US Patent 7207174 Apparatus for use with pneumatic device

A control valve assembly has a first chamber with a first port, a second chamber with a second port, and a first valve that is operative to open between the first and second chambers in response to elevated pneumatic pressure in the first chamber. A second valve is operative to open between the second chamber and a primary exit port to vent the second chamber in response to elevated pneumatic pressure in the second chamber. A third valve is operative to open between the first chamber and a bypass exit port to vent the first chamber in response to elevated pneumatic pressure in the first chamber.