What is the point of building the SD70AH?

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Posted by zkr123 on Thursday, May 14, 2015 5:45 PM

Bryan Jones

 

 
GDRMCo

200,000-216,000lbs depending on rail conditions.

 

 

 

 

An ES44AC or SD70ACe that has been ballasted to 432,000lbs and is also equiped with the High Tractive Effort software can only produce a maximum of 200,000lbs tractive effort. This is a software limitation. These units could produce more than 200,000lbs tractive effort but there is concern for wheel and rail damage.

While UP's SD70AH and C45AH's are equiped with extra ballast bringing the units in the 427,000-428,000lb range they lack the  High Tractive Effort software. In this case these units will only produce slightly more tractive effort than the standard weight SD70ACe's and C45ACCTE's on the UP roster. To reach the 200,000lb maximum tractive effort these locomotives would have to have both the additional ballast and HTE software. The CSX specification takes things a few steps further, requiring not only the additonal ballast and HTE software but rail conditioners and steerable/radial trucks.

AC traction locomotives are not the only ones to benefit from additional ballast, DC traction units also benefit. The whole heavy, high tractive effort locomotive program on CSX was inspired by a similar effort of the Western Maryland RR which had a pair of new SD40's ballasted to 420,000lbs in an effort to increase tractive effort/adhesion. This is why CSX chose to have its fleet of ES44DC's ballasted to 432,000lbs. In years past Burlington Northern had ordered SD40-2's weighing 425,000lbs and Chicago & North Western C40-8's weighting 420,000lbs, among others.

 

Bryan Jones

 

Would NS ever dare to make the SD80mac's into AH units?

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Posted by NorthWest on Thursday, May 14, 2015 8:26 PM

They and the SD90MACs will be rebuilt to SD70ACe specifications (whatever that means, there are variations among the units) so there is a possibility. We'll see what NS ballasts them to.

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Posted by GDRMCo on Saturday, May 16, 2015 3:01 AM
What is meant by 'ACe specs' is that NS will gut the SD90s and rebuild them with ACe internals. The SD80s will get the same treatment (tho they will keep the 20-710) and both will receive new cabs.

ML

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Posted by NorthWest on Saturday, May 16, 2015 10:19 AM

Yes. I can't imagine that the SD90MACs would be ballasted much higher than they are now, considering the fun UP has had with frame cracks.  

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Posted by Wizlish on Saturday, May 16, 2015 10:24 AM

NorthWest
Yes. I can't imagine that the SD90MACs would be ballasted much higher than they are now, considering the fun UP has had with frame cracks.

Surely the 'refit' procedure that fixed the frame cracks has enough strength to prevent a reoccurrence!

I'd also suspect that any added ballast would be in the area over or adjacent to the trucks, not in the center or the fuel tank area where it would contribute to frame bending stress.  Even slabs applied to the running-board area on both sides should do the trick fairly easily for the amount of 'weight gain' involved...

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Posted by beaulieu on Saturday, May 16, 2015 12:28 PM

NorthWest

Yes. I can't imagine that the SD90MACs would be ballasted much higher than they are now, considering the fun UP has had with frame cracks.  

 

 
 
The frame cracks were caused by the weight of the fully loaded fuel tank, which is larger and heavier on the SD90MAC than the SD70MAC, and just four attachment points. If the SD90MACs are ballasted the weight would be spread out over most of the frame.
BDA
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Posted by BDA on Monday, April 30, 2018 11:18 AM

The Phase 2s have extra bracing bars and plates welded in , no more cracking issues .

 

BDA
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Posted by BDA on Sunday, May 13, 2018 3:31 AM

I should add that the Phase 2s I know of have the tank continuously seam welded to the frame , not bolted on .

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Posted by geomodelrailroader on Wednesday, May 30, 2018 7:02 PM

The railroads are using tried and true locomotives. Most of these are rebuilt SD90MACS just upgraded. UP, CP Rail, CN, NS, Rio Tinto, BNSF, and most of the heavy railroads are buying them because they are hauling heady freight over steep passes or heavy coal and ore trains. The SD90MAC and the SD70AH are the same locomotive having one of these up front adds more horsepower with two engines instead of three and burns less fuel this is why they were the first to be upgraded and this is why everyone is buying them.   

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Posted by VOLKER LANDWEHR on Thursday, May 31, 2018 8:37 AM

Perhaps I understand your post completely wrong, but...

To call a SD70ACe a rebuilt SD90MAC seems a wide fetch to me. Different horsepower, different length, different traction motors, different engines (SD70: 2-stroke 710 with 4300 hp up to tier 3, SD90MAC: 4-stroke 256H with 6000 hp), a presumably different construction as crashworthiness requirements were tightened in the meantime.

It was the GE ES44C4 that introduced an AC-locomotive with 4 AC traction motors and an A1A-A1A wheel arrengement to replace ES44DC locomotives in (intermodal) traffic were speed is more essential than traction effort at very low speed.

All these locomotives have just one diesel prime mover.

Currently the only roadswitchers offered by EMD and GE have 4300 hp and 4400 hp respectivly. And from 2015 on they to be certified according to EPA Tier 4. So there is not much choice. Knoxville locomotive Works offers a Tier 4 3200 hp locomotive.

The SD70AH is a SD70ACe ballasted to the allowed axle load for better tractive effort.

There are a number of Tier 4 switchers certified.

If I got something wrong, correct me please.
Regards, Volker

 

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Posted by YoHo1975 on Thursday, May 31, 2018 3:08 PM

I think what he meant was that that the SD9043 and the SD70ACe are effectively the same. This is also not entirely true, but it is a reasonable statement to make. They are both 4300HP V16-710 AC motored 6 axles units with Radial boagies and safety cabs. The 9043s used Siemens electrical gear and are longer and have older style cabs. They also don't meet Tier 2/3. But in comparison to say and SD40-2 or SD60, they are effectively the same to the power desk.

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Posted by VOLKER LANDWEHR on Thursday, May 31, 2018 3:54 PM

I disagree. Even if he meant the SD 9043 and SD70ACe are same I find the statement very far fetched.

The SD90MAC (6000 hp) was the designed locomotive, the SD9043 was an makeshift solution using an 710 engine because there was nothing else available.

Don't forget, the SD70MAC was available since 1993 two years before the SD9043. If you look for a predecessor of the SD70ACe you get to the SD70MAC, I think.
Regards, Volker

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Posted by SooBoy61 on Thursday, May 31, 2018 8:13 PM

Speaking of the UP SD9043MAC's, I've noticed there seems to be several groups of these parked at the Bailey Yard front and center of the camera view.  Any idea what UP intends to do with these?   

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Posted by NorthWest on Thursday, May 31, 2018 11:44 PM

Probably in the process of either reactivation or sale. A bunch have been reactivated lately. I think that as NS has retired their last units for rebuild, the UP is the last railroad operating the model.

The whole series was a bit confusing, with three models-

SD90MAC -the 4300HP convertibles

SD90MAC-H -the subsequent H-engine 6000HP model, none now in use

SD90MAC-H II -improved H-engine model. None in use in North America.

The SD90MAC convertibles have weird electrical systems as a result of the history of their birth, and were not well loved by the shops as a result.

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Posted by Leo_Ames on Friday, June 01, 2018 3:16 AM

Should be more out there than just on Union Pacific. CEFX bought 40, which should leave them with 30 after the NS acquisition. I imagine most of these are active, although perhaps not necessarily all 30 are still under CEFX ownership. 

Appalachian & Ohio has returned their CEFX units, but Indiana Rail Road should still be running a fair number of their CEFX units and I imagine San Luis & Rio Grande still has their two. North Shore Mining also seems to be leasing several. And I imagine many of the others live a nomadic existense as short term lease units that largely go unnoticed by the railfan world, but are generally active. 

I wonder when the next step will happen with the CPR fleet. There have been occasional rumors of a NS style rebuilding for them. I believe Hunter Harrison even said once that they were going to undertake such a program to return them to service. Yet they still sit, with no sign of CPR doing anything like trying to sell them, part them out before scrapping the rest, etc. 

I imagine they're not viable for reactivation as-is anymore with the computers probably shot after sitting outside in Winnipeg so long with no care invested into them, but still have potential with a NS style rebuild program. 

But even that clock has got to be ticking down pretty quickly after so much time.

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Posted by BDA on Friday, June 01, 2018 8:35 AM

SD90MAC in either form is a very different machine to an SD70ACe . To walk around and through you can see some similarities but virtually nothing is the same . I think you can look at a 70ACe as a more refined standardised evolution of the SD90MAC/4300 . By the way this is what EMD call them - SD90MAC/4300 on their Operation Manual .

My take on the 90 is that it was a unique development that originally had to have space for the 20-710 - SD80MAC format . EMD obviously thought the extra heat generated by the 5000 Hp engine needed the larger wider radiator cab , compared to a 70MAC anyway . This was carried over to the 90MAC and in a similar fashion on the 70 ACe . 80s/90s had the larger bulkier traction motors needing larger diameter wheels to keep them off the ground . The HTCRII bogies had a longer wheelbase and wider axle centers too . So unique rad cab/bogies/frame length/ fuel tank made these units different to any previous EMD design . 

When the H engine went out the window EMD could revert to a more standardised pattern frame length and bogie wise . You could look at an SD90MAC/4300 as being overbuilt for what it had to do .

Also engine wise I believe the earlier Tier 2 70ACe's had 4300 gross Hp where the updated Tier 3 version had 4500 . I'm told all 16-710 powered SD90s had the 4300Hp version .

As for the recently upgraded SD90s , as far as I know they chucked the Siemens control gear and inverters and fitted the same Mitsubishi components that the 70ACe's got standard . I think the 70ACe cab was fitted to meet later crash protection standards , and later cab electronics because they fall in .

You'd think that these would perform much the same as a 70 ACe because they have more in comon with them .

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Posted by YoHo1975 on Friday, June 01, 2018 3:32 PM

The point is that from the power desk perspective, the SD90s that UP has are the functional equivalent of an SD70ACe. UP doesn't have 70Macs and in any case, they were all 4000HP. 70ACes can either be 4300HP or 4500HP I believe.

None of UP's have been upgraded. They are still all Siemens gear. the NS units are being converted to SD70AU which means swapping the AC system and replacing the cab. I think the computers get updated too.

 

Also, all the SD9043s got reactivated. Roseville had a bunch come in as well. Power crunch.

 

Also, NorthWest, to the best of my knowledge, none of those terms are official. EMD called them all SD90MAC.

H-Mac was a fan term.

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Posted by rdamon on Friday, June 01, 2018 3:48 PM

Posted today from Portland, OR

http://railpictures.net/photo/659779/

BDA
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Posted by BDA on Friday, June 01, 2018 8:58 PM

EMDs Operators Manuals , for Phase 2 versions , say .

Electromotive - SD90MAC/4300

October 1998

Pn O00352EP

Or

Electro - Motive

SD90MAC Locomotive

(6000 HP - Phase 2)

November 1999

Pn O0036EP . 

The specs I have for the SD70AH show a mass of 430,000 pounds or approximately 195 metric tonnes .

 

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Posted by YoHo1975 on Saturday, June 02, 2018 1:56 AM
SD90MAC/4300 isn't a Phase 2. There were SD90MAC/4300s that were phase one, they look mostly (but not completely) like an SD80MAC. There are SD90MAC Ph1 6000HP. which have the angled roof profile over the prime mover, but look the same as the SD90MAC/4300 in most other respects And there are the SD90MAC-Ph2 which were also 6000HP, but have the cabs that look more like the SD70ACe cab. I believe the Ph2 also only have the 2 larger radiator fans as seen in the ACe. There was never a phase 2 unit with a 710 in it.
BDA
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Posted by BDA on Saturday, June 02, 2018 4:45 AM

That must be correct , the 90MAC/4300 manual shows diagrams of units with the earlier cab and 3 rad fans . It mentions the engine as a 710 G3C-ES .

The 90MAC Phase 2 manual shows the later cab and two rad fans .

 

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