The 4763 type electric valve positioner and 4765 type pneumatic valve positioner are samson company's positioning devices used to control pneumatic control valves, which have compact structure, low maintenance, arbitrary installation position, no mechanical vibration, positive and negative action adjustable, good dynamic response characteristics, suitable for conventional or step control, adjustable ratio / gain, adjustable output gas volume, low gas consumption, special type can use oxygen gas source, can be installed on the casting bracket or rod bracket of the control valve conforming to IEC 60534-6 standard.