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Stephen D. Richards

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« Reply #15 on: December 16, 2007, 04:32:25 AM »

I agree with third rail.  The boiler would be the fuel tank(steam as fuel).  The piston and drivers would be simuliar to the engine of a motor vehicle.  Boy,  this could get deep!     Stephen
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jsmvmd

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« Reply #16 on: December 16, 2007, 11:45:07 AM »

Dear pgarman,

Not to get off the subject of trains, but to respond to your comment about playing sports at altitude, I have a comment.

Red blood cells (RBC) traversing the pulmonary capillaries will exchange oxygen, carbon dioxide and nitrogen across the capillary endothelium, alveolar basement membrane and capillary endothelium down a concentration gradient and restricted by the membranes' permeability.  This is nicely explained by a graph called the oxyhemaglobin dissociation curve. 

The partial pressure (PP) of oxygen at the alveolus is calculated at sea level at 70 degrees F as the PP of oxygen (21%) times atmospheric pressure (14.7 psi or 760 mm of mercury) minus the PP of water vapor in the inspired air (47 mmHg).  Thus,  (760) x (.21) - 47 = 100 mm Hg of oxygen PP at the alvelous.

The RBC will pick up its full complement of oxygen, and beome "saturated" in 1/3 the time it takes to traverse the alveolus.  This leaves 2/3 the time as reserve to increase oxygenation.

How does this increase happen?  With time spent living at altitude, the heart chambers enlarge and the heart rate increases to pump more blood per time, known as increasing cardiac output.   The body produces more RBC's in the bone marrow, and the spleen and other storage organs release more RBC's to the blood stream.  The body produces a chemical, 2,3-DPG which lowers the RBCs' affinity for oxygen and thereby increases oxygen delivery to the tissues.  The lungs will expand and increase the amount of air delivery.

These are some of the adaptations that the body does, called acclimatization,  to adjust for the lowered partial pressure (PP) of oxygen at altitude.  There are more RBC's to move through the pulmonary capillaries at a faster rate.  This maximizes the volume of oxygen that can  be pumped to the tissues.

To put it in railroad terms, the RBC's, or coal hoppers move faster through the tipple, which is dumping coal as fast as it can, but at a slower rate which is analoagous to the reduced PP of oxygen at altitude.  A faster train will pick up more coal than a slow train.  So, as an example, 100 coal cars 90% full have more volume of oxygen than 80 cars 98% full.

That is how the cardiovascular system at altitude delivers more oxygen to the tissues.

This is not analogous to a mechanical system, but a biologic adaptation in mammals.

As I said, this is for pgarman, and is FYI for anyone else who might be interested.

I sure learn a lot from you train guys!

Best Wishes & Merry Christmas!

Jack


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THB-DAVE

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« Reply #17 on: December 17, 2007, 11:47:07 AM »

I have always thought that the engine of a steam locomotive consisted of the Valve chamber, piston cylender, connecting rods and drivers.

Dave
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pgarman

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« Reply #18 on: December 18, 2007, 11:00:06 AM »

WOW!!!!!!! I'm overwhelmed, Jack,   Roll Eyes  that's way to techie for me,lol .  My personal experience was a tendency to black out when standing suddenly from a sitting position. which dissipated over a period of three to four years.  That's 50 yrs ago now....... oh well.                                                                                                                                                                                                                                                          Best wishes and a Merry Christmas to all!
















 
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Paul
taz-of-boyds

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« Reply #19 on: January 15, 2008, 11:43:17 PM »

Jim Banner,

Your question:  "Trivia question - what parts of a locomotive constitute the engine?  Or if you prefer, what parts of a locomotive are NOT part of the engine?"

OK, what part is the engine?  Or not the engine....

Thanks,
Charles
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Woody Elmore

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« Reply #20 on: January 16, 2008, 08:36:46 AM »

I think the question, "What is an engine?" is open for debate. In the last century Babbage created a "calculating engine," a huge, steam driven monster of an adding machine.

I was always lead to believe that the engine part was the part that did the work - frame, wheels, cylinders, rods, etc. The boiler was ancillary; it supplied the power to the "engine."
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Joe Satnik


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« Reply #21 on: January 16, 2008, 12:12:57 PM »

Greetings, All.

Weren't the long tunnels (with little air circulation) the main reason for using electrics in the mountains?  (Cough, cough, gasp, choke.)   

I think SP had cab forward steam engines to avoid asphyxiating their freight engineers and firemen in the tunnels.     

Possible secondary reason: Cheap hydro-electric power nearby.

Sincerely,

Joe Satnik 
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If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.
Conrail Quality


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« Reply #22 on: January 16, 2008, 09:45:45 PM »

Greetings, All.

Weren't the long tunnels (with little air circulation) the main reason for using electrics in the mountains?  (Cough, cough, gasp, choke.)   

I think SP had cab forward steam engines to avoid asphyxiating their freight engineers and firemen in the tunnels.     

Possible secondary reason: Cheap hydro-electric power nearby.

Sincerely,

Joe Satnik 

Joe,

Both of those are very true. Another point to consider is regenerative braking. With those steep downgrades, the regenerative braking adds up to substantial amounts of energy (e.g. money) saved compared with diesels and steam.
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Timothy

Still waiting for an E33 in N-scale
SteamGene

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« Reply #23 on: January 16, 2008, 10:42:53 PM »

There is a whole lot of talk on the Milwaukee Road board on the decision to de-electrify the western sections of the Milwaukee Road. 
My feeling is that it was a mistake, but I don't know that much about the Western Extension.
Gene
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Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"
ebtnut

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« Reply #24 on: January 17, 2008, 12:53:08 PM »

The choice of steam vs. electric had to take in a number of factors.  The primary one would be the potential savings vs. cost.  The usual mantra is that electrification is very expensive to build, but very cheap to operate.  Roads like the Virginian, the Great Northern, and the Milwaukee Road looked at the tunnels and grades they had to deal with, and determined that electrics could work for the operational savings.  Most important would be the elimination (or at least a greatly reduced need) for helpers.  In steam days, each locomotive needs a crew, and the loco needs fuel, water, servicing, etc.  Electrics, with their M.U. capability, could haul the trains with one set of "motors" and one crew.  Other roads, like the PRR and NYC, had very extensive commuter and passenger traffic that ran much more efficiently with electrics (and still do today in the Philly- New York region).  The downside to electrics was the expense of the installation of the overhead, and perhaps the need to build a generating station to power it, since back in those early 20th century days, the availability of commercial power was a real issue, especially in the remote areas. 

Diesels, of course, are simply electrics with self-contained motor-generator units.  I suspect most of the reason that Conrail abandoned all of the old PRR freight-only electrified routes was to simplfy their operations.  Diesels could do the same work, they didn't need a separate maintenance force for the eletrics, they didn't have to stop and change power; they didn't have to maintain all that overhead, etc.
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SteamGene

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« Reply #25 on: January 17, 2008, 02:47:08 PM »

On the Milwaukee Road Yahoo group there has been a long running discussion/argument about the de-electrification of the early 1970s.  Apparently the Road was able to sell excess electricity and the de-electrification took place just as the 1973 oil embargo took place, leading to a lot of controversey.
Gene
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Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"
Woody Elmore

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« Reply #26 on: January 18, 2008, 10:55:13 AM »

Where is the electricity coming from? In California they are debating a bill that would put digital thermostats in houses so that the power company could raise or lower your home temperature. This is because there is not enough capacity.

Out here on Long Island Steven Spielberg (Al Gore's good buddy) put in gas fired generators because the power company can't provide him with enough power to illuminate his estate in the Hamptons.

Maybe they should bring back the Atomic Train (remember that silly TV movie made in the seventies?)
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