European freight yard operations vs US Operations

Really? The high pressure engine was somehow pivoted separately from the frame? Model mfgrs do this all the time to enable reduced radii, but a prototype? How'd they manage it? Drawings, please.

Not true!

They didn't. The boiler was attached to the rear engine and only the front engine was free to pivot.

The Garratt had a problem which the Mallet didn't have. As a Garratt consumes water and coal, it's weight for traction becomes less thus TE reduces as the train rolls along. By having a conventional tender, this doesn't happen to the Mallet which retains all its weight for traction although it does have to lug the tender around.

The Garratt is probably more limited in water and fuel capacity too shown by some African Garratts having a water tank wagon connected.

See MRR's Loco 1: steam locomotives, p. 235ff. Ther are also lots of photos showing how the front engine swung away from the main engine on curves.

Tha back end of the engine frams was pivoted to the main frame, the front end had a centering arrangement, and the steam lines had rotoationg glands and sliding joints.

FWIW, in the 70s IIRC, MRR ran a series of articles on upgrading an HO Big Boy, which included duplicating the front end centering system: two facing shallow vees with a roller between. the weight of the loco tended to keep that roller centered.

HTH

wolf k.

Thought so - thanks for the confirmation.

I know that the front engine (low pressure engine on a Mallet) pivots - I work regularly as a docent describing SP's AC-14 #4294, the only surviving cab forward. In fact, we have a clamp lamp attached under the frame shining on the pivot point - although most visitors don't notice unless it's pointed out. But the rear (or in the case of a cab forward, the front) engine, to my knowledge, was always part of the rigid main frame in North American articulateds, compound or otherwise, with that engine, the cab and firebox and boiler always maintaining the same alignment while the engine under the smokebox end of the locomotive swiveling to either side while supporting the boiler on a sliding bearing. Do you mean otherwise?

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.

The Meyer and Kitson Meyer engines did this. As did the Beyer Garrats, Fairlies and Masons (Mason's first articulated engine was laid out like a double Fairlie: two boilers with the cab in the middle and two power trucks.

But if a Mallet did this it wouldn't be a Mallet in thr first place.

The first Garratt, which was a compound:

Yes, I remember seeing UK LMS Garratts as a kid, on the Birmingham - Derby line. Always scruffy and very dirty. They were not very successful, I understand that the wheel bearings were under sized, against Beyer Peacocks advice. I think I've got that right. They had a peculiar 'cement mixer' rotary coal bunker.

You got your attributions wrong. That was a quote. (That's what the little " marks mean.)

But not impossible anyway as the Beyer-Garretts did exactly that: both engine units swiveled with the boiler suspended between and above them.

~Pete

Auxiliary tenders were not terribly uncommon in the dry American southwest either, and today the Union Pacific's Challenger 4-6-6-4 runs with not only it's own tender but with two additional auxiliary water tenders salvaged/converted from old gas-turbine tenders.

An AC-14? Cool!

I always thought they stopped at AC-12! };-P

~Pete

Steve Caple wrote: [...] But the rear (or in the case of a cab forward, the

No, I understand it just the way you describe it.

Cheers, wolf k.

Yes to both.

They were too big for the lines they ran on. They could pull trains too long for the yards, and sometimes the weight of the train broke the couplings.

It had been the Midland Railway's practice to use double headed

They wanted to replace these with a bigger engine. A Garrett is ideal for this sort of thing, but as you say, they retained too many standard Midland features that didn't get thrown out until Stanier took over, one of which were the poor axle bearings.

A less known problem is that the water columns were placed for double headed 0-6-0s. And the Garratts had different spacing for the tank fillers. So they would have to stop, fill the front tank and then draw forward, doubling the waiting time.

But where from? Wikipedia?

Yeah, steam lives! (the docent's parking lot shows a lot of stickers with a feather that say "WP Lives") Anyway, dyslexic fingers strike again.

And now you can get a 1:20.3 scale model for only a 50th of the original AC-12 cost.

Yep, Wiki. Edited to remove "two swiveling" and also "USRA" in reference to first C&O 2-6-6-2 order in 1911, before USRA existed.

Good for you.

I noticed both of those, but I don't know how to correct a Wiki article so I left 'em be.

~Pete