I asked a question a while back that probably was too narrow to get a
detailed answer. Basically the US and European coupler systems are
different. This has to lead to a difference in how yard operations, in
assembling a freight train are performed. If I remember right from books I
read many years ago in some US yards a box car could be pushed onto a
slooped section and allowed to coast and automatically couple to the end of
a freight. With the European coupler I would exoect you would "gently" move
the new car to the end of the freight - perform the hookup and then back off
the yard switcher engine. Where can I get details of this.
Val Kraut
Yes, but not particularly gently. The buffers would be compressed so
the chain had enough slack to hook it up.
Britain and (I think) the rest of Europe had what they called "hump"
marshalling yards which sound a bit like the sloped section you talk
about - the wagons were pushed over a small hill and then freewheeled
through a fan of turnouts onto the right track. There were retarders
to slow the wagons down to the right speed.The only real difference
was that coupling up was done manually.
http://mikes.railhistory.railfan.net/r135.html
1) The don't use a "chain" in Europe, it's "coupler", in Europe usually a
"screw coupler" and in the UK they used three types. The "three link", the
"instanter" and the "screw" coupler.
2) Europe and the UK are two different entities. I can only speak for the
UK.
The three link coupler was only used on freight cars that had no automatic
brake. The three link coupler leaves a gap between the buffers and thus an
unfitted (Unbraked) freight has a fair bit of slack.
The instanter coupler was used on fitted (braked) freight cars and was
cheaper than a screw coupler and was used to limit the amount of slack
between freight cars.
The screw coupler was used on all passenger cars, though some used knuckle
(Buckeye in UKese) couplers and on passenger rated freight cars. When
coupling up screw couplers the cars are pushed together (gently) to compress
the buffers and the screw coupler is tightened up so as to eliminate any
slack between the vehicles. When the train loco couples up to a passenger
train, the loco "sets back" so that the buffers between the loco and the
first passenger car compress, the screw coupler is then tightened to
eliminate slack. Unlike a North American passenger train, a UK passenger
train has no slack, zero. It's one complete unit from nose to tail.
Almost all countries that had railways/railroads probably had hump yards.
The still do in North America though they've all closed in the UK.
As with most hump yards the "bowl", all the yard tracks, were usually very
gently sloped away from the hump and then level for something like 3/4s or
2/3rds of their final length. Something like that and it probably varied
between gentle slope and no slope. Freight cars came over the hump and were
braked by retarders, automatic in "modern" yards and manually operated in
older yards. Once the car are sorted, they are (usually) moved over to a
departure yard when the various blocks of cars are made up into a train, the
caboose or these days the EOT is attached, the cars connected to yard air to
charge the brake system and at some time before departure, the power is
attached to the head end.
I think the original question asked if cars in North America were pushed and
let to roll freely onto the rear of trains but were pushed onto trains in
Europe.
The answer is "No", cars were never let to roll freely onto trains in North
America. When attaching a block of cars to a train, they are always pushed
by a locomotive and never let to free wheel onto the end of a train. You
need to define "train" as a "train", contrary to what the media and the
unwashed masses think, isn't a freight car.
Roger T. wrote:
[...] Unlike a North American passenger train, a UK passenger
Erm, Roger, on our trip to Alberta with Via last year, I noticed no
slack. Several times I didn't realise were moving until we hit a rail
joint (the train took siding for almost every freight train, and in N.
Ontario almost all sidings had jointed track.)
cheers,
wolf k.
"> [...] Unlike a North American passenger train, a UK passenger
Perhaps not on Via Wolf but I'm not sure about commuter trains. Besides,
like the vast majority of North Americans, I don't travel by train. The
last time I was on a train in North America was probably around 1975 and
that was, IIRC, on the Turbo from Toronto to Dorval. :-)
Hi,
Roger T. wrote:
> (screw coupler)
It should be mentioned, that a screw coupler *has* to have buffers - in
Europe they are roughly above the rails with the coupler in between.
Without buffer, the screw coupler won't work... But this is just for
completeness ;-)
Now, this is the idea, though it's far from usual practice.
First of all, when traveling on passenger trains labeled as "local"
(still going 120 km/h, sometimes more) I do notice slack now and then.
This may be due to personnel shortage (meaning less time to do more
work), but none the less happens.
Second of all, the buffers are sprung (no matter whether by real springs
or whatever). So, while the coupler being tightened means some
compression, it is always possible to compress them further and thus
relieve the coupler tension. Actually when the train goes around the
bend, the inner coupler is compressed more, while the outer coupler
releases some (but the compression is kept up).
So I guess the compression by the screw coupler is mostly to prevent the
coupler from un-coupling at rough spots in the track and has less or
nothing to do with yard operation ;-)
But anyway, a screw-coupled train is less of a complete unit than a
train with center-couplers - because with center couplers there is a
firm connection between two couplers. That does not mean that current
center couplers are ideal - the Scharfenberg coupler is too complicated
(expensive), the American couplers have too many extensions (shelves) by
now to be considered "simple" and the Russian type probably has other
deficiencies... There have been attempts at an "European center coupler"
but they never went past some prototypes...
That is probably the important point - the type of coupler has some
influence on the procedures in the arrival tracks and in the sorting
tracks, but otherwise all yard operations are similar between Europe and
North America.
Arrival track:
- in America someone has to walk the train to close the brake valves at
the wagons' ends and uncouple the brake lines.
- in Europe someone has to walk the train, close the brake valves and
uncouple the brake lines as well as uncouple the screw couplers.
Hump:
- in America someone has to stand next to the track at the hump to open
the couplers between cuts. This can probably be done while the train is
driving slowly.
- in Europe the cars are already uncoupled, so they'll roll by themselves.
Sorting track / departure track:
- in America someone has to walk the train and couple the brake lines as
well as check the couplers
- in Europe again someone has to walk the train and couple brake lines
as well as screw shut all the couplers
So I guess, the center couplers do have some advantage - coupling and
uncoupling is faster, but as long as the brake lines have to be coupled
by hand, the only difference in procedure is the time taken to actually
work the couplers...
...
The "yard air" probably is a very good idea ;-)
As far as I recall - and you mention it above - there are hump yards in
North America. That would mean, that cars are left to free-wheel onto
the end of a "train" - which would not have an engine connected to it.
But this is exclusively done with freight trains and even then there are
cars that need to be shunted by a loco because they may contain fragile
goods.
Anyway, modeling a hump yard is possible (there is an operational one at
the DB-Museum in Nuremborough (Germany)). Still it is quite a major
undertaking ;-) It might be much simpler to model a locomotive-shunted
"flat" yard... But as far as procedural differenced between the
continents are concerned I'd guess they are more of an administrative
nature than of a technical one...
Ciao..
"Bernhard Agthe">> The answer is "No", cars were never let to roll freely
onto trains in North
That is not a "train". Rules are _very_ specific about what a train is.
And usually, in North America at least, trains (As defined in the rules) do
not depart from the bowl tracks in the hump yard. After the cars are
humped, and sorted out on the bowl or yard tracks, these blocks of cars are
then transferred to an arrival/departure track where the consist of the
train is made up. Before departure, the caboose (when they were used) is
attached, the power added and in the days of cabooses the marker lights are
add or these days the EOT is attached. Now you have a train but not until
the marker lights or the EOT is added.
It is the presence of the marker lights and or the EOT that makes it a
train.
On 8/29/2009 6:42 AM Christopher A. Lee spake thus:
I thought that coupling had/has to be done "manually" in any case: how
else are the air hoses going to get connected? The couplers (at least in
the US) will automatically couple when, say, a car is rolled down a
"hump" (same here as in Yurp, apparently), but a trainman still has to
come along and connect the trainline, right?
--
Found--the gene that causes belief in genetic determinism
On Sat, 29 Aug 2009 10:13:33 -0700, David Nebenzahl
What air hoses?
Most British steam era freight only had hand brakes on the wagons. The
only brake force on a moving train was from the engine and tender, and
the guard's hand brake at the back of the train.
Not 100% true. It is true that a lot of UK freight, especially mineral
traffic, moved in unfitted train but there were also freight trains the were
fully fitted or partially fitted that ran with a fitted head and they used
vacuum brakes and not air brakes. The vacuum brake hoses had to both manual
connected and disconnected, unlike air brake hose which can pull apart
without damage.
These days, since the early 1980s(?), all UK trains are air braked, except a
few carriages that remain vacuum braked for use behind steam excursions.
Goes without saying. They use the same metal coupling or "gladhand" on the
end of the airhose as we use in North America. It's a pretty universal
fitting for not only for brake hoses but for all kinds of pneumatic hoses.
Even the constructon crews with jack hammers use the same fitting.
You're talking passenger, I was discussing freight. And the UK is like much
of the rest of the "modern" world when it comes to fixed formation trains
aka "multiple unit" trains. They also use automatic air connections that
are all part of the coupler. Not universally, unfortunately, which can
create major problems when an m.u. (Fixed consist) train fails on the
mainline and the following train has a completely incompatible coupler
system so it cannot come up behind and push the failed train forward.
That's why they have or had "Thunderbird" diesels. Why "Thunderbird"?
Google the TV show "Thunderbirds" and the answer becomes obvious. :-)
I have video, supplied by a friend, of a long 30+ car or more intermodale
train roaring through Winchester and that's not a fixed rake. :-)
I didn't know that modern UK freight ran in fixed rakes.
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.
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 http://en.wikipedia.org/wiki/Well_car . 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.
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