I didn't want to derail the other guys post anymore than I already have so. I was told deciding which FVM wheel sets I use (33" or 36") would depend upon the load capacity of the freight car. Using my trusty Atlas 90 ton hopper as an example again, first off I realized my eyes are going bad. Went to the store and picked up a little pocket sized lighted magnifying glass in 3x power. Which has given me another newbie question.. Why does atlas call this thing a "90ton hopper"? The side of the car reads: CAPY 204000 LD LMT 204600 LT WT 58400 First, what do those numbers mean and more importantly where does the name 90ton hopper come from? Isn't 90 tons 180,000 pounds?
WWwweeeeelllllll....if my age hasnt messed me up to bad...and my math isnt as bad as it was in high school...90 tons should be 201600 pounds. So 204000 would be close enough to 90 tons I would think. That would be in 'long' tons of course....JMO * yes....180000lbs. would be 90 tons in 'short' tons .
I guess I just showed my ignorance because I thought a ton was 2000lb and had no idea there were "long" and "short" versions. I didn't graduate at the top of my class so that doesn't shock me LOL
Matt - I didn't graduate top of my class either. You have the creative edge as did I. Find a strong partner who will channel it and you will be a very happy person. As for wheels and tons? Yikes! Don't confuse me with the details. edit: I do admire your care in not derailing the other thread. Kudos.
Grey One, thanks for the kind words George, thanks I will make a note of that. Learning is fun (when it's about trains) LOL
1 tonne = 1000 kilograms down here, our tons were 2240 lbs but we got rid of them in 1974.:tb-biggrin: Reference to a hopper or other car as 90, or whatever, tons may not be an exact weight it can carry but a general description for cars around that size. Often if you look at a car's lettering under a magnifying glass you can see somewhere '36" wheels' as the real railroads shop forces also have to know what size wheels a car takes, if you find that on a model or a prototype car any similar cars will probably also have 36" wheels. Also someone will correct me if I'm wrong, but I think 36" wheels were less common under the lighter cars of the steam era.
I think you're right. In fact I thought the size of the wheels was more time based than weight based, but I was confused as always. LOL
Looking at the Atlas 90 Ton Hopper with the magnifying glass again (gotta love N scale lol) it has "12-80" on the side. I'm guessing that is a rebuild date? Or is it the build date? How can you tell?
The decal is wrong. CAPY is supposed to be a structural capacity of the railcar. As it is, it's not used anymore.
Load limit is NOT the loaded weight of the car on the rail... it's the rated capacity of the trucks minus the total car weight. The Atlas car is called a 90T hopper becuase it's a compromise car. When the Atlas model was made in the 70s, they had no correct 100T truck (i.e, 36" wheels on a 5' 8" axle spacing), so they used the 70T truck they did have and just called it a 90T hopper. As built, the prototype was a 95 ton car, later uprated to 100 tons concurrent with the AARs raising of axle limits on 6.5 x 12 bearings from 251K to 263K in 1961.
WOW! It's guys like you who make me realize how very little I know about trains (and I mean that as a compliment) Thanks for the info!
Thanks for the unneeded correction. I had already changed the information as I misstated what I was trying to point out in the issue. The problem is I've never seen a 251K, 255K, or 263K car which has a CAPY within a few hundred pounds of the LD LMT. Usually the unit will volume out prior to making LD LMT and do so by a fairly significant margin. A good example of this can be seen here - http://www.rrpicturearchives.net/showPicture.aspx?id=85754 Note the CAPY is almost 10,000 pounds lighter than the LD LMT because the car can't physically hold the full 164,000 pounds of commodity.
Wow, very interesting. I was a bit curious about that myself since I was looking at 100 ton hoppers in G scale and then thought: "so why are those N scale hoppers 90T?". And don't feel bad about the math thing at all. I'm majoring in chemistry and astrophysics, and until today I had no idea that there were two different "ton"s. I would have assumed 2000lbs as well. But then again we science types always like kilograms more : )
Yup... ...and if you take the 102 minus the 90 = 12 and divide that by pi r squared...add the length of the hopper....minus the width...multiplied by the number of axles...divided by wheel diameter...add the depth of the car...and....and... ...you go back and remember that when you took the 12ton difference and divided that by pi r squared you suddenly realized pi arent squared...pie r round and cake r squared... ...you rip the paper off the pad...wad it up...and trash it...and go with the explaination robbman posted above... :tb-tongue::tb-biggrin::tb-biggrin: .
