What is the point of building the SD70AH?

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  • Member since
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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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    April, 2018
  • 7 posts
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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