Re: Detail of AAR 1937 boxcar - Murphy and Hutchins Roofs


buchwaldfam <duff@...>
 

Ted,
The MM article which covered the Milwaukee Road rib side cars
had a table which showed the various doors, ends, and roofs used on
each series. Several series were listed as having Hutchins roofs.
Photos show these to be single rectangular raised panels like the
Murphy. Just trying to get it straight in my head: there were
rectangular panel roofs which were marketed under the
name "Hutchins"? This would make sense out of the table in that
article.
Also, along with the discussion about single sheet vs multi-
panel roofs: The Milwaukee cars' roofs were welded at the seam caps,
which effectively made them one piece roofs. But the West Milwaukee
Shops were huge, very modern facilities (for the 1930s, at least!)
which could handle picking up a 40' x 9' piece of sheet metal. Were
other railroads' repair and construction forces geared to handle
this big chunk of steel? Take a look at the D&H chapter in the 1932
car book and there's a good picture of a roof being assembled by
hand. Let's assume that the roof would be built up out of two
halves, with the seam running longitudinally under the roof walk.
For a 1/4" thick sheet metal roof, that's roughly a 40' x 4.5' sheet
of steel. My Ryerson book says that 1/4" sheet weighs 10.21 pounds
per square foot. So that half-roof weighs 1840 pounds. That gets
kind of hard for two men to handle! On the other hand, a single
panel of a Murphy roof (12 panels) weighs about 150 pounds, which is
starting to sound like a two man job.
My money is on several of the theories already presented in
this string: Transportability, and repairability. Repairability
includes both the ability to have one damaged panel replaced, as
well as being able to handle the panels with reasonable size crews.
(I'm lumping railroad built or upgraded cars into the "repair"
category, since they would use the same facilities and crews.)
Now, to consider the reasons for making stamped car ends in
two or more pieces. If it was a matter of having large enough
presses to make the end in one piece, then how come there is a
horizontal seam in flat panel ends, such as those on the X29 cars?
The answer lies in the gage of the sheet used for the panels. On
both flat panel and the various corrugated ends, the bottom panel is
thicker than the top panel to resist the loads from shifting lading.
Going from 1/4" to 3/16" sheet on, say, a 9'x 5' upper end panel
saves 115 pounds. Hey, everything adds up. On refrigerator cars such
as the Phaudler cars which we've been discussing, the seams run
vertically. Because the lading is in tanks, there is no shifting
freight hitting the ends, so the lower portion of the ends does not
have to be thicker.

Sorry for drifting here... I find this structural stuff
fascinating!
Regards!
Phil Buchwald
>
Steve:

A shameless plug, but refer to the 1932 ARA box car book
(www.speedwitch.com) for more info on these two types of roofs.
The
Hutchins roof on C&O 4000-4500 is actually a "Murphy" rectangular
panel
roof manufactured not by Standard Railway Equip. but by
Chicago-Cleveland. For our purposes (HO scale), they are same and
the
differences are quite subtle anyway. These cars did NOT have the
Hutchins Dry Lading roof of the 'teens and 20s. They just used
the
same name on them. The radial roof on the 1932 ARA cars is a
Hutchins
radial roof.

Regards,
Ted Culotta

Speedwitch Media
645 Tanner Marsh Road, Guilford, CT 06437
info@s...
www.speedwitch.com
(650) 787-1912

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