Me again!

[Mookie]

Without raising too much fur and dust - just a comment and a question.

"Hear" SD70's and Dash 9's a lot. "Heard" a Dash 9 - 5734 - coming 3 blocks away before it was in front of me. What makes them so much more "noisy" than the SD70's.

Even around a corner, I can tell the difference, since the 9's are always so much louder, while the 70's just do a low rumble. Is it a difference in engines, set up, sheet metal or what?

Mookie

[Noah Hofrichter]

Just guessing, but would there be some reason that the Dash 9's would have to be in a higher notch or something, do they get less pulling power than an SD70?

Noah

[AlcoRS11Nut]

I know what you mean, however, instead of Dash 9's there is AC4400CW's, and instead of SD70M, there are SD9043AC's where I live. I would say it is the engines (personal guess), I can definately tell if the inbound coal train has a GE[:(!] or a EMD [:D] on the point. One time (in March) a coal train came into town severly over powered! Yes, over-powered, there were 2 AC4400CW's (UP and ex SP), and 3 SD70M's, and 1 SD60M!!!!!!! I took lots of pictures, because I hardly ever see UP useing DC traction motor equiped locomotives on coal trains. What buges me is that I can't not come up with a reason they would be on the train, other than it being a freak of nature. The city I live in is at the end of the sub-divsion and the are hardly and trackege to other side of town (basicly dead ends). The heavest train that traverses the subdivsion is the coal-train inbound to the power plant, and that normally takes 2 AC4400CW's, or 2 SD9043AC's, or a combo of both. No, idea of why six locomotives came into town, do you have any?

[Train Guy 3]

I can always tell when a GE loco is comming. You can't miss the crackling of fire. [8D]

[Randy Stahl]

Mookie,
Beginning with the 50 series EMDs were equipped with exhaust silencers, they look like a big 55 gallon drum sitting atop the turbo. You should have heard the F-40s before the silencers were installed, god it was painful when a pair would pull into the depot screaming in throttle 8.
Randy

[corwinda]

For some reason I've always found GEs sound louder close up; but the EMDs can be heard from a lot farther away. (Many miles under the right conditions when they're climbing a grade.)

[Anonymous]

I got back from my trip on Sunday afternoon. While at the farm I drove out into the hay field to take a few pics of a passing train. There was a GE as a pusher. It sounded terrible, like it was having a really hard time just keeping up with the train. I was beginning to think something was wrong with it. It looked pretty new, but still sounded like it was about to break. No wonder 99 out of 100 railroaders perfer EMD over GE. Really makes you wonder about the one who does like GE, doesn't it? [;)]

[daveklepper]

There are more and more local government organizations that hire acoustical engineers and do noise surveys and pass local restrictions on noise. To comply, railroads have had to in some cases modify operations. A good case was the UP at Lttleton, Colorado. Locomotive builders are meeting this challange by improving noise suppression technology, including mufflers or silencers. Look at the variation in noise of private automobiles, from the deliberate roar of a stock car racer to the quiet purr of a Mercedez or Cadillac or Lincoln limousine!

[mudchicken]

At Littleton, CO the issue is not noise, its vibration & energy put into the ground. The noise is secondary and it came with the issue of relocating the main tracks towards the houses to the east of the joint main line...to make room for RTD's light-rail toy trains..The location in Littleton is primarilly north and east of Jackass Hill Road (an oddly fitting name for the developers, urban planners and homebuyers who should never have located there....from 1970 till today)

[Mookie]

QUOTE: Originally posted by AlcoRS11Nut

I know what you mean, however, instead of Dash 9's there is AC4400CW's, and instead of SD70M, there are SD9043AC's where I live. I would say it is the engines (personal guess), I can definately tell if the inbound coal train has a GE[:(!] or a EMD [:D] on the point. One time (in March) a coal train came into town severly over powered! Yes, over-powered, there were 2 AC4400CW's (UP and ex SP), and 3 SD70M's, and 1 SD60M!!!!!!! I took lots of pictures, because I hardly ever see UP useing DC traction motor equiped locomotives on coal trains. What buges me is that I can't not come up with a reason they would be on the train, other than it being a freak of nature. The city I live in is at the end of the sub-divsion and the are hardly and trackege to other side of town (basicly dead ends). The heavest train that traverses the subdivsion is the coal-train inbound to the power plant, and that normally takes 2 AC4400CW's, or 2 SD9043AC's, or a combo of both. No, idea of why six locomotives came into town, do you have any?

Were they all "working" or were some just along for the ride?

Moo

[Mookie]

QUOTE: Originally posted by daveklepper

There are more and more local government organizations that hire acoustical engineers and do noise surveys and pass local restrictions on noise. To comply, railroads have had to in some cases modify operations. A good case was the UP at Lttleton, Colorado. Locomotive builders are meeting this challange by improving noise suppression technology, including mufflers or silencers. Look at the variation in noise of private automobiles, from the deliberate roar of a stock car racer to the quiet purr of a Mercedez or Cadillac or Lincoln limousine!

To further explain my thoughts - if you weren't "listening" for the trains like I do or like another train person would do, you probably wouldn't even notice that much of a noise. But when you really listen - and it was a very quiet morning - you can really hear the difference. The GE's sound a little like they are in need of shop time (like my mother's old Singer sewing maching running hard) and the EMD's have a more low rumble and are far quieter. But the EMD's don't have the distinctive "whoop" that GEs do.

Mook

[CShaveRR]

That's the difference between a four-stroke engine (GE) and a two-stroke engine (most EMDs). GEs sound like old tractors (though Pat will get a kick out of the hard-working sewing machine!), while EMDs just sound...well, powerful!

There are other differences, too...to me, GEs at speed seem to emit a screeching, almost metal-on-metal sound that I equate with the huge machines used by the evil empire in the Star Wars movies. Yet, in spite of their strange sounds, they're always more powerful, cylinder for cylinder, than the GMs. I also believe that they're more fuel efficient, despite the significant percentage of fuel that seems to go through the stack in one form or another.

The "whoop" is distinctive to GEs--it's the air compressor starting up. After the "whoop" you hear the rapid chugging of an air compressor. Again, as with the tractor, it sounds like something you'd keep in your own garage, or barn. EMD compressors are tied directly to the prime mover; you'll hear a pinging noies the keeps rhythm with the engine itself.

[zardoz]

QUOTE: Originally posted by AlcoRS11Nut
No, idea of why six locomotives came into town, do you have any?

Sometimes after a major repair or if the unit has been having problems it will be sent out for evaluation. It will not be used for "dependable" power; instead it will be 'extra' so that if it does fail, the train will not fall down and block a main track. But four of them...?

[Anonymous]

Correct term would be 'online'

QUOTE: Originally posted by Mookie

QUOTE: Originally posted by AlcoRS11Nut

I know what you mean, however, instead of Dash 9's there is AC4400CW's, and instead of SD70M, there are SD9043AC's where I live. I would say it is the engines (personal guess), I can definately tell if the inbound coal train has a GE[:(!] or a EMD [:D] on the point. One time (in March) a coal train came into town severly over powered! Yes, over-powered, there were 2 AC4400CW's (UP and ex SP), and 3 SD70M's, and 1 SD60M!!!!!!! I took lots of pictures, because I hardly ever see UP useing DC traction motor equiped locomotives on coal trains. What buges me is that I can't not come up with a reason they would be on the train, other than it being a freak of nature. The city I live in is at the end of the sub-divsion and the are hardly and trackege to other side of town (basicly dead ends). The heavest train that traverses the subdivsion is the coal-train inbound to the power plant, and that normally takes 2 AC4400CW's, or 2 SD9043AC's, or a combo of both. No, idea of why six locomotives came into town, do you have any?

Were they all "working" or were some just along for the ride?

Moo

[AlcoRS11Nut]

QUOTE: Originally posted by Mookie

QUOTE: Originally posted by AlcoRS11Nut

I know what you mean, however, instead of Dash 9's there is AC4400CW's, and instead of SD70M, there are SD9043AC's where I live. I would say it is the engines (personal guess), I can definately tell if the inbound coal train has a GE[:(!] or a EMD [:D] on the point. One time (in March) a coal train came into town severly over powered! Yes, over-powered, there were 2 AC4400CW's (UP and ex SP), and 3 SD70M's, and 1 SD60M!!!!!!! I took lots of pictures, because I hardly ever see UP useing DC traction motor equiped locomotives on coal trains. What buges me is that I can't not come up with a reason they would be on the train, other than it being a freak of nature. The city I live in is at the end of the sub-divsion and the are hardly and trackege to other side of town (basicly dead ends). The heavest train that traverses the subdivsion is the coal-train inbound to the power plant, and that normally takes 2 AC4400CW's, or 2 SD9043AC's, or a combo of both. No, idea of why six locomotives came into town, do you have any?

Were they all "working" or were some just along for the ride?

Moo

Yes, they were all "online". You could see heat comeing from all of the exhaust stacks.

[Anonymous]

I like the sound of GE's, one of the few advanages of NS having 1,022 C40-9W's is that they sound better than EMD's.

[AlcoRS11Nut]

QUOTE: Originally posted by dougal

I like the sound of GE's, one of the few advanages of NS having 1,022 C40-9W's is that they sound better than EMD's.

Dem dare are fightin' words![;)]

[espeefoamer]

I think I smell another GE[:(!] vs EMD[:)] fight brewing.[B)]

[Mookie]

Naw - we are all Ladies and Gentlemen here. Besides, Big Brother is watching.....

However, we could go brawl on another forum and then come back here....

[:D]

[zardoz]

QUOTE: Originally posted by Randy Stahl

Mookie,
You should have heard the F-40s before the silencers were installed, god it was painful when a pair would pull into the depot screaming in throttle 8.
Randy

Just imagine how loud it was in the engine room! Before I would enter, I would put in the foam ear plugs, then cover my ears with industrial earmuffs. (My decibel meter indicated 125db!)

[zardoz]

So would the GE's be the republicans and the EMD's be the democrats?

[Anonymous]

I'm not sure but I think both EMD and GE have gone to two smaller turbos instead of one big turbo.

Also, higher frequencies of sound are more directional and travel faster, while lower frequencies are non-directional and travel slower, so over distance the individual components of a sound "spread out". Sound waves slow down as they travel, so the faster waves catch up and pile up giving the effect of fading in and out. Individual waves also become longer with distance, expanding the relative scale of time within the sound; given enough distance you can hear the pulses of individual exhaust strokes. The higher frequencies remain more constant, while the lower frequencies will drop below hearing. The next time you hear a train from a long distance, think about it.

Possibly why the EMD has more bass is because it is a two stroke of uniflow design. Air enters through ports in the bottom of the cylinder when the piston is passing BDC, and will exhaust from all four valves in the cylinder head during the exhaust portion of the piston's stroke. A two stroke's exhaust timing is also earlier than a four stroke's, while there is still pressure in the cylinder, the "pop" helps exhaust scavenging.

In comparison, a four stroke engine exhausts through only two valves (w/4 valves per cyl.) and at or near atmospheric pressure. With half the valve area and no "pop", it's no problem because with a whole stroke for exhausting gases, there is plenty of time.

A good analogy would be to cover the open bottom of a drum, and then drill two holes, listen to the drum and then drill two more holes and listen to the difference.