Does anyone know right offhand what the maximum aggregate size (OD) would be for USRA 55-ton and GLa and 70-ton 2-bay hoppers? Or, to put it another way, how wide do the louvered doors open on these hoppers?
Thanks for the help…
Tom
Since they were designed, for coal the biggest coal sizes are about 8" in diameter.
However most aggregate is a smaller, 4" or less, size. Most aggregate is less than 2" in diameter.
If they are like more modern hoppers, the doors swing from sloped to vertical, leaving a pretty wide opening. Still, I wouldn’t put rock larger than 8 mor 10 inches in size in one and expect it to come out the bottom. Any larger would be hard on the car too. Any larger use a gon or side dump. These can handle rocks larger than a pickup.
So, if I were to use an HO-scale ballast to represent rock (e.g. Woodland Scenics) in an open hopper, the fine (0.9"-2.9") or medium (2.9"-4.3") grade would do the trick. And, I would assume on the prototype that there would be uniformity of stone size in a given hopper?
Tom
About the largest regularly used aggregate is used in septic fields - ranging in the softball-to-grapefruit range.
During construction of the Hoover Dam the largest aggregate (defined as cobbles) was between three inches and nine inches in size. Anything larger went to the crusher and was reduced to (much) smaller size. Altogether there were five sizes of aggregate that went to the concrete mixing plants, ranging from sand through three sizes of gravel to cobbles. Trains running from the gravel pit to the cleaning/sorting plant were tilt-bed side dump gons, loaded with whatever the shovels dug up. Trains running from the sorting/washing plant to either of the two concrete batch plants would have only one size of aggregate in each car, the number of carloads of each determined by the mix being used and the contents of the storage silos at Lomix and Himix. Both standard 50 ton hopper cars and drop-bottom gons were in use (judging from the rather poor quality photos in The Story of the Hoover Dam. The book is a compilation of articles from Compressed Air Magazine, a trade publication for pneumatic equipment manufacturers and users, originally published between 1933 and 1935.)
Chuck (Modeling Central Japan in September, 1964)
Tom.
I have worked for aggregate producers most of my life. Removing sand grading and stone dust size most stone is sold as a nominal size minus. Which means that if you had a hopper full of 1 1/2 inch stone there would also be some smaller stone too. This means that a majority would only pass through a screen with 1 1/2 inches square or round on punch plates. Popular sizes of stone either crushed to size or screened from another source is 3/8 inch, 3/4 inch, 1 1/2 inch, and 4 inch. There are other sizes popular for concrete products and asphalt are 1/2 inch, 5/8, and 1 inch.
The determining factor in what would be loaded into a railroad hopper would be the risk of damage while loading. You would really not want your hopper to have an 8 inch rock dropped into it. Our rock bodies are double walled with oak planks sandwiched between the steel. Railroad hoppers are not built like rock bodies and be damaged very easily with rock of any size larger than rip rap size (4 inch). Larger than 4 inch would probably be loaded onto low side gons or flats by an excavator or loader with handling buckets and grapples.
Pete
Did you mean the other way around, Wayne - i.e. a half-loaded hopper of the limestone weighs ~8 oz and a fully-loaded hopper of the coal weighs just over 4 oz? I’m assuming that an 55-ton open hopper of ballast would also be only partially full?
Tom
For the real ones, a half-load of stone weighs about the same as a full load of coal, around 50-55 tons (that’s the capacity of a car similar to the Athearn model).
My Athearn cars, with a half-load of stone (loose limestone screenings) weigh just over 4oz., while the same cars fully-loaded with coal weigh 8oz. That’s because I use a sandblasting medium called Black Beauty instead of real coal. It actually looks more like Anthracite than soft coal, but it’s a lot cleaner and I got about 30lbs. of it for free. It’s made from coal and slag, and while some of it is slightly magnetic, it hasn’t caused any difficulties.
Here’s a hopper loaded with it:
For my locomotives though, I use coke breeze - basically fine industrial coke. It’s fairly light, and rather dirty, but I like the looks of it. I use it loose here, too, and because I open the coal bunkers on all my steamers, it’s easy to show them full, half-full, or even almost empty.
Gidday Tom, there may be some helpful information in this post where I asked about Ore loads in coal hoppers
http://cs.trains.com/mrr/f/13/t/211291.aspx
That is if I can get it to link.[banghead]
Cheers, the Bear.