JayPotter The ES44C4 and ES44AC use the same model traction motor. I suppose that some modifications might have been made within that particular model; however the 36K TE limit wouldn't necessarily indicate that. That limit, which is intended to prevent excessive mechanical stress, is software-imposed, just like the standard 30K limit. The reason counter emf came to mind is that I was once told -- and I think it was in a discussion related to the ES44C4 -- that one western railroad -- I don't recall which one -- which operated SD40s or SD40-2s in high-speed service had a practice of cutting out one traction motor on each truck in order to increase speed by reducing counter emf. Being more interested in tractive effort than speed, I didn't pay as much attention to that part of the discussion as I probably should have.
The ES44C4 and ES44AC use the same model traction motor. I suppose that some modifications might have been made within that particular model; however the 36K TE limit wouldn't necessarily indicate that. That limit, which is intended to prevent excessive mechanical stress, is software-imposed, just like the standard 30K limit.
The reason counter emf came to mind is that I was once told -- and I think it was in a discussion related to the ES44C4 -- that one western railroad -- I don't recall which one -- which operated SD40s or SD40-2s in high-speed service had a practice of cutting out one traction motor on each truck in order to increase speed by reducing counter emf. Being more interested in tractive effort than speed, I didn't pay as much attention to that part of the discussion as I probably should have.
During the initial testing phase of the prototype ES44ACs(original 6 motor model), GE tested them (on CSX I believe) with software changes that uprated the units to 5000 HP. IIRC, the traction motors had no problems with this. IIRC, they are the same model motors as used on the AC6000....
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
carnej1During the initial testing phase of the prototype ES44ACs(original 6 motor model), GE tested them (on CSX I believe) with software changes that uprated the units to 5000 HP.
I'm unfamiliar with EVO testing on roads other than CSXT; however the only ES44ACs tested on CSXT before CSXT received its own units were pre-production units that GE had sent to UP. Two of them, 5695 and 5696, tested on CSXT between August and December 2004. They were rated for 4400 horsepower at the time; however GE indicated that the ES44AC could be uprated to 5000 horsepower. So I'm not surprised that some units were tested elsewhere at that horsepower.
JayPotterI wonder if there's a difference in speed rating because at high speeds four motors produce less counter-electromotive force than six motors produce?
Ever see the TE-vs-speed curve for a GP50, in the 1980 or 1984 Cyc? It's the usual hyperbola up to 62-63 mph, then it drops more sharply-- presumably because the AR15 (?) has reached its voltage limit. In other words, at 70 mph an SD50 should outpull a GP50 on level track (assuming the same 70:17 gearing on both).
timzEver see the TE-vs-speed curve for a GP50, in the 1980 or 1984 Cyc? It's the usual hyperbola up to 62-63 mph, then it drops more sharply-- presumably because the AR15 (?) has reached its voltage limit. In other words, at 70 mph an SD50 should outpull a GP50 on level track (assuming the same 70:17 gearing on both).
If "Cyc" refers to something called the Locomotive Cyclopedia, I've heard of it; but I've never actually seen one. I just use a number of CSXT charts. The curve for a GP50 with an AR15 alternator does drop off at around 63 mph; and the curve for an SD50 with an AR11 alternator doesn't drop off until around 66 mph. But when I compare a curve for a GP60 with an AR17 alternator against a curve for an SD60 with an AR11 alternator, there doesn't seem to be much difference between the curves. Perhaps that reflects the difference between the AR17 and the AR15; but I really have no idea.
I did notice that the curves for the AC6000CW, AC4400CW, and ES44AC all continue to 75 mph.
Just joining in on this thread.
I believe that the BNSF owned (GE produced) ES44C4’s are in the A-1-A configuration. Like the Alco RSC-2’s were. They have a Dynamic Weight Management System that raises the center axel when the locomotive exceeds 15mph. And vise versa when it drops below 15mph. The locomotive other than this it the same as a normal EVO Same V-12 GEVO prime mover, alternator, motors, radiators etc.
Please correct me if I’m wrong.
Justin
The road to to success is always under construction. _____________________________________________________________________________ When the going gets tough, the tough use duct tape.
bubbajustin Just joining in on this thread. I believe that the BNSF owned (GE produced) ES44C4’s are in the A-1-A configuration. Like the Alco RSC-2’s were. They have a Dynamic Weight Management System that raises the center axel when the locomotive exceeds 15mph. And vise versa when it drops below 15mph. The locomotive other than this it the same as a normal EVO Same V-12 GEVO prime mover, alternator, motors, radiators etc. Please correct me if I’m wrong. Justin
It seems to be the center axle on the A-1-A configuration is raised slightly by that air activated cylinder that look like a brake cylinder removing about 25% of its load weight below below 12 mph to add weight to the other two axles. Above that certain speed, either 12 or 15mph ( I have read both numbers) , the center axle carries its full load. The extra traction feature only works if needed when starting or dropping below that speed if the computer needs to add traction. That was the explanation in the GE information. It might be an option for the operator to select the extra traction during the start up, but that is not known at this time. The unit is an AC model from what I read and looks like any other unit except for that linkage and extra cylinder on each side frame. There is a good picture on Railpictures of the unit.
Almost all of their other units on the BNSF have been DC models for general use. They do have some AC models for coal train service purchased more recently. Maybe someone can fill us in on those units.
CZ
The picture below shows the extra cylinder and linkage from Photobucket by Ryan Slaton
Nice photo. Thanks! Look closely and you will notice that there are two cylinders to raise/lower the middle/idler axle (on each side). No brake cylinders for it, just like the EMD E-units. Funny. When EMD built the DD40Xs, they had four brake cylinders, one for each axle/wheelset on both sides. Of course, they were all powered axles.
If you look lower in the pic you can see the rigging to apply the shoes that are on the center axle. Think something simalar to the old Blomberg M truck one brake clyinder for both axles.
I can't discern that from the photo. Wouldn't a brake cylinder, that activates on two wheel-sets, be a bit larger than the one that activates on only one? Anyone got engineering drawings? BNSF 6609 came thru here a week ago. I was in the midst of my nap, so I missed it. I'll be on the lookout!
BNSFwatcherI can't discern that from the photo. Wouldn't a brake cylinder, that activates on two wheel-sets, be a bit larger than the one that activates on only one? Anyone got engineering drawings? BNSF 6609 came thru here a week ago. I was in the midst of my nap, so I missed it. I'll be on the lookout!
The GE trucks have always used two brakes cylinders for the three axles. It could be that each cylinder activates one axle and one brake shoe each on the middle axle.
It is interesting that the traction control lifting device does have two cylinders to do the job. That must indicate it requires more power to lift the axle that the same cylinder type does for brake service. They appear to be the same type of cylinder as the brake system uses, but someone will have to look closely at the unit to tell if that true.
I would still like to know how the air cylinders and their linkage unload an axle with many tons of weight on it works. A picture of the inner workings of the truck would be much appriciated
BNSFwatcherI can't discern that from the photo. Wouldn't a brake cylinder, that activates on two wheel-sets, be a bit larger than the one that activates on only one?
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
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