Automatic reservoir drain valve

Claim 1

An automatic reservoir fluid drain valve including a housing, formed and adapted for connection with a reservoir, first and second fluid chambers in said housing, a shuttle valve member controlling communication between said chambers, an outlet in said housing communicating said second chamber with atmosphere, said shuttle valve member having a portion controlling communication of said second chamber with atmosphere through said outlet, an axially disposed fluid inlet connectable to a reservoir, a radially disposed inlet identical with said axially disposed inlet and alternatively connectable to said reservoir, a passage communicating said inlets with said first chamber, said shuttle valve member permitting flow of fluid pressure from said first to said second chamber and precluding flow of fluid pressure from said second to said first chamber, said shuttle valve member portion being movable away from said outlet to open the same in response to excess fluid pressure in said second chamber over that in said first chamber, said shuttle valve member being operable entirely and solely in response to fluid pressure differentials in said first and second chambers, and a safety valve means controlling communication of both said inlets through said passage to said first chamber and yieldingly urged into a position closing said passage in response to a predetermined low pressure level delivered at said hoUsing from said reservoir, a crescent-shaped depression in said housing and about said axially disposed inlet, the opposed ends of said depression being positioned adjacent and on opposite sides of said radially disposed inlet and an electrical heating element positioned within and extending substantially throughout the length and depth of said depression.