Linear choke shuttle/orifice check valve mechanism for a twin tower air dryer

A check valve mechanism for a twin tower gas drying system having two drying assemblies, such twin tower gas drying system for cleaning and drying a stream of unpurified pressurized gas received from a source thereof and for supplying such purified gas alternately from each such drying assembly to said check valve mechanism for distribution in an output percentage to a pneumatic system and in a purge percentage back into such twin tower gas drying system for purging moisture previously collected therein therefrom, said check valve mechanism comprising:

• (a) a check valve body defining a first channel connected to a first such drying assembly, a second channel connected to a second such drying assembly, a shuttle tube having a first end connected to said first channel and a second end connected to said second channel, and an output passage through which said output percentage flows having an initial end communicating with such pneumatic system and a terminal end communicable with said shuttle tube;
• (b) a shuttle choke slidable between said first and said second ends of said shuttle tube, said shuttle choke defining a purge orifice therethrough and having a first end, a second end and a bearing means for controlling rotation and axial movement of said shuttle choke as said shuttle choke slides between said first and said second ends of said shuttle tube;
• (c) a first o-ring at said first end of said shuttle choke for sealing said shuttle choke against said first end of said shuttle tube when such purified gas flowing from such second drying assembly forcibly slides said shuttle choke against said first end of said shuttle tube;
• and
• (d) a second o-ring at said second end of said shuttle choke for sealing said shuttle choke against said second end of said shuttle tube when such purified gas flowing from such first drying assembly forcibly slides said shuttle choke against said second end of said shuttle tube;
• such that when such purified gas flows from such first drying assembly, said shuttle choke slides sealingly against said second end of said shuttle tube thereby allowing such purified gas to flow from such first drying assembly through said first channel through said output passage in said output percentage to such pneumatic system and through said purge orifice in said purge percentage through said second channel for purging of such second drying assembly and when such purified gas flows from such second drying assembly, said shuttle choke means slides sealingly against said first end of said shuttle tube thereby allowing such purified gas to flow from such second drying assembly through said second channel through said output passage in said output percentage to such pneumatic system and through said purge orifice in said purge percentage through said first channel for purging of such first drying assembly.