SP/SSW Chief spotting differences - AC-5 compared with AC-12 locomotives

SteamDonkey74 Jul 11, 2012

  1. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    I would like to draw on the hivemind here for some information on the chief spotting differences between AC-5 and AC-12 class locomotives.

    Looking at photos, it seems the main differences are the style of tender and the cab, but most of the rest is the same. The driver diameters are the same, the cylinders are the same size, and the side-rods/etc. look pretty much the same. The monkey deck is present on each.

    Thanks in advance,
    Adam
     
  2. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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  3. bremner

    bremner Staff Member

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    AC5's also weighed less and the air pumps were on the side
     
  4. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    Weighing less may be hard to notice in a model, but the air pumps definitely need consideration. Thanks for the tip!
     
  5. TWhite

    TWhite TrainBoard Member

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    Tractive Effort was up from 116,000 lbs (AC-5) to 124,000 lbs (AC-12). Horsepower up from 5460 to 6000. Spoked 63" drivers on AC-6, Baldwin Disc 63" drivers on AC-12. Air pumps mounted on boiler side of AC-5, Air pumps mounted on boiler front on AC-12. Large Worthington Feedwater heater mounted on side of boilder on AC-5, smaller Worthington mounted on top of boiler in front (back) of smokestack on AC-12.
    Actually, the early AC4-5 classes were very similar. The 'transition' AC was the AC-6, with the AC-7 through 12 being the more 'modern' cab-forward (the AC-9 was a conventional cab-backward 2-8-8-4 built by Lima, instead of Baldwin).

    If you were thinking of 'kit-bashing' an AC-5 into an AC-12, you'll need new drivers, pumps, FWH, tender, cab and a great deal of 'cosmetic' work. The more likely 'kit-bash' for an AC-5 would be into an AC-6, which would really only entail replacing the side-mounted Worthington Feedwater heater and moving the pumps from the side to the front of the boiler.
    Tom
     
  6. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    Actually, since I am in N scale I am thinking of kit bashing an AC-12 to something earlier since we don't really have AC-5 locos. I really like the spartan appearance of the AC-4 and -5 cabs.

    Thanks for the spotting details. The drivers would be difficult to change
     
  7. bremner

    bremner Staff Member

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    the AC6 was the last of the flat noses, and is closer to the AC12
     
  8. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    That is good to know. I was primarily looking at AC-5 locos mainly because I thought they were the last of the flat-noses.

    Hmmm... I wonder if I should start a separate thread for spotting differences between AC-6 and AC-12 locos, i.e. if converting an AC-12 model to an AC-6 do these steps...

    Differences between AC-12 and -6??
     
  9. bremner

    bremner Staff Member

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    first, more AC4-5 info...the AC4-5's had a feedwater heater on the side as well.

    The first 23 AC-6 class engines were built in 1930 and the last two in 1931 by Baldwin. These differed from previous AC-4's and AC-5's with amongst other things a higher boiler pressure of 250lbs, a weight of 648,000lbs and a tractive effort of 124,300lbs.

    http://espee.railfan.net/nonindex/steam-02/4134_sp-steam-ac06-gene_deimling.jpg
    http://espee.railfan.net/nonindex/steam-02/4144_sp-steam-ac06-byron_bostwick.jpg
    http://espee.railfan.net/nonindex/steam-02/4148_sp-steam-ac06-gene_deimling.jpg
    http://espee.railfan.net/nonindex/steam-02/4150-2_sp-steam-ac06-byron_bostwick.jpg

    Look at the boilers, closer to the AC12's, look at the pumps, on the "back" of the boiler, and there is a vandy...Other than the noses, the biggest difference is the drivers.

    for fun, you could model 4129. She was photographed in Oakridge, OR on 12-21-1945 with a modern nose (page 81 of Harlan's "Those Amaizing Cab Forwards" Library of Congress Catalogue Cars 82-90198)
     
  10. bremner

    bremner Staff Member

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    more fun....2-8-8-2 AC3 4045 also had a stramlined cab with a whaleback tender....same book as above, page 39
     

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