Steam & Excursion > Railroad related?

Found this about forty years ago in the weeds near a scrap yard we were switching. The facility in Canton, Ohio had cut up a lot of railway equipment over the years. It is brass, about 2 3/4" in diameter by 1 1/2" thick. What appears to be a plug in the base of the gauge actually has a tiny hole drilled in it. It seems too small to be off of a locomotive but I thought I'd ask. Any thoughts?



Edited 1 time(s). Last edit at 03/15/19 15:36 by OldCond.

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Probably NOT locomotive related.
Possibly a traction engine.

Back pressure is a characteristic of reciprocating engines.  It is the build-up of pressure in the side of the cylinder that is opened
 by the valve to the exhaust stack.   The “draft appliances” are the prices that make up the Venturi jet, used to create a
high partial-vacuum above the grates, at the opposite end of the boiler structure.   The nozzle of the Venturi is smaller than the volume of the exhaust passages .... thus, it is a restriction of the exhaust steam.

The pressure below the nozzle can be measured .....and that pressure is created by the pistons cramming the exhsust steam
into the nozzle, and up the stack, forming a smooth slightly expanding, jet up the stack....sucking all of the smoke cinders and combustion up and out the stack, drafting fresh air into the inferno of the ‘furnace’.

That successful design of the locomotive boilers was emulated by manufacturers of “traction engines”, used in large agricultural 
operations —- generally in harvesting and threshing operations.

The use of the back pressure gauges, is another aid in optimizing the engines’ running smoothness.   
Remember, that the back pressure acts against the positive pressure, from the boiler, on the side of the piston doing the work of that stroke portion.

if you send boiler pressure into the pistons at 200 PSI, and are running back pressure at 30PSI, the effective pressure acting on the piston is 170 PSI used to turn the crank.... so, you can reduce the valve travel and thus reduce the excess steam in the cylinders ....   Thus, the crowding in the Venturi jet is relieved, and the engine runs smoother.   

The smaller size of traction engines,  makes the use of a good back pressure gauges a very important tool.


W.

no proofed yet..

Thank you for the detailed answer. I can remember steam on the B&O and NKP as a child but was gone by the time I hired out.

Doesn't look substantial for a locomotive;   also not the usual Ashton or other mfg name on the face.