English to Italian Tech/Engineering Mechanics / Mech Engineering piston actuator

The actuator assembly is pneumatically operated, connected to the body assembly with a yoke, and to the plug stem with an actuator shaft. The actuator assembly extends or retracts the plug assembly within the body assembly by pressure applied to either side of the piston (see Figure 5.1).
b. Air to position the actuator shaft within the cylinder is received at the air port, forcing the actuator shaft to move in the appropriate direction. This transfers mechanical force through the shaft to reposition the plug within the body assembly. In the event of power failure, the air tank when supplied, will force the piston to move the plug into the specified fail position.