Abstract: A three position electrically operated actuator has a self centering system so that if power is off for the actuator, it returns to a central position. The actuator comprises a center cavity with a first solenoid on one side and a second solenoid on the other side, a shaft extends through the center cavity and is joined to a first magnetic core of the first solenoid and a second magnetic core for the second solenoid. The shaft has a connection at least at one end for connection to a gearbox or the like. When the first solenoid is energized the shaft moves axially in one position so the connection is at a first position, when the second solenoid is energized, the shaft moves axially in the opposite direction so the connection is at a second position. A coil spring is provided in the cavity, and when neither solenoid is energized the spring moves the shaft so the connection is in a third position midway between the first position and the second position.

Abstract: Apparatus including series-connected pitch inching pilot valve, load control pilot valve, pressure feedback valve assembly, pitch direction selector valve, and servo power cylinder assembly. A load control bypass valve is connected in parallel with the pressure feedback valve assembly and a pitch reduction damping check valve is connected in parallel with the load control pilot valve. Counterbalancing pilot signals in the pitch inching pilot valve are received from a pressure varying manual control valve and a pitch feedback transmitter; in the load control pilot valve either from a manual load control valve and a governor load feedback valve or from each side of the pressure feedback valve assembly; in the load control bypass valve from the outlets of the inching pilot valve and the load control pilot valve.