Trains.com

Alaska Railroad's SD70MACs

4409 views
19 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    April 2007
  • From: Bridgman, MI
  • 283 posts
Alaska Railroad's SD70MACs
Posted by bogie_engineer on Saturday, September 16, 2023 10:51 AM

I saw this article by Carl Swanson yesterday: 

https://www.trains.com/trn/railroads/locomotives/alaska-railroads-sd70macs/

which contains this statement "its computer-controlled HTC-R “steerable” trucks glide around the line’s many tight curves".

There is nothing computer-controlled about the HTCR truck, it simple steers itself in response to the creep forces generated at the wheel-rail interface. No idea where the author got this idea. He uses the term "steerable", which is the term used by GE to describe their radial steering truck which EMD has never used; we called it a "self-steering radial" truck. 

I hate to think that railfans and ChatGTP would now use this poorly researched article as authoritative reference material. But it must be true if it is on the internet.

Dave

  • Member since
    June 2003
  • From: South Central,Ks
  • 7,170 posts
Posted by samfp1943 on Sunday, September 17, 2023 9:58 AM

bogie_engineer

I saw this article by Carl Swanson yesterday: 

https://www.trains.com/trn/railroads/locomotives/alaska-railroads-sd70macs/

which contains this statement "its computer-controlled HTC-R “steerable” trucks glide around the line’s many tight curves".

There is nothing computer-controlled about the HTCR truck, it simple steers itself in response to the creep forces generated at the wheel-rail interface. No idea where the author got this idea. He uses the term "steerable", which is the term used by GE to describe their radial steering truck which EMD has never used; we called it a "self-steering radial" truck. 

"...I hate to think that railfans and ChatGTP would now use this poorly researched article as authoritative reference material. But it must be true if it is on the internet..."

Dave

 

"...I hate to think that railfans and ChatGTP would now use this poorly researched article as authoritative reference material. But it must be true if it is on the internet..."

Dave

Unfortunately,DAVE, you are really on to something......In today's society;the old 'saw": That says;  "...TRUTH is just getting its pants on, while Internet lies, are half-way around the world..." seems a real truism.

  I seem to recall seeing exactly that 'defined problem'; you've described, show up in more than one published piece,and  seemimgly, confused comments after those published pieces.

 

 

 


 

  • Member since
    September 2011
  • 6,434 posts
Posted by MidlandMike on Sunday, September 17, 2023 9:41 PM

The September issue of Trains has an article on the ARR.  On page 25 they have a photo of the "704-foot Mears Memorial Bridge spanning the Yukon River."  It actually crosses the Tanana River.

  • Member since
    November 2008
  • 1,873 posts
Posted by Leo_Ames on Monday, September 18, 2023 10:11 PM

It's since been fixed, but the news article about the retrucking of the Mark Twain Zephyr referred to the EMD switcher donor as a "SW-600".

While the pages of Trains was once a sea of inconsistency with diesel designations back in the 1960's and earlier (even in EMD's own ads of the era), this was the first misstep like this that I can recall in many decades for an as-built locomotive with a factory applied model designation.

  • Member since
    September 2003
  • 21,607 posts
Posted by Overmod on Tuesday, September 19, 2023 5:49 AM

What's wrong with that, the hyphen?

Everything authoritative I have seen, including a post at RyPN from one of the people doing the work, indicates that the engine donor for the MTZ is indeed one of the 15 SW600s.  (They wanted a C-block 6-567).

They do have four SW1s, but that is circumstantial.

  • Member since
    November 2008
  • 1,873 posts
Posted by Leo_Ames on Tuesday, September 19, 2023 6:40 PM

The generally accepted form for EMD model designations in modern times is to not have a hyphen after the model family. Hence why you wrote SW1 rather than SW-1.

For instance in the pages of Trains Magazine, the last time SW was followed by a hypen (not counting line breaks) was the April 1969 issue in the article 'When it's shortline time down South' by Jim Boyd, with the appearance of SW-1500 in the first sentence.

Correct or not (EMD themselves flip flopped regularly back then and Jim Boyd was an EMD field instructor), Kalmbach sought consistency in model desiginations and SD, NW, SW, GP, F, E, and so on have never been followed by a hyphen in the pages of Trains since ~1970 and the railfan world has generally tagged along with such standardization.

Hopefully a one-off mistake, but perhaps further evidence of a decline in quality for a publisher that has traditionally kept mistakes, outside of perhaps maps where they have a checkered history, to a minimum.

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Tuesday, September 19, 2023 7:19 PM

There was a period in the late 1960s or early 1970s when EMD used a "forward slash" or "/" as in SD/39 and SD/45. This was fairly short lived, but did appear in "Trains".

I myself think that some break might be useful in the more complex model numbers, such as GT46C ACe. I've added a space after the first "C", since GT46C is a separate class of its own, with DC traction, and makes it clear that the "AC" indicates AC traction and the "e" indicates a modification in the type of power electronics.

Peter

  • Member since
    November 2008
  • 1,873 posts
Posted by Leo_Ames on Tuesday, September 19, 2023 8:03 PM

Despite holding Kalmbach to a higher standard, I do this myself from time to time, especially with Fairbanks-Morse power. H-24-66 looks just as correct to my eyes as H24-66 does for an example and I'm sure there's no consistency with what form I personally use such as at this forum.

I'm not even sure which format is considered the most proper. Wikipedia goes with the extra hypen format for what little that's worth, but Trains traditionally seems to prefer the latter form with the single hypen between the horsepower rating and the axle/traction motor count (although the dual hypen format does make occasional appearances in Kalmbach publications, including in modern issues of Trains).

  • Member since
    March 2003
  • From: Central Iowa
  • 6,872 posts
Posted by jeffhergert on Tuesday, September 19, 2023 9:59 PM

Leo_Ames

The generally accepted form for EMD model designations in modern times is to not have a hyphen after the model family. Hence why you wrote SW1 rather than SW-1.

For instance in the pages of Trains Magazine, the last time SW was followed by a hypen (not counting line breaks) was the April 1969 issue in the article 'When it's shortline time down South' by Jim Boyd, with the appearance of SW-1500 in the first sentence.

Correct or not (EMD themselves flip flopped regularly back then and Jim Boyd was an EMD field instructor), Kalmbach sought consistency in model desiginations and SD, NW, SW, GP, F, E, and so on have never been followed by a hypen in the pages of Trains since ~1970 and the railfan world has generally tagged along with such standardization.

Hopefully a one-off mistake, but perhaps further evidence of a decline in quality for a publisher that has traditionally kept mistakes, outside of perhaps maps where they have a checkered history, to a minimum.

 

Now you tell me.  I never got the memo.  I've sometimes used the hyphen, sometimes not, usually for the dash 2 designations.  But when not using the hyphen I usually leave a space between the SD or GP and the model number.  I don't think I'll change.

The next thing you'll tell me is that Pluto isn't a planet.

Jeff

  

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 13,524 posts
Posted by CSSHEGEWISCH on Wednesday, September 20, 2023 10:08 AM

jeffhergert

The next thing you'll tell me is that Pluto isn't a planet.

Jeff

Actually, it still is considered a planet, but it's a minor planet, falling somewhere between the eight known major planets and the asteroids.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    July 2010
  • From: Louisiana
  • 2,308 posts
Posted by Paul of Covington on Wednesday, September 20, 2023 11:01 PM

   Maybe we could call Pluto a planette?

   This thread has gone through an interesting evolution.  It started out about a misrepresentation about the EMD radial truck, mentioned a misplaced bridge,  became an extended discussion about the use of the hyphen, then on to the planets.

_____________ 

  "A stranger's just a friend you ain't met yet." --- Dave Gardner

  • Member since
    September 2003
  • 21,607 posts
Posted by Overmod on Thursday, September 21, 2023 3:15 PM

We're just killing time until Carl Swanson, who I see posting in another thread, comes on and tells us his sources for the computer-controlled truck action.

  • Member since
    April 2007
  • From: Bridgman, MI
  • 283 posts
Posted by bogie_engineer on Sunday, September 24, 2023 7:56 AM

I see a corrected article is now posted, thanks Carl.

Dave

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,874 posts
Posted by wjstix on Wednesday, October 4, 2023 11:50 AM

Regardless of what EMD did, using a hyphen ("SD-9") was very normal and commonly used when talking about EMD locos. It may have become an 'issue' when people started using the word "dash" in reference to GE units...so a C44-9 became a "Dash 9". Maybe the concern was that people would start saying "SD dash 9" instead of "SD 9"?

In any case, it's a meaningless issue, kinda like when listing three things, do you use a comma or two ("A,B and C" vs. "A, B, and C"). People who are experts in the use of grammer and punctuation say it doesn't matter, either way is fine.

Stix
  • Member since
    September 2003
  • 21,607 posts
Posted by Overmod on Wednesday, October 4, 2023 1:05 PM

I'd be willing to note that using a hyphen in an EMD designation isn't really the sky falling, even for purists.  But I also disagree with tolerating it as 'acceptable' once pointed out.

It has never been any more 'correct' to hyphenate something like GP7, SD9, or SD40 than it is to hyphenate a PRR designation like K4.

On the other hand, you can't even mention something like SD40-2 without the explicit phrase 'dash-2'.

And spelling is as important as 'grammar'... Wink

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Friday, October 27, 2023 8:38 AM

To get back to the Alaska SD70MAC locomotives, I understand that one of the two traction inverters is used to provide the head end power for the train.

This would suggest that only one traction inverter is used to provide traction power, which would suggest that only one truck and three motors are used for traction in passenger service. This would probaly be adequate for even large passenger trains.

However, I recall hearing that one inverter could power four traction motors, two on each truck, when operating as a passenger unit. If limits were imposed on the maximum current per motor, this would seem possible.

Does anyone have definite information on this pont?

Peter

  • Member since
    April 2007
  • From: Bridgman, MI
  • 283 posts
Posted by bogie_engineer on Friday, October 27, 2023 9:27 AM

As far as I know, the switchgear at the rear of the long hood adjacent to the inverters and HEP transformer only switches the inverter output between the 3 traction motors in the rear truck and the HEP transformer. The lead truck inverter is unaffected so only 3 motors pull the train in HEP mode. We had just finished the LIRR DE/DM30AC's prior to this project so the system architecture was borrowed from that loco along with the HEP transformer from Trafomech in Italy.

Jay Boggess was the lead engineer on the system for Alaska and could confirm or correct what I recall.

Dave

  • Member since
    July 2016
  • 2,607 posts
Posted by Backshop on Friday, October 27, 2023 9:56 AM

M636C

 

This would suggest that only one traction inverter is used to provide traction power, which would suggest that only one truck and three motors are used for traction in passenger service. This would probaly be adequate for even large passenger trains.

Peter

The Alaska has some 2% grades, especially on the Anchorage-Seward segment.  Our train had a push-pull consist with a GP40 on the head end and an SD70 on the rear.

  • Member since
    July 2008
  • 2,325 posts
Posted by rdamon on Friday, October 27, 2023 11:24 AM

I recall reading that the METRA SD70MACH's design is 6 inverters with 4 powering the B1-1B trucks and one for the HEP with #6 as a standby.

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Friday, October 27, 2023 7:50 PM

The locomotive that had confused me was not the Alaska SD70MAC but the contemporary Indian Railways WDP-4, Model GT46PAC, which had the B1-1B arrangement of motors. However, this locomotive did not provide head end power, and retained both inverters powering two motors each.

The motors were reduced to four to reduce the locomotive weight and track impact at the higher speeds expected compared to the freight WDG-4, model GT46AC. However, later locomotives were built with six motors as type WDG-4B, because the four motor units were found to have trouble hauling larger trains with more than 24 cars. The later locomotives were only one imperial ton, 1.4 short tons heavier.

Peter

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

Newsletter Sign-Up

By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy