Frisco mid-1950's Diagrams #9a - EMD F's, A-units

Discussion in 'Diesel Diagrams' started by meteor910, Nov 12, 2009.

  1. meteor910

    meteor910 2009 Engineer of the Year Staff Member Supporter

    SLSF 5000-5004,5006,5008-5017, EMD F3A
    SLSF 5005,5007, EMD F9A (F3A rebuilds)
    SLSF 5018-5039, EMD F7A
    SLSF 5040-5051, FP7

    Following are the early (1957) diagram sheets for the array of Frisco EMD F A-units. The original order was for 18 F3A & B sets. Note how the original diagram shows the locomotive as an A-B-B-A set. They were considering the locomotive to be a four-unit set at that time. Quickly, they realized that each unit was a locomotive, and a set of them could be arranged in any combination necessary to get the job done. This allowed much more flexibility for both operations and maintenance.

    Note this first diagram also indicates an intent to order 24 F3 ABBA sets, not 18, in 1948. The corrections to the numbers on the diagram were made by me several years ago. Does anyone know the story behind the apparent change to 18 units from 24 F3 units?

    In February, 1954, two F3A's, SLSF 5005 and 5007, were rebuilt into F9A's, 1750HP, including the addition of dynamic braking. These units were used on run-throughs with the ATSF (I think), who wanted d/b on the units to better handle the mountains on their routes west.

    The F7's followed the F3's in 1949 and 1950. The FP7's, useful for both freight and passenger power, followed in 1950 and 1951. None of the EMD F A-units came from EMD with d/b's. Later, in 1954-1957, the Frisco would order F9B's with factory d/b's.


    Attached Files:

  2. meteor910

    meteor910 2009 Engineer of the Year Staff Member Supporter

    FYI, a couple of people have asked what the designation F37A and F37B means on the Frisco F3A and/or F3B diagrams above.

    Shortly after the arrival of the Frisco F7's, the SLSF operating people realized how much better the F7 was than the F3. The improvements were of about the same magnitude as was the F3 improved over the FT/F2.

    The Frisco rebuilt all of their F3A's and F3B's to bring them up to F7 standards. I don't know what all was rebuilt, but it most likely was electrical related. The rebuilt F3A's & F3B's were then designated as F37A's and F37B's by the Frisco. Units SLSF 5005 and 5007 were not rebuilt, as they were in the process of being rebuilt into F9A's by EMD.

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  3. Karl

    Karl 2008 Engineer of the Year Supporter

    I have been trying to ascertain what modification the Frisco made to each F-3’s in order to to create the F-37’s. The earliest diagram that I can find that uses the F-37 model is 1952, which might be the year that the modification was made. After comparing Ken’s F-3, four unit diagram (see the first post in this thread) and his 1954 F-37 diagram with my 1952 F-37 diagram, the only difference that I can see is the prime mover. The 1948 digram indicates that the Frisco F-3’s had 16-567A prime movers. That is at odds with every EMD or Frisco reference that I can find. Anyone have an F-3 diagram that dates between 1948and 1952?

    BTW Ken, the late 1940’s ETT’s show that the Frisco rostered F-3 units, 5000-5023, and 5100-5123. The Annual Reports are silent about “missing" 8 units.

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  4. gna

    gna Member Supporter

    Is it possible they updated the traction motors? The D27 was the F7 traction motor, as opposed to the D17 that normally came with F3s. The first diagram doesn't say what traction motors the F3s have, unfortunately.

    I've seen reference to an interim model, the F5, in a late F3 carbody but with F7 traction motors:
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  5. My experiences are with mining excavators - but...... The generators (and GE mill motors) have much in common with the locomotives. Of interest is the relatively common value of "at speed" torque versus the variable "stall torque" settings. Changes in this usually had to do with the heat capacity of the armatures and field coils - and improvements in insulation ratings. Also in my industry - the addition of high capacity blowers to the motors made a difference in how high we could "juice" them to temporarily increase the stall (jack up the allowable amps = torque) and for how long, before the control would back off the generator. Thermal capacity of the system was managed for longevity.
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  6. Karl

    Karl 2008 Engineer of the Year Supporter

    I have been giving this addition thought, and I have delved further into the Frisco F-37’s. I believe that your thoughts are correct. The Frisco upgraded the F-3 traction motors with the new D-27 motors. In essence, the Frisco F-37’s were the equivalent of the unofficially designated F-5’s. The prime mover discrepancy remains. Ken’s diagram indicates that the Frisco’s F-3’s bore 16-567-A prime movers, which by all accounts was a 1350 HP engine, and not used on the F-3 units. My latter 1952 diagram indicates that the F-37’s had a 16-567-B prime mover.

    I also think that the upgrade of the F-3’s to F-37’s (F-5’s) is the reason behind the cancellation of the last 6 F-3A’s and 6 F-3B’s. The “improved” F-7’s were on the horizon, so I as I see things, the Frisco exchanged the last 12, F-3’s for improved F-7 technology.
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  7. meteor910

    meteor910 2009 Engineer of the Year Staff Member Supporter

    Interesting. We learn more of these details every day.
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