Southern Pacific F-unit diesels

Among the iconic images of the Southern Pacific in the steam-diesel transition era were freight trains powered by Electro-Motive F units. This is a complex subject on both the prototype and model sides, and I will only touch on a few aspects in this and following posts. My plan is to present my own modeling choices and approach to these locomotives.
     Nowadays it seems to have faded from memory, but Southern Pacific, together with subsidiaries Cotton Belt and T&NO, owned by far the largest American fleet of F7 locomotives, 573 all told. And even their fleet of F3 locomotives, 180 in total, made them third in North America behind UP and Southern. The year that I model, 1953, was chosen because it was the last year that steam power was more prevalent on the Coast Line than diesels, but it also needs to be remembered as a time of relatively few diesel roadswitchers on SP, and an awful lot of F units. That’s why it is essential for me to model them.
     I’ll begin with resources for information. First, I should mention the “bible” on prototype SP units, Joe Strapac’s superb volume in his Southern Pacific Historic Diesels series, Volume 10, “EMD Freight F Locomotives” [Joseph A. Strapac, Shade Tree Books, Bellflower, CA, 2003]. If you are serious about understanding the SP prototype F units, this is indispensable, so if you don’t have a copy, you need to get one. Here is the cover, featuring a fine painting by Ernie Towler.

     For those who have a set of the SP Historical & Technical Society magazine, Trainline, Joe also wrote an article which kind of previewed the book, in Trainline issue 66 (Winter 2001). As that article is necessarily briefer and far less fully illustrated than Volume 10, I might otherwise not mention it, except that Trainline 66 also contains an F-unit modeling summary, written by me (pages 25 to 29).
     By the way, this and other back issues of Trainline are available from the Society. For this one, go to: http://www.sphtsstore.org/servlet/the-Trainline-back-issues/s/65/Categories .
     The summary attempted to include all the details essential to accurate modeling, and to reflect the various time frames for those details. A core part of the piece was a graphic by John Signor, showing the approximate time span for various details of the locomotives, such as nose grab irons, diaphragms, multi-chime horns, etc.
     I have scanned the pages of the summary and posted them to Google Drive, for the convenience of those who may not have access to a magazine now more than ten years old, or who may not wish to buy one. Here is the link:

https://drive.google.com/file/d/0Bz_ctrHrDz4wVVUzNzRYUzE0dzA/edit?usp=sharing

The only drawback to this modeling summary is that the list of model parts, and some of the paint listings, are pretty old and not too helpful today. For a painting guide I recommend the SPH&TS volume, SP Painting and Lettering Guide, by Jeffrey Alan Cauthen and John R. Signor, SPH&TS, Upland, CA, 2013. It can be purchased direct from the Society on line.
     What I will discuss, with these publications as background, is my own choices for modeling SP F units. Partly because my trains on the main line aren’t very long (a limitation of my staging tracks), I will use the common arrangement of F units on the SP Coast Line, an A-B formation. The question then is, to choose particular A and B units, and that is what I will discuss in the next post on this topic.
Tony Thompson