"F" Unit Questions, Hey Hot Water, this one's for You

The Burlington had E5’s not F5’s. No such thing as an F5 unless we’re talking tornados lol 

Odd.  E units did not skip numbers.  But GP and SD did.

There is some PRR paperwork somewhere about an F5 coming from EMD.  That was in the KEYSTONE a while back.  But I have read this was in house.  Again HW and others can give some history

F5 was an unofficial designation for a “Phase IV” F3. Google is your friend, search on “EMD F unit phases”. 

Much of the mysteries of the F-Unit are covered in the Spring 2015 issue of Classic Trains.  I'm using that as my source.

As I recall reading somewhere, the FT was simply a designation for "freight" locomotive.  I think had EMD decided on numbering in those early days, it would have been called the "F1."  (I'm sure Hot Water will say I'm full of hot air on this thought...)

The F2 was the result of redesign to make the F-Unit more suitable for mass production.  The increase in horse power from 1350  to 1500 and solving some generator issues changed the designation to F3.

According to the article, the reason for skipping F4 is lost to the ages.

An F5 was planned.  Production changes to the F3 to F5 were eventually considered not worth applying for a new model number by the Sales Department and F3 remained cataloged.

There were enough (mostly internal) product improvements to justify the F7. 

The F9 was the result of an improved prime mover, the 567C.

Again why F6 and F8 weren't used are unknown.

Then there was the FG9, which was to use a free-piston gasifier on an FL9 frame that made it to a prototype stage:

As far as I can tell, it never made it off EMD property.  Outside of being very noisy, EMD determined the gasifiers created vibrations that would break welds.

Also, EMD considered a 1800 h.p F18 and 2000 h.p. F20, but by that time the railroads were buying the more practical GP's and SD's.

Rusty

645 posted:

Not that I consider Wikipedia to be an accurate definite source (but usually is a good starting point) for most things their entry for EMD's FT model says this:

"The "F" stood for 1400 horsepower (rounded from 1350) and the "T" for twin, as it came standard in a two-unit set."

Which is TOTALY incorrect!  Originally, the EMD Engineering management "named" the various locomotive models, i.e. "E" originally stood for eighteen hundred horsepower, while SC stood for six hundred horsepower, cast underframe (the later SW model had a welded underframe, thus it was named SW).

The "FT" model designation was F for freight and T for twenty seven hundred horsepower (remember that originally, FT units came draw-bar connected into what is referred to today as an A-B pair).

Dominic Mazoch posted:

There is some PRR paperwork somewhere about an F5 coming from EMD.  That was in the KEYSTONE a while back.  But I have read this was in house.

And apparently it was, Dominic.  Santa Fe had 36 Phase IV F3's (Engines 30 through 36 for passenger and 200-201 for freight) and identified them as F3's.  

And I do believe that Burlington or one of its subsidiaries did buy a few Phase IV F3's.  It would be interesting to know what was shown on the large stainless steel Model Number plate specified by the Q to be applied by EMD on Burlington cab units.  That plate was apparently an EMD part, applied only when specified by the buyer.

Hot Water posted:

Which is TOTALY incorrect!  Originally, the EMD Engineering management "named" the various locomotive models, i.e. "E" originally stood for eighteen hundred horsepower, while SC stood for six hundred horsepower, cab underframe (the later SW model had a welded underframe, thus it was named SW).

The "FT" model designation was F for freight and T for twenty seven hundred horsepower (remember that originally, FT units came draw-bar connected into what is referred to today as an A-B pair).

That's CAST underframe, is it not?.

palallin posted:

Hot Water posted:

Which is TOTALY incorrect!  Originally, the EMD Engineering management "named" the various locomotive models, i.e. "E" originally stood for eighteen hundred horsepower, while SC stood for six hundred horsepower, cab underframe (the later SW model had a welded underframe, thus it was named SW).

The "FT" model designation was F for freight and T for twenty seven hundred horsepower (remember that originally, FT units came draw-bar connected into what is referred to today as an A-B pair).

That's CAST underframe, is it not?.

CORRECT!  Good old auto spell correct got me again.  I'll go back up and "force" the corrected spelling.

Thanks.

For what it's worth, the Great Northern had EMD F5 units.

challenger3980 posted:

Jack is probably the BEST source for this info, but if anyone else knows, Please chime in.

EMD, seems to have "Skipped" the F1, F4,  F6 and F8 models, did they indeed "Skip" these model designations? 

Yes, the F1, F4, F6, and F8 model designations were "skipped".

What would be the reason for skipping those model #'s

Early on, i.e. pretty much prior to 1945, the Management of the Engineering Department developed/set locomotive model designations. After WWII, the Sales Department expanded in size and influence, and changes in model designations and "pattern/policies" changed depending on who the General Sales Manager was. For example, when the GP30 was designed/developed, the Engineering Dept. "named it "GP22", and early internal paperwork documents that designation. The General Sales Manager, upon learning of GE's entry into the main line diesel locomotive market with the U25B (at 2500 HP), the change from "GP22" (which had 2250 HP) to GP30, was made in order to "compete" with the GE U25B. 

The FT, F3, F7 and F9's and their variants are well known, and I believe that the F2, was essentially a transition unit between the FT, and the F3, basically, IIRC, having for the most part FT machinery, and an F3 body style. 

Except the F2, specifically "developed" quickly for the CB&Q, did have electric cooling fans and an improved main generator with a companion alternator to power the cooling fans.

Again, to the best of MY knowledge, the F5, was only sold to the CB&Q, and had Stainless Steel skin.

No. You are confusing the CB&Q E5A passenger unit, which was essentially an E3A with all fluted stainless steel carbody sides, with the "intermediate" F5 freight units, which the GN purchased. 

EMD simply not liking "Even" numbers doesn't explain an F2, but no F1.

Again, prior to WWII, the EMC/EMD Engineering Dept. pretty much developed model designations, based on mechanical/technical and horsepower of the unit. Thus, contrary to Wikipedia and possibly other internet sources, the FT model designation was: "F" for Freight and "T" for Twenty Seven Hundred Horsepower (remember that the FT "A" and "B" were drawbar connected together totaling 2700HP). The internal EMD Engineering Dept. documents, which I personally have seen, bare this out. This followed the pattern from the 1930s of "SC" was for Six hundred HP, with a Cast underframe, and the later "SW" was for Six Hundred HP, with a Welded (fabricated" underframe.  

Does Jack, or anyone else on here know the method behind the madness of EMD's "F" unit model numbering scheme?

I must admit, that none of the "old timers" still working at EMD when I started in 1962, could LOGICALLY explain why some model number designations were "skipped". By the time of the early 1960s through the 1990s, the Sales Department was pretty much in total control of EMD model designation names.

Thanks, Doug

Figured I would go back up to this original post, and try and answer most of the questions.