I COULDN'T WAIT UNTIL APRIL 1. Last night I was doing some more research on the Andreyev and I came across the Berlinerwerke Apocrypha, evidently the work of someone with a bit more skill with a Dremel (scroll around and see what one can do with cheap HO plastic diesels) and Photoshop as well as a bit more imagination than I.
The author was laboring under the impression that the Septipede was a railroading urban legend when he reported the discovery of the 4-14-2 Pennsylvania V1 "Rocky."
In subsequent research, the author discovered that there was indeed a seven-coupled Soviet locomotive, comrades. His explanation is in the spirit if not quite up to the standard of proper socialist self-criticism.
Chesapeake and Ohio were also working on seven-coupled power.
The Pennsylvania, not to be outdone, took a different C&O design with dual cylinders and modified it.
(Some quibbles: C&O would have provided more sand delivery pipes, and that crosshead and valve motion configuration would have snapped under a heavy load. To have expected a single crosshead to handle the reciprocating mass of two pistons boggles the mind. Look carefully at the diagrams for the Andreyev, which include tandem crossheads, an extra connector between the eccentric and the reverse lever and articulated connecting rods. The forward crosshead guide hanger and valve stem guide are similar to those on the front engine of a Challenger or Big Boy. Whew, one less applied engineering problem.)