You don't need to know. If we told you, in fact, we'd have to shoot you. Articulated steamers tended to have a section of telescopic pipe even to the rigid frame (rear) cylinders because when you make a chunk of metal that long that hot, its length tends to change quite a bit. That widget looks complicated just to be a sliding sleeve. But could that be all it is?
The latest UP steam update says the 4014 has an oil fire lit in the firebox as of April 9th. Looks promising for seeing a Big Boy roaming the rails soon.
