem was solved. I don't know what voltages each rairoad used or how they were wired. Back in those days, I think all cars still ran with steam heat. Even the stainless cars.

    kevin
  3. kitsune

    kitsune Member

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    Head end power did not exist in the 1940s and 1950s in any significant way. Cars were heated using steam, provided by steam generators aboard the power and distributed through a steam line under the cars in much the same way that air is distributed to the air brake system.

    Power to each car was provided by on-board generators, mounted below the floor of the car.

    The number of PAs was determined by the weight of the train and the necessary HP to haul it as well as to accelerate it quickly. A PA is roughly equivilant to an E-unit, approxamately 1800 HP. If you want an exact rating I can find it.
  4. kitsune

    kitsune Member

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    Oh, and for the record, there is only one PA restoration in the U.S at this time, the NKP 190 project. The Smithsonian project has not been started yet, and probably will not be for many years.
  5. shaygetz

    shaygetz Active Member

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    I know that Amtrak requires one power unit for every eleven cars. Regardless of what my real roads ran, I selectively compressed this down to six per unit. When I saw that a 10 car passenger consist is nearly 10 feet long, it made for a nice balance to head it up with two units.
  6. Herc Driver

    Herc Driver Active Member

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    Thanks for the info guys! Oh the Smithsonian project isn't going on??? Wow, I must have read an old article about it and thought the restoration was already going on. I saw pictures of the one that was slated to go to the Smithsonian (I thought)...but now I'm going to do some research and see what's going on with the whole project.

    Thanks again for the info.
  7. Triplex

    Triplex Active Member

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    I know there are some modellers who compress freight trains but not passenger. Definitely shows you where their priorities lie...

    I hold that, because passenger trains are shorter than all but local freights in reality, this should hold true on a model as well.
  8. Herc Driver

    Herc Driver Active Member

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    I hate to say it...but with me it's all about the power on the point. I'm an engine freak - the more power the better. I know this breaks with reality, prototypical operations, etc. Must be the aviator in me or something - I dunno. So the idea of running two warbonnet PA's is probably what I'll opt for. Plus, I like the look of the PA's along with the Super Chief cars...Sure those F-units are great, but something about that PA...
  9. shaygetz

    shaygetz Active Member

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    PAs, Fs and E units just don't look right running one up anyway, always run two---even for switch jobs:thumb: And you're right, nothing will ever replace that warbonnet scheme.
  10. kitsune

    kitsune Member

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    The Smithsonian project will be undertaken by Doyle after he finishes the 190. There is not enough room (much less manpower) to do both above what Brooklyn already handles.
  11. railohio

    railohio Active Member

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    If you all are so picky you'd probably have an aneurism if you saw a photo of a diesel Norfolk & Western passenger consist... GP9s! Oh, the horrors of it all!

    ~BS (sarcastic as ever)
  12. brakie

    brakie Active Member

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  13. kitsune

    kitsune Member

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    Which doesn't contradict the point that before they did not.
  14. brakie

    brakie Active Member

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    Doesn't matter..When you say N&W that is a open statement..Now if Brain said before the N&W/NKP/WABASH merger then he is 100% correct..Gotta watch general statements concerning railroads because one could give out incorrect information by mistake by omitting cut off dates..
  15. kitsune

    kitsune Member

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    Err... okay, noted. All future posts will come with a disclaimer.
  16. Herc Driver

    Herc Driver Active Member

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    Actually, I run a Southern SD35 with a lone passenger car as a day-trip'er once and a while. So, there's no problem with just one engine doing the work. But, I like running a few at a time. So, prototypical or not, I thinking I need another warbonnet PA.

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  17. brakie

    brakie Active Member

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    BTW..I had to learn the hard way about using general statements not once mind you but,twice to ensure I got it right.sign1
  18. liven_letdie

    liven_letdie Member

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    I thought I heard a long time ago that PA units were run like FT units always requiring a second unit? Maybe I heard wrong. At one of the layouts I visit we have a ABB E set that pulls a daylight consist of 6-7 cars, it looks just fine.
  19. Russ Bellinis

    Russ Bellinis Active Member

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    The Pa's and E units ran more units per ton than Amtrak for 2 reasons. First I think a Pa put out 2000hp while the E units put out 1800hp. The Amtrak F40ph is mechanically a Gp40-2 I think, which would mean about 3000hp per unit. The newer Ge Units are even more powerful. Basically 2 F40ph's have about the same horse power as three of the old units. The other reason why they would run multiple units was that the technology wasn't as high tech or reliable in the early days of diesel as it is now.
  20. brakie

    brakie Active Member

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    The PAs,E units and other passenger units could run singularly on a short train of 1-5 cars.