Re: Dished Tank Head

Tom Birkett <tnbirke@...>


Remember that as you are looking at a photo of a Class V car that you
are looking at the jacket head and not the tank head. The shape of the
tank head is "semi-ellipsoidal" in general but the 1930 American
Railroad Association "Specification for Tank Cars" under "ICC-105A300"
states that "the tank head shall be an ellipsoid of revolution in which
the major axis shall equal the diameter of the shell and the minor axis
shall be on-half of this." I think this is enough information to answer
your question. I'd have to pull out some old math books in order to
write the equation for the tank head.

The lagging is to be 4" between the exterior of the tank and the
interior of the jacket. The jacket is specified as 1/8" thick.


I'm building a cad model of a UTLX type V tank car per the drawings
found on
page 344 of the 1906 CBD. I have a question about the term "Dish" as it
relates to the tank head. I hope some of you guys can help define **an
aspect of the term** that I don't understand.

It is apparent to me that "dish" refers to some how far the metal has
pressed so as to form the tank head - afterall, looking at the pressed
from the inside of the tankcar, it would look like a dish. My question
when the drawing says a 6" dish, that dimension is between two points.
is obviously in reference to the furthest point out that the steel has
pressed - but 6" from what relative to the anything else? And is that 6"
dish measured to the inside or outside of the head?

Looking at photos, what I see is the car end is a solid sheet of steel,
after being pressed into a dish, retains some distance of metal that
tightly into the tank, for use in riveting end to tank. That is to say,
extending beyond the dish itself is a steel cylinder, marginally more
than the tank itself. A small portion of this inserted cylinder remains
exposed, just outside the end of the tank. This cylinder begins to curve
inwards, oh, on perhaps a 1 inch radius and then takes on the outlines
the dish.

So. is the 6" dish relative to the end of the car, the end of the
where that 1" radius curve begins, or right where the dish form begins?

Yeah, I know. some of you HO scale guys are going "you gotta be kidding
right?". Nope. It's getting the model done correctly.

Can anyone help me out here? Ummm, I think I should also ask, anyone
of where I might find a more complete drawing(s) for anything of this
I'm also wanting to do the X-3 design after this one.

Thanks in advance!

Dave Nelson

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