AC traction rebuilds

Pardon the amateurish question, but why haven't there been more rebuilds of DC locomotives to AC?

There were a number of experimental one-off rebuilds; those wouldn't have to be economical. The only "production" AC rebuilds were the FL9ACs, and those weren't too successful. I don't know how much that says about the general feasibility of such schemes, as they were rebuilt by Republic, whose DC locomotives didn't turn out well either.

Did most locomotives simply not have the room? I know the F40PHACs required a frame stretch. The rebuilt SDP40F would've had the space originally used for a steam generator. I'm guessing an FL9 has a significant amount of internal space free.

Theres no point in doing it there bud, think thats the biggest thing. Right now most of them DC's are in storage or being sold off. Cost is why someone like a shortline or third party switcher cant do something like that.

The FL-9AC was started at Republic, but never even got to actual building stage, the first two units (1/3 complete) had to be removed from Republic before bankrptcy court took hold of them, and towed to Elmira, the 10 FL-9ac's were nearly totally built at ABB in Elmira New York.

Sorry, Triplex, but your guess about an FL-9 having a lot of extra room inside is off by a mile. I walked through one earlier this year. The diesel genset for HEP sits crosswise in the rear, and you can only get around it on the engineer's side. At the generator end, there is a massive electrical cabinet; because the units ran as both D/E s and straight electrics, they required much more switchgear. And even the cab seemed packed. With an FL-9, you're talking about ten pounds of stuff in a five pound bag

Didn't FL9s have steam generators, not HEP, when new? But yeah, that probably would've taken up a lot of space as well.

That is correct, as delivered the FL9's did have steam generators for train heating. In the HEP era the generators were removed with a HEP package (barely) fitting in the compartment.

As for the original question, rebuilding older locomotives with AC traction is cost prohibitive. The original ABB test beds, the F40AC and the M640, were just that; platforms to test the theory of operation in America. EMD went one step further building AC prototypes in the form of the F69AC and the SD60MAC. The issues with the F69's are well documented and the SD60MAC ultimately yielded the SD70MAC as well as the rest of EMD's AC production.

As for the FL9AC, it was learned that the entire locomotive had to be reengineered to make it work and for that kind of time and expense it's best to build new. The best line I ever heard about them was, "Don't do that again."

EDM5970 wrote:Sorry, Triplex, but your guess about an FL-9 having a lot of extra room inside is off by a mile. I walked through one earlier this year. The diesel genset for HEP sits crosswise in the rear, and you can only get around it on the engineer's side. At the generator end, there is a massive electrical cabinet; because the units ran as both D/E s and straight electrics, they required much more switchgear. And even the cab seemed packed. With an FL-9, you're talking about ten pounds of stuff in a five pound bag

your confused with F-10 where HEP sits crosswise , The FL-9 has the HEP lenght wise it occupies the pace of steam generator and watertank.

The 10 FL-9AC's, 3 for LIRR and 7 for MNCR were test beds and EMD failed but GE learned from the mistakes, I ran all 10 units in test trains

Dutch, I'm not one to split hairs over something little like this, but I've never been in an F-10, and know I was in an FL-9 at the time. This was up in CT, at one of the museums. Regardless of the gensets orientation, there is no extra room in an FL-9; I'm sure we can agree on that point.

correct, but no fL9's have a sideways HEP , only the F-10's , I have been operating these things for over 20 years now.
All units in museums have the Cummins KTA HEP unit installed lenght wise in FL-9 with generator facing rear door.

Maybe I'm thinking of an "LV" F-7 that I walked through recently; sometimes little details can blur together.

Triplex wrote:Pardon the amateurish question, but why haven't there been more rebuilds of DC locomotives to AC?

There were a number of experimental one-off rebuilds; those wouldn't have to be economical. The only "production" AC rebuilds were the FL9ACs, and those weren't too successful. I don't know how much that says about the general feasibility of such schemes, as they were rebuilt by Republic, whose DC locomotives didn't turn out well either.

Did most locomotives simply not have the room? I know the F40PHACs required a frame stretch. The rebuilt SDP40F would've had the space originally used for a steam generator. I'm guessing an FL9 has a significant amount of internal space free.

Getting to your original question RE freight locomotives my understanding is that the cost of rebuilding a Unit is extreme, so much so that it becomes more economical to trade it in for a new AC locomotive. The rebuilding costs on the FL9AC's were very high...

Correct but the 10 FL-9ac's were basicly test locomotives to see if a AC propulsion Dual mode was feasable.
It was and because of the data the Genesis P32acdm was created, Ge just improved on the ABB system.
instead of two traction inverters for 4 motors, GE went with 4 traction inverters for 4 motors with about a 50% over capacity in KW.
Its possible to run at 100% power with one motor cut out , either for emergency HEP inverter or incase of traction failure.

Though didn't EMD stick with one inverter per truck on the SD70MAC, et al.?

yes they did, and it caused GE to be big winner in AC propulsion race.

As an aside - the NJT PL42s, even though they have an EMD powerplant, have 1 inverter per axle as well as another inverter for HEP, for a total of five. They were built by the lovely folks at Alstom......