operations of rotary car dumper

Hi folks

by seeing the pictures of americans coals trains (here) (here) (here) (here) (here)
I want know how they will be unloaded.
little digression: European trains unloads their bulk goods (coal or iron ore) via gravity.
I heart something about rotary car dumper in the USA and Australia. Are they still in use?


Two facts that i found in the web confirm that;
first

The AAR coupler [...] and has seen only minor changes: [...] rotating-shaft couplers (type "F") introduced for use in rotary car dumpers

Source: Wikipedia 'Rotary_car_dumper' and Wikipedia 'Janney Coupler'
and second these picture: here

Now some questions about the operations of rotary car dumper:
How many cars can be rotate on the same time?
(I think there are many differnt versions aviable, but what is the most common size for a car dumper?)

When i heard about the rotary car dumper for the first time, i thought the single cars have to seperate from the rest of the train and only one car can be rotate. But now i know, that with these F-type couplers the single cars at least mustn't seperate.

How much coal or iron ore can be unload hourly?
Can the leadings engine run through the dumper or have the cars to shove into the unloading facility?

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Now i found these picture (here) : OK, these cars will be unload via gravity. So in the USA there to way possible to unload bulk goods; via gravity or via rotate car dumper.

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At the end, i found these Picture: here
The caption said, that these Hullett Electric Ore Loader can unloads 70 car per hour?! Pretty fast, specially if only uncoupled single cars can be liftet and rotate.


Hope my grammar isn't too bad
Greets

Well, in the US rotary dumps are extremely common, and a significant amount of the coal-hauling fleet is Beth-Gons or equivalents, which have fixed bottoms and so require rotary dumping (or some sort of payloader/backhoe to manually unload, which is rare). I have read of even older dumps (from the 1950s) achieving 1 car per minute, and I believe modern cars are approaching 110-125t loads. The most common coal gondola is the bathtub one (aka Beth-Gon) distinguished by their cylindrical bottoms (two, one on each side of the frame - if your gonna have a fixed floor, why not increase the loading by adding more cubic capacity inside the plate clearance using these cylindrical extensions at the bottom.
Now, as you mentioned, there are high-capacity gravity discharge systems, and these require bottom discharge doors - these look more like standard hoppers of the old days because, well, flat doors are easier than curved ones to maintain. Not sure of the ratio between coal gondolas (fixed bottom) & coal hoppers (bottom discharge doors) on the current US fleet...also, it seems that MSW (household trash) is usually transported in fixed bottom gondola (look like bathtub woodchip gondolas) when not carried in sealed containers.

Edit: I think the Hulett Ore Unloaders are no longer used - apparently about 75 were constructed, and the last one placed out of service in the 1990s.

Unloaded many a coal train in eastern Colorado and western Nebraska at electric generating stations that used rotary dumper mechanisms.
The dumpers that are familiar to me dumped one car at a time.
When all was working as it should, about 15 to 20 cars at 100 tons of coal each could be dumped each hour.
The engine consist would pull the train through the dumper and then spot the first three cars. After spotting the third car the dumper machinery would take over and proceed to pull the train ahead, one car at a time until the unloading was complete.

TB Diamond wrote:Unloaded many a coal train in eastern Colorado and western Nebraska at electric generating stations that used rotary dumper mechanisms.
The dumpers that are familiar to me dumped one car at a time.
When all was working as it should, about 15 to 20 cars at 100 tons of coal each could be dumped each hour.
The engine consist would pull the train through the dumper and then spot the first three cars. After spotting the third car the dumper machinery would take over and proceed to pull the train ahead, one car at a time until the unloading was complete.

TB was the Pawnee one of them?

Thx for the answers!

The engine consist would pull the train through the dumper and then spot the first three cars. After spotting the third car the dumper machinery would take over and proceed to pull the train ahead, one car at a time until the unloading was complete.

Ahh, that the dumper machinery pulls the cars itself is a option too!
Because i thought first, the enignes would pull the whole train through the dumper; with stopping and accelerating for every car; very inefficient.

Does the dumper machinery pull the cars with a winch system or with smaller remote controlled, electrical driven engines ?

Taurus: The train is pulled through the dumper shed via a trackside trolley which is connected to a system of cables and pulleys. A huge arm is mounted on the trolley and this drops down over the drawbars between the cars to provide a pulling point . I was told that the machinery was manufactured in Germany.

git a....: Yes, Pawnee. Spent many a lovely day and/or night there.

Hello
thx for the answer

in the meantime i found this Website, on which some pictures and a video about the Duluths rotary car dumper are available. (below of Entry 'September 21')