British Railway Operations

[CSSHEGEWISCH]

Question about buffers and link-and-screw couplers: How is slack minimized with this sort of coupling? American knuckle couplers are castings and have a relatively small amount of slack but link-and-screw couplers look like fancy chains with a lot of play in them.

[Anonymous]

The slack is taken out by tightening the screw link until the buffers make good contact - this can cause problems on very sharp curves (in industrial or dock areas) but they can be loosened off if needed. It's not dissimilar to the use of a turnbuckle adjuster as part of a securing chain for a machine load. The fun (if you can call it that!) was with the old 3-link couplers which had no adjuster. Goods trains so fitted tended to run at 25mph or less, and the guard would be expected to keep the train stretched using the brakes on his van to avoid snatching.

[Hugh Jampton]

They are just fancy chains, the buffers are hydaulic (now, but sprung in the past) devices that cushion and absorb the compressive forces.
The fancy chain has a screw on it that you can adjust the slack and create a preload on the buffers if you fancy.
UK trains are also short by comparison. Also in the US the slack is not only in the knuckle, but mainly in the drawbar where there is a spring type thing I recall.

[Murphy Siding]

QUOTE: Originally posted by Railroading_Brit
the guard would be expected to keep the train stretched using the brakes on his van to avoid snatching.

Snatching? What would we call that? Thanks

.

[germanium]

If the couplers are slack, starting off suddenly with a jerk suddenly stretches the couplers and could break the coupling chains. A sensible railroad engineer would start off gradually with knuckle couplers, else could break the couplers - similarly with chain couplings. (the jerk of course is the one in the couplings, not the one in the cab !!!)

[jchnhtfd]

QUOTE: Originally posted by Murphy Siding

QUOTE: Originally posted by Railroading_Brit
the guard would be expected to keep the train stretched using the brakes on his van to avoid snatching.

Snatching? What would we call that? Thanks

.

Slack run-out.

Couple of other notes -- many US passenger trains have very little slack action, in spite of standard draft gears, because it is taken up with buffers between the cars. They're light enough so that they can start as a unit without problems.

Also, in the US, the slack action is much more in the draft gears than in the couplers -- the couplers should have very little slack (they have to have some), but the draft gears may have anything from several inches to several feet, depending on the gear.

[Murphy Siding]

QUOTE: Originally posted by jchnhtfd

Also, in the US, the slack action is much more in the draft gears than in the couplers -- the couplers should have very little slack (they have to have some), but the draft gears may have anything from several inches to several feet, depending on the gear.

Several feet of slack per car? I always thought it was just a couple inches per car. What kind of cars would have lots of slack built into the draft gear? Thanks

[Hugh Jampton]

The old cushion cars had long travel draft gear.

[Murphy Siding]

QUOTE: Originally posted by Hugh Jampton

The old cushion cars had long travel draft gear.

OK What's a cushion car? Thanks

[CSSHEGEWISCH]

QUOTE: Originally posted by Murphy Siding

QUOTE: Originally posted by Hugh Jampton

The old cushion cars had long travel draft gear.

OK What's a cushion car? Thanks

A cushion car usually refers to a freight car equipped with long travel draft gear and hydraulic cushioning in the underframe. Many were prominently lettered as being equipped as such: Shock Control (ATSF), Smooth Cushioned Load (Seaboard Coast Line), etc. They were often found in auto parts service.

[Murphy Siding]

The hydraulic cushioning makes sense, but why the long travel draft gear? Wouldn't having more slack make for a bumpier ride? Thanks

[Hugh Jampton]

Not necessarily, a second rate engineer could probably get a train going along like a slinky, but the hydraulic cushioning provides what dynamicists refer to as a heavily damped response where motion in the draft gear is stopped.
The extra travel in the draft gear reduces the likelyhood of it "bottoming out" which is when the actual shock occurs. The springs in the gear are also non linear, where they get stiffer as they are compressed which also helps to reduce the motion.

[jchnhtfd]

QUOTE: Originally posted by Hugh Jampton

Not necessarily, a second rate engineer could probably get a train going along like a slinky, but the hydraulic cushioning provides what dynamicists refer to as a heavily damped response where motion in the draft gear is stopped.
The extra travel in the draft gear reduces the likelyhood of it "bottoming out" which is when the actual shock occurs. The springs in the gear are also non linear, where they get stiffer as they are compressed which also helps to reduce the motion.

Oh what a lovely image! I can see it now...

But Hugh's got it: all the cushion draft gears had some form of hydraulic dampening (except a few very early ones, which were friction and didn't work for beans). Both it and the springs were deliberately non-linear, so even if you had a really ham-fisted engineer it was almost impossible to bottom the gear in normal operation. You could bottom the gear, however, in hump yards; there is a very definite limit to how much impact could be absorbed. Many of these cars were used to transport more or less delicate stuff, though, and were not supposed to be humped.

[Simon Reed]

Sorry it took a while but....

916 preserved narrow gauge steam loco's - that's from 15" up to standard.

Quite a few of these will be "new build" - ie. constructed within the last few years specifically to work on preserved or restored railways.

[daveklepper]

Are some of these 15" gauge locomotives actually model locomotives, models of standard gauge? Or would that be a separate listing?

[Murphy Siding]

Something came up on another thread that made me wonder....as it always does. British steam locomotives were built with inside cylinders because of -why? Was it just tradition, that the first one was built that way, and everybody followed? Were all the standard gauge locos built that way? Surely, the narrow gauge, especially the 15" mentioned above were outside cylinders. Thanks

[Hugh Jampton]

So that 916.. is that an in steam total is it?

Thay never all had inside cylinders, I'm sure most steam running in the UK have the cylinders outside the frame. Obviously in a 3 cylinder loco the 3rd cylinder is between the frames.
A lot of UK locos used the Stephenson valve gear which have the motion between the frames. This is different to the Walschaeartes(?) gear which is comon in the states and on later UK locos where the motion is outside the frames. (there are other types of motion)

Look at an original Bullied Pacific, it's got connecting rods between the drivers and a connecting rod from the mid driver to the outside cylinder. Although these have Bullied's own chain driven affair). Compare that with something like a Class4 tank engine which has that Belgian guy's motion.

it's pronounced bullyed round our end, like whay the bully did

[Tulyar15]

QUOTE: Originally posted by Murphy Siding

Something came up on another thread that made me wonder....as it always does. British steam locomotives were built with inside cylinders because of -why?

Not all British steam locos had inside cylinders - Rocket and Locomotion and most early had outside cylinders. What they found early on was that by positioning the cylinders inside it reduced sideways vibrations. Of course as cylinder (and loco's!) got larger it became necessary to put the cylinders outside.

Some pre-1923 railways in Britain favoured inside cylinder locos on lines where clearances were restricted. Examples included the South Eastern & Chatham (which had the notorious Hastings line with its narrow tunnels - this line needed special narrow stock until it was converted to standard British loading gauge in the 1980's), the Great Eastern and the Furness. This last line built some large (by British standards) 4-6-4 tank engines with inside cylinders.

[Simon Reed]

916 is my count from the Industrial Railway Society's most recent list and will vary, I'm sure, between loco's used on a regular basis and rusted frames which will never move again.

Many of the 15" loco's are based, more or less, on prototypes from standard gauge, whereas others are strictly freelance. A 15" gauge working loco is a fair size and would'nt really constitute a model.

[John Bakeer]

Cushion cars in UK were known as Shock Vans & Wagons. The body was shorter and mounted on spring dampers within the vehicle frames in order to absorb the shocks caused when the slack was taken up when starting a train of loose coupled stock.
To day all stock is close coupled using screw links as in passenger stock.therefore snatching is no longer a problem.

[John Bakeer]

There are more LERTS in Stockport thanks to emigration from Yorkshire.
Who are you Hugh? I've a feeling that I've met you.

[CSSHEGEWISCH]

At the risk of opening up a can of worms, what exactly was OVS Bulleid's chain-driven valve gear, and how successful (or not) was it?

[Murphy Siding]

A photo and caption from an old magazine reminded me of some discussion we had on here a time back. From the August 1996 issue of Railfan & Railroad magazine: "Wisconsin Central painted the first loco for its English,Welsh & Scottish lines in U.K. The 37057 [i]Viking[/] (left) was just out of Totton shops on April 23,1996. The Class 37's are the "Alco PA's" of England".
A little blurb later in the magazine mentions that the units "have been painted .......with safety-mandated yellow ends", something I didn't know.
I do believe the railroading roots run a little deeper in Britain, than in the U.S.

[Anonymous]

I suspect the problem with the Bulleid valve gear was just that it was ahead of its time. Judging by the information I found here http://www.semg.org.uk/steam/mn_01.html there was nothing inherently wrong with the design, it just took rather more care and attention than could be provided.

Yellow ends were brought in (if I remember rightly) due to the new diesels being a lot quieter than steam. A steam loco at speed made a lot more noise giving MOW crews time to get off the line, but a diesel could appear with very little warning.

[Anonymous]

There is a picture of Bulleid Chain drive in "British Pacific Locomotives" by C.J. Allen, a very good book but very English. There must be a picture of it on the web somewhere as it is a very difficult gear to describe, but if you see a diagram of it all becomes clear. It cannot have been all bad as BR did not bother rebuilding all the Bulleid pacifics and the unrebuilt ones lasted to the end of steam and several unrebuilt ones still run with the gear.

[malcolmyoung]

QUOTE: Originally posted by CSSHEGEWISCH

At the risk of opening up a can of worms, what exactly was OVS Bulleid's chain-driven valve gear, and how successful (or not) was it?

It was basically three miniature sets of Walschaert's valve gear driven by a chain from the driving axle and all enclosed in an oil bath. Problems were caused by the chain stretching which didn't do the valve events any good, and the supposedly oil tight casing leaking oil onto the track causing the drivers to slip. All the Merchant Navy class were eventually rebuilt but not all the Battle of Britain/West Country class were rebuilt and a few are preserved in their original form. The rebuilds consisted mainly of fitting three sets of conventional Walschaert's valve gear and removing the semi-streamlined shrouding, making them a lot better looking locos in my opinion.
Malc.

[mhurley87f]

QUOTE: Originally posted by Townsend

There is a picture of Bulleid Chain drive in "British Pacific Locomotives" by C.J. Allen, a very good book but very English. There must be a picture of it on the web somewhere as it is a very difficult gear to describe, but if you see a diagram of it all becomes clear. It cannot have been all bad as BR did not bother rebuilding all the Bulleid pacifics and the unrebuilt ones lasted to the end of steam and several unrebuilt ones still run with the gear.

IIRC, in his book on Bulleid's Pacifics, Winkworth (or was it Brinkworth) stated that a conscious decision had been taken to retain a number of unmodified West Country / Battle of Britain locomotives for the peak summer trains on the ex Southern Railway North Deven and North Cornwall branches, whose axle loading limits would have precluded the use of the Modified members of the class.

Martin

[Simon Reed]

Rather prosaically, I seem to recall that another problem with the valve gear on the unrebuilt examples was sheer inaccesibility.

Despite that I think both versions were fine looking. I've not had time to find decent photo's to paste, sadly.

[germanium]

The rebuilt "Merchant Navy" class were IMHO one of the most handsome machines to run on British rails (rather like the Midland "Duchess" class (also a Pacific). The overall conclusion on the Bulleid Pacifics would seem to me to be "great boilers, shame about the rest".
Townsend is right about some of them not being rebuilt, but I believe this was more to do with lack of interest in rebuilding steam locomotives with a short limited life, rather than any virtues or otherwise of the original valve gear.

[John Bakeer]

What about OVS's Leaders then? Now they were something else, I believe only two were built. I seem to remember a "Loco Profile" or some such was published about twenty years ago.