Once the coil is energized and generates a magnetic discipline, the core is attracted, which opens or closes the valve. Core Spring: ServoPlace™ Precision Nut Placement This higher speed electric rod actuator is suitable for precision nut & bolt (stud) placement in projection welding apps for elevated productivity and throughput. https://andrevgqcl.tribunablog.com/the-basic-principles-of-pneumatic-actuator-ball-valve-29339419