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What do you think is more powerful?

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What do you think is more powerful?
Posted by Berk765 on Tuesday, December 4, 2007 9:37 PM

Were the electric locomotives that operated by an overhead wire more powerful than the diesal electric locomotives?

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Posted by Anonymous on Tuesday, December 4, 2007 9:49 PM

It comes down to how much amp can you feed a traction motor between the wheels for how long?

My vote is with the electric, Ive heard stories of three GG1's on the same wire. It is my understanding they could not feed em all.

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Posted by chefjavier on Tuesday, December 4, 2007 9:56 PM
 Berk765 wrote:

Were the electric locomotives that operated by an overhead wire more powerful than the diesal electric locomotives?

Keep in mind the mechanical aspect of a Diesel Engine. It's the production of electricity that produce traction to the wheels. Electric like GG-1 would produce faster because it goes straight to traction. Thumbs Up [tup]

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Posted by YoHo1975 on Tuesday, December 4, 2007 10:51 PM

Who cares how much power you can generate if all it does is spin the wheels?

 

It's not the engine size or traction motor size that dictates how much power is actually applied to the rails, it's the physics of a round steel wheel on a flat steel rail. I'd say your average SD70ACe could out pull any 3 GG1s, because it can translate the power to moving the train better. 

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Posted by chefjavier on Tuesday, December 4, 2007 11:09 PM
 YoHo1975 wrote:

Who cares how much power you can generate if all it does is spin the wheels?

 

It's not the engine size or traction motor size that dictates how much power is actually applied to the rails, it's the physics of a round steel wheel on a flat steel rail. I'd say your average SD70ACe could out pull any 3 GG1s, because it can translate the power to moving the train better. 

I suggest check your information.Sign - Ditto [#ditto]

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Posted by YoHo1975 on Tuesday, December 4, 2007 11:33 PM

Sure thing Champ,

the GG1 can produce 70,700 lbs TE unspecified via DC (unspecified is always assumed to mean starting TE.)

 

The SD70ACe can produce

191,000 lbs starting TE 

157,000 continuous TE

 

So, I apologise, I mispoke. It can ALMOST produce as much as 3 GG1s. 3 gg1s producing 213,000 lbs TE  

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Posted by Railway Man on Tuesday, December 4, 2007 11:39 PM
 chefjavier wrote:
 YoHo1975 wrote:

Who cares how much power you can generate if all it does is spin the wheels?

 

It's not the engine size or traction motor size that dictates how much power is actually applied to the rails, it's the physics of a round steel wheel on a flat steel rail. I'd say your average SD70ACe could out pull any 3 GG1s, because it can translate the power to moving the train better. 

I suggest check your information.Sign - Ditto [#ditto]

Here http://www.spikesys.com/GG1/specs.html we find that the Maximum Tractive Effort for a GG1 is 77,500 lbs. And here http://www.emdiesels.com/lms/en/locomotive/na_freight/sd70ace/index.htm we find that the Continuous Tractive Effort for a single SD70ACe is 157,000 lbs.  But there's no way the GG1 with its primitive adhesion systems and electrical transmission is going to exert maximum tractive effort except under the very best conditions, and for only a few minutes, whereas the SD70ACe can exert its CTE under poor conditions until it runs out of diesel fuel a few days later.  So maybe the SD70ACe on paper can only outpull two not three GG1s, but in the real world the SD70ACe probably could.

As speed rises eventually the GG1 is able to draw more amperes from the catenary than the SD70ACe can from its main generator, but it's a spurious capability because railroading isn't done that way.  It's so rare it's statistically invisible the number of times that a train is (or was) dispatched with a locomotive that can't start it on level track without assistance from a helper locomotive.

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Posted by YoHo1975 on Tuesday, December 4, 2007 11:45 PM
I didn't post links for my data. I pulled the SD70ACe data from Electromotive Diesel's webpage and I got the GG1 details from Wikipedia. I did a google search to figure out what they mean when the didn't specify what the TE was and that's where I saw it almost always mean Starting TE.
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Posted by Railway Man on Tuesday, December 4, 2007 11:55 PM

I agree!  Generally when a source says "maximum" tractive effort or just "tractive effort" they have selected the number that shines the best possible light on the locomotive.  Usually that number is starting tractive effort, which includes undisclosed limiting caveats such as a percentage adhesion that requires dry, nongreasy rail, good rail and wheel profile, straight level track, etc.  And of course 1 minute later in the real world the locomotive slips and tractive effort goes to 0.0, or 5 minutes later the traction motors overheat and short out ...

The meaningful number is maximum continuous tractive effort.

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Posted by edbenton on Wednesday, December 5, 2007 6:54 AM
Compare Apples to Apples.  The GG1 was a PASSENGER locomtive and the SD70ACE is a Freight locomotive they are Geared totally differant and also weigh different.  A GG1 was designed to run at 100+ for long stretches and acclearate like a rabbit the Sd70Ace is a Draft Horse and designed to pull a heavy load.  Considering the GG1 was designed and Built in the 30'3 and lasted until the 80's and then took an IMPORTED DESIGN to replace it not to bad.  The best thing would be match a SD70Ace against say a Boxcab the Milwaukee road ran and see which one would win.
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Posted by CSSHEGEWISCH on Wednesday, December 5, 2007 8:19 AM

Another factor to consider is the source of the energy.  Any self-contained locomotive (diesel, steam, or gas turbine) is constrained by the amount of energy that can be produced by its prime mover (diesel engine, steam boiler, or gas turbine). A straight electric is not self-contained since it draws its energy from an outside source (the power plant) and is constrained more by the capacity of the catenary and feeders to carry that energy than by the capacity of the power plant to produce that energy.

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Posted by YoHo1975 on Wednesday, December 5, 2007 11:14 AM

But energy production isn't the biggest limitation AT ALL. Transferring the energy into locomotion is.

As for the GG-1 comparison, I made the comment because others in the thread had brought it up, not because I felt it was the best comparison to make. Gearing however is not a big deal in this discussion. Traction motor enhancement, AC traction motors, wheel slip controls, steerable trucks. All these things have helped to make the modern 3rd gen (or are we at 4th gen) significantly more powerful then anything to come before it. 

Milwaukee Boxcabs suffer the same issues as the GG-1 old technology.

 

A better question of whose most powerful would be ACe vs. GEVO or perhaps 90MAC-H vs. AC6000 though I think the ACe and GEVO would probably outperform. 

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Posted by wjstix on Thursday, December 6, 2007 9:48 AM
I suspect if we compare apples and apples - 1930's electric engines vs. 1930's diesels, the electrics would come out far ahead. It would be interesting to see what could be built today as far as a straight electric freight engine.
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Posted by CSSHEGEWISCH on Thursday, December 6, 2007 10:10 AM

 wjstix wrote:
I suspect if we compare apples and apples - 1930's electric engines vs. 1930's diesels, the electrics would come out far ahead. It would be interesting to see what could be built today as far as a straight electric freight engine.

The most recent straight electric freight designs that we have were the GM6C and GM10B demos of the late 1970's and the GF6C's in British Columbia of the 1990's.  The GM10B seemed to be the design that was pushing the limits of the envelope.

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Posted by carnej1 on Thursday, December 6, 2007 11:56 AM
 CSSHEGEWISCH wrote:

 wjstix wrote:
I suspect if we compare apples and apples - 1930's electric engines vs. 1930's diesels, the electrics would come out far ahead. It would be interesting to see what could be built today as far as a straight electric freight engine.

The most recent straight electric freight designs that we have were the GM6C and GM10B demos of the late 1970's and the GF6C's in British Columbia of the 1990's.  The GM10B seemed to be the design that was pushing the limits of the envelope.

 I am no engineer(of either stripe) but my understanding of the difference in design between High Horsepower European and North American locomotives are all about high speed versus tractive effort. There are a number of European electrics with impressive ratings (10,000 HP or greater!) but they do not have the pulling power in heavy freight service of the average North American unit (4400 HP GE or 4300 HP EMD). They are designed to pull passenger and short freigth trains at 100 MPH plus speeds.

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Posted by Anonymous on Thursday, December 6, 2007 4:23 PM

Ive heard of some Electrics running in the Alps that are quite the brutes; I could be wrong.

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Posted by beaulieu on Friday, December 7, 2007 12:21 AM
 carnej1 wrote:
 CSSHEGEWISCH wrote:

 wjstix wrote:
I suspect if we compare apples and apples - 1930's electric engines vs. 1930's diesels, the electrics would come out far ahead. It would be interesting to see what could be built today as far as a straight electric freight engine.

The most recent straight electric freight designs that we have were the GM6C and GM10B demos of the late 1970's and the GF6C's in British Columbia of the 1990's.  The GM10B seemed to be the design that was pushing the limits of the envelope.

 I am no engineer(of either stripe) but my understanding of the difference in design between High Horsepower European and North American locomotives are all about high speed versus tractive effort. There are a number of European electrics with impressive ratings (10,000 HP or greater!) but they do not have the pulling power in heavy freight service of the average North American unit (4400 HP GE or 4300 HP EMD). They are designed to pull passenger and short freigth trains at 100 MPH plus speeds.

 

That is an oversimplification, the current SD70ACe and ES44AC are capable of 75mph, and UP runs them at 70 mph on the Z-trains were track conditions allow. BNSF does similar with their ES44DC locomotives. One of the most powerful European locomotives, the Swiss Re 6/6 (now Re 620) is rated at 10,500hp. and has a top speed of 87mph. But is designed around the requirement of pulling a freight train up the 2.7% grade of the Gotthard Pass at 50mph. The Re 620 paired with a Re 420 (6300hp.) is required to take a 1540 ton (US) freight up the 2.7 % grade at 50mph without helpers. 

 

The best match for US diesels would be the IORE electrics built for MTAB in Sweden. They are double unit, but cutting the figures in half yields 7300hp  134,000lbs Continuous TE. top speed 50 mph.

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Posted by Virginian on Friday, December 7, 2007 12:33 PM
If you are interested in electrics you need to look at the VGN electrics.  The EL-2Bs were quite unique.
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Posted by da_kraut on Saturday, December 8, 2007 8:01 PM

Hi there,

here is the web site from Siemens,  they manufacture in whole or part a lot of locomotives for all around the world.  Just browse on the site and you will see the data of the different locomotives that they have produced. Modern technology, sheer weight of the locomotive, gearing as well as HP and torque play a huge roll in the abilities of the locomotives.  With so many variables it seems that it is impossible to determine which locomotive is more powerful.  

Here is the web site:

http://transportation.siemens.com/ts/en/pub/products/lm/refs/electrical.htm

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Posted by ndbprr on Monday, December 10, 2007 1:59 PM
The other factor being overlooked is that G's could be overloaded for a short time and generate much more HP than rating.  So if they could get it to the rails they should be superior.
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Posted by Railway Man on Monday, December 10, 2007 9:43 PM

 ndbprr wrote:
The other factor being overlooked is that G's could be overloaded for a short time and generate much more HP than rating.  So if they could get it to the rails they should be superior.

I don't think anyone has overlooked short-time ratings; their existence is widely known.  It doesn't matter much anyway, as short-time ratings are not a place where a locomotive can usefully go very often.  Typically a locomotive that is trying to exert that kind of amperage is also up against its adhesion limits; there's no point in trying to design a locomotive with greater adhesion to make use of the short-time because the short-time is VERY short.

And the GGI couldn't get it to the rail; they didn't have enough drivers with enough weight on them as well as a primitive wheel-slip system.

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Posted by GP40-2 on Tuesday, December 11, 2007 6:38 PM
 Railway Man wrote:

 ndbprr wrote:
The other factor being overlooked is that G's could be overloaded for a short time and generate much more HP than rating.  So if they could get it to the rails they should be superior.

I don't think anyone has overlooked short-time ratings; their existence is widely known.  It doesn't matter much anyway, as short-time ratings are not a place where a locomotive can usefully go very often.  Typically a locomotive that is trying to exert that kind of amperage is also up against its adhesion limits; there's no point in trying to design a locomotive with greater adhesion to make use of the short-time because the short-time is VERY short.

And the GGI couldn't get it to the rail; they didn't have enough drivers with enough weight on them as well as a primitive wheel-slip system.

RWM



Not entirely correct when talking about pure electric locomotives. By virtue of the overhead power supply, the GG1 could overload its traction motors at speed--it was not just limited to overloading the traction motors in a high amp/low speed manner such as with a unit with a fixed power level (e.g. the diesel-electric, turbine electric, etc). A DC motored diesel-electric can only go into the short time rating zone at low speeds and high amps--a situation used to develop high tractive effort for a heavy pull where adhesion is a huge factor. The GG1 could go into overload after the train was moving at a steady clip. It could double its standard rating for a short time to provide acceleration. At the higher speeds, any locomotive will need to develop less tractive effort for a given horsepower (Drawbar Horsepower=Tractive Effort x Speed/375 therefor as speed increases, tractive effort must go down). In these situations, rarely is adhesion a factor with dry rail. At speed, the GG1 had enough adhesive weight to fully use the short term 8000HP-9000HP it could develop.

To answer to original question, the SD70 can develop more low speed pull than the GG1, but the GG1 will blow the SD70 away with higher speed horsepower.
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Posted by erikem on Wednesday, December 12, 2007 12:52 AM

Short term rating is likely more important for passenger operations than freight (one possible exception being fast freight service). For example, the tractive effort of an F40PH is horsepower limited above 15 MPH, where the short term rating for the AEM-7 is adhesion limited to ~45MPH and the short term tractive effort can exceed the low speed continuous tractive effort at speeds less than 80MPH. In short, the electrics will get up to track speed quicker than a diesel.

As mentioned earlier, at starting an SD-70 can easily outpull a GG-1 (possibly a couple of GG-1's), but the GG-1 could outpull the SD-70 at speeds over 30MPH. 

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Posted by ValorStorm on Thursday, December 13, 2007 6:25 AM
 erikem wrote:

As mentioned earlier, at starting an SD-70 can easily outpull a GG-1 (possibly a couple of GG-1's), but the GG-1 could outpull the SD-70 at speeds over 30MPH. 

But "outpull" needs a definition. Do you mean a GG-1 can outpull, above 30, the same kind of train that an SD70ACe is called for? (It is the ACe we're talking about & not the SD70.) Or is it simply that the GG-1 pulls its train better than an ACe pulls its train? Does "outpull" refer to horsepower or tractive effort? They're not synonymous. And as mentioned earlier, continuous tractive effort of a GG-1 is nowhere near that of an SD70ACe.

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Posted by JT22CW on Thursday, December 13, 2007 7:33 AM

Looks to me like all these comparisons are apples/oranges.  When indeed was the last purpose-built freight electric locomotive built in the USA?  The early 70s, for Black Mesa & Lake Powell RR?  The "big dog" in the diesel arena back then was the SD40-2, and the top speed on those, apart from UP's 90-mph "Fast Forties", was about 65 mph.  Besides that, there was no market for electric freight motors due to Conrail eschewing electricity in the Northeast.

It's certainly not fair to compare a passenger locomotive from the 30s-40s to an AC-traction diesel from the 21st Century.  You've got a technology gap of over seven decades, there.  Now were GE to suddenly create a new E-(something), such a motor would make the AC diesels look quite anemic.  But until then, we've got what we got and there are no real valid comparisons.

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Posted by oltmannd on Thursday, December 13, 2007 11:23 AM
 ValorStorm wrote:
 erikem wrote:

As mentioned earlier, at starting an SD-70 can easily outpull a GG-1 (possibly a couple of GG-1's), but the GG-1 could outpull the SD-70 at speeds over 30MPH. 

But "outpull" needs a definition. Do you mean a GG-1 can outpull, above 30, the same kind of train that an SD70ACe is called for? (It is the ACe we're talking about & not the SD70.) Or is it simply that the GG-1 pulls its train better than an ACe pulls its train? Does "outpull" refer to horsepower or tractive effort? They're not synonymous. And as mentioned earlier, continuous tractive effort of a GG-1 is nowhere near that of an SD70ACe.

I think you're exactly right!  The definition of terms really determines the answer.

"Pull" means force, and "outpull" might mean peak force or it might mean maximum sustained force.  Then, you would have to specify the conditions.  Dead stop?  Clean rail? 

But, based on the numbers, a coupler to coupler tug of war would be won handily by the SD70ACe.

If you start talking about "pulling" at some speed, then you are talking about HP since force x speed = power.  If you are talking about the max, then you are definitely allowing short time operation and at speed, the GG1's gonna generate more tractive force.

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Posted by erikem on Friday, December 14, 2007 1:02 AM
 ValorStorm wrote:
 erikem wrote:

As mentioned earlier, at starting an SD-70 can easily outpull a GG-1 (possibly a couple of GG-1's), but the GG-1 could outpull the SD-70 at speeds over 30MPH. 

But "outpull" needs a definition. Do you mean a GG-1 can outpull, above 30, the same kind of train that an SD70ACe is called for?

Above 30 MPH, the GG-1 could generate more tractive effort than the SD70ACe. At low speeds, there would be no contest - the SD70ACe would win hands down.  A similar case would be comparing a GP40 with and SD7, at low speeds where the SD7 is adhesion limited and not horspower limited, the SD7 could generate more tractive effort than the GP40. get up to 20MPH or so, then the tractive effort from the SD7 would be horsepower limited and the GP40 (having twice the horsepower) could generate more tractive effort.

To get back to your question of whether a GG-1 could handle the same train as an SD70ACe - if the SD70ACe could maintain 30MPH with the train, then the GG-1 would likely be able to handle it as well. Since the continuous horsepower rating of the GG-1 isn't much higher than the SD70ACe, the GG-1 wouldn't be much faster than the SD70ACe, unless the trip involved frequent acceleration from 30 to 60-70MPH.

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Posted by ValorStorm on Friday, December 14, 2007 10:44 PM
 YoHo1975 wrote:

the GG1 can produce 70,700 lbs TE unspecified via DC (unspecified is always assumed to mean starting TE.)

The SD70ACe can produce

191,000 lbs starting TE 

157,000 continuous TE

So, (an SD70ACe) can ALMOST produce as much as 3 GG1s. 3 gg1s producing 213,000 lbs TE  

I'm trying not to hurt anyone's feelings, but a proper understanding of terms is needed in this thread. YoHo1975 is absolutely correct. There is no circumstance where the tractive effort of a GG-1 can ever approach the tractive effort of an SD70ACe. CTE is never equal to or higher than STE. Not at any speed. I think some of us are making valid points but using the wrong terminology. I know a good primer on HP curves, TE curves, & adhesion. But I'll have to dig thru the mess that is my bedroom to remember the name of the book. I'll get back to you.
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Posted by YoHo1975 on Saturday, December 15, 2007 2:02 AM
 erikem wrote:
 ValorStorm wrote:
 erikem wrote:

As mentioned earlier, at starting an SD-70 can easily outpull a GG-1 (possibly a couple of GG-1's), but the GG-1 could outpull the SD-70 at speeds over 30MPH. 

But "outpull" needs a definition. Do you mean a GG-1 can outpull, above 30, the same kind of train that an SD70ACe is called for?

Above 30 MPH, the GG-1 could generate more tractive effort than the SD70ACe. At low speeds, there would be no contest - the SD70ACe would win hands down.  A similar case would be comparing a GP40 with and SD7, at low speeds where the SD7 is adhesion limited and not horspower limited, the SD7 could generate more tractive effort than the GP40. get up to 20MPH or so, then the tractive effort from the SD7 would be horsepower limited and the GP40 (having twice the horsepower) could generate more tractive effort.

To get back to your question of whether a GG-1 could handle the same train as an SD70ACe - if the SD70ACe could maintain 30MPH with the train, then the GG-1 would likely be able to handle it as well. Since the continuous horsepower rating of the GG-1 isn't much higher than the SD70ACe, the GG-1 wouldn't be much faster than the SD70ACe, unless the trip involved frequent acceleration from 30 to 60-70MPH.

 

Unless of course the SD70ACe is utilizing it's modern Anti-Slip and Adhesion control to maintain said 30MPH in which case, the GG-1 would be unable to maintain control of the train.

In short on straight dry track, yes.

Nobody has given a CTE number for the GG-1.

 

Oh, and if the SD70ACe has radial trucks then fugedaboutit. 

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Posted by erikem on Saturday, December 15, 2007 2:01 PM
 YoHo1975 wrote:
 

Unless of course the SD70ACe is utilizing it's modern Anti-Slip and Adhesion control to maintain said 30MPH in which case, the GG-1 would be unable to maintain control of the train.

Quite true.

My recollection is that the GG-1 had a continuous rating of ~4500 HP and a short time rating in excess of 8000 HP. The short time rating is about the same as two SD70ACe (rail horsepower).  Keep in mind that these two locomotives are designed for very different services - the GG-1 is emphatically not the locomotive to use for low speed drag service, which is where the SD70ACe excels.

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