GE chugging
Prime Mover Software Development
GE's chugging have long been a part of my railroad memories. I grew up on the
Erie Lackawanna Boonton Line, and their freight U33C/U36C's were fairly
common. But even better were their U34CH commuter units - their HEP generators
were run off the prime mover; hence, they were always running at the
equivalent of Run 6 - so you can imagine the sound as they accelerated from a
stop! WOW! Today's Susquehanna's DASH 8-40B's still have that familiar GE
chug, though I think GE's figured out how to quiet 'em down - you can only
hear the Suskie's units when they notch out climbing up Sparta Mountain or on
the grade out of Butler. The spirit is still there.
As for explanations... GE's and Alcos share a common trait: four-cycle
engines. GM's have a two-cycle engine, which "explodes" its cylinders at a
high rate of speed. The four-cycle timing of GE's and Alcos allows a short
pause, and a deadening of sound temporarily before the next "explosion." I
think this allows the sound to reverbrate better, and makes the next
"explosion" seem more loud; hence, the "stalk-chopper" sound.
Another neat sound I enjoy are turbocharged EMD's - especially the 50/60
series. Their turbochargers are slightly more melodic, but they all have that
neat high-pitched humming...
- Paul Tupaczewski
Stevens Tech
Hoboken, NJ
u93_pt...@vaxa.stevens-tech.edu
Evan L. Werkema
In a previous article, U93_PT...@VAXC.STEVENS-TECH.EDU (Prime Mover Software Development) says:
>Ah, yes, a favorite topic of mine...
>
>GE's chugging have long been a part of my railroad memories. I grew up on the
>Erie Lackawanna Boonton Line, and their freight U33C/U36C's were fairly
>common. But even better were their U34CH commuter units - their HEP generators
>were run off the prime mover; hence, they were always running at the
>equivalent of Run 6 - so you can imagine the sound as they accelerated from a
>stop! WOW! Today's Susquehanna's DASH 8-40B's still have that familiar GE
>chug, though I think GE's figured out how to quiet 'em down - you can only
>hear the Suskie's units when they notch out climbing up Sparta Mountain or on
>the grade out of Butler. The spirit is still there.
GE came up with an exhaust silencer in 1980 to comply with EPA regulations.
The "fat" stack on late Dash-7's and Dash-8's is a result. They are much
quieter than the old stacks...I was surprised to hear how loud a old U36C was
compared to a C30-7. Amtrak's DASH 8-32BWH's draw HEP off the main generators
too, but they're still fairly quiet beasts, and FAR quieter than an F40PH.
>As for explanations... GE's and Alcos share a common trait: four-cycle
>engines.
They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
as the Alco 251. I made some recordings of GBW C424's last summer, and
was surprised at how similar they sounded to the B23-7's I got on the ATSF.
>GM's have a two-cycle engine, which "explodes" its cylinders at a
>high rate of speed. The four-cycle timing of GE's and Alcos allows a short
>pause, and a deadening of sound temporarily before the next "explosion." I
>think this allows the sound to reverbrate better, and makes the next
>"explosion" seem more loud; hence, the "stalk-chopper" sound.
We liked to call them "cabbage cutters," but now that they've muffled them,
the discriptor isn't quite so apt.
>Another neat sound I enjoy are turbocharged EMD's - especially the 50/60
>series. Their turbochargers are slightly more melodic, but they all have that
>neat high-pitched humming...
I haven't noticed it on any other engine, but DASH 8-40B's seem to have
a charasteristic whine they emit under load. It makes them easy to pick out
in recordings.
--
-----_._._,_,,_,__._._ _._.__,_,,_,_._._----
_Ioo I === ====I I==== === IooI____ I~~~~~~~~~~~~~~~~~~I
|_II___I____Santa Fe____I_| |_I__Evan Werkema__I__I___I_| I el...@po.cwru.edu I
`-~O==O~===========~O==O~-`~`-~O==O~=============~O==O~-`~~o==o~\/~\/~\/~o==o~
carl.a.benevit
idling. The quiet burble suddenly increases in rpm and is accompanied
by something starting up (like a big fan, increasing revs, etc.)
accompanied by a compressor like sound and a whine, which runs
for a couple of minutes and then shuts down. This may or may not
be operating when the engine is in motion. I'm not sure.
______________________________________________________________________________
Opinions and commentary are personal and not those of AT&T and subsidiaries.
______________________________________________________________________________
Carl Benevit - att!cbnewsm!cab - 215-439-7664
AT&T Bell Laboratories - 555 Union Boulevard, Allentown, PA 18103
|
...be ready... ---|--- ACTS
| 1:11
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______________________________________________________________________________
COIFMAN
am particularly interested in the mac version (does it require a color
machine or sys7) but I would like an overview of the game in general.
Thanks much
Benn
John Mosbarger
: There's another GE 40-8 "sound" that I've heard while the engine is
: idling. The quiet burble suddenly increases in rpm and is accompanied
: by something starting up (like a big fan, increasing revs, etc.)
: accompanied by a compressor like sound and a whine, which runs
: for a couple of minutes and then shuts down. This may or may not
: be operating when the engine is in motion. I'm not sure.
This is probably the humongous radiator fan starting up. UP's DASH8-
40C's in Portland seem to do it on a fairly regular basis when idling or
moving slowly with a train. Sorta sounds like Scotty just stuck the Enter-
prise into warp drive :-).
John
--
*****************************************************************************
| John Mosbarger | |
| | "One thing the world needs is popular |
| HP McMinnville, OR | government at popular prices." |
| | --George Barker |
| jo...@hpmcaa.mcm.hp.com | |
|***************************************************************************|
| Opinions are mine and mine alone. |
*****************************************************************************
Prime Mover Software Development
this all the time on the Susquehanna B40-8's) is the air compressor kicking
in. The radiator fan is usually spinning most of the time (remember, unlike
EMD's, the GE just has one BIG fan, and it's gotta keep going to keep that
4000 hp prime mover cool!). The sound is identifiably by a quick two-toned
"tweeting noise," and then a quick stammering noise for about 10 seconds. If
anyone's ever used a home air compressor, it's virtually the same sound
(albeit at a lower pitch, due to the size of this compressor). Another
annoying thing about GE's (particularly the newer ones, especially ones built
in the past year or so) is that "rat-a-tat" sound they make 90% of the time,
letting out built-up air...
GE's exhaust silencer works, but find a big grade and a big train - and it'll
bring back memories!
J. T. Thorpe
Hello again, folks!
I don't have any information about the Mac version of A-Train, but I
certainly have had fun with the IBM version! The overall goal of the
game is clear--build a working *profitable* rail line for a city. There
are 6 scenarios to choose from, ranging from using your power as a
railroad builder and investor to build a small rural town into a
metropolis, to starting out with a big city that is running its rail
line at a loss.
The graphics look fairly nice, and are still simple enough to not
overwhelm you. Maxis/Artdink threw in a bunch of "fun" things like
Santa Claus on Dec.24, and UFOs in July. The major problem that I have
with the program is that it runs on a day-by-day basis, so it can take
a LONG time to run (you can control the speed of days, tho').
The game is a lot more complex than things like Rail Tycoon, etc.,
especially considering the "size" of the city you are working on. The
majority of your rail revenue comes from your passenger load, but a lot
of your major revenue comes from your investments, rents, and other
real estate revenues.
Your railroad "empire" is really more like a commuter line than a
railroad. You have a limited amount of real estate to work with.
Building your rail lines is costly, as is building real estate. You can
invest in the stock market (Note: the market skyrockets every 1.5 - 2
years and then crashes--hey, even the manual tells you this). It is a
bit difficult to figure out what will help you generate a profit, esp.
since initial railroad startup costs are HUGE! Hint: for quick cash,
play around with real estate, and don't invest in leisure estate
property until you have a sufficient population base.
I have been semi-successful with the program. I have managed to get the
commuter lines alone to generate over $170,000 per month, and I get even
more with the real estate revenues. My friend around the hall goes the
real-estate route and generates the majority of his revenue that way.
If you want more specific information, just ask!
JTThorpe
--
JT Thorpe __________________ ===+==___()__o_][ c
Clemson |[][][] |[]| | _/-----| |=|=| | | ]}
University [_|_______|__|_|_]|_______|=|___|-----------___
CS Dept oVo oVo oVo oVo (o) (o) (o) oo \\
Bill Gripp
>
>In a previous article, U93_PT...@VAXC.STEVENS-TECH.EDU (Prime Mover Software Development) says:
>
>>GE's chugging have long been a part of my railroad memories. I grew up on the
>>Erie Lackawanna Boonton Line, and their freight U33C/U36C's were fairly
>>common. But even better were their U34CH commuter units - their HEP generators
>>were run off the prime mover; hence, they were always running at the
>>equivalent of Run 6 - so you can imagine the sound as they accelerated from a
>>stop! WOW! Today's Susquehanna's DASH 8-40B's still have that familiar GE
>>chug, though I think GE's figured out how to quiet 'em down - you can only
>>hear the Suskie's units when they notch out climbing up Sparta Mountain or on
>>the grade out of Butler. The spirit is still there.
What is really dramatic is to find a U34CH which needs a tune up. Catch
one of those accelerating from a station stop and not only do you get
that chug, but black smoke that almost rivals the best Alcos!
> They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
>as the Alco 251. I made some recordings of GBW C424's last summer, and
>was surprised at how similar they sounded to the B23-7's I got on the ATSF.
Speaking of Alco, ever notice how the older ones idle just above
"stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
You'd swear they would stall at any moment. But they never did, they
just kept on.
Prime Mover Software Development
Prime Mover Software Development
>What is really dramatic is to find a U34CH which needs a tune up. Catch
>one of those accelerating from a station stop and not only do you get
>that chug, but black smoke that almost rivals the best Alcos!
Nowadays, this is pretty much every one of them! I've noticed when I go home
and look at these beasts leaving town that accompanying the stalk-chopper
sound is a nice little amount of flame/sparks out the stack (!), bright orange
shooting out about a foot. This always surprised the hell out of me.
Unfortunately, their lives are not much longer... I've alreay seen a couple of
them cannibalized, as well as spare C trucks on flat cars at the MMC...
>Speaking of Alco, ever notice how the older ones idle just above
>"stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
>You'd swear they would stall at any moment. But they never did, they
>just kept on.
Yeah, the Morristown & Erie Centuries do that too! It sound like they're
revving up, then slowly die down almost until they stop, then magically, rev
up again! I'll have to ask my brother the mechanic about that one!
Evan L. Werkema
In a previous article, bi...@bony1.bony.com (Bill Gripp) says:
>In article <1ea25l...@usenet.INS.CWRU.Edu> el...@po.CWRU.Edu (Evan L. Werkema) writes:
>> They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
>>as the Alco 251. I made some recordings of GBW C424's last summer, and
>>was surprised at how similar they sounded to the B23-7's I got on the ATSF.
>
>Speaking of Alco, ever notice how the older ones idle just above
>"stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
>You'd swear they would stall at any moment. But they never did, they
>just kept on.
CVL's RS3 4099 seemed pretty stable when I heard it, but 539-engined Alcos
another story. There's a recording on the record _First Generation Diesels
Volume II_ of C&NW RS1 1069 in which the engine really does stall, twice!
And this was while it was being used! The crew would throttle it up, and when
they notched it back down to idle, the governor wouldn't pick up in time and
the engine would stall. I don't know where the isolation switch is on an RS1,
but if it's back in the engine room like an EMD, I can imagine restarting the
engine might get a little tedious after a while. I'd guess after about three
incidents like this the engineer probably cried, "Screw it! Get me a geep!"
737...@gw.wmich.edu
>
> In a previous article, bi...@bony1.bony.com (Bill Gripp) says:
>>In article <1ea25l...@usenet.INS.CWRU.Edu> el...@po.CWRU.Edu (Evan L. Werkema) writes:
>>>In a previous article, U93_PT...@VAXC.STEVENS-TECH.EDU (Prime Mover Software Development) says:
>
>>> They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
>>>as the Alco 251. I made some recordings of GBW C424's last summer, and
>>>was surprised at how similar they sounded to the B23-7's I got on the ATSF.
Yea, the Alco 251B is particularly loud. The other day, I was watching a CP
Rail runthrough to Chicago over CSX, and it had an MLW C424 and an MLW RS18
and boy was that RS18 chugging along, a lot louder than that C424, of course
the RS18 is 6-8 years older, but it was rebuilt for yard use sometime in
the 80's. The 424 might have been rebuilt too, I'm not sure.
But hearing both of them together is quite neat.
I also heard an all MLW consist one night pulling a heavy train up about a
1% grade. It had 3 M636's on it, probably the best train I've ever heard!
Now where's that tape recorder when you need it ;^)
Fred
Atrw93
>
>
> > They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
> >as the Alco 251. I made some recordings of GBW C424's last summer, and
> >was surprised at how similar they sounded to the B23-7's I got on the ATSF.
>
> Speaking of Alco, ever notice how the older ones idle just above
> "stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
> You'd swear they would stall at any moment. But they never did, they
> just kept on.
Don't overlook the fact that the Alcos, 539, 244, & 251 as well as
all of the GE engines are four cycle engines (like most cars)
and that EMD stuck with the two cycle concept (like your B&S
lawn mower engine). The near stall sound on the Alcos was due to the
GE electric governor cycling.
-------------------------------------------------------------------------
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ATRW 93 <atrw0176>
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| gvls1!tredysvr!cellar!atrw0176
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737...@gw.wmich.edu
> bi...@bony1.bony.com (Bill Gripp) writes:
>>
>>
>> > They share more than that...GE's FDL-16 has the same bore, stroke, and RPM
>> >as the Alco 251. I made some recordings of GBW C424's last summer, and
>> >was surprised at how similar they sounded to the B23-7's I got on the ATSF.
>>
>> Speaking of Alco, ever notice how the older ones idle just above
>> "stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
>> You'd swear they would stall at any moment. But they never did, they
>> just kept on.
>
> Don't overlook the fact that the Alcos, 539, 244, & 251 as well as
> all of the GE engines are four cycle engines (like most cars)
> and that EMD stuck with the two cycle concept (like your B&S
> lawn mower engine). The near stall sound on the Alcos was due to the
> GE electric governor cycling.
>
Lawn boy's, most chainsaws and weed-wackers (gas powered) are 2 cycle
I love nitpicking ;^)
Fred
George Robbins
>
> >Speaking of Alco, ever notice how the older ones idle just above
> >"stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
> >You'd swear they would stall at any moment. But they never did, they
> >just kept on.
>
> Yeah, the Morristown & Erie Centuries do that too! It sound like they're
> revving up, then slowly die down almost until they stop, then magically, rev
> up again! I'll have to ask my brother the mechanic about that one!
Sounds like a governer that needs cleaning or adjustment. As far as about
to stall, I'd imaging that the generator makes a pretty effective flywheel...
--
George Robbins - now working for, work: to be avoided at all costs...
but no way officially representing: uucp: {uunet|pyramid|rutgers}!cbmvax!grr
Commodore, Engineering Department domain: g...@cbmvax.commodore.com
khar...@fnalo.fnal.gov
(Bill Gripp) writes:
[Other text deleted]
> What is really dramatic is to find a U34CH which needs a tune up. Catch
> one of those accelerating from a station stop and not only do you get
> that chug, but black smoke that almost rivals the best Alcos!
Yeah, what about the smokey Alcos? What is the general opinion on
the cause of this excessive smoke? A railfan friend of mine mentioned that the
turbocharger was poorly designed.
How do the roads that still operate Alcos manage to avoid fines for
air pollution?
Apologies if this topic has been beaten to death in the past, I'm
new to your group. Thanks for the information!
Ken
Anthony Edward Prattico
> Yeah, what about the smokey Alcos? What is the general opinion on
>the cause of this excessive smoke? A railfan friend of mine mentioned that
>the turbocharger was poorly designed.
I remember reading once that the smoke was caused by turbocharger lab. Basic-
ally, the fuel was dumped into the engine but the air was slower in coming, so
the fuel burned very poorly, emitting lots of neat black smoke. Sort of an
afterburner effect.
I have no proof of this, but it makes sense to me.
> How do the roads that still operate Alcos manage to avoid fines for
>air pollution?
Very powerful lobbying group? Actually, there are several exceptions to the
emissions laws. For example, NYS's new automobile emissions law states that
you must make repairs to your car if the emissions are too high, unless the
cost to do so is excessive (ie, greater than $400). Then you aren't required
to do anything. Also, antique cars and steam engines are exempt as well. So
the railroads have probably found a way around the laws.
> Apologies if this topic has been beaten to death in the past, I'm
>new to your group. Thanks for the information!
No problem. There are always going to be new people, and it doesn't matter what
you ask, as long as when someone asks it in the future you'll be able to answer
it for them. After all, someone has to keep the group going after the present
contributors leave.
> Ken
-------------------------------------------------------------------------------
Anthony Prattico pra...@rpi.edu
-------------------------------------------------------------------------------
All opinions are mine and mine alone.
-------------------------------------------------------------------------------
"Wherever you go, there you are" - from that hit movie, "The Adventures of
Buckaroo Bonzai"
-------------------------------------------------------------------------------
Kershner Wyatt
>bi...@bony1.bony.com (Bill Gripp) writes:
>all of the GE engines are four cycle engines (like most cars)
>and that EMD stuck with the two cycle concept (like your B&S
>lawn mower engine). The near stall sound on the Alcos was due to the
Sorry, Briggs and Stratton are 4 cycles. Lawn Boy/Toro (some models) are
2 cycle, as are most leaf blowers, chain saws, and outboards. Not to mention
the SAAB popcorn machine.
Nit pick, nit pick.
BTW, a lot of diesel trucks also tend to idle down then
back up. I've heard every reason from keeping the turbocharger spinning, to
avoiding overheating, to keeping the engine running in the max torque band,
and providing fuel economy at the same time.
--
Kershner Wyatt
kwy...@ccscola.ColumbiaSC.ncr.com
My opinions are my own and aren't necessarily my employer's.
Bill Smith
bi...@bony1.bony.com
> (Bill Gripp) writes:
> [Other text deleted]
> > What is really dramatic is to find a U34CH which needs a tune up.
Catch
> > one of those accelerating from a station stop and not only do you
get
> > that chug, but black smoke that almost rivals the best Alcos!
>
>
>
> Yeah, what about the smokey Alcos? What is the general
opinion on
I think it was indeed turbo design. Anyway, you should have
seen the good old C855's. Talk about Mt. St. Helens.
On the maiden voyage of the things out of Omaha when they
finally reached transition, there was a tremendous explosion
in all three of them. The Alco engineers had wired the
transistion circuitry across the cabinets instead of the
traction motors. Scared the crew to death! UP never
trusted them to be main power again. Too bad. They
were really ugly-pretty!
-Bill
--
Professor William V. Smith
Phone: 1-801-378-2061 Fax: 1 801 378 2800
email: smi...@hamblin.math.byu.edu or
uunet!hamblin.math.byu.edu!smithw
NeXTmail: bi...@mathnx.math.byu.edu
SMail: Math Dept. -- 314 TMCB; BYU; Provo, UT 84602 (USA)
Evan L. Werkema
In a previous article, khar...@fnalo.fnal.gov () says:
> Yeah, what about the smokey Alcos? What is the general opinion on
>the cause of this excessive smoke? A railfan friend of mine mentioned that the
>turbocharger was poorly designed.
Either that or the turbo was too small. When ATSF was test driving the
first PA1's, the test report came back favorable in all catagories as compared
to the F3's with the exception of "objectionable smoking at the stack, possibly
due to the turbocharger being undersized." (paraphrased) Guess Alco never
learned their lesson though, as the 251's were just as smokey as the 244's
> How do the roads that still operate Alcos manage to avoid fines for
>air pollution?
In fact, that was one reason for the final demise of ATSF's HH1000's
operating in the LA area in the 1970's. They were getting old, and, according
to Ex2200, "City officials were starting to make noises about air pollution
(who could argue with that?)"
I guess in many places where Alco's yet roam, it's rural enough (thinking
of the GBW, Indiana Hi-Rail, and Arkansas & Missouri) that air pollution
restrictions aren't too tough.
john.a.welsh
> In article <1992Nov18.1...@bony1.bony.com>, bi...@bony1.bony.com
> (Bill Gripp) writes:
>
>
> [Other text deleted]
>
>
> > What is really dramatic is to find a U34CH which needs a tune up. Catch
> > one of those accelerating from a station stop and not only do you get
> > that chug, but black smoke that almost rivals the best Alcos!
My favorite place to see them is Denville, though any station on the
Boonton line will do. If the train departs up hill and you are track
side at night, you will also probably see a flame at the stack.
> Yeah, what about the smokey Alcos? What is the general opinion on
> the cause of this excessive smoke? A railfan friend of mine mentioned that the
> turbocharger was poorly designed.
Alcos, at least the earlier ones, had belt driven turbochargers. Smoke
is caused by what is known as turbocharger lag, and this belt seemed to
enhance the effect. This lag is actually the time that is takes to get
the extra compressed air into the cylinder. When the throttle is opened
an increased amount of fuel is shot in through the fuel injectors. This
happens more quickly than the turbocharger can supply air. You then get
unburned hydrocarbons blown up the stack (translation: smoke). This lag
seems to be more prominent in 4-stroke engines. The only 2-stroke locomotive
engines are the EMDs. I believe the word for blowing the exhaust out
and getting a clean air-fuel mixture ready for ignition is scavenging.
EMD engines, by virtue of being 2-stroke and using a Roots Blower (a
direct connected supercharger), scavenge more quickly than their 4-stroke
competitors (GE, Alco, Baldwin, Lima, etc.). I believe they use Roots
Blowers on turbo and non-turbo models. Notice though, that well
maintained Alcos and GEs run as cleanly as EMDs when at speed.
> How do the roads that still operate Alcos manage to avoid fines for
> air pollution?
Currently, Alcos are not put to the test like they were, so these engines
are not causing pollution problems. It is weird to think that Alco PAs
were at one time a greater pollution problem than steam engines. This was
caused by the belt driven turbocharger. The SP ran GS class Daylight
4-8-4s instead of PAs on some trains because the oil-fired steamers could
start out of one city more cleanly than the PAs. To solve this, the SP
bought EMD cabs and killed steam.
Dennis H Lippert
>In article <1992Nov22...@fnalo.fnal.gov>, khar...@fnalo.fnal.gov writes:
>Alcos, at least the earlier ones, had belt driven turbochargers. Smoke
>is caused by what is known as turbocharger lag, and this belt seemed to
>enhance the effect. This lag is actually the time that is takes to get
>the extra compressed air into the cylinder. When the throttle is opened
>an increased amount of fuel is shot in through the fuel injectors. This
>happens more quickly than the turbocharger can supply air. You then get
>unburned hydrocarbons blown up the stack (translation: smoke). This lag
>seems to be more prominent in 4-stroke engines. The only 2-stroke locomotive
>engines are the EMDs. I believe the word for blowing the exhaust out
>and getting a clean air-fuel mixture ready for ignition is scavenging.
>EMD engines, by virtue of being 2-stroke and using a Roots Blower (a
>direct connected supercharger), scavenge more quickly than their 4-stroke
>competitors (GE, Alco, Baldwin, Lima, etc.). I believe they use Roots
>Blowers on turbo and non-turbo models. Notice though, that well
>maintained Alcos and GEs run as cleanly as EMDs when at speed.
This needs to be cleared up...
Early EMD locos (and some late... aka GP15, GP38) used a roots gear-driven
supercharger. This kind of supercharger makes boost (puts more air in)
almost instantaneously.
Alcos, GE's, and most modern EMD's use exhaust-driven turbochargers to
compress the intake air. This allows a larger compressor, so more air
is pumped in. However, the turbocharger is driven by a turbine fan in
the exhaust line, and therefore has a "lag" before it spins up to speed.
It is this lag that causes GE's and Alcos to smoke. How EMD keeps their
turbos from smoking is unknown to me! Unless it has something to do with
the 2-stroke engine...
Which brings us to topic #2 - 2-stroke (EMD) vs. 4-stroke (everyone else).
A four-stroke engine is like the one in your car (unless it's a 1970-vintage
Saab, but I digress). In order to describe a four-stroke engine, we'll
look at one "compression cycle". We will start with the piston at the
bottom of the stroke, just after the fuel has exploded. On the piston's
first up-stroke, it pushes the exhaust gas out of the cylinder. The intake
valves open for the down stroke, and air/fuel is pulled into the cylinder.
The piston then starts it's second upstroke, known as the compression
stroke, which compresses the air/fuel so that it explodes nicely. At
(approximately) the top of the stroke, the fuel explodes (in a diesel
it's because of the compression heat, in a gas engine, the sparkplug fires)
and the piston starts the Power stroke. This is where the power is
generated. Notice the up-down-up-down in a cycle... hence FOUR-strokes.
A two-stroke engine does all the same stuff in only two strokes. The
procedure is as follows (starting at the bottom of a power stroke again).
The piston moves up, is simultaneously pushes the exhaust gas out of the
cylinder, and pulls the intake air into the cylinder from below. This is
the "scavenging" mentioned above. When the piston gets to the top (again,
approximately), the fuel is injected in, and the explosion occurs, pushing
the piston down in the power stroke. A simple up-down for a cycle...
or TWO-strokes.
As an example of the fact that superchargers "spool up" faster, witness that
there are few/no turbocharged Drag Race cars. I hope that this will clear
things up a bit. I hope that my three years in the school of engineering
taught me something useful!!
>> How do the roads that still operate Alcos manage to avoid fines for
>> air pollution?
I don't know about your "neck of the woods", but I know of no regulations
on diesel exhaust here in PA. Automobiles are emmissions-inspected unless
they are "diesel-exempt", and there are some NASTY diesel trucks out there.
Besides... most (99%) Alcos were retired years ago... in the 70's.
-Den
--
===============================================================================
Dennis Lippert - mac...@pitt.edu or mac...@vm2.cis.pitt.edu
The "Mac Maniac" operator at the Hillman Research Lab - Univ. of Pittsburgh
"All comments are mine, you'd look like a fool if *you* used them"
Lewis E. Wolfgang
>Alcos, at least the earlier ones, had belt driven turbochargers. Smoke
^^^^ ^^^^^
Is this an oxymoron or is there something I don't know?
>I believe they use Roots Blowers on turbo and non-turbo models.
Would they have a clutch on the gear-driven Roots Blower to cut it out
when the turbocharger takes over? I have heard of 2-cycle marine engines
doing this to increase economy.
Lewie
wolf...@nosc.mil
Robert MacDowell
Paul Tupaczewski started quite a conversation by saying:
>The primary reason most Alcos smoke is due to the design of their
>turbochargers. They work correctly, for the most part; however, a design flaw
>in them...
Many people have replied, and as a diesel technology "expert", I
thought I'd add this to the flurry of information...
The usual reason for smoke in a diesel is that fuel is not being
burned completely... bad fuel, injectors not atomizing it well. But
the *big* reason (especially re: turbo lag) is that the governor is
injecting too much fuel; i.e. the engine has more fuel than air and
can't burn it all. So it goes out the stack as particulate smoke.
We're getting some mis-information as we deal with three dramatically
different technologies. The four-cycle engines work about the same but
there are two dramatically different approaches in the EMD engines.
A turbocharger on a four-cycle engine (EMD, Alco) always uses a
turbine driven by exhaust gases (back pressure) to spin a rotary
turbocompressor, which stuffs more air into the engine's intake than
it would normally inhale by itself. The reason these smoke at
throttle-up, is turbo lag. The governor has moved the fuel racks wide
open, but the turbo, being a free-wheeling rotary device, hasn't
accellerated to the new speed yet. It's not pumping air as fast as it
will when it speeds up, so for that moment while it accellerates, the
engine is air-starved. Too much fuel, not enough air, smoke.
Although when Alcos do it all the time... cheap fuel or the fuel
racks are set wrong, on at least a few cylinders.
Two-cycle engines work very differently. They don't have the extra two
cycles to pump exhaust out and air in, so they must be force-fed air
all the time. The engine won't run without it. A chain saw or
Fairmont motor car does this by using the back side of the cylinder
(the crankcase) as a little compressor, thus the need to put oil in
the gas, to lube the crankshaft bearings. That doesn't work as well
with 16 cylinders :-) so an EMD or Fairbanks-Morse uses an external
device of one of two types.
The "Normally Aspirated" (non-turbo) EMD's (7,9,15,38,most switchers)
and all Fairbanks-Morse engines use a Roots blower that is gear-driven
off the engine. A Roots blower is a mechanical, high volume, low
pressure compressor that just basically shoves a bunch of air into the
EMD's intake ports. It spins all the time and in syncopation with the
engine: no turbo lag, no smoke.
Turbocharged EMD's (30,35,40,45,15T,50,60,70) are something else.
They do *not* have a Roots blower at all. They have one device: a
special design of turbocharger. Adding a standard turbocharger to an
EMD just won't work... the turbo won't pump air until the engine's
working hard, and since EMD's need pumped-in air even to start, how do
you start the engine?
EMD's solution was an over-running clutch on the turbo. The EMD turbo
has an exhaust-driven turbine, but it's *also* got a gear drive to the
engine, which keeps the turbocompressor spinning when there's not
enough exhaust to do the job. The over-running clutch will let go
once the engine is at high load and exhaust gases can keep it running.
So when you start an EMD engine, the turbo spins, driven by the
crankshaft. Likewise when you idle or use low throttle positions. At
this point there's no advantage to the turbocharger- it's just a
high-maintenance direct-drive radial blower that's dragging along a
useless exhaust turbine.
But when you open up to Run 8 for the attack on Donner Pass, the
turbine has enough exhaust pressure to take over from the direct-drive
clutch, and the thing becomes a "true" turbocharger, with strong
performance improvements. That is the point at which a GP-40 gains
1000 horsepower over a GP-38. This is also the point that
you'd get any "turbo lag" smoke from an EMD.
I have an interesting text called "Facts and Fables of Diesel
Locomotives" which was written by E.M.D. in the Forties and is, uh,
quite "enlightening" :-) about diesel technology. Though fifty years
old, most of it applies today. It's about 200-300 lines, so I'll post
it if requested... (having just flamed someone for posting a GIF, I'd
better be careful :-)
Well good night...
--Bob MacDowell
"You know, I really never doubted myself for a minute,
and I think that's a key to success in general."
-Deborah Gibson
P.S. Jerry, re: GIF: you hit it right on the head with "One test is
worth 1000 expert opinions." You were correct in trying it given the
requests made, it was the only way to learn what the media was capable
of. (i.e. what rec.railroad could handle). I hope you didn't get
burned too badly by the flames, mine included... :-)
Craig Dewick
>>Speaking of Alco, ever notice how the older ones idle just above
>>"stall"? I remember listening to CNJ RS3's and NYS&W RS1's idling.
>>You'd swear they would stall at any moment. But they never did, they
>>just kept on.
>Yeah, the Morristown & Erie Centuries do that too! It sound like they're
>revving up, then slowly die down almost until they stop, then magically, rev
>up again! I'll have to ask my brother the mechanic about that one!
This is an easy one! It's because of the governor. We've got a fleet of
DL-500 'World Model' Alcos based on the 251 engine, ordered in two lots.
The first series all have GE governors, which are renowned for 'hunting'
in idle. I've never figured out why, but when I'm driving them it takes
a while to remember that they're not sick when they do this!
I think it is something to do with hysteresis in one of the spring
mechanisms inside the governor. The later Woodward governors don't have
this 'feature', so they don't sound so unique.
--
Craig Dewick | - Railway Preservation Industries -
Send email to: | Supporting the Preservation
cr...@kralizec.zeta.org.au | of Australia's Railway Heritage