Bear With Me.

[Shaun]

I recently looked up information on the GE U50 and U50C units and the article says that in the end they were trouble some, and did not perform well. They also used a B-B+B-B truck arrangment.

I realize that this technology was in it's pioneering stages, but the article states that they had trouble getting that much HP (5000HP) to be transffered to the wheels.

Since then a lot has changed, and newer locomotives have 6000HP or more, but less trucks.

So i'm wondering if it wasnt a physical limitation of transfering that much horsepower to the wheels? Obviously not since they can do it now....but is more to have to do with traction control systems, and the distribution of power rather than the physical limit?

Hopefully you can see what i'm trying to get at here...which is....why can they do it now....but they couldnt before? And is there a practical limit to the amount of HP a locomotive can have before it is unable to be transffered into tractive effort? Will we be seeing 8000hp locomotives such as the DD40 series which had 6600HP.

[smallspy]

First off, there were two versions of the U50....one with 4 2-axle trucks (U50) and the later version with 2 3-axle trucks called the U50C.

The problem with the U50's was not traction-based...in fact, they had no issues even as 6-axle beasts. The problem was the use of aluminum cables in their wiring, and thus they were particularly prone to electrical-based fires.

There is no such thing as a physical limitation to the amount of power put out by a locomotive....consider than there are TGV trainsets that have 6 powered 2-axle trucks that put out 24,000 horsepower...and have no problems with traction.

In fact, horsepower has virutally nothing to do with traction, particularly with diesel locos. It just means that the diesel inside can produce a maximum of that number....the traction motors can generally produce far more power than that. All diesels since the first generation diesels of

EMD, ALCo, Baldwin, etc (and possibly before) have limited the horsepower output at low speeds since the motors can't make use of it anyways.

The only thing that the advancement of traction control systems has done is to allow for the reduction of units needed to haul trains.

Dan

[D. DeLarge]

As for UP's other units, I've read the DD35's had their share of problems from sand getting into the electrical systems because of the location of their sandboxes (not to mention the 35-series electrical systems weren't known to be the best in the world ).

The DDA40X's performed great relative to the competition. Racking up many miles in fast freight service until being retired in the 80's (with a bunch being reactivated and subsiquently re-retired in the mid 80's).

The C855's? Well, UP only ordered 3 so they were pretty much oddballs .

A good source of UP information is UtahRails.net.