Four mode pneumatic relay

A four-mode pneumatic relay comprising:

• a relay body including two input and two output ports communicating with corresponding first and third and second and fourth chambers respectively in said relay body;
• diaphragm means in said relay body communicating with said second, third and fourth chambers;
• a movable orifice shaft means coupled to said diaphragm means and including a valve seat for coupling said second chamber to said third chamber;
• a movable valve plug assembly for pneumatically coupling said first and said second chambers, and for pneumatically coupling said second and said third chambers via said orifice shaft means;
• and
• a pair of mechanical switches for selectively pneumatically coupling said second and said fourth chambers and venting said fourth chamber and for selectively applying input pressure to said first and said third chambers.

A pneumatic relay selectively operable in direct/snap, direct/proportional, reverse/snap and reverse/proportional modes responsive to operation of first and second mechanical switches comprising:

• a relay body;
• diaphragm means supported in said relay body;
• four chambers formed by said diaphragm means in said relay body;
• two inlet ports and two outlet ports communicating with respective ones of said chambers;
• orifice shaft means responsive to external forces coupled to said diaphragm means;
• valve means cooperating with said orifice shaft means for enabling communication between said two inlet ports and one of said output ports;
• said first mechanical switch selectively supplying pressure to one and venting the other of said inlet ports and supplying pressure to the other and venting the one of said inlet ports;
• and
• a second mechanical switch selectively venting one of said outlet ports and coupling said outlet ports together.