The rebuilding that UP is doing to their SD40 fleet to meet Tier 0+ standards got me thinking. Would it be worth it to put an AC generator & traction motors in an SD40-2? Or is the ROI not enough to justify the expense?
Dan
I suspect all the other electrical gear required to have a properly performing AC locomotive would require a complete re-engineering of the ENTIRE locmotive. Changing from DC to AC is not a simple plug & play type operation.
Never too old to have a happy childhood!
I didn't mean to imply that...but perhaps the technical challenges weren't worth it "back in the day" when the SD40s were new. I wonder if it'd be worth a second look today.
Just as an aside. The first AC units were the four SD60MAC's that were built in 1991 and 1992 and tested on the BN as 9500-9503. They became BNSF 9500-9503. Returnd to EMD in 1998 and are EMDX 9500-9503. These testbeds became the basis for the very successfull SD70MAC. and SD70ACe's.
igoldberg Just as an aside. The first AC units were the four SD60MAC's that were built in 1991 and 1992 and tested on the BN as 9500-9503. They became BNSF 9500-9503. Returnd to EMD in 1998 and are EMDX 9500-9503. These testbeds became the basis for the very successfull SD70MAC. and SD70ACe's.
Maybe even as an SD32AC/ECO with the EMD rebuild program...
What service are these SD40s going to perform? Converting one to AC would create a locomotive with much less HP/max TE than any other existing AC unit. Unless there was some specific service that would be a good fit for such a low speed drag machine - and could keep it highly utilized - it just wouldn't be worth the $$. You are basically keeping the frame, engine, trucks, radiator, air compressor and cab. Everything else would be new and even parts you keep would need quite a bit of modification.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
igoldbergThe first AC units were...
SD40s and SD40-2s have a AC main gen. Fresh DC traction motors would make them pull pretty well.
I believe all production AC motored EMDs have the HTCR radial truck, which doesn't slide under the older frames, but would require all kinds of work to make them fit.
Besides, what line would have the capacity to have drag freights rolling up at 10 mph or less? Put enough power on the trains to keep things rolling 20mph+, increase capacity.
For the price involved to add AC traction, might as well get a new one, fresh engine, new frame, etc.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
The HTCR trucks were initially tested on an SD60, so that suggestion that they wouldn't fit is not entirely true. The SD60 rides on the same HT-C trucks as the SD40-2
The only place that I could possibly see anything like this working out would be say Horseshoe Curve area where Manned Helpers are stil common. This way they get AC traction Motor Reliablity and pulling power in a 3000 HP package.
YoHo1975 The HTCR trucks were initially tested on an SD60, so that suggestion that they wouldn't fit is not entirely true. The SD60 rides on the same HT-C trucks as the SD40-2
A gentleman on this forum ("bogieenginer" I want to say) was involved in this project. Much frame modification was done to get the HTCR truck under the SD60 frame. Should be a post about it somewhere...
Are the Progress Rail PR43s AC locomotives or did they leave them DC powered when they swapped the EMD prime movers for CATs?
episette Are the Progress Rail PR43s AC locomotives or did they leave them DC powered when they swapped the EMD prime movers for CATs?
The Progress Rail PR43C's as well as PR30C's and PR22B's are all DC traction.
Also these units did not merely have EMD prime movers swapped out for CAT's. All mechanical and electrical components were replaced. The core locomotives were essentially empty shells.
Bryan Jones
WSOR 3801 YoHo1975: The HTCR trucks were initially tested on an SD60, so that suggestion that they wouldn't fit is not entirely true. The SD60 rides on the same HT-C trucks as the SD40-2 [Below quote from YoHo1975] "...A gentleman on this forum ("bogie engineer" I want to say) was involved in this project. Much frame modification was done to get the HTCR truck under the SD60 frame. Should be a post about it somewhere..."
YoHo1975: The HTCR trucks were initially tested on an SD60, so that suggestion that they wouldn't fit is not entirely true. The SD60 rides on the same HT-C trucks as the SD40-2 [Below quote from YoHo1975]
[Below quote from YoHo1975]
"...A gentleman on this forum ("bogie engineer" I want to say) was involved in this project. Much frame modification was done to get the HTCR truck under the SD60 frame. Should be a post about it somewhere..."
Here is the link to the Threads referenced by YoHo1975:
http://cs.trains.com/TRCCS/forums/p/132421/1489217.aspx#1489217
I will point out that many of the SD70ACe locomotives are equipped with the non-radial steer HTSC truck rather than the radial HTCR II truck. Some companies feel that the extra expense of the radial steer truck isn't worth it.
An SD40-2 has a minimum continous speed of 11.1 mph and lays down 83,250# of TE at that speed. An SD40-2 converted to AC propulsion at 35% adhesion, would lay down 133,000# of TE at 6.9 mph.
A couple of SD40-2s can take a 75 car, 6000 ton train up a 1% grade at 12 mph and would just to 50 mph on the flat.
A couple of AC SD40-2s could take a 140 car, 11,000 ton train up a 1% grade at 7 mph but wouldn't quite make 35 mph on the flat.
A locomotive like this would not be able to keep up with the flow of traffic handled by the current crop of AC and DC locomotives.
If you had an application that could withstand such low speeds, and you could keep that locomotives busy in that service, you might be able to justify the expense of conversion.
If there were some serious curves on the portion of the route with the ruling grade, you'd need the radial trucks in order to achieve the 35% adhesion.
samfp1943 Here is the link to the Threads referenced by YoHo1975: http://cs.trains.com/TRCCS/forums/p/132421/1489217.aspx#1489217 "SD60 EMD 3 Radial Trucks" [Thread title]
Yes, Bogie engineer.
It sounds like the orginal trucks were 2" shorter, but the engine needed no frame mods to fit the trucks. Lots of bolster mods though.
So, it sounds plausible that it could be done though it wouldn't be a straight swap.
There have been some DC motored diesel electric locomotives rebuilt to AC but the only case of this being done in North America was with Metro North's FL9 fleet and the cost per unit was close to that of a brand new locomotive. It's not just a matter of installing AC traction motors, you have to install inverters as well as a number of other complicated and expensive electrical components.
Amtrak rebuilt most of it's AEM-7 fleet with AC drive and that was quite costly as well..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Your forgetting the 1st one also. Amtrak F40ph 202 was the First one ever coverted over to AC traction in the USA. It led the way to the F69PHAC and to all the AC units that roam the Rails today. Hard to imagine that a Wrecked F40 was the First unit in the USA to ever have AC Traction Motors put into it.
And another one was CPR's M-640, #4744. It was converted in the early 1980s as a test bed with several sources funding the work. This was perhaps the first use of AC traction in North American freight service.
The 6 DC traction motors were replaced by 4 AC motors, in an A1A wheel arrangement. While it was a pioneer, rapidly advancing technology probably meant the electronics quickly became obsolete. Nevertheless, the unique engine ran for quite a few years in this form, and is now preserved at Exporail, the railway museum just outside Montreal.
John
carnej1 Amtrak rebuilt most of it's AEM-7 fleet with AC drive and that was quite costly as well..
Amtrak has 29 rebuilt AEMs with AC traction motors. That leaves 20 still as DC traction. 3 units have been wreck retired. [AC or DC at retirement not known]
Amtrak considered the rebuilding a success as the ACs could haul a 9 car train vs the DCs only 7. Those numbers reflect the required performance acceleration curves. The rebuilt ACs also had regenerative braking installed. The HHP-8s [ units very similar to Acela power units ] were AC and so Amtrak decided not to rebuild the remaining 20 DCs. However the lack of reliability of the HHPs had Amtrak looking at rebuilding more AEM-7 DCs. Then Amtrak decided to buy new electric motors and the procurements has progressed to the point that 70 ACS-64s will be delivered in 2013 - 2014. The AEM-7 ACs will then be put into a reserve fleet with the DCs retired.
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