On 8/29/2009 5:07 PM Roger T. spake thus:
Wow. How quintessentially ... British, which is to say insular. Little
cars trundling around a little island ...
I'll try and find some photos. But I've seen rakes of wagons with
standard couplings on the outside and semi-permanent drawbar
connection inside. Could have been wagons for ISO containers. It's
been a while since I went back to the UK.
"Christopher A. Lee
These are articulated freight cars and we have them in North America. It's
not the "train" running in fixed rakes but articulated freight cars within
the train. Like these
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. Not quite
the same thing as an "fixed rake" freight train. Trains that run in
(generally) fixed rakes are known as "unit trains" in North America or in
the UK, "merry-go-round" or "mgr" trains and these will be made up of
similar but individual cars that remain coupled together and run from
source, usually a coal mine, to a customer, say a generating plant or
perhaps a lake head or sea port. Try Google for "unit train",
"merry-go-round train" or "mgr" train for a fuller explanation.
No. They're not articulated - each has two bogie trucks. It's a rake
of several wagons with a standard coupling on the outside to couple
with an engine of a similar rake. Between the bagons is a different
kind of simpler coupling more like a drawbar that is not designed to
be separated in service.
I've never heard them called articulated before, they're separate
wagons with standard couplers on the outside of the rakes,
Now I understand. I think they made some hoppers like that in North America
and perhaps some intermodal cars. Two cars, with drawbar and carrying one
number.
[...]
I lived in England off and on 1945-54, in Stratford-upon-Avon my
mother's hometown), about 1/2 a block from the GWR. Most freight trains
were "unfitted." You could here the slack running in and out from a mile
away, if the wind was right.
These trains were short (30 wagons was a "long" train", and travelled
slo-o-o-owly - about 15-20mph by my (hindsighted) estimate.
cheers,
wolf k.
And many unit coal trains have cars fitted with special couplers (so
they can be rotated) or bottom hatches (so that they don't need manual
opening) in order to unload them without uncoupling, or without
stopping.... Now that's an operation I'd like to see done in HO. ;-)
wolf k.
Local HO club has it.
Starts with a working coal loding facility all the way around the layout to
a working rotary dump facility.
Cars have custom modified rotary couplers on them.
Umm, not really! Many freight trains, but more especially coal, were often
built up through accessing many short branch lines, collecting from, and
delivering to, other short branch lines, throughout industrial districts
or coal mining districts, with difficult access. They were often very
short runs.
The merry-go-round coal trains for power stations came very much later
with longer runs, collecting from fewer and much larger coal pits. (I
worked on some of the coal handling plants which received these trains)
The system was and is very efficient.
If I may take the opportunity and go slightly OT, I have never been able
to understand US practice with coal drags, where as many as 100 wagons (?)
were coupled (10,000 tons ?) being typical but frequently ran at well
below locomotive economic running speed, walking speed no less, and, I
understand, often stalled. How come? This has puzzled me for a long time.
I have several CD's of C&O showing Allegheny H8's just crawling with mile
long coal drags!
Any explanations, please.
I mean, one could equally ask, why choose the Mallet system as opposed to
the Beyer Garratt?
[...]
Ore trains in the Missabe Range were in that range, too. That's the
reason for the Yellowstone, a 2-8-8-4 that had greater weight on drivers
and greater tractive effort than the Bog Boy (which was heavier overall.)
Here are some of the things I've figured out from my reading, and from
recall of the thermodynamics course I took many years ago. I don't claim
it's a complete explanation, but it's certainly part of it.
Those locos were designed as "drag" locos, for low speed and heavy
trains. The economics of steam locomotive speeds are complicated. The
drag locos were designed to be most economical at low speeds, in the
15-20mph range. Articulation was used because you essentially get two
engines for the price of 1-1/2, with a single crew. And as with all
engines, bigger means more efficient.
Mallet vs Beyer-Garratt is a "cultural" difference, heavily influenced
by NIH syndrome. Also, IIRC, Beyer-Garratt was patented, while the
Mallet was just a compound articulated loco, anybody could build one
without paying royalties. A lot of so-called Mallets were simple
engines, though.
There are other aspects to the economics of trains. The sheer amount of
coal to be hauled is one. The logistics of managing many short, lighter,
faster trains are complex compared to fewer, longer, heavier, slower
ones, and it's worse when they run on the same tracks. Railroads hate
mixing freight and passenger trains for this reason. It requires extra
tracks and passing sidings, more complex signalling, and so on.
By the time all these and other factors are balanced against each other,
running a heavy trains at less than the engine's most economical speed
was a minor cost compared to others.
I'm sure there are many things I've overlooked.
HTH
wolf k.
Yes, they were big weren't they. As I understand it the Big Boy wasn't
especially efficient, or wasn't run efficiently, and threw a lot of coal,
unburnt, up the stack. The fuel was just so cheap that it didn't matter.
Sometimes, it depends how you run them.
I'm sure your right!
True! That must have influenced decision making.
The early one's, yes.
I think that 'all' the later ones were, weren't they?
That's certainly true in the UK.
But, weren't many US long haul tracks virtually dedicated solely to coal
and/or ore, though?
ie. fuel was cheap at the time. But, as an admirer of the engineering of
both the Yellowstones and the Lima H8's, I am aware that the economical
running speed of both was far higher than what was current running
practice. I mean, CD's showing Yellowstones on the Doluth Missabe and Iron
Range show them to be really shifting, whereas the H8's were capable of
far higher speeds than was normal practice which appeared to be slow coal
drags. I think that I am correct in thinking that C&O didn't really know
the H8's full capabilities until it was far too late to utilise it.
No worries, me too.
Brian
Not all - the last of Norfolk & Western's Y6bs was built in 1952, and
they were compound to the end. It is said that the next N&W drag loco
(the Y7) would have been a simple, however.
Tim
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