PRR J1/J1a

@nikkormat posted:

For those in the know,what are the knobs on the side of the cylinders of the Pennsylvania Railroad J1/J1a locomotives (i.e. what are they for,their function)?

No idea what you are referring to, without photo/phots!  Are you asking about the real locomotive, or someone's model of a PRR J1/J1a?

could be  snifter valves

The real thing. .This is the best photo I could find. In that pocket on the side of the cylinder case is a handle which looks like a valve handle.  Thanks   

@nikkormat posted:

The real thing. .This is the best photo I could find. In that pocket on the side of the cylinder case is a handle which looks like a valve handle.

Generally, the high pressure valve oil lubrication lines are joined together inside that "pocket". To my knowledge, there is no "valve handle" in that location.

For what's worth, the "snifter" valve is located at the top center of the valve chest, within its own "pocket".

Thanks  

that's a better photo than I found. the one I looked at had something protruding in that area that looked like a the top of the snifter valve.  

@Rick Rubino posted:

that's a better photo than I found. the one I looked at had something protruding in that area that looked like a the top of the snifter valve.  

Except,,,,,any drifting valve, i.e. "snifter valve", would NOT be placed that low, as it must be on top associated with the valve chamber, in order to eliminate vacuum being drawn on the smokebox.