Re: K-28, was K-36 and K-37

Earl Knoob

Another fun little item is the boiler diameter shown is the first course, which is generally the smallest diameter of the entire boiler.  Even straight top boilers get bigger as the go to the rear.  The smokebox is usually bigger than the first course as it telescopes over the first course.  The second course telescopes over the first, and on down the boiler.  So, even a straight top boiler is larger in the rear that at the front.  Each course is larger by twice the thickness of the barrel steel, which is at least 1/2" or 5/8" thick.  Some (like 463) are 3/4".  So, the fully lagged and jacketed boiler could be 4 or 5 inches larger at the firebox end of the boiler than is shown in a folio drawing.

From: <> on behalf of John Stutz <john.stutz@...>
Sent: Wednesday, May 29, 2019 12:04 PM
Subject: [HOn3] K-28, was K-36 and K-37
Jim & Earl

Regarding folio and similar measurements:  The D&RGW locomotive diagrams
issued in the 1950's, and formerly available from the Maxwell
Collection, do indeed show boiler barrel "OD"s. This is a contrast with
the industry's standard, which is to give the inside diameter of the
front sheet.  So Earl's additional 3-4+  for lagging should be added to
a model boiler.   And misinterpretation of such dimensions is doubtless
why some models come up so short on visual boiler diameter.

For the K-28s we have much more much more specific information, from a
seven page ALCo publicity piece in the Railway Review of January 24,
1925, V 76, No 4, pp 179-185.   This was also formerly available from
the Maxwell Collection, but I believe it is now online, possibly as the
'Railway & Engineering Review".   The table of dimensions and quite
detailed drawing both give the following:

       Diam, smoke box                      65 3/4"

       Diam, first course, outside      63 1/2"

       Dim, second course, outside  66 1/16"

However such sources rarely if ever give any details about the lagging,
so I cannot improve on Earl's dimensions.

This ALCo publicity piece is an unusually detailed exposition of a
locomotive's design goals, the means by which they were achieved,  and
the operating results.  It is essentially a demonstration of the
advantages to be expected from modern 'super powered' steam, although
the ALCo publicist never even hints of that phrase.  The K-28 was a 
thoroughly modernized K-27, incorporating all applicable elements of the
intervening 20 years'  improvements in steam locomotive design.  In the
K-28, the D&RGW obtained an engine that could take a K-27's load
wherever a K-27 could go, while making remarkable savings in fuel, water
and time over the road.  Regarding NG operations in 1924, the ALCo
publicist reports that "For the first six months of this year ton miles
per locomotive mile have increased 13 per cent; freight train speed has
increased 22 per cent and gross tone miles per train hour have increased
35 percent."   Much of the improvements was doubtless due to the
increased number of heavy NG freight engines, from 15 to 25, but it was
clearly the K-28s' performance in freight service that justified
upgrading the principal NG lines with rail and bridges heavy enough to
allow introduction of the K-36 and K-37 classes.

John Stutz

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