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What do the numbers and letters mean in locomotives?

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What do the numbers and letters mean in locomotives?
Posted by AJ Gonfiantini on Tuesday, August 24, 2010 3:49 PM

I know what SD and GP stand for, but what does the number mean in the SD or the GP. Also what does the 40,41,44, and 45 mean in C40-8(W), C41-8(W), C44-9(W) C45AC(CTE). And thewhat does the CW stand for in AC4400CW. Then the last one, in something like SD40-2, what does the -2 stand for? Thank you.

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Posted by locoi1sa on Tuesday, August 24, 2010 5:09 PM

 SD stood for super duty had 3 axle trucks and the numbers behind it were the horsepower times 100. An SD35 would be a six axle 3500 HP locomotive. The -2 was a modified or second generation.

 On the General Electric locos the CW stands for C truck (3 axles) W = wide cab. An AC4400-CW would be a locomotive with AC traction motors, 4400 rated HP prime mover on 3 axle trucks with a wide cab.

  It gets a lot more confusing as you go along. 

       Pete

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Posted by jrbernier on Tuesday, August 24, 2010 9:24 PM

locoi1sa

 SD stood for super duty had 3 axle trucks and the numbers behind it were the horsepower times 100. An SD35 would be a six axle 3500 HP locomotive. The -2 was a modified or second generation.

 On the General Electric locos the CW stands for C truck (3 axles) W = wide cab. An AC4400-CW would be a locomotive with AC traction motors, 4400 rated HP prime mover on 3 axle trucks with a wide cab.

  It gets a lot more confusing as you go along. 

       Pete

  SD stands for 'Special Duty', and the 35 is for the '35' line - nothing to do with hp.  The SD35 was a 2500 hp offering in the early 60's.  EMD briefly flirted with a hp naming system in the late 50's - the GP18 was rated at 1800 hp, the SD24 was rated at 2400 hp.  EMD dumped this system in 1962 with the release of the 2250 hp GP30 locomotive.  They have sort of revived it with some special engine like the GP15/SW1500/BL20 - but the regular line seems to jump 10 digits with a new series of models.  The current '70' line may be the longest running model line by EMD.

  GE basically uses hp in their naming convention, but they seem to keep changing the order of the prefix/suffix

Jim

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Posted by silicon212 on Tuesday, August 24, 2010 9:24 PM

AJ Gonfiantini

I know what SD and GP stand for, but what does the number mean in the SD or the GP. Also what does the 40,41,44, and 45 mean in C40-8(W), C41-8(W), C44-9(W) C45AC(CTE). And thewhat does the CW stand for in AC4400CW. Then the last one, in something like SD40-2, what does the -2 stand for? Thank you.

On the GE engines, 40, 41, 44 mean horsepower (4,000, 4,050 and 4400).  The 45 on the UP engines distinguishes these engines from the older AC4400 series (the 45s are GEVOs).  C means 3-axle truck (6 axle locomotive), W means Wide cab, so AC4400CW would be AC traction, 4400 horsepower, 6 axle, widecab.  CTE stands for Controlled Tractive Effort, a software upgrade to Union Pacific's GE locomotives so designated.

 

On EMD locomotives, the model designation is just that - a model designation.  Such as SD40 or SD40-2.  It's a 40 series locomotive (16-645E3 engine, 3000 HP although some made from 1982 to the end were actually 3200 HP).  50 series were 3500 HP 16-645F3s, 60 series were 3800 HP 16-710G3s, 70 series were 4000-4350 HP 16-710G3B/Cs.

The original 40 series line was introduced in 1965, and was substantially redesigned in 1972.  The redesigned 40 series are the Dash 2s.  Among improvements was better wheelslip control, redesigned trucks on the SD series with traction motors all facing the same direction, improvements in the locomotive wiring, as well as other various improvements.  As a result of redesigned trucks, the SD40-2 locomotives are 3 feet longer which gives them even larger 'porches' - this is a spotting feature.  Some railroads opted for the original Flexicoil trucks (the newer trucks are called HTCs), although these locomotives still rode on the longer -2 frame.

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Posted by nssd70m on Tuesday, August 24, 2010 9:29 PM

Actually, the SD35 was rated as 2500hp. EMD 30 series units were 2250hp, 35 series were 2500hp, 38 series were 2000hp, 39 series were 2300hp, 40 series were 3000hp, 45 series was 3600hp, 50 series was 3500hp, 60 series was 3800hp, 70 series was 4000hp, 80 series was 5000hp, 90 series was 6000hp. Dash 2 means upgraded electrical parts.   On the GE side, the number after the "B" or "C" was the first two digits of the horsepower rating, like C39-8, 3900hp. Earl...  

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Posted by silicon212 on Tuesday, August 24, 2010 9:36 PM

To further expand what I was talking about in regard to the GE units above, keep in mind that UP designates its AC GE locomotives into its own 'scheme'.

AC4400CW = C44AC.

ES44AC = C45AC.

Both units are 4400 HP AC units made by GE.  The former is a 16-cylinder while the latter is the newer 12-cylinder.

ES = Evolution Series (GEVO).

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Posted by locoi1sa on Wednesday, August 25, 2010 6:58 PM

   Thanks Jim for the corrections. Like I said it gets confusing as you go along. I think I will stick with steamers instead.

    Pete

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 I started with nothing and still have most of it left!

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Posted by cx500 on Thursday, August 26, 2010 12:21 AM

silicon212

..........As a result of redesigned trucks, the SD40-2 locomotives are 3 feet longer which gives them even larger 'porches' - this is a spotting feature.  Some railroads opted for the original Flexicoil trucks (the newer trucks are called HTCs), although these locomotives still rode on the longer -2 frame.

 

I had understood the main reason for the switch to the longer frame was it provided space for a larger fuel tank.  The days of servicing the power at every division point were fast disappearing and increased fuel range became an important feature for many railroads.  I'm sure that using the same frame for the SD40-2 and SD45-2 provided some manufacturing savings too.  

John

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Posted by CSSHEGEWISCH on Thursday, August 26, 2010 10:20 AM

EMD has had a fairly consistent pattern of model designations for its various export designs:  http://emdexport.railfan.net/frame_layout.html   Also see:  http://community-2.webtv.net/ajkristopans/ANDRESGMLOCOMOTIVE/page2.html

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