D&RGW FS and FT Locomotives
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This page was last updated on November 18, 2022.
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D&RGW's First Road Locomotives
D&RGW's first four road locomotives, set up as four A-B-B-A sets of two cab units and two booster units, were delivered in 1942 and 1943 as D&RGW 540-547, with couplers between all four units (16 units; numbered as D&RGW 540A through 547D).
D&RGW's next group of road locomotives, also set up as four A-B-B-A sets of two cab units and two booster units, were delivered in 1944 as D&RGW 548-551 with drawbars between the cab units and the booster units, and couplers between the two booster units (8 units; numbered as D&RGW 548A through 551D).
D&RGW 540-547, delivered in 1942-1943, were fitted with couplers between the cab units and their corresponding booster units, instead of the standard drawbar. EMD designated this coupler-equipped version as FS, rather than FT.
Strapac's Rio Grande Diesels, Volume 1, page 70, includes a photo of D&RGW's FS number 540 at EMD. The photo shows that both ends of the booster units have steps and grab irons, indicating couplers rather than a drawbar. Later sets (548-551) have steps and grab irons at the rear of the booster unit only.
The same volume, on page 71, includes a photo of D&RGW FT number 550 with steps and grab irons only at the far end of the booster units.
Photo: D&RGW FS 540 at EMD in 1942
Photo: D&RGW FT 550 at EMD in 1944
Updated roster listings... D&RGW FS 540A
The two types of the first road locomotives on D&RGW delivered in 1942-1944 can be further determined by the external features of the booster units. Steve Seguine wrote on November 18, 2006:
- The first eight sets, 540-547, have five port holes in one side of the B-units, steps on all ends, and couplers between all units.
- The last four sets, 548-551, had only four portholes on either side of the B-units, no steps on the rear of the A or the front of the B, drawbars between the A and B-units, and steam generators in the rear of the B-units.
(An Otto Perry photo, OP-10829, shows D&RGW 540 on April 27, 1942 with footsteps and grab irons on all units, and a fifth porthole on the side of the second booster unit for the hostler controls.) (View the photo; zoom-in to see the detail)
D&RGW FS and FT Road Numbers
(Read about how the D&RGW FS and FT locomotives were numbered in the early years)
FS and FT Type
It has been reported that EMD's Field Service News, Volume 2 No, 7 dated July 15, 1947, describes EMD's locomotives built with 567 series engines. Among those are the FT and FS units. At the bottom of the page it states that the D&RGW owned FS units.
At the bottom were these notes:
"FS locomotives differ basically from FT locomotives in the following respects:
1. Different underframe.
2. Different end platforms.
3. Each FS unit is equipped with couplers at both ends.
FT locomotives are permanently linked between the "A" and "B" units and may be either coupled or linked between the "B" units of a four unit (5400 HP) locomotive.
A. T. & S. F., D. & R. G. W., M.P. and the Southern railroads are the only ones that have FS type locomotives."
Glenn Leasure wrote on March 18, 2022:
There were four-unit locomotives connected entirely by drawbars.
There were four-unit locomotives with drawbar-connected A&B units, and couplers at the front of the A and rear of the B.
There were four-unit locomotives with couplers at each end of each A and each end of each B.
The Grande had the latter two flavors.
"When did Electro-Motive finally assign the FT designation? EMC operator's Bulletin 159 of November 1,1939, for the 103 demo calls it 'Model F Freight Locomotive.' Revision 'A' dated November 15,1941, for Southern 6100A-D and 6101A-D (the former 103 set), has no model designation but calls it a '5400 h.p. Diesel Freight Locomotive.' A 1941 EMC brochure to market the FT promotes three locomotives: a 2,700 h.p. two-unit set, a 4,050 h.p. three-unit set, and a 5,400 h.p. four-unit set, but does not mention 'FT.' No pre-war ads in my collection refer to 'FT.' A booklet for a 1946 EMD management conference has text discussing FT vs. F3 differences, the earliest EMD document I have found that references 'FT.' (Steve Dolzall, Classic Trains, Summer 2015, page 12)
Converting FT to FS
A discussion on the LocoNotes discussion group in July 2008 described the process of converting a drawbar-equipped FT to a coupler-equipped unit. James Mischke wrote that "The FT drawbars were at a different level than couplers, so adding standard draft gear at standard height altered the end structure of the unit. Not trivial."
Andre Kristopans wrote that "If the presence of rear steps on A units and 5th porthole on B units is a definite identifier, ALL Santa Fe's were separate FS locomotives. I remember reading that EMD developed a special offset shank coupler so that they would not have to make major modifications to the normally-drawbar coupled ends."
Some of the differences of FTs versus FS locomotives were described by Andre Kristopans when he wrote on July 14, 2008, that in the mid-1940s on the Southern and its subsidiaries, the drawbar-equipped FT locomotives were converted to coupler-equipped FS locomotives (with the 'S' denoting 'single'). The conversion included adding batteries to cab units, adding hostler controls to booster units, and replacing drawbars with couplers.
Earlier, in 2006, Andre Kristopans wrote that the FT designation denoted "Freight Tandem," and that the FS designation denoted "Freight Single." As newer versions of freight locomotives were developed in the early 1940s, the FT designation was supposedly changed to denote "FreighT" to allow the 'F' to be continued for the newer F2 and F3 locomotives (Freight 2nd version and Freight 3rd version).
The 'FT' designation was applied during the early 1940s as newer designs were being considered and developed. Variations of what the 'FT' meant include "FreighT", "Freight Tandem", "Freight Twenty seven thousand". Even "Fourteen hundred," referring to the 1350 horsepower.
The variations are the result of different researchers citing different sources, including various internal EMD documents, and internal documents from owning railroads, and recollections of retired employees of both EMD and the railroads. There is no definitive source or answer.
Scott Chatfield wrote on LocoNotes on July 15, 2006:
Regarding the FT and FS, when I wrote my article on these models some years ago for "Railmodel Journal" (November 1995 issue) I talked to several past EMD employees to see if there was an "official" answer to this mystery. In short, nope. The names "FT" and "FS" were applied when the F2 was being developed. It appears that "FT" came more from EMD Marketing's calling it the "Freight Train" locomotive in advertising, as little as they did in the war years. The "FS" was really not a "single" unit version, at least not to EMD. It was a drawbarred A-B-A set with a special short-body booster. That booster was later called an "FTSB" for FT-Short Booster, although I have not found the date of first use of that term. Bottom line, it appears Marketing called the model naming shots, and logic had little to do with it.
Scott Chatfield wrote on LocoNotes on February 7, 2000:
I was told by an EMD source that EMD Engineering just called it the "F", and EMD Marketing called it the "Freight Train". By the time of the FT, EMD had given up on the idea of using the first-letter-is-the-hp system, as the NW2 (introduced in early 1939, months before the FT) had 1000hp. This lends credence to FT = Freight Train.
Tom Lundeen added during the same discussion in February 2000, "The Specifications page for the FT and the F2 in the 1946 EMD Service Handbook refer to 2700 HP FREIGHT LOCOMOTIVE, which lends credence to your supposition."
Short Booster Units
As a side note, some have wondered if D&RGW owned any of what some authors and researchers have called EMD's FS "short" booster units, using the FTSB designation. No, D&RGW did not own any of these short booster units. These short booster units were those that were among the FT locomotives delivered in three-unit sets of one cab unit and two booster units (A-B-B) to railroads such as NP and M&StL, with the middle booster unit being the shortened version. The short version was possible because these three-unit sets were connected by drawbars, and the short booster units in the middle had permanent drawbars at both ends and thus no need for a draft gear, and the resulting extra length. The cab units had couplers (and draft gear) at the front, and the second booster units had couplers (and draft gear) at the rear.
FS Designation Didn't Stick
"As to the 'FS' term, which was to designate separable (non-drawbar-connected) A and B units, EMD used it for only a short while. The Sales Department tried at least twice in postwar years to designate drawbar units as FT and coupler units as FS, but there is no mention of 'FS' in the wartime manuals or parts books, or in locomotive specifications. The effort to change the designation seems to have been retroactive, years after the units were built." (Preston Cook, Classic Trains, Summer 2015, -age 12)
EMD Field Service News, July 15, 1947 -- An image of the single page document that mentions FS locomotives on D&RGW.
EMD FT Article -- A PDF of the articles in the October, November and December 1989 issues of Railfan & Railroad magazine. (PDF; 46 pages; 43MB)
Bruce Kelly wrote about Preston Cook's article on October 15, 2014:
No discussion about the FT would be complete without mention of Preston Cook's three-part article in the October, November, and December 1989 issues of Railfan & Railroad, which coincided with the 50th anniversary of the FT's debut and demonstrator tour. The series earned Cook the David P. Morgan Article Award from the Railway & Locomotive Historical Society. A former EMD employee himself, Cook had an enormous body of research material at his fingertips during production of that multi-part story, and it showed throughout the more than 50 pages of story, photos, diagrams, maps, and rosters.
Preston Cook's three articles in Classic Trains magazine, Spring 2015: "F Units, T to 9" (page 20); Marketing and Delivering the FT" (page 36); and "Re-Engineering the FT" (page 39).