Why more horsepower?

[Ulrich]

Is it more economical to operate one 4000 hp than two 2000 hp locomotives coupled together? A lower horsepower locomotive like a GP38-2 is probably more versatile than an AC4400CW...so why have builders been trying to outdo each other on horsepower? When those AC4400CW get old they probably won't be of much interest to short line operators whereas a lower horsepower more bi-directional hood unit would be, and that would be reflected in its resale value.

[TomDiehl]

Is it more economical to operate one 4000 hp than two 2000 hp locomotives coupled together? A lower horsepower locomotive like a GP38-2 is probably more versatile than an AC4400CW...so why have builders been trying to outdo each other on horsepower? When those AC4400CW get old they probably won't be of much interest to short line operators whereas a lower horsepower more bi-directional hood unit would be, and that would be reflected in its resale value.

Maybe you should ask Tim Allen. (insert grunts here)

[Ulrich]

I don't think he would know either... maybe someone around here with an engineering background can shed some light?

[oltmannd]

Much lower ownership costs.  Far fewer moving part, less cab equipment, fewer wheels, axles,  & brake shoes, fewer inspections to do, less periodic maintenance to do, etc. 

[Ulrich]

Makes sense...now why has four axle power fallen out of favor?

[Ulrich]

According to those cost criteria the DDA40X should have been a resounding success... two engines on one frame... one cab...8 traction motors as opposed to an SD40/SD45 combo with two cabs...TWELVE motors etc...Yet the DDA40X didn't really catch on. You would think twin engine locomotives that can use existing engines to generate 9000 hp would be a hit...but where are they? 

[n012944]

According to those cost criteria the DDA40X should have been a resounding success... two engines on one frame... one cab...8 traction motors as opposed to an SD40/SD45 combo with two cabs...TWELVE motors etc...Yet the DDA40X didn't really catch on. You would think twin engine locomotives that can use existing engines to generate 9000 hp would be a hit...but where are they? 

 

Well, if you have something go wrong on a DDA40X that takes it out of service, you are losing what would be two SD40's.  Its just a balancing act for the right package.  Railroads do not look at resale costs when it buys equipment, they just look at performance and cost issues.  No one can predict what a locomotive resale value will be in 30 years.

[Ulrich]

Good point on the resale...the GP9 is going on 60 years and many are still in service.

[beaulieu]

A couple of points, first the DDA40X isn't two SD40-2s on a common frame it's two GP40-2s, second the Centennials were reasonably successful, they were retired about the same time that high-horsepower 4 axle locomotive production went into serious decline, and for the same reason. Light fast TOFC trains started disappearing, being replaced by either long and heavy doublestack trains or at least much heavier TOFC trains. Necessary locomotive equipment combined with current output prime movers became too heavy to place on a 4-axle locomotive. Santa Fe had to reduce fuel capacity on its GP60Ms in order to keep the locomotive within weight limits.

[WSOR 3801]

The AC4400 should pull like 2.5 SD40-2s, making it more useful.  These days, only little pup trains will get up to track speed around here with 2 GP38s.  The trains are getting bigger, need more HP to get them moving, and maintain speed.  Many trains have 2 AC4400s, or more power.  That would be at least 4 SD40-2s, or 6 GP38s, or 8-10 GP7s, if there were all running.

[oltmannd]

According to those cost criteria the DDA40X should have been a resounding success... two engines on one frame... one cab...8 traction motors as opposed to an SD40/SD45 combo with two cabs...TWELVE motors etc...Yet the DDA40X didn't really catch on. You would think twin engine locomotives that can use existing engines to generate 9000 hp would be a hit...but where are they? 

 

Well, if you have something go wrong on a DDA40X that takes it out of service, you are loosing what would be two SD40's.  Its just a balancing act for the right package.  Railroads do not look at resale costs when it buys equipment, they just look at performance and cost issues.  No one can predict what a locomotive resale value will be in 30 years.

...you're losing 2 GP40s..... 

And, a DD40AX only saves you the cab and a pair of couplers and draft gear.  You still have two complete locomotives under the hood - and the same number of axles and TMs.

[n012944]

Thats right, 2 GP40's.....I knew that

[TomDiehl]

According to those cost criteria the DDA40X should have been a resounding success... two engines on one frame... one cab...8 traction motors as opposed to an SD40/SD45 combo with two cabs...TWELVE motors etc...Yet the DDA40X didn't really catch on. You would think twin engine locomotives that can use existing engines to generate 9000 hp would be a hit...but where are they? 

 

Well, if you have something go wrong on a DDA40X that takes it out of service, you are loosing what would be two SD40's.  Its just a balancing act for the right package.  Railroads do not look at resale costs when it buys equipment, they just look at performance and cost issues.  No one can predict what a locomotive resale value will be in 30 years.

...you're losing 2 GP40s..... 

And, a DD40AX only saves you the cab and a pair of couplers and draft gear.  You still have two complete locomotives under the hood - and the same number of axles and TMs.

Plus, those 4 axle trucks were probably a real headache.

[WSOR 3801]

Plus, those 4 axle trucks were probably a real headache.

 

They are great for testing the track.  The UP engineering dept. uses the 6936 on inspection trains.  If there are any irregularities in the track, the engine wiggles and waggles, and sends the extra motions to the office and testing cars. 

[Wyonate]

I know around here (Powder River Basin) They need all the power they can get I would imagine.  There is 1.75% for a few miles heading toward Montana.  I would guess with 15,000 tons of coal astern You need everything you can get as long as wheel slip dosn't become a problem. Average horse power around here is about 21,000, (3 SD70MACs and 2 SD75M helpers).  I have to admit, it does get kinda boring just seeing SD70MACs, SD70ACes, SD75Ms and Is, ES44ACs, AC4400,SD60Ms and the rare Dash 9 and SD40-2.  I haven't noticed a GP unit come thru in months. Not to say there hasn't been.  I did see a unique one about a month ago, it was a CN loco.  Don't know Canadian to well, but it looked like the size of an SD45, but with the wide cab option.  Pretty Cool!

[Ulrich]

That's funny I used to say the same thing 25 years ago about the SD40-2. Back then all you ever saw anywhere around here was the SD40-2. Now that these locos are being replaced it is nice to see one of these old beasts once in awhile.  

[Paul Milenkovic]

I got to see a WSOR SD40-2 tie up traffic on University Avenue while switching a long cut of hopper cars at the Randall crossing on the Friday before the Indiana game.  It made a cool whistling sound as it powered up to back that string of cars through the crossing, although I don't quite understand the logic of an EMD turbocharged 6-axle unit used as a switcher.

At the same crossing, I saw a two-unit consist of GP-38's today, with the lead unit making lots of smoke as it accelerated the train through the crossing, and the smoke didn't smell like Diesel fumes but more like the fumes from smoke oil drops you put in a model train steam engine with a smoke unit.

If I work at one of the PC's at Computer Aided Engineering, I can look out these big picture windows and watch the trains go by, and they blow their horns to tell you they are coming after the Mayor of Madison lost the battle with the Federal Railroad Administration about no-horn crossings.  Who needs a model railroad when there is 12 inch scale?

[WSOR 3801]

The SD40-2s are what is available.  I think they work pretty good.  Try watching a SD40 go through the UW heater.  There is only 1 skunk left at this time.  The cars are getting heavier, and there are more of them.