Abstract: According to principles of this invention, an override controller is structured for being placed in pressurized fluid lines between a valve position transducer and a valve position actuator of an automatic position-controlled valve assembly, with the override controller receiving uncontrolled supply pressurized fluid and having an exhaust. The override controller receives pressurized fluid at first and second inlet ports from the valve position transducer and furnishes this pressurized fluid to the valve position actuator through first and second outlet ports for controlling the position of the valve during normal operation. However, valve mechanisms of the override controller can also be placed in positions for stopping flow of pressurized fluid through the first and second inlet ports and providing fluid flow from the uncontrolled pressurized fluid to the first and second outlet ports for controlling the position of an industrial valve during override operation.

Abstract: A valve position controller (10) for controlling the position of an industrial-valve element (29, 29') includes a check valve (72, 74) in each of closing and opening pressurized-fluid input lines (68, 70) for respectively leading pressurized fluids from a pressurized source (30) to closing and opening solenoid actuating valves (106, 104) via a common input fork (62). The valve position controller can be changed between a fail-in-place" mode, and a "fail-closed" mode by interchanging input and exhaust lines (68, 88) to an opening actuating valve (64) and reversing electrical operation of a solenoid (104) of the opening actuating valve. A needle valve (94) in a common exhaust line allows speed of the system to be optimized for a set resolution.