Valve Help

MDNLansing

Does anyone know what kind of radiator valves these are, and where I might find some more info on them?



None of them leak, but all are hard to turn. I am assuming they're either dirty or need some kind of oiling / maintenance. But before I start tearing into one I'd like to understand what they are and how they work. I have the handle off of this one, but they all have wooden handles with a pin that slides through the wood and valve stem. I would assume these are circa 1910 if that helps any.

MDNLansing

Dole Packless Radiator Valve

Formerly known as an E. P. Allen valve



http://books.google.com/books?id=hqnmAAAAMAAJ&pg=PA18&lpg=PA18&dq=radiator+valve+with+spring+and+ball+bearings&source=bl&ots=xqYML0qiHC&sig=DyDuwcmqBrvTWnWcQZ7Tz0iDCU8&hl=en&sa=X&ei=TLxuUvXtIoeMyAHa-IDoCQ&ved=0CD4Q6AEwBA#v=onepage&q=radiator%20valve%20with%20spring%20and%20ball%20bearings&f=false