Valve turning mechanism with pneumatic or hydraulic piston

摘要

The mechanism has a pneumatic or hydraulic piston (4) which moves up and down in its cylinder (5). Linear motion is transmitted by the collar (3) to the bolt (1). Ball bearings (10) running in grooves (8) convert linear motion into rotary movement, through either 90 or 180 deg , to turn the axle (6). The pitch angle of the grooves varies from 70 to 30 deg to alter the delivered moment with output shaft angle. Maximum moment occurs at valve closure, falling smoothly to half moment at 15 deg and remaining constant for the remainder of angular travel.