August 2018
My comments on various statements made in this thread:
Claimed specifications - GE764 traction motors is about the only thing I can agree with here. To my knowledge, there is no option for what they need the diesels to be able to do. UNLESS - they cheap out and use Yongji traction motors (Chinese built under GE license) who I know has supplied some GE761 "equivalents" for some export 42" units in the last few years.
While weight isn't mentioned, let's consider a K-37 which should have about 74 tons on its drivers, or 37,000 pounds per axle. I would imagine that would be the target weight of the diesel-electric.
At 2,000 hp, the new diesels should generate about 61,600 pounds of tractive effort at 10 mph. This would require the engine to weigh 123 tons to have 25% adhesion (same as a steam engine). In reality, a GE764 won't be capable of 500 hp anyway (the rating of an EMD D77, the standard traction motor for their standard gage units in the 1960s-mid 1980s). So this likely going to be a six axle unit, so the GE764 traction motors would have to be rated at 333 hp each which I believe a brand new one might be able to handle with modern construction techniques. As far as weight, keeping at the 37,000 pound axle load you are looking at a weight of 111 tons. Back to the 10 mph speed, you are now at around 28% adhesion. Since nominal rail adhesion varies from 20 to 30%, this is going to be a slippery engine at speeds below 15 mph. There are modern adhesion control systems, but their use will increase the complexity, cost and affect the maintainability of the locomotives. Another thing I have discovered about modern adhesion systems, they do increase usable tractive effort under good to fair rail conditions. But, if the system is malfunctioning, or they are on poor rail, they seem to fall down in a hurry and you end up stalling the train. Another option is to limit the horsepower at lower speeds, but that typically any "extra" horsepower wouldn't be usable unless speed is over 15 mph.
I also question the need for so much horsepower. This may be an exaggeration, as this may not be the Cat's continuous rating, and if its the brake horsepower rating you need to subtract 100-200hp for auxiliaries, and don't forget any high-altitude losses. What speed does D&S need to maintain their schedule? Even at 15 mph, you still should have 41,000 pounds tractive effort. A U20C spec I have shows CTE as 43,230 for 6GE764, so that suggests an updated version might be around 45-50,000 pounds continuous. So regardless, they should outpull a K-36/37 at 15 mph.
Assuming the 41,000 pounds tractive effort 15 mph, at 3% with some curvature it should have a tonnage rating of about 435 tons which is what Wikipedia claims is the maximum grade. If they're only figuring 8 cars, that's almost 55 tons per car! The Durango Telegraph article says "The two 2,000-horsepower diesels will be able to tow eight cars each; the oil train, 12 cars." So if the 493 with 37,000 pounds tractive effort can handle 12 cars at 15 mph, then you would only need 2/3 of that to handle 8 cars (Don't forget the a full tender is dead weight.) So all you would really need is 1200 traction hp input to generate 25,000 pounds tractive effort at 15 mph, good for about 320 tons, or 40 tons per car. And - you could do this with a four axle unit which is cheaper and easier on the curves.
Typically builders have been using commercial 3-phase alternators for these types of locomotives. The problem is the high speed diesels operate at 1800-2100 rpm, and most railroad locomotive traction alternators/main generators of this hp range were designed to operate around 800-1300 rpm. GE does make several high speed medium hp traction alternators for diesel-electric mining trucks, but these have yet to find their way into locomotive applications. Unfortunately the commercial grade 3-phase alternators don't seem to have the durability and reliability required by locomotives. And the modern control systems that MP&S is claiming to use have been a problem as far as long term support. Some of the earlier micro-processor controlled locomotives have already had to have their entire control systems replaced due to inability to maintain them. That also means you have to pay for new custom operating control software unique to your locomotives.
The trucks, regardless if they are two axle or three axle will be an issue. They have four options: adapt a standard gage road truck (not likely), obtain used trucks from South America; fabricate trucks (possible, but they have a history of cracking welds and most designs do not have secondary/lateral suspension typical of road designs; or try to obtain new cast road trucks - GE do Brasil still uses a narrow gage floating bolster two axle truck, and a few years ago Dofasco was still casting their three axle truck (used by Bombardier).
There would have been an advantage if they had actually purchased some junk GE locos of a usable design and had them rebuilt in kind. By constructing "new" locomotives, they may very well have to meet all the modern FRA requirements (including air conditioning). The biggest issue has been Tier 4 emissions compliant diesels. The engine suppliers were barely able to get Tier 2, then Tier 3 engines to be reliable, before they were forced to Tier 4. Everyone is still trying to get all the bugs worked out. The first Tier 4 locomotives I can think of from Caterpillar are their EMD/Progress Rail subsidiary F125 designs for Metrolink that are finally entering service about 2 years late due to a myriad of issues, and California is already pushing for Tier 5.
"The D&SNGRR has not determined the final cab design..."; "Since nobody builds new diesel locomotives, the two new D&SNG engines ... are being built from existing 8-foot engine platforms"; "The D&SNGRR is investing over $3 million in the two new MP2000NG repowered diesel locomotives..." (There is an incomplete link on Google as $3.2 million.) OK - I see some problems here. How can you have a purchase contract and price on a basic design that apparently hasn't been agreed on, much less been engineered enough to create a reasonably complete estimate? And how can it be a "new ... repowered" locomotive? The only sizeable diesel-electric locomotive I am aware of is the GE SL50, unless is something left over at a steel mill. New York subways have almost all the SL50s so it's possible MP&ES picked up a couple wrecked/salvage units for their frames (MPI delivered them some new work train designs a few years ago) or maybe there was something left over at a steel mill. A SL50 is only 34 feet long which is too short to mount 2000 hp on. The "standard" 36-42" gage clearance diagram is 9 feet wide and 12 feet tall, though there are sometimes additional clearance issues at the roof line. 8 foot wide makes no sense, and it makes working on them harder and the cab more cramped.
Honestly I can't get the numbers to add up. Anything beyond "GE764" traction motors is suspect in the specifications.
The suggestion that D&S could/would regain some of the diesel's cost by selling the other diesels or a steam loco is not realistic in my mind. How many people want heavy steel mill 36" gage diesel engines? There isn't really a big demand for them. Even if the Loop or C&TS was interested - if they aren't real sutible for D&S they aren't going to be that suitable for them either. And if they were to offer a steam loco for sale - again, who would want it (presumably it would be well worn and require a total rebuild regardless of model). The value of something is what someone else is willing and able to pay for it. Which means, you either need a plan to finance it and recoup your investment, or a fool and his money are soon parted. (In my case, one affordable toy, one paid for itself, one I was foolish and now I'm broke.) I could be wrong ....
Dan
