Big trains question about coupling

Watched "Von Ryan's Express" last night on TV, and was surprised when it showed an Italian trainman coupling up cars: you could see the cars
being pushed together, and when the buffers met, the guy ducked under one of them, grabbed the coupling hook and connected it, then quickly ducked back out.
Anyone know if this was realistic? Seems incredibly dangerous to this North Americano; but maybe that's just because of too many years of indoctrination to such things as FRA regs and working rules ...
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Everyday occurrence on practically every railway that used screw couplers and buffers. Probably frowned upon but men did it anyway.
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Roger T. wrote:

> > -- > Cheers > Roger T. > See the GER at: - > http://www.islandnet.com/~rogertra /
Used to see it happening all the time at our local station back in the 60's. Knew a shunter once who happened to have his head in the wrong place when the buffers met. Didn't duck quite low enough I guess but it was 3'6" "main line" narrow gauge when all was said and done. Much facial remodeling was the result. He survived but his own mother wouldn't have recognised him after the event. His accident caused a major reshuffle, along with an altered attitude to training, in the TGR back about 40 years ago.
Krypsis
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wrote:

It's still normal throughout Europe.
They screw couple against the sprung buffers so that the entire train moves as one unit. The advantage is that there is far less shock damage to goods being carried. The disadvantage is that the loco must be powerful enough to start the train all at once, but as European trains are short and run fast this is not a problem.
Greg.P.
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Hi,
David Nebenzahl wrote:

Actually in the "Old World" there are no "Janney Couplers" - only the buffer-and-hook-and-screw type (Russia has a central buffer coupler, but that's incompatible to everything else).
So what you did see was actually the harmless variant - I did personally observe the trainmen walking in there (between the buffers) just a few seconds before the trains actually met. While this might be against regulation, ducking under the buffers (especially when he comes from atop a platform) is acrobatic...
An effort was made in the 60ies or 70ies to develop a "european center coupler" which should have been compatible to Russia and feature air and electric connections. They wanted the gold-emitting donkey, but it should cost nothing... The result follows this line: "the hook-and-screw couplers are working well, there are few accidents and everything else costs too much"... That the manual couplers cost a lot in terms of personnel isn't in the calculation... Don't try to understand this.
Along the same lines, like I mentioned earlier, Knuckle-Couplers are exotic in European model railways... You can buy them via WWW, but you won't be compatible to your friends. They would solve a series of problems (semi-close coupling) but then, European modelers would blame the manufracturers for being non-prototypical (which the available ones aren't either) and for breaking compatibility (whatever) and not being traditional... Again, don't try to understand this, its just because it's always been done so...
Nothing against Europeans, the average person is just as nice as Americans, Asians, Russians, anyone else.
Have a nice day...
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On 10/21/2008 6:14 AM Bernhard Agthe spake thus:

>

First of all, thanks to all who answered my question.
Now to bring up a related issue: I hate to say this, but those Yurpeen cars and locos, with their prominent buffers, just look plain funny to me. The buffers sticking out always give them, in my mind, a sort of Thomas the Tank Engine look.
Now, before you type out an angry reply to this, understand that I do realize that this is totally due to my North American railroad prejudices, and my familiarity to knuckle couplers, which I'm sure also look funny to a lot of folks outside of N.A.
In a related vein, what about those buffers? Are there any inherent advantages to either system: the Yurpeen with its separate buffers on each side, or ours where the buffer is integral with the coupler and the members connecting it to the centerbeam? Do European trains experience the same issues with coupler slack that ours do? Inquiring minds want to know ...
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David Nebenzahl wrote:

One great advantage with side buffers and screw couplings is that slack can be completely removed by tightening the screw coupling. This is normally used on European passenger trains and makes the ride much smoother than I imagine is possible with the Janney-type couplers with a lot of slack in them.
Some types of automatic centre couplers used on European DMU and EMU trains (Scharfenberg types, for instance) have no slack when coupled.
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Venlig hilsen/Best regards
Erik Olsen
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The only difference between Europe and North America is that Europeans, even within the same country, mush the operational detriment, have not standardised on one coupler system.
This can and does result in a passenger m.u. failing on the mainline yet the following train cannot come up behind it and give it a push because their coupler systems and completely incompatible. They in effect, have to call a "tow truck" , in the UK known as "Thunderbirds" I gather after the 1960s/70s TV show of the same name, to come and rescue the stalled unit. Result? Delays of hours rather than minutes if both 'trains' were equipped with a standard coupler.
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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wrote:

Huhh???? They standardised in 1849!

Britain's railways aren't a part of "Europe" as such.

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No they haven't. There are all kinds of different couplers that are not compatable.

Agreed.
Like Canada isn't part of "America".
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Erik Olsen wrote:

They don't have any slack worth mentioning, actually. There buffers are in fact integral with the knuckle coupler (they are part of the coupler box.) Thus, there is little slack even in a freight train. The "issues with slack" mentioned by Dave are nothing compared to the bang-bang-bang that I used to hear when a British freight train slowed down or started up on the line a 1/2 block from where I used to live in England. OTOH, the springs in the buffers do stretch and compress as the trains move, that's prtesumably waht dave means by "slack." Hence the development of the "cushion underframe", which extends the spring travel, and thus reduces the acceleration/deceleration shocks.
On passenger cars, there is also a frame-mounted buffer above the coupler. This allows coupling with practically no slack at all. In my experience, Canadian passenger trains are as smooth as the European ones. If the track is well maintained, that is: there are stretches of track in Northern Ontario that feel a little like a roller coaster... ;-)

If there were no slack, as you call it, the ride would be exceedingly rough. The couplers in fact have an integral buffer.
HTH
--
Wolf Kirchmeir

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"Wolf Kirchmeir" <

Not true Wolf.
See:- http://www.ataassociates.com/RailArt.htm#Slack
"On mechanically sound cars, mechanical free motion or free slack between adjoining couplers can be one inch. Couplers are attached to draft gears that absorb the shock or impact. Draft gear slack is called spring slack. Spring slack on a conventional box car is about five inches. Many intermodal (piggyback) cars have shock control devises or sliding centre sills that can have fifteen inches of slack in each end.
A 100 car train of conventional cars in good mechanical condition will have 50 feet of slack. Intermodal trains and trains with cars in poor mechanical condition can have much more slack."
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Roger T. wrote:

Quite true, but what I said doesn't I think conflict with this. 1 inch of "free slack" is not worth mentioning, leastways not when you've heard and observed 4"-6" of free slack in European freight trains (plus as much or more in the buffers.) I should have been less ambiguous, I suppose, but I thought my reference to what I saw and heard in England way back when implied that the "free slack" on those freight cars was enormous compared to what we know and love in our N. American trains. ;-)
"Draft gear slack" is necessary - it's actually the buffing action, provided by the traditional side-buffers on European cars, and by integral buffers in all center couplers used today (some mine- and industrial tramway-cars excepted.) Cushion frames are designed to _increase_ that buffing action. By contrast, "free slack" is a necessary evil in knuckle couplers, it's the play within and between couplers that enables the knuckles to slide past each other and lock.
AFAIK, there should be no free slack with screw couplings, but when I observed switching in Austria a couple years ago, there was definitely more than an inch of free slack. The buffers parted 20cm or more when the loco started up the cut of cars. The coupler links were simply lifted into place (ie, "three link couplings" in effect), to save time I guess.

That's about 8ft of free slack, and up to 42ft of draft gear slack. But the train will be 5400 ft long (a 50ft car has a coupled length of about 54ft), so this slack amounts to less than 1% of total train length. Not much, really. The free slack 9the bad kind ) is less than 1/4% - very good, I'd say. Hence my "no slack worth mentioning." ;-)

It's the free slack that's the problem, since it causes unsprung shocks, which are bad, esp. for the couplers.
HTH
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Wolf Kirchmeir

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Wolf Kirchmeir wrote:

Loose-coupled British goods trains are quite a special thing. Please don't think that is the norm for European freight trains.
In Denmark screw couplings have been in use on freight equipment since the very beginning in 1847 except for a series of simple open goods wagons (gondolas) that were taken over from the builders of the first Danish line.
1 inch of free slack is indeed quite much. In European freight trains with screw couplings there may be that much slack if the screw couplings are not tightened properly, and it influences running remarkably. It even increases derailment risk on rough track.
In Denmark the norm is that on freight trains screw coupling shall be tightened enough that there is no free slack. On passenger trains screw couplings shall be tightened enough that the side buffers are sligtly compressed.
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Venlig hilsen/Best regards
Erik Olsen
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I agree. Free slack action is a serious concern to North American locomotive engineers. Freight cars will typically have at least 1 inch of slack per coupler if not more, that's about 2" per car and on a 100 car freight that's about 200 inches, or 16 feet or 4.9 metres of free slack and that's not including run in and run out of cushion underframe slack. 16 ft or 4.9 metres is nothing to sneer at when it comes to train handling. Not sure if you live in North America Wolf nor how often you get over if you don't but you need to read a bit more about our knuckle couplers. Even our North American passenger trains have some free slack action whereas, I know, European trains have none.
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Correction. I miss calculated.
If each car has 1" of free slack at each end, then a 100 car train has 199 coupled ends or 199 pairs of couplers coupled together which translates to (1" per coupler x 2 couplers coupled together = 2" of slack per pair of couplers) that's 199 x 2 = 398" or about 33' feet or about 10 metres.
Lots of free slack and that's not counting cushioned underframe slack.
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Roger T. wrote:

Ok, new figures accepted. But it's still not much compared to the length of the train. A 100 car train will be 5,000 feet or more. Less than 1% of train length.

So, what are the "issues with slack"? They vary, and not all of thme are bad. As I understand it, free slack can be an advantage when starting a train, as the load is incrementally increased as the slack runs out. I've read that engineers will actually reverse the engine against the train before moving forward. Is this common practice?
OTOH, on a line with many short grades, shorter than the train, slack action (both kinds) can cause problems, which are minimised by running shorter trains and running them slow. Eg, the Huron central (Sudbury - Soo, runs through my town) runs trains around 40-50 cars averaging 50ft, at about 15-20mph. They could run them up to 30-40mph, but the track is very bad. ;-)
Sprung slack has more complicated effects. A certain amount is necessary, to dampen horizontal shocks transmitted to the cars and lading. Too much can be a problem, especially when helpers are used on hilly lines on which long trains are run. Rough track can set up oscillations. Not easy to analyse, even by people who study it or work with it.
FWIW, the slack action in model trains is much more than on the prototype. I just tested it on my layout, on a 7-car train, it's about 4 scale feet (HO)!
HTH
--
Wolf Kirchmeir

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"Wolf Kirchmeir"

I was reading a technical article on line and it seems even my 2" of slack was conservative. The article quotes up to six inches of slack per car or 50 feet 15.24 metres of free slack plus buffing and drawbar slack.
http://www.arema.org/eseries/scriptcontent/custom/e_arema/Practical_Guide/PGChapter6.pdf
Top of the last page in this technical paper provides the 6" and 50 feet figures. It's difficult to find anything technical on the 'Net regarding slack between cars.
When starting a 100 car freight with the locos in notch one, it is quite possible for the front end of the train to be moving at between 10 to 15 mph before the last car begins to move. In the days of cabooses, crewmen were expected to be seated, facing forward, with their backs and heads firmly against the back of their seat in anticipation of the violent snatch of the slack running out. Crewmen were known to be suffer serious injury or even death caused by slack action.
-- Cheers Roger T. See the GER at: - http://www.islandnet.com/~rogertra /
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Back in the steam engine days, the slack was pretty necessary to start a long train. Remember that a steam engine can pull a train that it can't easily start while a diesel can start a train that it can't get up to a speed where it can run without running into heating problems in the electric motors. Back in the old days, the steam engines would start the head end of the train and maintain a slow speed until the entire train was moving an stretched out. At that time, the engineer would then start the acceleration of the train. Today, the engineers have to get the train up to a certain speed when at full power or the electronics on the engine would shut down the power to the electric motors as they would be overheating otherwise.
-- Bob May
rmay at nethere.com http: slash /nav.to slash bobmay http: slash /bobmay dot astronomy.net

I've
http://www.arema.org/eseries/scriptcontent/custom/e_arema/Practical_Guide/PG Chapter6.pdf
mph
the
even
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wrote:

You still need to accelerate the great mass of the train! "Stiction" which is the resistance to movement could be of the order of 3-4 times the rolling friction of plain bearings, but only double for roller bearings.
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