| 摘要 |
The invention concerns an actuator for the operation of on-off valves. Said actuator includes a supporting body (1) in which there is transversally one pneumatic cylinder (8, 9) at least, able to activate in the two directions a rack (7) which engages itself with a cogged wheel (31; 50; 100) co-axial with the central shaft (15, 66, 104) of said actuator and able to transmit its own rotation through a pair of free wheels (27, 28; 61, 62; 109, 110) which rigidly and alternatively engage themselves in discordant directions with a ring (33, 34; 62, 63; 108) integral with the central shaft of the actuator, operation means by pneumatic pistons being foreseen for the relative axial movement between the cogged wheel and the shaft of the actuator. Depending on the mutual distance between the free wheels, it happens that in the absence of the pneumatic signal the actuator has its central shaft blocked or manually manoeuvreable. Moreover, besides the direct rotation of the throttle valve being integral with the shaft of the actuator, the operation of guillotine-type valves is foreseen by providing the shaft of the actuator with a nut screw (68) and with a screw (59) integrated with said guillotine. |
