It's not a million dollars difference these days between a C4 (Or ES44DC when they were still making them) and an ES44AC. Back around 1995, Trains would regularly quote a half million dollars difference between something like the SD70M and SD70MAC (Or Dash 9 and AC4400CW).
And that gap has closed a lot which is one reason why most of the Class 1's just buy all six motor AC road power these days (And why a C4 with just two less AC traction motors and two less inverters can be sold for approximetely what an ES44DC would cost).
I bet we're talking about ~$250,000 or less these days for what BNSF saves by buying a C4 instead of a six motor unit.
They are not leavers, but pistons. If you look closely at a picture of one of the trucks, you will see cylinder on the outside of the center axle. That is the piston that raises and lowers the center wheels a little.
Don’t the ES44C4 units have, for lack of a better term, ”levers” that are supposed to raise the idler axles slightly so that more weight is on the powered axles to improve tractive effort when needed?
An ES44C4 costs about the same as an ES44DC. About $1,000,000 less than an ES44AC. That is a chunk of change per locomotive. I have read that BNSF engineers say that they are slippery, but he did not state in what service the locomotive was being used.
zardozbut if that is the case, why not just buy a new (and presumably cheaper) 4-axle unit?
What new 4 axle unit? I'm guessing (but have no clue if right) cheaper to do what they did and strip down an existing 6-axle than to engineer a whole new 4-axle.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
HP to the traction motor normally = Speed.
A GEVO with A-1-A trucks is putting 4400 hp into 4 traction motors - 1100 HP each. That much HP at a traction motor tends to make the engine 'slippery' in drag tonnage situations. With 'suitable' tonnage in a intermodal situation the train should easily maintain track speed.
To my mind, if the 'idler' axle is allowed to carry it's weight on rail, the engine would be even more 'slippery' in drag tonnage situations. Never having had any first hand dealings with these locomotives, I don't have the real answers.
Never too old to have a happy childhood!
I think the original theory was that BNSF's intermodal traffic was always powered highly enough that the trains wouldn't drag up grades at speeds low enough to require the tractive effort of 6 AC motors, so eliminating 2 reduced cost.
Of course they show up with some regularity on everything from coal trains to heavy manifests, but...
zardoz why not just buy a new (and presumably cheaper) 4-axle unit?
I'm not that knowledgeable about this, but I kinda remember that it has to do with weight. New locomotives are too heavy for four axles.
(edit) Oops, beaulieu beat me to it.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
The main reason for not using B-B type locomotives, but rather using A1A-A1A or on EMDs B1-1B powered axle arrangements is weight. Either you sacrifice fuel to hold the weight to allowable limits or engine size, or perhaps both. Both the GP60M and B40-8W locomotives were right at the maximum allowable weights, and both had reduced fuel capacity, and remember these locomotives were built to Tier 0 emissions standards. So imagine what enlarged cooling capacity carrying more water with more weight is going to do.
It should be noted that BNSF uses the four-motor power primarily in expedited service and FEC has no real grades. The horsepower is still getting used in either case.
In the thread "4-axle units" traisessive1 mentions those types of units could be called "four-axle" power. Which got me to wondering...
Why would any railroad bother with such an arrangement? Yes, I know part of the reason is to save a few $ by having less traction motors, but if that is the case, why not just buy a new (and presumably cheaper) 4-axle unit?
If not getting to use all the HP you've paid for is what you're after, then the units make sense; otherwise--what a stupid concept!
Buying such a unit would be something I could see a railroad like NS or CSX doing, but not a supposedly 'smart' railroad like BNSF.
Opinions or thoughts......?
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