I did a quick search of the site but found very little on radial roofs.
Were the Central Valley radial roofs (from the CV stockcar) specific to
the NP or could it be used on other roads' cars? Did other
manufacturers of radial roofs use a more prominent seam cap on their
roofs? Obviously the general shape of the roof is not difficult to
model but the ribs would be. I have some old Silver Streak roof ribs
(stamped metal) which were an excellent idea but probably not very
close to scale given our current injection molded roofs.
On Dec 18, 2008, at 10:01 AM, dssa1051 wrote:
I did a quick search of the site but found very little on radial
The CV roof represents the NP's unique "circular" outside metal roof,
which (AFAIK) was not used by any other RR.
Did other manufacturers of radial roofs use a more prominent seam
Yes, and on the Hutchins, Viking, and Murphy radial roofs the curve
or arch of the roof was shallower. Also, both the Hutchins and
Murphy roofs had small intermediate stiffening ribs in each panel,
and the Viking roof had two such stiffening ribs in each panel.
Does anyone have any ideas or tips for modeling a more typical radial
roof than the NP style? Does any manufacturer offer a separate
injection molded or resin roof rib that could used on a roof whether it
was peaked or radial? It could be useful in modeling a flat panel roof
--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
Mr. James Dick of the Northern Pacific Railway Historical Association
sent me copies of a bunch of NP company correspondence about these
roofs, which unfortunately raises more questions that it answers. Many
of these letters appear to be testimonials in response to a request
for same having been sent out by Mr. H. M. Robertson MCB of the
Northern Pacific Ry.
Here are some highlights:
A letter from the Twin City Joint Car Inspection Association dated
9/11/23 refers to the roof as the "Gilman-Robertson Circular Roof."
and states that it dates to 1909. It also states that the
Chicago-Cleveland Car Roofing Co. are to sell this style roof.
There is a memo from the NPRy. Mechanical Dept. dated 12/26/24
comparing the weight and cost of the "N.P. Composite Circular" roof to
the Hutchins All Steel roof and the Murphy X.L.A.
There is a request of information from the Norfolk Southern Railroad
dated 2/2/26, and the response on 3/8/26 which claims that, "This
construction is covered by a patent issued to our master car builder,
Mr. H. M. Robertson, and I understand the royalty for use of same is
$1.00 a car." However, I have not been able to confirm the existence
of this patent.
There is a letter addressed to Mr, Ralph Simpson, Mech'l Eng'r, Mps.
St.P. & S. Ste. M. Ry. (Soo Line) dated 6/21/27 asking if he would
please send, "a duplicate set of prints showing Mr. Robertson's design
of circular roof applied to the 500 boxcars which you recently had
built." Mr. Simpson responded in the affirmative 6/25/27. I feel that
this confirms that the arch roof cars the Soo had built in the late
twenties did indeed use the same roof the NP was using.
A letter dated 8/8/27 that appears to be signed by H. M. Robertson
concerning a inquiry by the Milwaukee Road states, "I informed him
that the patent covering the roof construction had been sold to the
Hutchins Car Roofing people." This surprises me, as the Soo purchased
additional cars with this roof in 1928, 29, and 30, and the Soo
equipment diagram claims the roof is Chicago-Cleveland.
There is a letter dated 8/11/27 to the Mech. Supt. of Fruit Growers
Express that states that the roofs on the NP 93000 series of
refrigerator cars, "were purchased from the Hutchins Car Roofing Co.
and that company also controls the diagonal roof board construction."
Speaking of the construction. These were simple outside metal roofs,
the light guage sheet metal being supported by wood sheathing. Reading
this correspondence, I realize the design intent was to allow the
entire roof to be one unbroken plane, so that the sheathing could be
laid at a 45* angle to the car, which improved the stiffness of the
roof structure and lessened "weaving", the tendency for the roof to
rack back and forth. This plane was bent into a gentle arch and
covered with sheet metal to shed water, but the important part of the
design was the diagonal sheathing.
As far as I can tell from this correspondence, while several other
roads inquired about the design, only the NP and Soo actually used it.
Interesting stuff, Dennis. Thanks for posting it, and to Jim Dick
for making it available. I knew that roof had been invented in the
NP mechanical department but wasn't aware that the Soo had also used
it, or that the patent had been sold to Hutchins.
--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
Guy Wilber was nice enough to send me a copy of the Gilman – Robertson
patent; it is No. 1,155,563, issued Oct. 5, 1915. Those interested in
seeing it can go to the USPTO web site at:
http://patft.uspto.gov/netahtml/PTO/srchnum.htm and search on the
When I first went through the correspondence that Jim Dick sent, I was
hoping to be able to write the definitive history of this roof design,
but the fact that two vendors are cited, and the fact that the Soo
Line diagram for cars built three years after Mr. Robertson claims
that the design is "controlled" by Hutchins still list the roofs as
Chicago-Cleveland has left somewhat of a muddle. In reality, it
supports my growing suspicion that while each of the roof suppliers
had there own designs that they advertised, each of the three also
likely made components that fit their competitors roofs, which is why
Bill Welch can find paperwork that shows the FGE cars were re-roofed
with Hutchins products, even though some of the roofs physically match
drwings of Chicago-Cleveland "Zenith" roofs, and the Soo could
continue to purchase circular roof components from Chicago-Cleveland
after Hutchins was also selling them.
In the interest of providing a complete roster of cars using the NP
style Circular roof, other than the NP itself, I offer this list:
SOO 2600 - 2609 MILK SOO AT SHOREHAM 1925
SOO 134400 – 135398(e) BOX Pullman 1926
SOO 40200 – 40598(e) BOX Pullman 1928
SOO 40600 – 40998(e) BOX Siems-Stembel Co. 1928
SOO 41000 – 41398(e) BOX Pullman 1929
SOO 41400 – 41798(e) BOX Siems-Stembel Co. 1929
SOO 135400 – 135798(e) BOX Siems-Stembel Co. 1930
The Boxcars can all be modeled with variations of Sunshine kit #78,
except the cqrs built in 1930, which had bottom supported doors that
Sunshine missed. The Soo milk cars were recently the subject of a
construction article by Dave Lieder in RMC within the last year or two.
One might wonder why both the NP and the Soo stuck with what would
appear to be an antiquated roof design after several vendors began
offering "all steel" or "solid steel" roofs that would seem to be a
better solution to the "weaving" problem. Mr. Dick sent me an equally
thick batch of correspondence concerning damage claims from millers
where warm flour had been loaded in steel roof boxcars during the
winter, and the moisture in the warm flour condensed on the inside of
the unlined roof sheets and rained back down, soiling the top of the
load. It would seem that both roads having heavy involvement with
traffic out of the Minneapolis milling district, saw value in
continuing to use roofs having wood sheathing on the exposed underside.
I'm not sure what changed to make both roads adopt the AAR design
boxcars with their unlined steel roofs in the thirties.