10-13-2012, 07:13 AM
EM-1_7600 Wrote:I do however need to find a set of cylinders like on the one you built as the rear set of cylinders on my 0-6-6-0 needs to be the slide valve type, not piston valve type as it is!
Interesting that they had piston valve and slide valve motion on the same locomotive. I wonder how that affected the front and rear engines working together? I am currently reading a book that you steam heads would enjoy, called Set Up Running, The Life of a Pennsylvania Railroad Engineman. In it, the author goes into how his dad, the man who the book is about, went into detail about the differences in how the engines he operated with piston valve and slide valve motion. It is not a technical book about steam locomotives, but there is a lot of interesting info on how the engines were run and used.
As for the Articulated Vs. Mallet, I believe the main difference is that the Mallets (pronounced Malley or Mallay) are compound locomotives, they use their steam twice. Typically they used steam in the rear engine in the smaller, high pressure, cylinders... then the steam was piped to the front engine, superheated again, and used in the larger, low pressure, cylinders, before being exhausted. As a result you only got 4 chuffs per revolution of the drivers, like a regular steamer, because you only hear the front engine exhausting to the smokebox, as opposed to a simple articulated which would have 8 chuffs per revolution of the drivers since both engines were exhausting their steam to the smokebox and the atmosphere.
Dave
-Dave