Post #236,573
11/30/05 1:26:40 PM
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Erm...Huh?!?
Automobiles do not run on tracks. They do not contain "stationary engines" and their operating environment is orders of magnitude more complex. Have you ever worked on one? Have you ever tried even starting one? You're gonna have a very hard time convincing me (or anybody else that has ever been up close and personal with an SD90MAC) that a 6000bhp mobile power plant is "orders of magnitude more complex" than a car. Sorry, thanks for playing.... jb4
shrub●bish (Am., from shrub + rubbish, after the derisive name for America's 43 president; 2003) n. 1. a form of nonsensical political doubletalk wherein the speaker attempts to defend the indefensible by lying, obfuscation, or otherwise misstating the facts; GIBBERISH. 2. any of a collection of utterances from America's putative 43rd president. cf. BULLSHIT
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Post #236,575
11/30/05 1:31:36 PM
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Reading with comprehension?
He said the operating environment is much more complex, not the engine itself. Also, he's claiming that the car's operating environment is more complex than the locomotive's operating environment, not that the big honking locomotive engine is more complex than a car.
--\n-------------------------------------------------------------------\n* Jack Troughton jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca] [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
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Post #236,579
11/30/05 1:37:52 PM
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I guess that depends on what the definition of...
..."operating environment" is.
I took that to mean the localized environemnt of the machine itself, not the exterior environment around the device. I do see your interpretation, however...I wait for Andrew to clarify.
jb4
shrub●bish (Am., from shrub + rubbish, after the derisive name for America's 43 president; 2003) n. 1. a form of nonsensical political doubletalk wherein the speaker attempts to defend the indefensible by lying, obfuscation, or otherwise misstating the facts; GIBBERISH. 2. any of a collection of utterances from America's putative 43rd president. cf. BULLSHIT
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Post #236,584
11/30/05 1:42:54 PM
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Yes, I meant the external environment - sorry to be unclear.
I am sure there's plenty to be concerned about when running a deisel-electric locomotive, but generally busy intersections, and lane changes by untrained drivers with cell phones aren't among them.
[link|http://www.aaxnet.com|AAx]
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Post #236,612
11/30/05 2:59:25 PM
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Understood. However, you may not have heard about...
...[link|http://www.suntimes.com/output/news/cst-nws-crash24.html|this] The train's engineer, a 30-year veteran with an "impeccable record," according to Pardonnet, told authorities he saw cars on the tracks as he approached the intersection and threw on his emergency brakes before striking the vehicles. He was among those hospitalized.
The speed limit for trains along that stretch is 70 mph, although trains travel an average of about 68 mph there, Pardonnet said.
Marino said cars on the track had played follow-the-leader. "I think someone tried to beat the gates, and a bunch of people followed him," he said. So they do deal with "busy intersections", even if they shouldn't really have to. Unfortunately, most engineers have had some form of grade-crossing accident. In general, they are not at fault; it doesn't, however, make their life after such an "incident" any easier, especially if the collision includes loss-of-life. jb4
shrub●bish (Am., from shrub + rubbish, after the derisive name for America's 43 president; 2003) n. 1. a form of nonsensical political doubletalk wherein the speaker attempts to defend the indefensible by lying, obfuscation, or otherwise misstating the facts; GIBBERISH. 2. any of a collection of utterances from America's putative 43rd president. cf. BULLSHIT
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Post #236,751
12/1/05 12:12:19 PM
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Trying to stop 21,000,000# plus consist...
(Beware I did not RTFA, if it about commuter train, they are far worse off... fewer contact patches to aid in stopping)
with 12 or 24 (even 36) quarter-sized contact patches (initially until the air brake system generates enough volume and pressure to start stopping the cars too) is like trying to plow New York City during a major snow-storm with a toy beach sand shovel.
@68MPH a consist of 100 cars, each car being quite near ~100 Tons of total weight and the locomotive being 400 tons to 500 tons (sometimes more than one locomotive is at the head end), takes a few feet to stop it, or even slow down.
((100x100)+(450x2))x2,000#=21,800,000#
Let me see, @68MPH with 21.8M#... how many Newtons (Contact Patch downforce on the rail is the limiting factor, but the Brakes also need to produce that amount of braking force) would it need to be able to slow to 0 in ~500ft. Figuring that the cars would start to aid in slowing @ the rate of 2 cars per second. Figuring the amount of time the car gets pushed into the the forward one with the slack, the brakes applying then the slack being taken out the other way)
Ha, the train's last car won't stop for 35 seconds after the locomotive does. But the 2 locomotives cannot generate enough Air Volume or pressure to stop in 500ft which then pushes the locomotive to nearly 1900ft.
So, unless all the brakes on the cars were fitted with electric or instant action (yeah right) air bakes... 500ft cannot be achieve.
Many people forget that trains have a very long reaction time. In fact, you could compare them to Large Oil Super Tankers. You start stopping about 3-10 minutes before you need to be stopped... YMMV.
-- [link|mailto:greg@gregfolkert.net|greg], [link|http://www.iwethey.org/ed_curry|REMEMBER ED CURRY!] @ iwetheyFreedom is not FREE. Yeah, but 10s of Trillions of US Dollars? SELECT * FROM scog WHERE ethics > 0;
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Post #236,873
12/2/05 2:26:10 PM
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It was a commuter train.
In full emergency (or "Big Hole" to the "locals") an F40PH can generate something on the order of 2.3MPH/sec deceleration before wheel slip; the cars are reported to be able to create something like 3MPH/sec. A full air application (like an emergency application) has the cars actually dragging the locomotive.
Now in Chicago, we're famous for the "push-pull" approach to running commuter trains. In general, inbound trains have the loco at the end pushing, while outbound trains have it pulling from the front. This was an outbound train, so the thing was running in the normal direction, and the brake application "stretched" the train. Figure about 3MPH/sec. linear deceleration, and you can see that it still taks a long time to stop such a beast at 68MPH.
As fas as the concept that the "train's last car won't stop for 35 seconds after the locomotive does" on a 100 car consist, that's what the FRED (Flashing Rear End Device) is for (among other things, like relegating the position of brakeman to the dustbin of history). In Big Hole, the FRED dumps air from the back of the train simultaneously, drainig the air pipe from both directions. There is the outside possibility of breaking the train under such conditions, but in a full Emergency application, the engineers simply don't care...all they wanna do is stop the thing, keeping it greasy side down in the process. And if the train does break (in two), then the pipe will drain in 4 places further reducing the aggregate stopping time.
jb4
shrub●bish (Am., from shrub + rubbish, after the derisive name for America's 43 president; 2003) n. 1. a form of nonsensical political doubletalk wherein the speaker attempts to defend the indefensible by lying, obfuscation, or otherwise misstating the facts; GIBBERISH. 2. any of a collection of utterances from America's putative 43rd president. cf. BULLSHIT
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Post #236,912
12/2/05 10:33:26 PM
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FRED... fergot about it.
Also, I forgot that the Cars also run with air applied to keep the brakes off.
-- [link|mailto:greg@gregfolkert.net|greg], [link|http://www.iwethey.org/ed_curry|REMEMBER ED CURRY!] @ iwetheyFreedom is not FREE. Yeah, but 10s of Trillions of US Dollars? SELECT * FROM scog WHERE ethics > 0;
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