A friend of mine doing research on Western Maryland pacifics found an AFE from 1938 stating some of the engines were being equiped with a Prime auto protection valve. This is a new one on me. I suspect it may be a drifting or by-pass valve but those are only guesses. Does anyone know what this valve is and does?

Thanks in advance.

John Bohon

I am just bringing the topic back to the top in hope that someone will know what a Prime auto protection valve is.

Thanks.

John Bohon

It is a cylinder cock that incorporates a relief valve, which in the case of large amounts of condensate in the cylinders will open automaticallyand relieve the hydraulic pressure before it can do any damage, sort of like a safety valve for cylinders.

I thought it must have been a cylinder cock, drifting valve, or bypass valve of some kind.

Thanks for your help.

John Bohon