[Genma Saotome]

http://www.elvastowe...eenshot&id=1979
File Name: Union Pacific A-50-4 Auto Boxcar Drawings
File Submitter: Genma Saotome
File Submitted: 19 Feb 2015
File Updated: 19 Feb 2015
File Category: Modeling Reference Material (handbooks, drawings, photos, maps, etc.)

A handful of mechanical drawings that were reproduced in Railway Age Gazette in 1919... should be enough information to make a 3d model.

Pages are reproduced here about 4X larger than the originals -- THAT"S VERY LARGE -- because many of the dimensions in the original size were hard to read. I suggest you re-sample copies of the images to some lower size for practical use and retain the originals only as a "safety net" while making any models.

Click here to download this file

[captain_bazza]

Dave, is the top car what's called 'outside frame? Were they for transporting vehicle parts between factories? I doubt you'd get more than one built-up "Yank tank" aboard?

Cheers Bazza.

[Genma Saotome]

Actually it's just the drawing showing what was underneath the exterior steel sheathing. But you do raise a question worth answering and that is what are the different types of trusses used in building boxcars.

From the earliest years of building boxcar and the mainstreaming of the all steel monocoque boxcar there was always a truss built into the car sides -- Pratt or Howe. Without a truss the box of the boxcar would bend apart on its longitudinal axis with the ordinary buff and slack forces found in any train. This is the first all steel boxcar and the truss was included because few understood that the steel sheathing was probably enough to hold everything together.

Once steel was used for the truss on some cars was left exposed to the elements -- what is often called single sheathed. Some people also called it outside braced. On other cars the truss was covered, usually with wood, and that is what is often called Double Sheathed. Both worked equally well. Given it is rather obvious that the Double Sheathed car would be heavier it's hard to understand why any of those were built... which leads to the truss itself and the Master Car Builders who built the cars.

The choice of using Pratt vs. Howe truss was a local choice -- each Railroad had it's own opinion on matters such as that. But facts are facts and the facts of the matter are that the strength of wood comes from compression while the strength of steel comes from tension -- being pulled. One style truss (often I don't recall which) is ideal for supporting materials in compression and the other is ideal for materials in tension. So an all-wood truss should use one truss design and an all-steel truss should always use the other. Master Car builders being conservative fellows. often w/o a formal engineering education. when constructing steel trusses, often stuck with the truss design they knew from years of building all-wood trusses and did so w/o knowing it was inferior. That's why you see both kings of trusses on cars with only single sheathing.

[ED_4]

MSTS/OR could use more of these kinds of box cars. The ones specifically marked for automobile moving. I have the only two or three models ever made that is freeware. And I think two were in Union Pacific markings. The models were made by Larry Gross. And Tim Muir did the texturing. The third one is with the "Auburn Automobile Company" markings. Same model maker for this one and Steve Spivey did the texturing.

But we surely could use a whole fleet of these, for the various railroads. It would be more appropriate for us that love to use steamers. Than to see the giant car carriers that are much too modern for the steamers.