Automatic position-control valve assembly

An override controller for an automatic position-control valve assembly comprising:

• first and second inlet ports, each for receiving pressurized fluid controlled by a valve-position transducer for moving a valve to a position determined by the valve-position transducer;
• first and second outlet ports for being attached to a valve-position actuator, each for furnishing the pressurized fluid controlled by the valve-position transducer to the valve-position actuator for moving a valve in either of opposite directions;
• an override exhaust port for exhausting fluid from an outlet port when the other outlet port is pressurized;
• an auxiliary air-supply port for receiving pressurized supply fluid uncontrolled by the valve-position transducer;
• first and second inlet valves respectively for each of said first and second inlet ports, said first and second inlet valves each having a normal position for allowing flow of pressurized fluid through the respective first or second inlet port and a closed, or override, position for blocking flow of pressurized fluid through the respective first or second inlet ports;
• an override valve mechanism coupled to said first and second outlet ports, said exhaust port and said auxiliary air-supply port, said override valve mechanism including a manipulator for moving said valve mechanism to a stop position in which the valve mechanism blocks pressurized fluid flow through said auxiliary air-supply port and said override exhaust port, to an open position in which the valve mechanism allows fluid flow between said auxiliary air-supply port and said first outlet port and between said override exhaust port and said second outlet port, and to a closed position in which the valve mechanism allows fluid flow between said auxiliary air-supply port and said second outlet port and between said override exhaust port and said first outlet port;
• whereby, control of a valve position actuator can be taken over by said override controller by moving said first and second inlet valves to the override position and thereafter using the manipulator of the override valve mechanism for controlling the valve position actuator.