Re: K-27 valves converted in stages . . .
| October 22, 2019 06:00PM |
|
SebJ Wrote:
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> Yes Casey it is known that 456 remained for some
> time with piston valves and Stephenson valve gear.
> During my researches, I read somewhere on NGDF a
> post from Earl quoting a D&RGW paper with a hand
> written note about that with #456, but that some pic-
> ture proof was still to be found.
> So thank you Bruce, it is the first time I've seen
> a picture of it !
I'll second that motion -
It appears that the first engines converted to superheat, which for various reasons pretty much requires piston valves, were #454, #456, #458 and #461 (not necessarily in that order), and that this was done before the obvious advantages of Walshearts valve gear over Stephenson were apparent, so the new castings for the cylinders were made with the piston valves inboard of the pistons so that the valve stems aligned (more or less) with the existing Stephenson gear. Subsequent conversions to superheat and piston valves were done to accommodate a change to Walshearts at the same time, so the new castings were made with the piston valves outboard of the pistons. When #454, 456, 458 and 461 were later converted from Stephenson to Walshearts an extra crank was added to the linkage to avoid the considerable extra expense of casting yet another four pairs of cylinder blocks. (See [ngdiscussion.net] for a simplified drawing of the valve gear for these four engines.)
- El Abuelo Histœrico, Greengo y Curmudgeoño de los Locomoturas Viejos y Verdes,
aka Der Grossväterlich DünkelOlivGrünDampfKesselMantelLiebHabender
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> Yes Casey it is known that 456 remained for some
> time with piston valves and Stephenson valve gear.
> During my researches, I read somewhere on NGDF a
> post from Earl quoting a D&RGW paper with a hand
> written note about that with #456, but that some pic-
> ture proof was still to be found.
> So thank you Bruce, it is the first time I've seen
> a picture of it !
I'll second that motion -
It appears that the first engines converted to superheat, which for various reasons pretty much requires piston valves, were #454, #456, #458 and #461 (not necessarily in that order), and that this was done before the obvious advantages of Walshearts valve gear over Stephenson were apparent, so the new castings for the cylinders were made with the piston valves inboard of the pistons so that the valve stems aligned (more or less) with the existing Stephenson gear. Subsequent conversions to superheat and piston valves were done to accommodate a change to Walshearts at the same time, so the new castings were made with the piston valves outboard of the pistons. When #454, 456, 458 and 461 were later converted from Stephenson to Walshearts an extra crank was added to the linkage to avoid the considerable extra expense of casting yet another four pairs of cylinder blocks. (See [ngdiscussion.net] for a simplified drawing of the valve gear for these four engines.)
- El Abuelo Histœrico, Greengo y Curmudgeoño de los Locomoturas Viejos y Verdes,
aka Der Grossväterlich DünkelOlivGrünDampfKesselMantelLiebHabender
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488 stops for water at Los Pinos tank on closing day Oct. 1979. Photo courtesy Don Richter
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