There is a good discussion of the development of the rib sides by the Milwaukee Road in the recently published book, Hiawatha - Nothing Faster on Rails. The new set of Hiawatha cars built in 1936 used Cor-Ten steel and improved welding methods. Those cars had ribs, or corrugations (half round contour belts), above and below the side windows, and the ribs both covered the weld seams and added structural strength.
The Milwaukee Road's experience with those cars convinced them that additional ribs were needed to adequately maintain the integrity of the car sides. Thus equipment built in 1937 had four horizontal ribs. The 1938 cars had 7 horizontal ribs, however two of those ribs between windows were purely cosmetic, so there were five "real" structural ribs. The use of ribs continued in the 1942 built passenger cars. And as older lightweight cars were shopped they often but not always had ribs added.
The horizontal ribs on car sides were really the Milwaukee Road's innovation and idea for structural stability but also for an interesting and unique decorative look on passenger cars. Presumably they were strictly structural on their freight cars and cabooses.
Of course horizontal stamped corrugations had been common on the steel ENDS of boxcars and other house cars from the early days of all-steel cars, with some flat slab-ended cars such as the PRR's X29 as important exceptions. I have even seen a photo of an early steel boxcar where the ends were concentric circles of corrugations, like the bottom of an old frozen orange juice can!
I believe the Soviets copied the Milwaukee Road's idea for horizontal ribs and I have also seem them on photos of older Chinese rail equipment although that might have been Soviet built or designed.
Dave Nelson
I've spent some more time studying the plans for the MILW 40' box under duscussion. The plans, incidentally, appear to be for the final version of the car, as opposed to the one Exactrail did. They are in the 1953 Car Builders Cyclopedia.
One thing I noticed is that what I took for a rivet or a bolt (to attach the sheet) looks like, on closer examination, a very small rib. It's not much taller than the thickness of the sheet metal. It doesn't look to me to be big enough to add much rigidity to the sheet. It perhaps is there for assembly purposes.
So, on this further investigation, it appears that the side sheets were 13'-11" long, 19 1/2" wide (tall) and had a small horizontal rib maybe 1/8" high 1 3/4" down from the top, and a much larger one (the one we see) 1 3/4" up from the bottom. This one is about 3/4" high and 1 1/2 wide.
It's interesting that the side sheets were .067" (1/16") thick. On a typical boxcar, they were .010". Also, the MILW car had 16 side posts, while an AAR had 10. Depending on how one counts. So it would appear that MILW wanted to use thinner side sheets, but felt compelled to close up the spacing between posts.
The sideposts on an AAR car are 42" apart. On the MILW car, they are 26". It appears that one could have made a boxcar in the AAR style with thinner side sheets and more posts.
It's interesting that MILW chose to build the car sides out of sheet metal strips. Why not just put up panels like a regular boxcar? Perhaps it had something to do with the assembly process. Remember, the car was welded, not riveted.
Another reason to have that rib there could be to allow the sheet metal to expand during welding without warping the flat element of the side. Essentially making the rib a thermal expansion device.
It would be really neat to learn more about how MILW put these cars together. In this case, the sides especially.
One more thing I see on the plans. The ribs are not "ribs", they are "Bumps".
So we're talking about a bump sided car. Right?
Ed
7j43kIt's interesting that the side sheets were .067" (1/16") thick. On a typical boxcar, they were .010".
Are you sure about the side sheet thickness of a "typical" boxcar, Ed? 10-mil (0.01") is only 2-3 sheets of printer paper thick. Did you mean 0.100"?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Yes, Tom. It's .10".
Thanks.
On the plus side, at least I know someone is reading what I wrote.
7j43kI suspect many of our citizens would view them as "zip lok access" cars. Americans' free enterprise tendencies can be pretty vigorous.
Cheers, the Bear.
PS. I am reading.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
Guy Papillon Wayne, Do you know if any model of this car exist?....
Wayne,
Do you know if any model of this car exist?....
Not that I'm aware of, Guy. The CPR did numerous "experimental" cars, with only, at most, a few examples built of each. Another one was a Fowler Patent single sheathed boxcar with corrugated steel side panels instead of wooden planks for sheathing.
.....
wp8thsubA major difference between the two appears to be the CP design using separate roof panels, while B&O used a continuous sheet that bypassed this seam. I wonder if anyone with the B&O was aware of the older CP idea when the wagontop was developed?
It's difficult to know, Rob, but the B&O's continuous sheet version was a major improvement over roof systems of that time, when leakage to the elements (especially after the cars were in use for a few years) was a major problem for many commodities. I think that CP's version was more of an early foray into all-steel construction rather than having much to do with tight roofs. The photo is from a book owned by a friend, and it dates from, I think, the early part of the second decade of the 20th century.
Wayne
Semi-related: what is on the inside of the waffles on the waffle boxcars? I know it some sort of "load restraint system," but what does that actually mean?
Here's an interior shot showing the waffles:
Notice the horizontal bars inside the waffles--suitable for straps and ropes.
That's almost too simple an explanation!