An actuator circuit was an engineering component on Vulcan D'kyr-type starships and Xindi-Insectoid shuttlecraft. Aboard the latter vessel, the port actuator was a switch in the craft's cockpit, on the port bulkhead. While Commander Charles Tucker III and Ensign Travis Mayweather were endeavoring to learn how to pilot a Xindi-Insectoid shuttlecraft in 2154, Tucker tested Mayweather by asking him to "try the port actuator", a request Mayweather complied with. (ENT: "Azati Prime")