Abstract: A method includes using two parallel electrohydraulic servo valves EHSVs with a single transfer valve to move an actuator during a normal operation mode. The method includes upon failure of one of the EHSVs, using the single transfer valve to disconnect a non-operational one of the EHSVs and continuing to move the actuator with a functional one of the EHSVs in a backup mode.

Abstract: A hydraulic actuator system includes a hydraulic actuator having a housing with a piston having a piston shaft arranged within the housing. The housing is formed to have first, second and third regions, wherein the first region is between the second and third regions and has a larger major dimension than the second and third regions. The system also includes first, second, and third piston heads connected to the piston shaft with the first piston head being tween the second and third piston, wherein the first position head is within the first region and divides the first region into two volumes, the second piston head is in the second region and defines a first volume and the third piston head is in the third region and defines a fourth volume. The system also includes a mode selection device operably connected to the first, second, third and fourth volume.

Abstract: A method of determining density of a fluid within a system includes actuating a piston of a hydraulic cylinder at a target velocity. Additionally, the method includes determining differential pressure and volumetric flow rate of the fluid flowing through an orifice under actuation of the piston. The density of the fluid is determined based on the first differential pressure and the volumetric flow rate of the fluid, which is used by the system to regulate a mass flow rate of fluid within the system.

Abstract: An assembly includes a housing. A first set of coils is mounted to the housing. The first set of coils extends in an axial or rotational direction along the housing for a first length. A second set of coils is mounted to the housing. The second set of coils extends in the axial or rotational direction along the housing for a second length that is shorter than the first length. A core member includes a first core and a second core in series with one another in an axial direction along the core member. The core member is moveable within the housing along a stroke. For at least a first portion of the stroke, the first core is within the first set of coils. For at least a second portion of the stroke, the second core is within the second set of coils.

Abstract: Hydraulic actuator systems of aircraft are described. The hydraulic actuator systems include a hydraulic actuator having a housing and piston therein. The piston includes a piston head separating the housing into a retract cavity and an extend cavity. An actuator controller is hydraulically coupled to the retract cavity by a first hydraulic line and hydraulically coupled to the extend cavity by a second hydraulic line and configured to control a hydraulic pressure within each of the retract cavity and the extend cavity to control actuation of the hydraulic actuator. A position-lock controller is arranged along at least one of the first hydraulic line and the second hydraulic line, the position-lock controller is configured to hydraulically decouple the actuator controller from at least one of the retract cavity and the extend cavity.

Abstract: Hydraulic actuator systems of aircraft are described. The hydraulic actuator systems include a hydraulic actuator having a housing and piston therein. The piston includes a piston head separating the housing into a retract cavity and an extend cavity. An actuator controller is hydraulically coupled to the retract cavity by a first hydraulic line and hydraulically coupled to the extend cavity by a second hydraulic line and configured to control a hydraulic pressure within each of the retract cavity and the extend cavity to control actuation of the hydraulic actuator. A position-lock controller is arranged along at least one of the first hydraulic line and the second hydraulic line, the position-lock controller is configured to hydraulically decouple the actuator controller from at least one of the retract cavity and the extend cavity.

Abstract: A hydraulic actuator system includes a hydraulic actuator having a housing with a piston having a piston shaft arranged within the housing. The housing is formed to have first, second and third regions, wherein the first region is between the second and third regions and has a larger major dimension than the second and third regions. The system also includes first, second, and third piston heads connected to the piston shaft with the first piston head being tween the second and third piston, wherein the first position head is within the first region and divides the first region into two volumes, the second piston head is in the second region and defines a first volume and the third piston head is in the third region and defines a fourth volume. The system also includes a mode selection device operably connected to the first, second, third and fourth volume.

Abstract: An assembly includes a housing. A first set of coils is mounted to the housing. The first set of coils extends in an axial or rotational direction along the housing for a first length. A second set of coils is mounted to the housing. The second set of coils extends in the axial or rotational direction along the housing for a second length that is shorter than the first length. A core member includes a first core and a second core in series with one another in an axial direction along the core member. The core member is moveable within the housing along a stroke. For at least a first portion of the stroke, the first core is within the first set of coils.

Abstract: Actuator systems and methods of operation are disclosed. The systems include a hydraulic actuator having a primary piston having a piston head arranged within a housing defining retract and extend chambers on opposite sides of the piston head. A control element is configured to control a supply of pressure to each of the retract and extend chambers. An actuator valve is coupled to the housing and includes a secondary piston that is biased into the retract chamber in an open flow state and when the primary piston is in a fully retracted state the piston head urges the secondary piston into a closed flow state. The actuator valve defines a flow chamber where, in an open flow state, fluid can be passed through the flow chamber and in a closed flow state the fluid is prevented from passing through the flow chamber.

Abstract: A method of determining density of a fluid within a system includes actuating a piston of a hydraulic cylinder at a target velocity. Additionally, the method includes determining differential pressure and volumetric flow rate of the fluid flowing through an orifice under actuation of the piston. The density of the fluid is determined based on the first differential pressure and the volumetric flow rate of the fluid, which is used by the system to regulate a mass flow rate of fluid within the system.