• Switcher frames, falsies, and Flexicoils

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by Allen Hazen
When EMD started building switchers, in the mid-1930s, they offered a choice between cast underframes (models SC and NC with 600 and 900 hp engines) or welded underframes (SW and NW). I think the cast frame was more expensive and had no significant advantages, so they subsequently standardized on welded frames (there was no "C" counterpart to the 567-engined models SW-1 and NW-2).
But at least initially, the cast under frame seems to have been thought of as desirable. (Maybe railroad mechanical departments in the 1930s just thought that any PROPER locomotive would have a cast underframe!) So the welded-frame models were built with "decorative" metalwork to make them visually resemble their cast-frame counterparts: gussets at the ends of the frame. These took the form of right triangles, with a horizontal leg along the sideframe, a vertical leg along the step well, and a hypotenuse angling down near the outboard ends of the trucks. At least some railroaders apparently referred to these as "falsies."

(They may have had SOME structural function, reinforcing the joint between the horizontal frame and the end pieces, but evidently not a very important one: the final iterations of the traditional EMD switcher designs, the 645-engined SW-1500 and SW-1000 generally dispensed with them.)

Problem. In the 1950s, EMD started to offer the Flexicoil truck as an option on its switchers. And this seems to have led to clearance "issues" with the falsies. (The Flexicoil truck doesn't look much, if any, longer than the conventional, so-called "Type A," switcher truck -- they have the same 8-foot wheelbase -- but the Flexicoil truck has brake cylinders mounted outside the frame at the ends, and these -- on the ends of the trucks closer to the locomotive ends -- might have had problems with the falsies on sharp curves.)

(Note, by the way, the "may" and "might" in what I have written: these mark my conjectures, and I'd love to hear from anyone who actually KNOWS about these things. Either confirmation or correction!)

So. Just omitting the falsies from Flexicoil-equipped switchers might have seemed to radical a move. Instead, they were trimmed. In several different ways!
---The New Haven's Flexicoil-equipped SW-1200 had a triangle cut out of the middle of the falsie, so the whole gusset had the shape of an inverted capital L, with the bottom of the L along the sideframe, and the riser of the L going down beside the stepwell. The writer of a piece on the New Haven's SW-1200 in an old "Paint Shop" column in "Model Railroader"(*) thought this might be a unique New Haven feature. (You don't really want sharp angles in pieces of locomotive frames: the inner vertex of the triangle "removed" from the larger triangle of the falsie is rounded.)
---On the other hand, the Flexicoil-equipped SW-1200 of the Canadian National (the "SW-1200RS") had fully triangular falsies that were narrower than standard (the top leg of the triangle along the side-frame was shorter than on the standard falsie, so by the time it got down to the level of the truck brake cylinders it had tapered enough to lear them).
---At least some of the earlier (1967 and 1968 built) SW-1500 of the Souther Pacific(**), all of which had Flexicoil trucks, had falsies: they were cut off above the trucks, the the falsie was just a parallelogram along the sideframe, not extending down to truck level.

It seems like ad-hoc design work on each new order of Flexicoil-equipped switchers!

(*) Alf Bossaers, in the August 1990 issue.
(**) Going by photos and the build dates in Warren Calloway's article on the SP's SW-1500 in the July/August issue of "Diesel Era." It's a bit surprising that any SW-1500 got falsies. The "Second Diesel Spotter's Guide" (1973) has a photo of the first production SW-1500, the K&IT's 67, in what looks like as-built condition, and it doesn't have falsies. Did EMD start out thinking that such frippery should be omitted on their new 1966 line, then relent and make the nod to traditional aesthetics for a couple of years, and finally standardize on a design without the extra-cost feature for later switcher production?
  by Engineer Spike
One quick thought is that you may be correct that the CMOs had definite ideas of how locomotives should be built. I know from reading the Dilworth bio that he had to retrain railroad motive power people to accept the GM mass production business plan. Perhaps some concessions were made so as not appear too radical.

I think that some of the changes came about as the manufacturing processes were streamlined. Being around locomotives daily one can see how some of these changes came about even on the same model. My employer had early SD40-2 from 1972, up to some which overlap 50 and 60 series. Look at how the six sill was taller over the trucks than above the main reservoir. Later production had the shorter high along the entire length.
  by Allen Hazen
Engineer Spike--
I ONCE had a copy of the Dilworth biography, but gave it to a friend. It's very much history as Dilworth (and his employer! I think EMD may have sponsored its publication as "institutional advertising") wanted ti to be perceived. I think Kirkland, in one of his books on diesel locomotive history, criticizes it on a few points.
But the need to "educate" railroad managements was certainly real.
Railfans and model railroaders have come up with lists of "phases" in the production of various locomotive models: visible design changes made in the course of production. The change in the side sill of SD40-2 is typical. ... As a general rule: if one "phase" looks simpler (and so easier to fabricate), it's usually the later one. Curious, that. (Grin!)
  by Engineer Spike
Still, my point is that the builder will sometimes make changes based on functional deficiencies of the model, but some are due to streamlining the manufacturing process. As in my example above, EMS was able to take a piece of straight steel to form the later SD 40-2 sills, where they had to cut out the area around the main reservoirs before. I can't see how the thicker sill was advantageous before, since one could conclude that the part of the frame with. the most load would be in the centre, under the whole weight of the diesel and main generator.