oltmannd Leo_Ames There's documentation with their locomotive data books that confirms that they indeed derated them, not to mention 1st hand accounts. http://utahrails.net/sp/sp-r8-grip.php#heading_toc_j_6 Derating was likely done to get rid of traction motor field shunting while rewiring the locomotive. Note that GP35s were derated during rebuilds - and there was nothing wrong with the 16-567D3 at 2500 HP. The reason was you could skip field shunting at a 2000 HP rating.
Leo_Ames There's documentation with their locomotive data books that confirms that they indeed derated them, not to mention 1st hand accounts. http://utahrails.net/sp/sp-r8-grip.php#heading_toc_j_6
There's documentation with their locomotive data books that confirms that they indeed derated them, not to mention 1st hand accounts.
http://utahrails.net/sp/sp-r8-grip.php#heading_toc_j_6
Derating was likely done to get rid of traction motor field shunting while rewiring the locomotive. Note that GP35s were derated during rebuilds - and there was nothing wrong with the 16-567D3 at 2500 HP. The reason was you could skip field shunting at a 2000 HP rating.
IIRC, the field shunting problem was more of an issue with locomotives that did a lot of swiching work,particularly 4 axle EMD units.
Railroads that derated SD45 series locomotives mostly did so to reduce fuel consumption...
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Leo_Ames[SP] locomotive data books that confirms that they indeed derated them
Don't recall if all the SD45T-2s stayed at 3600.
carnej1 oltmannd Leo_Ames There's documentation with their locomotive data books that confirms that they indeed derated them, not to mention 1st hand accounts. http://utahrails.net/sp/sp-r8-grip.php#heading_toc_j_6 Derating was likely done to get rid of traction motor field shunting while rewiring the locomotive. Note that GP35s were derated during rebuilds - and there was nothing wrong with the 16-567D3 at 2500 HP. The reason was you could skip field shunting at a 2000 HP rating. IIRC, the field shunting problem was more of an issue with locomotives that did a lot of swiching work,particularly 4 axle EMD units. Railroads that derated SD45 series locomotives mostly did so to reduce fuel consumption...
Not following you... Field shunting (and transition) is needed to keep the HP up at high speeds because of voltage limits of the main generator (traction alternator/diodes). At low switching speeds, none of that comes into play. You just stay in full field all the time.
GP35s had something like 20+ stages of field shunting with transition requiring a mess of switch gear, a horrible electro-mechanical control system and miles of wiring. Conrail intstalled some Barco solid state controls and derated to 2250 HP with 8 (?) stages of shunting/transition. They were intended to keep running in road service.
SD45s weren't as bad - they had few steps of field shunting, but SD40s had none at all. By the time the Dash 2s came around, the diode max voltage had climbed high enough to eliminate field shunting altogether and eliminate transition in the four axles.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
carnej1Railroads that derated SD45 series locomotives mostly did so to reduce fuel consumption...
And to ease the stresses on the crankshaft and bearings. As I understand it, this is the primary reason why SP did so.
timzDon't recall if all the SD45T-2s stayed at 3600.
Never seen any mentions that they were ever derated.
By the 1970's, most of the issues with the 20 cylinder 645 that had cropped up after hundreds of thousands of miles of service had been addressed. So I suspect this effort never carried over to the Dash 2's.
Southern Pacific seems to have discovered that the benefits were neglible compared to the advantages of just stocking a single model governor for the fleet (No rewiring, changes to transition, and so on were associated with if a SP SD45 output at 3,200 HP, 3,400 HP, or 3,600 HP... the HP difference all depended on what governor was installed.).
timzSP data books show some SD45s (and all SD45Rs?) at 3200 hp. What was it-- maybe half of them?
Out of 354 SD45's, 167 were rebuilt as SD45R's. All had 3,200 HP governors installed. And a single unit was rebuilt instead as a SD44R, recieving a 16 cylinder 645 block.
But by the time of SP's disappearance, most, if not all SD45R's that remained active had been returned to their original HP rating as simplication of parts inventories with unrebuilt sisters won over.
There's a pretty good thread on crankshafts, particularly 20-cylinder crank fabrication, over on RyPN now.
http://www.rypn.org/forums/viewtopic.php?f=1&t=37404&sid=eda484af2572598f0e0dd89715ca4795
erikem GM made some 24 cylinder diesels for the USN during WW2 with a one-piece crankshaft. One of these engines was at the Diesel Engineering School at Cornell in the latter part of WW2 and my dad said the crankshaft broke about the time he was there. What impressed me was the cost of replacing the crankshaft, tough I don't remember enough of the details to say it was broken by torsional vibrations. - Erik
GM made some 24 cylinder diesels for the USN during WW2 with a one-piece crankshaft. One of these engines was at the Diesel Engineering School at Cornell in the latter part of WW2 and my dad said the crankshaft broke about the time he was there. What impressed me was the cost of replacing the crankshaft, tough I don't remember enough of the details to say it was broken by torsional vibrations.
- Erik
owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ?
CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL.
The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO.
Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL.
General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ?
Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ?
Johnny
M636C
My impression was that the Diesel Engineering School was more for surface ships as opposed to subs, which presumably had their own version of that school. In addition to the 24 cylinder GM diesel, the school had an Alco (which used pipes for the tappet rods), an FM and a double acting HOR. My dad said he liked the unitized injectors for the GM engine as he had an unpleasant experience when the high pressure fuel line on another engine wasn't fully tightened down on another when it was started up.
The USN had quite a few classes of surface ships running diesels, including the minesweeper my dad shipped out on VJ day (which eventually became the Philipines presidential yacht). LST's and destroyer escorts were a couple of other diesel powered types.
Winton 278 sounds right, my dad was emphatic it was not an EMD.
Erik,
The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs.
With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast.
Deggesty owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ? I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has.
I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has.
I'm no expert, but I remember reading that because of restricted breathing (the cylinder must be purged and re-charged at the bottom part of each stroke) the 2-stroke can't produce anywhere near double the power of the 4-stroke. I'm sure others on this forum can tell us more.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Paul, I am not taking issue with the comparative power produced in a power stroke.
Given equal cylinder displacement, a two-stroke engine will produce less than twice the power produced by a four-stroke engine running at the same speed, but it will produce more power than the four-stroke engine because it fires twice as often.
M636C VGN Jess Why has GE never had to build a 20 cylinder prime mover to achieve higher horespower, but EMD has had to build two (SD45 and SD80MAC) to do so? Even now, GE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder 70ACe. What does GE know that EMD doesn't? It isn't just a matter of the number of cylinders; The 20 cylinder 710 is more powerful than the 16 cylinder FDL or the 12 cylinder GEVO, however. The two sixteen cylinder engines, the GE HDL and the EMD 265H were both rated at the same 6000 HP. The experimental EMD 12-265H was the same power as the 12 cylinder GEVO. EMD chose for good reasons to sell the 16-710 instead, not least because that's what the customers wanted. EMD have an experimental 12 cylinder four stroke engine and it is expected that this will develop 4500 HP. In export locomotives, an Alco 12-251 developed 2000 HP and was a competitor with the 16-645E, and had the advantage of generally lower fuel consumption, but the EMD outsold the Alco (except in India, where the ALCO could be built locally). It is true that the 20-645E3 was necessary to match the 3600 HP of the FDL16, but the GE engine was not more successful than the EMD. At the time many more 3000 HP locomotives were built than 3600 HP. The 20-710G3 was more powerful than any GE engine of the time but only sold a few examples. In general, EMD engines last longer than GE engines. In time the cast crankcase of the GE FDL cracks and requires replacement, after ten to twenty years depending on the duty cycle. EMD 645 engines have lasted more than 40 years and many are still in service. These older engines might not be as economical or emissions friendly, but they still work. M636C LOOOKING FOR ANYBODY THAT WORKS ON THE EMD & GE ENGINES ESPECIALLY THE GE VO ENGINE. WHICH IS EASIER & HAS LESS PROBLEMS TO WORK ON. AT LA GRANGE THEY SAID THEY VERY SELDOM SCRAPED A BLOCK I LIKE THE GEVO HAVING A COMPLET POWER PACK. MY EXP HAS ALWAYS BEEN CLEVELAND & EMD. GREAT ENGINES. EPA BETTER KNOWN AS THE BUSINESS PREVENTION BUREAU. HERBYGD@AOL.COM
VGN Jess Why has GE never had to build a 20 cylinder prime mover to achieve higher horespower, but EMD has had to build two (SD45 and SD80MAC) to do so? Even now, GE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder 70ACe. What does GE know that EMD doesn't?
Why has GE never had to build a 20 cylinder prime mover to achieve higher horespower, but EMD has had to build two (SD45 and SD80MAC) to do so? Even now, GE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder 70ACe. What does GE know that EMD doesn't?
It isn't just a matter of the number of cylinders;
The 20 cylinder 710 is more powerful than the 16 cylinder FDL or the 12 cylinder GEVO, however.
The two sixteen cylinder engines, the GE HDL and the EMD 265H were both rated at the same 6000 HP. The experimental EMD 12-265H was the same power as the 12 cylinder GEVO. EMD chose for good reasons to sell the 16-710 instead, not least because that's what the customers wanted.
EMD have an experimental 12 cylinder four stroke engine and it is expected that this will develop 4500 HP.
In export locomotives, an Alco 12-251 developed 2000 HP and was a competitor with the 16-645E, and had the advantage of generally lower fuel consumption, but the EMD outsold the Alco (except in India, where the ALCO could be built locally).
It is true that the 20-645E3 was necessary to match the 3600 HP of the FDL16, but the GE engine was not more successful than the EMD. At the time many more 3000 HP locomotives were built than 3600 HP.
The 20-710G3 was more powerful than any GE engine of the time but only sold a few examples.
In general, EMD engines last longer than GE engines. In time the cast crankcase of the GE FDL cracks and requires replacement, after ten to twenty years depending on the duty cycle. EMD 645 engines have lasted more than 40 years and many are still in service. These older engines might not be as economical or emissions friendly, but they still work.
M636C LOOOKING FOR ANYBODY THAT WORKS ON THE EMD & GE ENGINES
ESPECIALLY THE GE VO ENGINE. WHICH IS EASIER & HAS LESS PROBLEMS TO WORK ON. AT LA GRANGE THEY SAID THEY VERY SELDOM SCRAPED A BLOCK I LIKE THE GEVO HAVING A COMPLET POWER PACK. MY EXP HAS ALWAYS BEEN CLEVELAND & EMD. GREAT ENGINES. EPA BETTER KNOWN AS THE BUSINESS PREVENTION BUREAU. HERBYGD@AOL.COM
IN THE 70s WE PURCHACED A CLEVELAND 16 278a. FROM THE NAVY AT ANAPOLIS MD. WAS A EXPEREMENTAL ENGINE WITH A 12 CYL. ROOTS BLOWER & A LARGE ELECTRIC BLOWER ON THE FLOOR ABOVE. WE PURCHACED IT & PUT A 16 CYL BLOWER BACK. IT RAN IN A DREDGE FOR MANY YEARS AFTER. NOT MANY LEFT TODAY. BUT THATS 70 YEARS AGO. HERBYGD@AOL.COM
Randy Vos
"Ever have one of those days where you couldn't hit the ground with your hat??" - Waylon Jennings
"May the Lord take a liking to you and blow you up, real good" - SCTV
Thank you to all who responded to my questions; I learned much. That said, I still don't feel the crux of my query was answered. I was asking for opinions (hopefully from EMD/GE experts), why would EMD use two stroke engines at 900-950 max RPMs (over 4 strokes at 1,050 RPMs), when GE gets more HP from using (in some cases) 4 less cylinders? It just seems to me, in looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"? Just curious. If someone thinks they already answered that, I apologize for not recognizing it. Merry Christmas to all! :)
Generally, conservatism. This is what gives EMD its reputation for reliability and longevity. There are some exceptions, but EMD was hesitant to push the limits of their design, because it had the potential to create problems. Look at the SD50, for example. Railroads tend to value reliability just as much as horsepower. GE caught up with the -8s and -9s in terms of reliability and longevity.
Thanks; I understand that (conservatism) as a probable reason.
VGN Jess In looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"?.
In looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"?.
GE only entered the market around 1960 with the U25.
At that time EMD produced the SD24 with the same number of cylinders but 100 HP less.
Apart from the SD45 and SD45-2 with 20 cylinders, to match the U36C, EMD and GE had matching engines, the 12-645E3 in the GP39 matchng the FDL-12 in the U23B and the 16-645E3 in the SD40 matching the FDL-16 in the U30C. So apart from the most powerful locomotives in the range (which were not the most popular) EMD and GE had matching engines.
Later with the 710 engine, the 12-710G3 in the GP59 matched the increased power of the FDL-12 in the B30-7A and later the 16-710 at 950 rpm in the SD75 was only 80HP less than the FDL-16 in the Dash9-44CW.
In the 6000 HP locomotives, the 16-265H matched the HDL-16.
It is only with the current GEVO-12 compared to the 16-710 that there has been a consistent period where GE has had a locomotive with fewer cylinders. EMD could have built the SD89MAC but customers asked for the the SD70ACe instead.
The EMD 16-710 engine pretty much matches the fuel consumption of the GEVO-12. The EMD engines are kbnown to last much longer than the GE FDL engines. Most of the Dash 8s rebuilt recently have new engines, while most rebuilt EMD locomotives retain their original engine, rebuilt with new power assemblies. In the long term, the EMD is cheaper to own.
To be fair, the GEVO is yet to establish whether it will last as long as an an EMD two stroke.
As from now, it appears that EMD and GE will again have equivalent engines with the same number of cylinders, with the new EMD four stroke engine against whatever GE are going to call their Tier 4 engine, with both producing 4500HP.
So there have been specific periods where GE had engines that were more powerful per cylinder, but this has not been consistent. In general EMD and GE have had matching engines with the same number of cylinders.
Best answer yet; thanks! Generally, I was primarily considering the 1965 period on, and should have been more specific in my query. Specifically, I just couldn't (can't) understand why EMD would use a 16 cylinder 2 stroke (SD70ACe) with less HP than a GE 4 stroke (ES44AC) w/only 12 cylinders and why customers would buy it (16)? Wouldn't 16 cylinders burn more fuel than 12?
It does not burn more fuel. It burns the same amount of fuel and the engine has been around longer. Everyone knows how to work on it.
VGN Jess Best answer yet; thanks! Generally, I was primarily considering the 1965 period on, and should have been more specific in my query. Specifically, I just couldn't (can't) understand why EMD would use a 16 cylinder 2 stroke (SD70ACe) with less HP than a GE 4 stroke (ES44AC) w/only 12 cylinders and why customers would buy it (16)? Wouldn't 16 cylinders burn more fuel than 12?
VGN JessWouldn't 16 cylinders burn more fuel than 12?
You're asking the wrong question. My father had a 12-cylinder E38 BMW that was good for over 28 mpg indicated at just over 80 mph, on a road that was far from flat. I have never seen an eight-cylinder model of the same car that would get even remotely similar mileage under the same conditions -- from less displacement.
There is a bit more loss, thermodynamic and mechanical, out of more cylinders, and of course the capital cost of more injectors, bearings, valves, etc. is higher. So there are advantages to building engines with fewer cylinders... if you haven't already costed-down much of your production cost, established a cadre of skilled maintenance people, developed a robust aftermarket for parts and supplies, etc. for an engine design with more cylinders.
The point is not just how many cylinders an engine has. I think most Class I railroads care more about ton-miles and over-the-road reliability (including the ability to work partially disabled without catching fire!) than about pure specific fuel consumption in the prime mover.
There are certainly cases where fuel economy is significant -- that's part of the appeal of older Alcos in shortline service, I believe. But that's normally a fairly small part of the overall cost of assuring motive power. Again, it's working reliability that matters, and railroads have (or ought to have) a pretty good idea of how the balance between fewer cylinders and easier maintenance, etc., works out economically.
Now, what the locomotive manufacturers say to the railroads when trying to sell their products is another matter. One that I suspect requires other criteria than straight factual truth to evaluate...
What difference is there between the hp per cc displacement of an EMD 2 cycle engine and a GE 4 cycle engine?
Does a 2 cycle engine run slower than a 4 cycle engine?
Partial answer to #1 has already been discussed. 2-cycle has more power strokes per unit time, so higher HP; 4-cycle is more efficient (and can use higher peak and mean pressure over a longer stroke) so greater unit power for a given displacement. Then you factor in the injection characteristics, the permissible machine speeds, etc.
M636C can probably provide actual numbers for various kinds of EMD 567/645/710 vs. GE and Alco 4-cycle service engines. If we ask him politely, he might work them up if not already available...
#2 -- the rotational speed is determined by a number of factors, ranging from how the engine is balanced net of power thrust on the pistons (which changes during the stroke) to how the firing order, etc. puts torsional strain on the crank. EMD engines were classically designed for the 900 rpm range, and running them even 25 to 50 rpm faster can significantly degrade reliability and engine life. GEs are, in my opinion, being overdriven at 1050 rpm, but I'm not in the industry and don't have reliability data -- under Welch, GE developed the power-by-the-hour guarantee system to cope with the real-world effects of diminished reliability at higher rotational speed.
The recent posts have thouroughly addressed my initial query; thank you very much. The answers have shown me that intuitive thinking is not always relevant in the railroad power industry. While a railroad supporter, I am ignorant of these kinds of technical issues for never having worked on a railroad (though my grandfather was an engineer on the Virginian RR for 35 years). Merry Christmas to all who helped me understand how complex something I thought was relatively simple!!!
Paul of Covington Deggesty owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ? I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has. I'm no expert, but I remember reading that because of restricted breathing (the cylinder must be purged and re-charged at the bottom part of each stroke) the 2-stroke can't produce anywhere near double the power of the 4-stroke. I'm sure others on this forum can tell us more.
GM Diesel also built some 16V71 engines with one piece crankshafts. They soon found out what a mistake that was. Cranks broke at the point of where the two 8V71 blocks were joined. They corrected that by going with a bolted two piece crank. Detroit Diesel also built some 24 cylinder engines. Far as I know, none of those had a one piece crank.
DKW built a lot of 2-stroke gasoline engines. One of their markings on some of their models were 3=6 pointing at their thinking you could get twice the HP. A little 3 cylinder 750cc DKW engine put out 34 HP.
D NICHOLS GM Diesel also built some 16V71 engines with one piece crankshafts. They soon found out what a mistake that was. Cranks broke at the point of where the two 8V71 blocks were joined. They corrected that by going with a bolted two piece crank. Detroit Diesel also built some 24 cylinder engines. Far as I know, none of those had a one piece crank.
My dad worked on a 24 cylinder GM diesel while attending the USN's Diesel Engineering school at Cornell, late 1944 early 1945. He was emphatic that it was a one piece cank as they had to replace a broken one at great expense.
M636C Erik, The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs. With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. M636C
The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines.
tdmidget M636C Erik, The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs. With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. M636C The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines.
Indeed, but I'm not in the US Navy....
That's true but FM opposed piston engines were the standard auxilary power for U.S Nuclear submarines up until quite recently and the older boats still have them installed..
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