Re: NNG - Oh Boy!! More Heisler Pics!!! PFI 92?

So the thread has already morphed a little toward general 90 ton Heisler discussion, so I hope no one minds if I carry this a little further for one out west. PFI 92 was built as a soak and converted to superheat at the NP shops in Spokane I believe. The above photos show an arrangement of snifter valves that is very curious to me. The line coming up by the stack is the air compressor exhaust. There is an angle globe valve missing it's bonnet, stem and handle, the the remains of a swing check valve. The line then goes into a tee either side of which are plumbed directly to the superheated steam lines going back to the engine cylinders. The snifters have the mech. linkage as shown with a small cylinder that would shove the bar from side to side doing something with the snifters? This cylinder may have been plumbed parallel to the steam supply to the superheater damper mech. which is still in place. The copper lines are gone due to jacket and lagging removal. Has anyone seen a set up like this, and have an explanation of how it function? I have looked at the big Heisler at Mt.Rainer Scenic and it does not have this, and apparently Erl's engine doesn't either. I am pretty sure this allowed the compressor exhaust to be sucked into the cylinders when drifting, but not sure where the exhaust would go otherwise.