I am looking for the valve gear described by this wikipedia entree:
Miniature Four-Cylinder Holcroft Gear Wikipedia Entree
I purchased a copy of Model Engineer, Vol. 115, Issue 2883, 1956 which includes an excerpt describing the gear.
I would also like to find the article that Holcroft wrote for the Railway Gazette
I received the Model Engineer technical journal and immediately found this schematic of the gear:
Finally this lost mechanism is available on the internet. I don't yet understand how it works but I will study it and its corresponding article to elucidate its function.
So after reading the portion of Facts About 'Tugboat Annie' that describes the gear in detail I have realized that the included drawing is incomplete. There are components described that are not clearly displayed in the drawing.
On July 30th 2022 I finally found complete documentation and drawings of the gear including drawings of individual components with measurements for all of them. I have decided that I will use the information to expand the conjugated gear article I have already written. I came to this decision because included in the new documentation is the method that holcroft used to derive all of the gears he made which gives me new insights into the general theory of conjugated gear.