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The SD70 series

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The SD70 series
Posted by Notch 8 on Thursday, May 7, 2020 12:38 PM

The SD70 series seems to be something of an anomaly in the history of locomotive model naming practices. The original SD70, SD70M, SD70I and SD70MAC models were all 4000 hp. As these were all variations on the same basic 4000 hp version of the EMD 710 prime mover, it's perfectly logical that they're all identified as SD70s.

The SD70ACe and later models, however, strike me as unusual in that they are essentially an all new design. The frame and body are quite different from earlier SD70s and the 710 prime mover is now rated at 4300 hp. As such, it seems to me that a new model designation would have been appropriate.

The SD70ACe-T4 is also unusual in its model designation. This model has a new truck design, a somewhat different body and the new J series 1010, four-cycle, 4400 hp prime mover. For all these reasons, this model seems to have been particularly deserving of a new designation.

Can anyone out there explain the logic, or lack thereof, as to why EMD insisted on maintaining the SD70 designation for at least three distinctly different locomotive designs?

Thanks!
Allan Manson

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Posted by NorthWest on Thursday, May 7, 2020 11:47 PM

With the exception of the SD18, SD24, GP18 and GP20, EMD nomenclature has never been rational.

Part of the issue, I suspect, is that the SD80 and SD90 series had already been used.

Though the SD70ACe might be better termed the SD75ACe, all the SD70 models have roughly equivalent horsepower which is apparently enough to give them similar designations.

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Posted by Leo_Ames on Friday, May 8, 2020 5:14 AM

Late model EMD switchers also tended to be logically labeled with their 1000, 1200, and 1500 horsepower ratings reflected in the model number (And the SW8, SW600, and the SW900).

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Posted by M636C on Friday, May 8, 2020 6:51 AM

Can anyone out there explain the logic, or lack thereof, as to why EMD insisted on maintaining the SD70 designation for at least three distinctly different locomotive designs?

After the brief period mentioned above with the 567C and 567D engines, EMD developed a GP22 (2250 HP) but since it was competing with the U25, EMD decided that it should be a GP30, based, supposedly on "30 engineering improvements" over the GP20, but, in fact, to have a higher number than GE. From then on the model number had no relationship with the power. 

The later uses of the SD70 model number were the exact reverse. After Union Pacific, in particular expressed disappointment in the SD90 locomotives, they then leased an even 1000 SD70Ms, based on the good performance of  a batch taken over with SP. Even more followed, and SD70 became a byword for simple reliable locomotives, certainly at UP. The SD70MAC was very popular with BNSF as well and had a good reputation. Some of the later SD70MAC units apparently had 4300HP at 950rpm.

The SD75 on the other hand had only two customers, ATSF and CN. Some SD75s were rated at 4500HP at 1000 rpm, but these were modified back to 4300HP at 950rpm.

So the entirely new locomotive was described as an SD70 ACe or SD70M-2 depending on the transmission, AC or DC. It would have been more accurate to call it an SD75 ACe or SD75M-2, but the SD70 description was felt to create a better impression.

Peter

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Posted by bogie_engineer on Saturday, May 9, 2020 12:19 PM

As Peter says, the thinking at EMD was that with the 1,000 unit UP SD70M order, EMD wanted to preserve a name that had a good reputation in the industry after the less than successful SD90MAC. So the marketing dept (a very small group) and the sales dept decided they would just keep naming everything SD70-something. I tried many times to use other names as I worked on different models but the answer was always the same.

Dave

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Posted by SD70Dude on Saturday, May 9, 2020 1:55 PM

In the numbering logic of the 40, 50, 60 and early 70 series locomotives, a six axle unit with a 5000 HP 20-710 engine should have been called a SD75.  

Units with the uprated 4300 HP/950 RPM 16-710 engine should have gotten a new model number, which should have been the 80 series.  

The SD90 would still have been called the SD90 in this alternate universe.

Just my thoughts from an outside railfan's viewpoint.

Greetings from Alberta

-an Articulate Malcontent

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Posted by BaltACD on Saturday, May 9, 2020 4:26 PM

SD70Dude
In the numbering logic of the 40, 50, 60 and early 70 series locomotives, a six axle unit with a 5000 HP 20-710 engine should have been called a SD75.  

Units with the uprated 4300 HP/950 RPM 16-710 engine should have gotten a new model number, which should have been the 80 series.  

The SD90 would still have been called the SD90 in this alternate universe.

Just my thoughts from an outside railfan's viewpoint.

30 SD80's were sold to ConRail.  In the ConRail split 17 went to NS and 13 went to CSX.  Later NS traded a group of SD40's to CSX to get the remaining SD80's.  In February this year NS sold all of them the CP and Progress Rail.

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Posted by Overmod on Saturday, May 9, 2020 5:39 PM

BaltACD
30 SD80's were sold to ConRail.

Implicit in what he is saying is that, in a coherent world, a six-axle unit with the uprated 5800hp 20-710 and the electrical upgrades should have been the SD85, with the comparable 16-cylinder locomotive the SD80.  

However, 'comparable' would probably have involved the AC drive, too, which at the time was exotic, expensive, and did not have much aftermarket motor and component support.  And the 90-series was assumed to be high-horsepower 4-stroke engined, only the default placeholding engines in the 710 series at all -- here you need a second convention, the use of 12-cylinder vs 16-cylinder 265s as the difference between "90" and "95" models at the two power points (~4400 and 6000 respectively) that the all-new wonderful world of future EMD power presaged.

Of course the future didn't work out that way, and the SD90s became tarred first with the brush of engine failure, then with the frame issues, and of course were bigger than needed at the time for competition with first the dash-9s and then the GEVO series.  As Mr. Goding pointed out, that wasn't going to sell, and he may have some comments about why "SD100" modern Century series, especially for something that wasn't going to walk forward in horsepower-per-unit for decades, wasn't something GM thought would appeal either at the time.

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Posted by SD60MAC9500 on Sunday, May 10, 2020 10:14 AM

Progress Rail wanting to keep familiarity with its customers decided on keeping the 70 series designation. Progress Rail still uses EMD branding for power products as well for the same reason.. Outside of that though.. I imagine instead of the mouthful SD70ACe-T4. PR44AC would’ve been a more practical model designation 

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Posted by Overmod on Sunday, May 10, 2020 2:19 PM

SD60MAC9500
PR44AC would’ve been a more practical model designation 

Even Caterpillar wouldn't make the mistake of naming its products to resemble the (now ex-)GE competition.  Or even imply that GE naming conventions reflected 'best sense' in the railroad industry...

(Or that "Progress" would become a more noted and respected name in the locomotive industry than "Electro-Motive" -- Caterpillar already being a watchword for motive-power disaster at any size much above bulldozer engines.  But stranger things have happened over the years with trademark names and branding.)

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Posted by SD70Dude on Sunday, May 10, 2020 2:29 PM

SD90MACe-JIII would actually be the logical name for the current EMD Tier-IV locomotive.

The 1010J engine appears to have been based on the 265H, much as the GEVO was based on the HDL.

The cab has been redesigned, and though I don't believe EMD has given it a name Phase III would be the logical next number.

The "M" could be deleted as the Spartan cab is no longer an option, and "-T4" could be added on the end, though the presence of the J engine already tells you that it is Tier-IV compliant.

As for the original SD90, that name made sense as it had a V16 engine.  A hypothetical SD95 would have had a 20-265H engine in this model numbering scheme.

At least one prototype unit was built with a 12-265H, this was the SD89.

Greetings from Alberta

-an Articulate Malcontent

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Posted by Overmod on Sunday, May 10, 2020 8:35 PM

SD70Dude
As for the original SD90, that name made sense as it had a V16 engine.  A hypothetical SD95 would have had a 20-265H engine in this model numbering scheme.

Except for the fact that there wouldn't be a 20-265 in locomotives -- the 16 already produced 'too much' horsepower for a single unit to tie up, even if there hadn't been problems with spot cavitation due to ultrasonic 'ringing' of the assembled-and-stressed block casting.  Since the 265H was the explicit replacement for the 20-710 in the first place -- to great sighs of relief from EMD over crank fabrication and longevity -- it would make little sense for EMD to make a special cast block to go with the specially made, and significantly beefed-up, crank for a 20-cylinder version, presumed not selling well even in the lower-power fabricated-block 2-stroke line.

All the 'convertibles' were built as SD90s and with the stock H engine that's what they would of course stay.  The SD89 would properly be a locomotive with a 12-cylinder 710 and AC transmission, money wasted by the potload; the presumptive SD90-family equivalent (which might have had some fancy turbocharging arrangements to make up some of the 'horsepower') would in proper logic be an SD99.  (We could argue whether a 'conventional' passenger or higher-speed 'Z-intermodal' engine using a sequential-turbocharged 12-cylinder H engine could be built with two-axle trucks and still have adequate radiators and so forth -- probably not much real competition for a P42 series, or for any of the later 'contenders' with high-speed powerplants...)

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Posted by SD60MAC9500 on Monday, May 11, 2020 12:02 AM
 

Overmod

 

 
SD70Dude
As for the original SD90, that name made sense as it had a V16 engine.  A hypothetical SD95 would have had a 20-265H engine in this model numbering scheme.

 

The SD89 would properly be a locomotive with a 12-cylinder 710 and AC transmission, money wasted by the potload; the presumptive SD90-family equivalent (which might have had some fancy turbocharging arrangements to make up some of the 'horsepower') would in proper logic be an SD99.  (We could argue whether a 'conventional' passenger or higher-speed 'Z-intermodal' engine using a sequential-turbocharged 12-cylinder H engine could be built with two-axle trucks and still have adequate radiators and so forth -- probably not much real competition for a P42 series, or for any of the later 'contenders' with high-speed powerplants...)

 

EMDX 92 the only prototype SD89MAC-H with it's V12-265H rated at 4500 THP was to be the replacement for the 70 series, if everything would have panned out during testing. Shame it didn't develop into a real contender against the AC44CW..

 EMD SD89MAC demo @ EMD plant @ Lagrange,IL 11/13/2011 -- Antique ...

 
 
 
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Posted by SD70Dude on Monday, May 11, 2020 4:13 PM

Overmod
SD70Dude
As for the original SD90, that name made sense as it had a V16 engine.  A hypothetical SD95 would have had a 20-265H engine in this model numbering scheme.

Except for the fact that there wouldn't be a 20-265 in locomotives -- the 16 already produced 'too much' horsepower for a single unit to tie up, even if there hadn't been problems with spot cavitation due to ultrasonic 'ringing' of the assembled-and-stressed block casting.  Since the 265H was the explicit replacement for the 20-710 in the first place -- to great sighs of relief from EMD over crank fabrication and longevity -- it would make little sense for EMD to make a special cast block to go with the specially made, and significantly beefed-up, crank for a 20-cylinder version, presumed not selling well even in the lower-power fabricated-block 2-stroke line.

All the 'convertibles' were built as SD90s and with the stock H engine that's what they would of course stay.  The SD89 would properly be a locomotive with a 12-cylinder 710 and AC transmission, money wasted by the potload; the presumptive SD90-family equivalent (which might have had some fancy turbocharging arrangements to make up some of the 'horsepower') would in proper logic be an SD99.  (We could argue whether a 'conventional' passenger or higher-speed 'Z-intermodal' engine using a sequential-turbocharged 12-cylinder H engine could be built with two-axle trucks and still have adequate radiators and so forth -- probably not much real competition for a P42 series, or for any of the later 'contenders' with high-speed powerplants...)

I misspoke in my previous post.  As the 1010J engine is a V12, an appropriate name in my fantasy world for the current EMD Tier IV locomotive would be the SD89ACe-JIII. 

Of course there was no SD95, and I've never seen anything to suggest that a 20-265H was ever considered, let alone built.

I have heard that GE considered developing a V18 HDL engine, though I am not sure if a prototype was ever built. 

All this is just fun railfan speculation, and I would be very interested in what alternate model designations were proposed by Dave Goding before the decision was made to keep the SD70 brand. 

Greetings from Alberta

-an Articulate Malcontent

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