I understand that GP stands for general purpose locomotives.
What does GE’s type"C" and “ES” and GM’s type “SD” denote?
C = 3 axle truck ( B = 2 axle truck)
ES = Evolution Series (this is the latest and most eco friendly prime mover that GE has used)
SD = Special Duty (EMD shorthand for a locomotive with 3 powered axles on each truck. The GP in EMD shorthand is for a locomotive with 2 powered axles on each truck. The EMD E series passenger engines used A-1-A trucks, two powered axles with a idler axle in the middle of the truck.
A bit of trivia, the “E” stood for Eighteen hundred horsepower (two 12 cylinder 201A’s). The original box-cabs delivered to the AT&SF and B&O were B-B’s, the later E’s going to A1A’s to deal with increasing weight.
- Erik
And, IIRC, the “F” in the F units stood for “fifteen hundred HP”, not “freight”.
GP was “general purpose” (Possibly because RS had already been used by ALCO for “road switcher?”).
The “SW” stood for “welded”, not SWitcher. it had a counterpart in the “SC,” which had a cast frame.
Can’t help you with the rest of your question.
The F in EMD designations stood for Freight.
Their original road freight engines, the FT…the F was for Freight and the T was for Thirteen or Twenty Seven, as the engines put out 1350 HP per individual unit or 2700 HP per drawbared pair. Subsequent series were the F2, F3, F7, F9, which in reality were just increasing model numbers as the equipment in the locomotives evolved and improved.
Further elaborating on Larry: The “S” in the SW and SC locomotives stood for Six (hundred horsepower); the “N” in the corresponding models (NW, NC) stood for Nine (hundred horsepower).
Actually, the original F units (Model FT) had 1350-horsepower prime movers. The “F” stood for Fifty-four (hundred horsepower), as the units were designed to be used in A-B-B-A configuration. The first TR units (Model TR) had a designation standing for Twenty-seven (hundred horsepower), as these cow-and-calf units (built for Illinois Central) had a pair of 1350-hp prime movers.
By the late 1940s, when designations like BL (Branch Line), GP, and SD came around, the horsepower-based models had pretty much become obsolete–F3 units had 1500 horsepower, NW2s had 1000, E3 units 2000, and TRs 2000 (kind of reversing the trend; they were redesigned to look more like switchers). By the early 1950s, SW units had 1200 horsepower, and “SW” stood for SWitcher, with no more NW units–the cast-steel underframes were long gone.
Thanks for the answers. For any newbies out there don’t hesitate to ask any simple or questions you may think stupid. There are a bunch of wonderful fans out there to help you.
Only a few CN freights pass through here daily and I’m having a hard time discerning the different models. The sidebars in many of my loco books are a great help.
Preston Cook wrote about the early F units in the July 2008 Railfan & Railroad. On page 45 he explains why he believes FT (with drawbars) stood for Freight Team, while FS (couplers) stood for Freight Single. EMD dropped the FS name later as nobody was using it.
Preston showed me around EMD in 1977 and I wouldn’t question his knowledge of the EMD operation.
However, if the letter “F” did not refer to horsepower I think it was the first unit type not to use that as the basis of the code, apart from some “retrospective” codes…
My firm belief is that it stood for “fourteen hundred horsepower”.
The 16-567 developed 1350 HP as input to the generator. The letter T had been allocated to the 16-201A in the CRI&P cab units type TA. So if “T” and “thirteen hundred” were unavailable, rounding up 50 HP to fourteen hundred was the logical next move.
I think the late Don Dover suggested this. While not as closely involved with EMD as Preston Cook, he certainly knew his stuff.
Now for “S” and “T”. Don had indicated in the 1980s that Santa Fe units were sometimes listed as FS since they were all single units. However I don’t see why “team” is a likely origin for the “T”. The FT, certainly the prototypes and most production units for other than ATSF and GN were “twin units” one cab and one booster coupled by a drawbar, although usually operated as two pairs together.
So clearly, I believe that FT was “Fourteen Hundred Horsepower, Twin unit”.
I don’t believe there is any written evidence to support any other alternatives. I’m convinced, but others should make up their own minds.
M636C
Why couldn’t they make it easy like FM or Baldwin?
H16-44 - Hood unit, 1600 horsepower, 4 motors and 4 axles.
Say, CPA16-5 - Cab unit, passenger with steam gen, A unit, 1600 HP, 5 axles.
DS-4-4-1000 - Diesel switcher, 4 axles, 4 motors, 1000 HP.
Easy peasy.
For the longest time at least, GP = 4 axles, SD = 6 axles.
[soapbox]If it had been made easy, there would be no need for this discussion!
Kind of like politics.[banghead] [:-^]
Gee, and here I thought the “F” was the designation for “full-width carbody”.
And whatever happened to the F4, F5, F6, F8?
Ask a simple question, get a complicated (but more interesting) answer.
What we’ve learned here is that in fact nobody knows what the heck this stuff stands for…at least beyond GP and SD.
Still does.
Obsolete before they ever got off the drawing board?
It is important to never confuse Marketing with Engineering!!! [swg]
Robert
General Electric and ALCo model numbers are easy to understand for the most part. Examples:
GE B36-7: B = B trucks (two axles each for a total of four powered axles) 36 = horsepower divided by 100 (3,600) -7 = Dash 7, GE’s then-current model designation. The Dash 8 and Dash 9 would follow later.
GE C40-8: C = C trucks (three axles each for a total of six powered axles) 40 = horsepower divided by 100 (4,000) -8 = Dash 8.
With GE, a ‘W’ following the model number indicates a widecab model. (Example: C40-8W)
ALCo RS1: RS = Road Switcher, and 1 = the first model made. (RS2 and RS3 being the second and third models produced)
ALCo C420: C = ALCo’s Century series of diesels, 4 = number of axles, and 20 = horsepower divided by 100. (2,000)
ALCo C636: C= Century class, 6 = number of axles, and 36 = horsepower divided by 100. (3,600)
ALCo also used the W’ suffix for their Canadian models with widecabs, as did their successor in Canada, MLW. (M420W)
EMD’s model numbers went all over the place, so are more difficult to trace. some are simple:
EMD GP18: GP = General Purpose, EMD’s designation for four-axle units, and 18 = horsepower divided by 100. (1,800)
EMD SW1000: SW = Switcher, 1000 = horsepower. (Earlier switchers used ‘SW’ to indicate Six hundred horsepower, Welded frame, ‘SC’ for Six hundred horsepower, Cast frame, ‘NW’ for Nine hundred horsepower, Welded frame, and ‘NC’ for Nine hundred horsepower, Cast frame.)
EMD’s road units are different. For instance, the GP38, GP39, and GP40 are numbered in chronological order of their release. A ‘Dash 2’ unit (GP40-2, etc.) signifies the unit has a computer-controlled wheelslip system, in addition to a few other changes. All of EMD’s ‘SD’ units (‘Special Duty’) are six-powered-axle locomotives. The logic behind a six-axle uni
Now that Caterpillar/Progress Rail bought EMD, there are new items to watch for:
PR43C, (upgraded SD50) PR30C (upgraded SD40)
AFAIK there are 2-3 PR43C’s on NS
not sure about PR30C or other PR lokies.