Re: Evolution of the K-27

Bill Lugg

John, thanks for the very interesting discussion of the K27 valve replacement program.  So, if I understand you correctly, the OF 2-6-6-2 idea never materialized, right?

In regard to replacing slide valves with piston valves.  This of course would require an entirely new cylinder casting.  Would they have gone back to Lima and contracted for these or is that something they could have fabricated locally?  Likewise for the valve gear parts; were these supplied by Lima or another contractor or fabricated in-house?


On 4/2/20 11:14 PM, John Stutz wrote:

I am not a D&RG guy either.

The Loree evaluation of the D&RG was commissioned in 1917. Mr Hess did the motive power aspects, Those regarding the narrow gauge power were generally ignored. Hess recommended that the K-27 engines be upgraded with piston valve cylinders for better steam distribution, outside valve gear that would be much easier to maintain and less subject to wear and damage, and super heating for the by then well documented steaming improvements. The D&RG's only immediate action was to fit four engines with piston valves.

Repeating O'Berry's quotation of Hess regarding this: "...We find that 5 of these locomotives have received new cylinders in the past 2 or 3 years, and that the majority of the balance of this series will require new cylinders in the near future, account of valve bridges being broken. It would be my recommendation that in applying new cylinders a piston valve cylinder be applied. This style of cylinder would cost about $200.00 more per locomotive than the slide valve type. An outside design of valve should be applied as locomotives pass through the shop for general repairs. With the application of piston valves, cylinders, and an outside design of valve gear, these locomotives would be easy to superheat. As they are the heaviest class of narrow gauge power now on this line, they will undoubtedly be maintained for long period of time."

In a slide valve engine, the valve bridges are the thin walls that separate the cylinder ports from the exhaust port at the valve face, over which the valve body slides to time the inlet and exhaust of steam from the ends of the cylinder. With a broken valve bridge, steam in the corresponding end of the cylinder can exhaust throughout the piston stroke This gives a very uneven pull, and could greatly reduce the available tractive. So with broken bridges cylinder replacement a very high priority, which is doubtless why it was being done. And since a piston valve's bridges are machined in an inserted cylindrical liner, instead of the cylinder casting itself, this explains why the four early conversions were never replaced by the later style, with the valve chambers aligned for outside valve gear.

Hess's recommendations regarding outside valve gear and super heating were not acted upon until almost two years after 10/23 arrival of the K-28s. The K-28s were a thoroughly modern version of the then twenty year old K-27s. They were effectively a super power version, though Lima had not yet publicized the term. A K-28 could take a K-27's load anywhere a K-27 could go, and do it while making significant improvements on either the K-27's time over the road or the K-27's fuel and water use. As the D&RGW's new principal NG freight power, they demonstrated what could be gained by modernizing the K-27s. That program starts as soon as the K-36s arrived to take up the load, and proceeded until falling traffic on the remaining lightly bridged lines could not justify further conversions. By then upgraded track and bridges had allowed the much heavier K-36 and K-37 classes to take over the heavy freight traffic, and the K-28s had been largely relegated to passenger service. The much lighter power remaining from the 1880's did not long survive the unimproved lines that could not handle the by then medium weight K-27s and K-28s.

Mike - regarding tenders:

O'Berry states " In 1918 new rectangular shaped tender tanks were drawn up and began to be fabricated at Burnham. Although the plan called for a six inch radius on the rear corners the first two fabricated, for locomotives 453 and 464, had virtually square corners. ..." I suggest a good second look at his historical section. While he largely limits himself to abstracts, Dennis clearly had access to a lot more details than have turned up in this discussion.

John Stutz
On April 2, 2020 at 9:11 AM Bill Lugg <@luggw1 <mailto:@luggw1>> wrote:

I'm not a D&RG guy so bear with me...

You mention the recommendation by Mr' Hess to replace scrapped
locomotives with OF 2-6-6-2s.  Was this recommendation followed?  I
don't believe I've ever seen a photo of one of these beasts.

Bill Lugg

On 4/2/20 2:27 AM, John Stutz wrote:
The following shows the conversion dates from Earl Knoob
<'s" rel="noopener" target="_blank">>'s <> AEF data book, with
entries beginning 12.1919, supplemented by simpling information in
O'Berry p12.  See O'Berry p13 for quotes from G.L.Hess, motive power
expert for the Loree evaluation of 1917, regarding advisable
improvements in the D&RG's NG motive power - essentially to upgrade
the K-27s, scrap everything else, and replace with OF 2-6-6-2s.

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