| 摘要 |
An actuation system is usable for a choke. The choke can be moved between open and closed positions by a variety of devices, including a stepping actuator. A rapid shutdown feature involving a hydraulically driven override allows the stem of the choke to be moved rapidly to close the choke. The actuator resumes its old position when the hydraulic shutdown mode is overridden, thus allowing the choke to return to its prior position before it was rapidly closed. Shutdown of the choke is rapid, while a return to its former position is gradual. |
