Dear Mr.Ellsworth:
I think that Valley Railroad would be quite interested in a copy of a drawing which shows Meiningen’s modifications to the floating heads of the Trofimov valve. Do you have one to share?
Thank you in advance for any help!
J.David
PS: Now back to the 1309... jdc

I regret that I never had any dimensioned drawing of the devices, but there were some remarkably clear pictures which showed what I thought was the mature form of the innovation. This involved the piston-valve heads being made hollow like box pistons, with only a partial 'bore' for the cushioning maybe half the diameter of the piston valve at most, but relatively deep; the cushioning pistons were likewise solid in outside contour and had two visible rings (I suspect the outer one with a red hair more clearance than the inner)

The picture that has survived for "Trofimoff" valves on a locomotive designed for freight service is this, which is radically different in detail design:



Here the valve head is substantially hollow, with a relatively large-diameter thin plate fitted with a single (bronze?) ring. I don't see any evidence of contact of this ring with the inside bore of the head, and the shaft surface on which the head moves is manifestly not cylindrical or polished, all of which lead me to think they represent designing to reduce 'stiction' and other tribological concerns.

As a design criterion: the force that keeps the heads 'bypassed' is the friction between the piston-valve rings and the bore; the amount of admitted pressure must be high enough to overcome this (with the intermediate condition likely being much the same 'blow' reported for the ATSF Wagners). The 'jingling' (and damaging impacts) involve what happens when there is not quite enough pressure to seat the heads against their stops; this was something that I thought the two-ring model was likely to solve fairly well in practice.

I don't think Meiningen would be averse to a request for a few detail drawings of various forms of these valves, particularly if Valley has an interest in improving their rig. That would specifically involve the arrangements for lubricating the smaller cushioning piston rings...