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OK, This should be No 1000 - So ask me a Technical Locomotive Question

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Posted by M636C on Saturday, February 12, 2005 12:26 AM
And there I was thinking that the thread had gone away! To answer the specific question posed by OS, Marine engines don't have "throttle notches" (although EMD engines should run at specific speeds to avoid torsional vibration problems, one of the origins of the eight notch throttle). I just checked the EMD web site, and the marine version has a rating approved by a classification society (such as American Bureau of Shipping, Lloyd's Register). The ABS rating for the 16-710G7B is 4000HP at 900 rpm, much the same as the similar engine (16-710G3B) in the SD70M at notch 8. This "Maximum Continuous Rating" (MCR) is what it says, the power which the engine can produce continuously without time limitations. Given the similarity in power, it could be assumed that an SD70M could produce 4000HP (at the alternator input shaft)continuously for days at a time, longer than the fuel capacity or track limitations would allow.

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Posted by Anonymous on Friday, February 11, 2005 9:42 PM
It's not a question I've ever heard come up at the railroad. The stuff is designed to run indefinitely at full horsepower, not like an automobile engine. We assume they can run continuously in any notch until the next required shop interval, 92 days, stopping for fuel, of course. But in marine and stationary applications, the engine is going to run, I suppose, for days or weeks in notch 8. (M636C -- your experience?) Not entirely uncommon to see a locomotive in notch eight for three-four hours at a time.

As for a D.C. traction motor, as long as the motor is not in the short-time rating, it's hours are limited only by required maintenance intervals on the commutator and brushes, I suppose. If it's A.C., the maintenance interval is in weeks or longer, and I would imagine the time at full horsepower might be months before they needed any attention.

OS
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Posted by Anonymous on Friday, February 11, 2005 9:08 PM
How long can a locomotive run i notch 8, and willit have an effect on the traction motors performance.[?]
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Posted by CSXrules4eva on Wednesday, December 8, 2004 8:46 PM
QUOTE: Originally posted by CSSHEGEWISCH

If you want huge, consider the Baldwin De La Vergne engine. Bore was 12 3/4 inches and stroke was 15 3/4 inches. Maximum speed was 625 RPM.
The 567 is 8 1/2 inches by 10 inches, 645 is 9 1/16 inches by 10 inches, 710 is 9 1/16 inches by 11 inches, and 244, 251 and FDL are 9 inches by 10 1/2 inches.

There are also some marine diesels that are even larger than the De La Vergne.


Yes there are maine diesels out there that are truely impressive. Check out cat.com and cummins.com There are some good looking diesel's there marine, and power generation diesels too. Hey you forgot to mention EMD's 16V265H engine.
SPECS:
6,000hp
265mm bore, 300mm stroke, 4cycle, 16cyl
iron cross-flow cyl head
twin turbos,
pump short line fuel injection,
6300 BHP at 1,000rpm
inboard camshaft
This is all I can think of for right now w/ those specs.
LORD HELP US ALL TO BE ORIGINAL AND NOT CRISPY!!! please? Sarah J.M. Warner conductor CSX
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Posted by Randy Stahl on Wednesday, December 8, 2004 6:48 PM
QUOTE: Originally posted by oltmannd

QUOTE: Originally posted by Randy Stahl

QUOTE: Originally posted by oltmannd

Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

That will work !!!!
Randy


Fuel in gals/hr by notch for GP40-2, E3 engine, AAR std conditions

N8 168.3
N7 141.2
N6 105.7
N5 79.4
N4 56.2
N3 38.1
N2 23.1
N1 8.6
idle (315 RPM) 5.0
Low idle (255 RPM) 4.0
DB4 14.5

Sorry it took me so long to get to this....
Thanks, those numbers will be put to good use.
Randy
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Posted by M636C on Wednesday, December 8, 2004 6:00 PM
QUOTE: Originally posted by Overmod

QUOTE: Originally posted by CSSHEGEWISCH
There are also some marine diesels that are even larger than the De La Vergne.


One of the great understatements of the year.

Consider the Mitsui-MAN-B&W 10K98MC, which from its designation shows it has a 980-mm piston diameter. If big numbers are impressive, I think a piston diameter of a yard beats piston diameter of a foot...

We have had previous threads on these, with some interesting links to pictures. I would note that information on this general class of engines can be obtained here:

http://www.manbw.com/category_000284.html


Strangely enough, I have the operating manual for MAN B&W "46-98 MC Engines" the range of cylinder bores used in this design being from 460mm to 980mm. The Royal Australian Navy recently purchased the newly completed tanker MV "Delos" (built in Korea) which is fitted with one such engine. It is to be modified and commissioned as HMAS "Sirius" for use as a fleet replenishment ship to refuel other ships at sea. I don't have the details of the particular engine to hand at the moment.

There aren't any dimensioned drawings in this manual, but the cover photo shows what I assume is the 98MC engine. It has two railed platforms mounted on it, one at the top pf the cylinder and one at the bottom of the cylinder. a man is standing on the lower platform, and the distance to the upper platform is half as much again as his height. A man on the upper platform does not stand as high as the cylinder heads.

Peter
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Posted by oltmannd on Wednesday, December 8, 2004 11:08 AM
QUOTE: Originally posted by M636C

QUOTE: Originally posted by oltmannd

QUOTE: Originally posted by jockellis

I used to rent an apartment from a retired road foreman of engines in Waycross, GA who had kept the owners manual from a U-25 he had once operated. I hope you can help me but it said something about the electric motor running in different modes and in my memory they were series, series shunt, series-parallel and parallel shunt (or something like that) . Could you refresh my memory and tell me what all that mumbo jumbo means?
Jock Ellis


It's the way GE kept the locomotive's performance on the 2500 HP curve throughout it's speed range. They had to do it because of current and voltage limitations of the main generator and traction motors.

In parallel, all 4 traction motors are connected to the main generator in parallel. As you go slower, the voltage goes down and the current goes up. Soon, it is too high for the main generator, so you reconnect the motors. You connect each pair of motors in series and then the two series pair in parallel to the main generator. This doubles the voltage but halves the current from straight parallel.

The shunting comes into play at the high voltage/high speed end. You weaken the field by shunting some of the field windings in the traction motor so that the voltage goes down and the current goes up a bit. This allows the locomotive to continue to produce full HP at high speeds.

Now, with traction alternators instead of generators and good, high voltage diodes to make DC from the AC, plus the advent of generator transition, a 4400 HP DC locomotive has no motor transition nor field shunting.


Since the manual refers to three connections,

These would be:

series = four motors in series
series parallel = two groups of two motors in series
parallel = all four motors in parallel (each taking full voltage)

These are "series-wound" motors, so all the armature current also passes through the field windings, generating a magnetic field (sometimes called "flux"). The motor speed is dependent on the voltage and the magnetic field. You can go faster by making the voltage higher, or the magnetic field smaller. The "resistance" of the motor to the current is the "back EMF" generated by the magnetic field. So when you can't raise the voltage to increase the speed, you can reduce the magnetic field by providing a "shunt" or diversion, that allows part of the current to bypass the field windings (and not generate "Back EMF") but still flow through the armature.

The field shunting or diversion, can be applied independent of the actual connection of the motors in series or parallel, but this will be determined by the control system which makes the connections.

It might actually be more complicated than it sounds.

I understand early U boats also had sixteen throttle notches, too, but only eight were used if in multiple with an Alco or EMD!

Peter


Full series? Wow. Hard to believe they'd need it.

Those U25B throttles had what were referred to as "half notches". If you took the next half notch, you got the next throttle notch's engine speed without the load. Then, if you took another half notch up to the next full one, you'd get the load. Maybe it was a way to allow the engineer to eliminate smoke from turbo lag? In later years, most RRs I know disconnected the half notches to simplify things.

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by Overmod on Wednesday, December 8, 2004 11:04 AM
QUOTE: Originally posted by CSSHEGEWISCH
There are also some marine diesels that are even larger than the De La Vergne.


One of the great understatements of the year.

Consider the Mitsui-MAN-B&W 10K98MC, which from its designation shows it has a 980-mm piston diameter. If big numbers are impressive, I think a piston diameter of a yard beats piston diameter of a foot...

We have had previous threads on these, with some interesting links to pictures. I would note that information on this general class of engines can be obtained here:

http://www.manbw.com/category_000284.html
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Posted by oltmannd on Wednesday, December 8, 2004 11:02 AM
QUOTE: Originally posted by M636C

QUOTE: Originally posted by Randy Stahl

QUOTE: Originally posted by oltmannd

Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

That will work !!!!
Randy



But not if it is supplying HEP power to a passenger train, as outlined in my comments above, because the engine will be running at a constant 900 rpm even at idle, and will have a load of a couple of hundred kW on top of any "locomotive" functions.

Peter


Notch 8 fuel rate will be the same whether in passenger or freight mode. Governor will go to N8 rack setting and then vary load regulator to balance engine speed.

I think N8 engine speed on an F40 is 896 RPM (to make 60 Hz HEP from gear driven HEP alternator) vs 904 RPM for std 16-645E3.

F40s have 3 modes you can select. Passenger mode, where it will run the engine at 896 RPM regardless of throttle notch. Standby mode, where it runs at appropriate notch (5?, 6?) to get 60 Hz out of AR10 for HEP - no power for traction. And, freight mode, where it runs engine at all 8 speeds (low idle through notch 8) according to the throttle setting.

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Posted by oltmannd on Wednesday, December 8, 2004 10:55 AM
QUOTE: Originally posted by Randy Stahl

QUOTE: Originally posted by oltmannd

Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

That will work !!!!
Randy


Fuel in gals/hr by notch for GP40-2, E3 engine, AAR std conditions

N8 168.3
N7 141.2
N6 105.7
N5 79.4
N4 56.2
N3 38.1
N2 23.1
N1 8.6
idle (315 RPM) 5.0
Low idle (255 RPM) 4.0
DB4 14.5

Sorry it took me so long to get to this....

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by CSSHEGEWISCH on Wednesday, December 8, 2004 10:07 AM
If you want huge, consider the Baldwin De La Vergne engine. Bore was 12 3/4 inches and stroke was 15 3/4 inches. Maximum speed was 625 RPM.
The 567 is 8 1/2 inches by 10 inches, 645 is 9 1/16 inches by 10 inches, 710 is 9 1/16 inches by 11 inches, and 244, 251 and FDL are 9 inches by 10 1/2 inches.

There are also some marine diesels that are even larger than the De La Vergne.
The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by AlcoRS11Nut on Tuesday, December 7, 2004 5:40 PM
QUOTE: Originally posted by M636C

QUOTE: Originally posted by AlcoRS11Nut

Nice on the 4th star....but here is my question.....what is the diameter of a piston (or cylinder) of a EMD H-series prime-mover? The reason I asked this odd question is that my cousin and I were talking the other day and he said that it was a foot across. I don't know that just seems kinda large to me, even the H series. Is he right or it is bigger/smaller?


This is one of the really easy ones!

EMD changed their method of engine classification, because (I think) the new H engine was more than 1000 cubic inches per cylinder, and would require a four digit number rather than a three digit number. So the decision was made to describe four stroke engines by their diameter in millimetres, in the H engine case it is "265H", about 10.43 inches. The engine STROKE is close to one foot, however. The small four stroke engine built by Caterpillar is described as a "GM170" when fitted in a GP15D, for example. While on the subject of Cat, their next size engine, the 3600, used in the now modified MK5000, was 270mm cylinder diameter. So you had a step of 100mm cylinder diameter between engine models! The MK5000 units now use EMD 645F engines.

Peter


Thanks Peter! That's friggin huge!
I love the smell of ALCo smoke in the Morning. "Long live the 251!!!" I miss the GBW and my favorite uncle is Uncle Pete. Uncle Pete eats Space Noodles for breakfast.
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Posted by Overmod on Thursday, December 2, 2004 6:58 PM
Amazing, a gobbler that survived Thanksgiving...
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Posted by Sterling1 on Thursday, December 2, 2004 6:44 PM
I am the Time-Gobbler . . . chomping to three stars!!! . . .
"There is nothing in life that compares with running a locomotive at 80-plus mph with the windows open, the traction motors screaming, the air horns fighting the rush of incoming air to make any sound at all, automobiles on adjacent highways trying and failing to catch up with you, and the unmistakable presence of raw power. You ride with fear in the pit of your stomach knowing you do not really have control of this beast." - D.C. Battle [Trains 10/2002 issue, p74.]
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Posted by Sterling1 on Thursday, December 2, 2004 6:09 PM
QUOTE: Originally posted by M.W. Hemphill

Welcome to the four-star time-wasting club!

Here's your question:

Are you ready?

Why?


GRRR!!! teeth nashing . . . slogging at 2 somes still hauling out to the three some stars . . .
"There is nothing in life that compares with running a locomotive at 80-plus mph with the windows open, the traction motors screaming, the air horns fighting the rush of incoming air to make any sound at all, automobiles on adjacent highways trying and failing to catch up with you, and the unmistakable presence of raw power. You ride with fear in the pit of your stomach knowing you do not really have control of this beast." - D.C. Battle [Trains 10/2002 issue, p74.]
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Posted by Randy Stahl on Thursday, December 2, 2004 4:50 PM
I'll take into consideration the HEP , I think the HEP is about 500 kw . I'll go ahead and consider how many gallons per horsepower , per hour. Or use the GP -40 chart and fiddle with the numbers.
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Posted by M636C on Thursday, December 2, 2004 4:43 PM
QUOTE: Originally posted by oltmannd

QUOTE: Originally posted by jockellis

I used to rent an apartment from a retired road foreman of engines in Waycross, GA who had kept the owners manual from a U-25 he had once operated. I hope you can help me but it said something about the electric motor running in different modes and in my memory they were series, series shunt, series-parallel and parallel shunt (or something like that) . Could you refresh my memory and tell me what all that mumbo jumbo means?
Jock Ellis


It's the way GE kept the locomotive's performance on the 2500 HP curve throughout it's speed range. They had to do it because of current and voltage limitations of the main generator and traction motors.

In parallel, all 4 traction motors are connected to the main generator in parallel. As you go slower, the voltage goes down and the current goes up. Soon, it is too high for the main generator, so you reconnect the motors. You connect each pair of motors in series and then the two series pair in parallel to the main generator. This doubles the voltage but halves the current from straight parallel.

The shunting comes into play at the high voltage/high speed end. You weaken the field by shunting some of the field windings in the traction motor so that the voltage goes down and the current goes up a bit. This allows the locomotive to continue to produce full HP at high speeds.

Now, with traction alternators instead of generators and good, high voltage diodes to make DC from the AC, plus the advent of generator transition, a 4400 HP DC locomotive has no motor transition nor field shunting.


Since the manual refers to three connections,

These would be:

series = four motors in series
series parallel = two groups of two motors in series
parallel = all four motors in parallel (each taking full voltage)

These are "series-wound" motors, so all the armature current also passes through the field windings, generating a magnetic field (sometimes called "flux"). The motor speed is dependent on the voltage and the magnetic field. You can go faster by making the voltage higher, or the magnetic field smaller. The "resistance" of the motor to the current is the "back EMF" generated by the magnetic field. So when you can't raise the voltage to increase the speed, you can reduce the magnetic field by providing a "shunt" or diversion, that allows part of the current to bypass the field windings (and not generate "Back EMF") but still flow through the armature.

The field shunting or diversion, can be applied independent of the actual connection of the motors in series or parallel, but this will be determined by the control system which makes the connections.

It might actually be more complicated than it sounds.

I understand early U boats also had sixteen throttle notches, too, but only eight were used if in multiple with an Alco or EMD!

Peter
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Posted by M636C on Thursday, December 2, 2004 4:23 PM
QUOTE: Originally posted by Randy Stahl

QUOTE: Originally posted by oltmannd

Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

That will work !!!!
Randy


But not if it is supplying HEP power to a passenger train, as outlined in my comments above, because the engine will be running at a constant 900 rpm even at idle, and will have a load of a couple of hundred kW on top of any "locomotive" functions.

Peter
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Posted by Willy2 on Thursday, December 2, 2004 3:46 PM
Congratulations on four stars! [tup]

Willy

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Posted by Randy Stahl on Thursday, December 2, 2004 2:20 PM
QUOTE: Originally posted by oltmannd

Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

That will work !!!!
Randy
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Posted by oltmannd on Thursday, December 2, 2004 2:15 PM
Randy-

You want the burn rate by notch? Should be almost exactly that of a GP40-2 in freight mode, which I can get you, if that's what you need....

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by Randy Stahl on Thursday, December 2, 2004 12:29 PM
OK... This ones for real ! Can anyone provide me with a formula or method for calculating fuel usage on an EMD F-40
Randy
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Posted by oltmannd on Thursday, December 2, 2004 11:04 AM
QUOTE: Originally posted by jockellis

I used to rent an apartment from a retired road foreman of engines in Waycross, GA who had kept the owners manual from a U-25 he had once operated. I hope you can help me but it said something about the electric motor running in different modes and in my memory they were series, series shunt, series-parallel and parallel shunt (or something like that) . Could you refresh my memory and tell me what all that mumbo jumbo means?
Jock Ellis


It's the way GE kept the locomotive's performance on the 2500 HP curve throughout it's speed range. They had to do it because of current and voltage limitations of the main generator and traction motors.

In parallel, all 4 traction motors are connected to the main generator in parallel. As you go slower, the voltage goes down and the current goes up. Soon, it is too high for the main generator, so you reconnect the motors. You connect each pair of motors in series and then the two series pair in parallel to the main generator. This doubles the voltage but halves the current from straight parallel.

The shunting comes into play at the high voltage/high speed end. You weaken the field by shunting some of the field windings in the traction motor so that the voltage goes down and the current goes up a bit. This allows the locomotive to continue to produce full HP at high speeds.

Now, with traction alternators instead of generators and good, high voltage diodes to make DC from the AC, plus the advent of generator transition, a 4400 HP DC locomotive has no motor transition nor field shunting.

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by oltmannd on Thursday, December 2, 2004 10:47 AM



....that's two questions.....

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Posted by jockellis on Thursday, December 2, 2004 8:38 AM
I used to rent an apartment from a retired road foreman of engines in Waycross, GA who had kept the owners manual from a U-25 he had once operated. I hope you can help me but it said something about the electric motor running in different modes and in my memory they were series, series shunt, series-parallel and parallel shunt (or something like that) . Could you refresh my memory and tell me what all that mumbo jumbo means?
Jock Ellis

Jock Ellis Cumming, GA US of A Georgia Association of Railroad Passengers

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Posted by M636C on Wednesday, December 1, 2004 9:30 PM
QUOTE: Originally posted by AlcoRS11Nut

Nice on the 4th star....but here is my question.....what is the diameter of a piston (or cylinder) of a EMD H-series prime-mover? The reason I asked this odd question is that my cousin and I were talking the other day and he said that it was a foot across. I don't know that just seems kinda large to me, even the H series. Is he right or it is bigger/smaller?


This is one of the really easy ones!

EMD changed their method of engine classification, because (I think) the new H engine was more than 1000 cubic inches per cylinder, and would require a four digit number rather than a three digit number. So the decision was made to describe four stroke engines by their diameter in millimetres, in the H engine case it is "265H", about 10.43 inches. The engine STROKE is close to one foot, however. The small four stroke engine built by Caterpillar is described as a "GM170" when fitted in a GP15D, for example. While on the subject of Cat, their next size engine, the 3600, used in the now modified MK5000, was 270mm cylinder diameter. So you had a step of 100mm cylinder diameter between engine models! The MK5000 units now use EMD 645F engines.

Peter
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Posted by AlcoRS11Nut on Wednesday, December 1, 2004 8:15 PM
Nice on the 4th star....but here is my question.....what is the diameter of a piston (or cylinder) of a EMD H-series prime-mover? The reason I asked this odd question is that my cousin and I were talking the other day and he said that it was a foot across. I don't know that just seems kinda large to me, even the H series. Is he right or it is bigger/smaller?
I love the smell of ALCo smoke in the Morning. "Long live the 251!!!" I miss the GBW and my favorite uncle is Uncle Pete. Uncle Pete eats Space Noodles for breakfast.
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Posted by M636C on Wednesday, December 1, 2004 5:10 PM
QUOTE: Originally posted by Paul Milenkovic

Gee, with all the good-natured ribbing going on, I hope I am not ruled out of order for getting serious.

The F40Ps had their Diesel going a mile a minute to provide HEP (Hotel Electric Power I am told is correct -- they also have HEP on a cruise ship). I understand that none of the GE Genesis units, the DC P40 and P42s as well as the AC P32ACs have their main Diesel reved up like this, but none have a separate HEP Diesel. I read that the P32ACs use a variant of a "traction inverter" (i.e. a whole lot of electronics) to generate the HEP from the variable-speed main Diesel.

Question 1: what is the HEP scheme on the DC Genesis (P40/P42) -- they don't have the fancy traction inverter electronics?

Question 2: what is the fuel penalty for running the Diesel at full RPM and at part load? I saw a Web site that a Diesel at low-speed idle uses very little fuel compared to full throttle. What percent of full throttle fuel usage do you have when the Diesel is going full tilt but you are drawing very little load?


Paul,

No, it's my thread and I volunteered to answer questions!

In fact, the P40 and P42 use the same technology as the P32AC to convert the HEP power to constant frequency AC. The process is that the variable frequency (dependent on engine speed and hence throttle notch) power is converted to DC in a rectifier and then converted further to constant frequency AC in an inverter, generally called a "static frequency converter". In the P40 and P42, the converter can only produce 60Hz three phase power for the HEP supply. In the P32AC there are five identical converters that take all the locomotive power, and four of them produce variable frequency, variable voltage three phase AC to drive the traction motors and the fifth produces only the 60Hz HEP power. Since the five are identical, it doesn't matter which one produces HEP, so if one converter fails, the P32AC can run on three motors and still provide HEP power to the train. The equipment in the P40/P42 is simpler because it doesn't have to be able to produce the varying frequency required to drive the traction motors at different speeds.

I'm sorry, I don't know the fuel penalty for running the 645E3 at 900rpm continuously at low power. Strangely enough I can give you the figures for the GE LM2500 marine gas turbine at 3600rpm (but I won't because it is quite different physics involved). Running diesel engines at high speed and low power is bad for them. One of the stupid features of the M636 was the use of the main blower to cool the dynamic brakes, rather than the braking current driven fans on most EMD, GE (and yes most Alco) designs. The M636 had to be run in notch 8 when in dynamics, and the same engines deteriorated faster than they did in the C636. So the F40PH wore its own engine out more quickly, hence the Amtrak F40PHs wearing out faster than, say the Conrail, ex PC, ex NYC GP40s that seem to have been around forever. While the engine is running at 900 rpm in the F40PH, the small amount of fuel being used probably doesn't give the EMD turbo enough exhaust to run free, so you are driving the big centrifugal blower at full speed from the engine, and there is a lot of power used there, and since this is being driven, the turbocharger related fuel economy increase won't occur during "HEP Only" operation.
Somewhere in the back of my mind is a statement, probably from the MBTA, that the F40PH used 30% more fuel than their "FP10" units on the same duty. Certainly, MBTA bought the first F40PH units with separate HEP generator diesel engines, and have had MPI rebuild their "standard" F40PH units with separate HEP.

Peter
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Posted by M636C on Wednesday, December 1, 2004 4:33 PM
QUOTE: Originally posted by Mookie

Peter: Here is a toughie. M636C?

Mook


About thirty years ago, I was working for the Mt Newman Mining Company, initially in Perth, Western Australia and later in Port Hedland much further north in the same state. They had just taken delivery of the last M636 which they insisted be fitted with Alco Hi Ad trucks, rather than the MLW Dofasco design that came as standard. The MLW Dofasco is a good truck, but it was designed to reduce curve forces in sharp curves and to reduce track stresses. Mt Newman felt that since they had a seven year old railroad with no sharp curves all laid with 136lb rail, they'd stick with the Hi Ad. These units were numbers 5469 to 5495. Later the builder refused to build any more units with Hi Ads, so, reluctantly they bought 5496 to 5505 with MLW Dofasco trucks. So we had to think of a way of telling the locomotives apart. A friend pointed out that MLW built C630s with MLW Dofasco trucks were called C630M, so our units with Hi Ads had to be M636C. (Montreal design with Century series trucks). They have all gone now, but all but one (5495) were rebuilt from the frame up as GE Dash 8s (keeping the Alco Hi Ad trucks). All the MLW Dofasco fitted units were scrapped or donated for preservation.

Peter

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