Abstract: An apparatus includes a wall that defines a shaft, a powder platform configured to support a powder bed within the shaft and configured to move through the shaft, and a sealing device that is in a compressed state from an outer perimeter of the sealing device to an inner perimeter of the sealing device such that the outer perimeter contacts the wall and the inner perimeter contacts the powder platform to form a seal between the powder platform and the wall. Another apparatus includes a wall that defines a shaft, a powder platform configured to support a powder bed within the shaft and configured to move through the shaft, and a sealing device comprising a non-fibrous material that is affixed to the powder platform and extends away from the powder platform, the sealing device contacting the wall to form a seal between the powder platform and the wall.

Abstract: A bistable hydraulic solenoid valve has a valve spool that transitions between two positions, remaining in one of the two positions under an attractive magnetic force when the solenoids are not energized. The valve spool has a first permanent magnet attached to one end and a second permanent magnet attached to the other end, so that the first permanent magnet faces a first solenoid, and the second permanent magnet faces a second solenoid. The first solenoid is energized to have a first polarity, and the second solenoid is energized to have an opposite polarity to concurrently push and pull the valve spool within the valve body between a first position and a second position, the first position establishing a first flow path and the second position establishing a second flow path through the valve body and valve spool so as to enable flow of hydraulic fluid.

Abstract: An apparatus includes a wall that defines a shaft, a powder platform configured to support a powder bed within the shaft and configured to move through the shaft, and a sealing device that is in a compressed state from an outer perimeter of the sealing device to an inner perimeter of the sealing device such that the outer perimeter contacts the wall and the inner perimeter contacts the powder platform to form a seal between the powder platform and the wall. Another apparatus includes a wall that defines a shaft, a powder platform configured to support a powder bed within the shaft and configured to move through the shaft, and a sealing device comprising a non-fibrous material that is affixed to the powder platform and extends away from the powder platform, the sealing device contacting the wall to form a seal between the powder platform and the wall.

Abstract: A landing gear strut assembly including an outer cylinder, an inner cylinder, and a latch mechanism including a first mounting bracket coupled to the outer cylinder, a second mounting bracket coupled to the inner cylinder, a first latching member pivotally coupled to the first mounting bracket, the first latching member having a latching position and a released position, and a second latching member coupled to the second mounting bracket, wherein in the latching position the first latching member is positioned relative to the second latching member so as to couple with the second latching member and retain the inner cylinder in a retracted position, and wherein in the released position the first latching member is uncoupled from the second latching member so that the inner cylinder is free to move relative to the outer cylinder in the direction of extension of the inner cylinder.

Abstract: A bistable hydraulic solenoid valve has a valve spool that transitions between two positions, remaining in one of the two positions under an attractive magnetic force when the solenoids are not energized. The valve spool has a first permanent magnet attached to one end and a second permanent magnet attached to the other end, so that the first permanent magnet faces a first solenoid, and the second permanent magnet faces a second solenoid. The first solenoid is energized to have a first polarity, and the second solenoid is energized to have an opposite polarity to concurrently push and pull the valve spool within the valve body between a first position and a second position, the first position establishing a first flow path and the second position establishing a second flow path through the valve body and valve spool so as to enable flow of hydraulic fluid.

Abstract: A snubber includes a head portion, a shank portion, and a threaded portion. The shank portion is attached to the head portion, and the shank portion defines a shank diameter. The threaded portion is attached to the shank portion, and the threaded portion includes an external helical thread wrapped around a central shaft. The external helical thread defines a threaded diameter, and the central shaft defines a central shaft diameter. The shank diameter and the thread diameter are sized such that the shank portion and the threaded portion define at least one fluid flow path when the snubber is installed in a pressure sensor.

Abstract: An example aircraft includes (i) a landing gear having a chassis, an axle, and wheels mounted to ends of the axle; (ii) a hydraulic actuator including a cylinder, a first piston coupled to the chassis, and a second piston coupled to the axle; and (iii) a directional control valve including: inlet ports configured to be fluidly coupled to a source of pressurized fluid, tank ports configured to be fluidly coupled to a tank, and workports configured to be fluidly coupled to the hydraulic actuator.

Abstract: Systems and methods are provided for enhanced valves. One embodiment is a hydraulic valve that includes a housing that defines a first port, a second port, and a third port for a hydraulic fluid, and a sleeve disposed within the housing that defines openings in fluid communication with the second port and the third port. The valve also includes a slide comprising a head and a shaft. The shaft is disposed within the sleeve and the slide is movable in a lengthwise direction from a closed position to an open position. The head includes a circumferential lip that extends perpendicular to the lengthwise direction, and that abuts the sleeve when the slide is in the closed position to prevent flow of the hydraulic fluid from the first port. The shaft provides a flow path between the second port and the third port when the slide is closed.

Abstract: Hydraulic systems for shrinking landing gear shrink are described. An example apparatus includes a landing gear strut, a transfer cylinder, and aircraft hydraulics. The landing gear strut has an outer cylinder and an inner cylinder. The inner cylinder moves relative to the outer cylinder from a first position to a second position as the landing gear strut moves from a deployed position to a retracted position. The landing gear strut has a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position. The transfer cylinder exchanges hydraulic fluid and gas with the landing gear strut as the landing gear strut moves from the deployed position to the retracted position. The aircraft hydraulics hydraulically actuate the landing gear strut to move from the deployed position to the retracted position.

Abstract: A snubber includes a head portion, a shank portion, and a threaded portion. The shank portion is attached to the head portion, and the shank portion defines a shank diameter. The threaded portion is attached to the shank portion, and the threaded portion includes an external helical thread wrapped around a central shaft. The external helical thread defines a threaded diameter, and the central shaft defines a central shaft diameter. The shank diameter and the thread diameter are sized such that the shank portion and the threaded portion define at least one fluid flow path when the snubber is installed in a pressure sensor.

Abstract: Hydraulic systems for shrinking landing gear shrink are described. An example apparatus includes a landing gear strut, a transfer cylinder, aircraft hydraulics, a pressure vessel, and a pressure-operated check valve. The landing gear strut has an outer cylinder and an inner cylinder movable relative to the outer cylinder between a first position and a second position. The landing gear strut has a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position. The transfer cylinder exchanges hydraulic fluid with the landing gear strut. The aircraft hydraulics exchange hydraulic fluid with the transfer cylinder. The pressure vessel exchanges gas with the landing gear strut. The pressure-operated check valve controls an exchange of gas between the pressure vessel and the landing gear strut based on hydraulic fluid received from the aircraft hydraulics.

Abstract: An example aircraft includes (i) a landing gear having a chassis, an axle, and wheels mounted to ends of the axle; (ii) a hydraulic actuator including a cylinder, a first piston coupled to the chassis, and a second piston coupled to the axle; and (iii) a directional control valve including: inlet ports configured to be fluidly coupled to a source of pressurized fluid, tank ports configured to be fluidly coupled to a tank, and workports configured to be fluidly coupled to the hydraulic actuator.

Abstract: A landing gear strut assembly including an outer cylinder, an inner cylinder, and a latch mechanism including a first mounting bracket coupled to the outer cylinder, a second mounting bracket coupled to the inner cylinder, a first latching member pivotally coupled to the first mounting bracket, the first latching member having a latching position and a released position, and a second latching member coupled to the second mounting bracket, wherein in the latching position the first latching member is positioned relative to the second latching member so as to couple with the second latching member and retain the inner cylinder in a retracted position, and wherein in the released position the first latching member is uncoupled from the second latching member so that the inner cylinder is free to move relative to the outer cylinder in the direction of extension of the inner cylinder.

Abstract: Hydraulic systems for shrinking landing gear shrink are described. An example apparatus includes a landing gear strut, a transfer cylinder, aircraft hydraulics, a pressure vessel, and a pressure-operated check valve. The landing gear strut has an outer cylinder and an inner cylinder movable relative to the outer cylinder between a first position and a second position. The landing gear strut has a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position. The transfer cylinder exchanges hydraulic fluid with the landing gear strut. The aircraft hydraulics exchange hydraulic fluid with the transfer cylinder. The pressure vessel exchanges gas with the landing gear strut. The pressure-operated check valve controls an exchange of gas between the pressure vessel and the landing gear strut based on hydraulic fluid received from the aircraft hydraulics.

Abstract: Hydraulic systems for shrinking landing gear shrink are described. An example apparatus includes a landing gear strut, a transfer cylinder, and aircraft hydraulics. The landing gear strut has an outer cylinder and an inner cylinder. The inner cylinder moves relative to the outer cylinder from a first position to a second position as the landing gear strut moves from a deployed position to a retracted position. The landing gear strut has a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position. The transfer cylinder exchanges hydraulic fluid and gas with the landing gear strut as the landing gear strut moves from the deployed position to the retracted position. The aircraft hydraulics hydraulically actuate the landing gear strut to move from the deployed position to the retracted position.

Abstract: Systems and methods are provided for enhanced valves. One embodiment is a hydraulic valve that includes a housing that defines a first port, a second port, and a third port for a hydraulic fluid, and a sleeve disposed within the housing that defines openings in fluid communication with the second port and the third port. The valve also includes a slide comprising a head and a shaft. The shaft is disposed within the sleeve and the slide is movable in a lengthwise direction from a closed position to an open position. The head includes a circumferential lip that extends perpendicular to the lengthwise direction, and that abuts the sleeve when the slide is in the closed position to prevent flow of the hydraulic fluid from the first port. The shaft provides a flow path between the second port and the third port when the slide is closed.

Abstract: A hydraulic strut assembly, for use in a semi-levered landing gear in an aircraft, comprising an actuator and a manifold associated with the actuator. The actuator comprises a housing, a first piston, a second piston, and a third piston. The first piston is positioned between outer and inner cylindrical structures of the housing. The outer and inner cylindrical structures and first piston form an outer chamber that receives a first fluid. The inner cylindrical structure, the first piston, and the second piston, which is nested within the first piston, form an inner chamber, which holds a second fluid comprising a gas. A volume of the inner chamber changes when at least one of the first and second pistons moves. The third piston is positioned between the outer cylindrical structure and the first piston. The first, second, and third pistons move in a direction parallel to an axis through the housing.

Abstract: A device including a first hydraulic piston, a second hydraulic piston disposed within the first hydraulic piston, and a third hydraulic piston disposed within both the first hydraulic piston and the second hydraulic piston. The first, second, and third hydraulic pistons are contained within a common outer wall. A manifold is connected to the first, second, and third hydraulic pistons. The manifold is disposed relative to the first, second, and third hydraulic pistons such that a fluid moving in the manifold can control positions of the first, second, and third hydraulic pistons.

Abstract: A hydraulic strut assembly, for use in a semi-levered landing gear in an aircraft, comprising an actuator and a manifold associated with the actuator. The actuator comprises a housing, a first piston, a second piston, and a third piston. The first piston is positioned between outer and inner cylindrical structures of the housing. The outer and inner cylindrical structures and first piston form an outer chamber that receives a first fluid. The inner cylindrical structure, the first piston, and the second piston, which is nested within the first piston, form an inner chamber, which holds a second fluid comprising a gas. A volume of the inner chamber changes when at least one of the first and second pistons moves. The third piston is positioned between the outer cylindrical structure and the first piston. The first, second, and third pistons move in a direction parallel to an axis through the housing.

Abstract: A hydraulic strut assembly, for use in a semi-levered landing gear in an aircraft, comprising an actuator and a manifold associated with the actuator. The actuator comprises a housing, a first piston, a second piston, and a third piston. The first piston is positioned between outer and inner cylindrical structures of the housing. The outer and inner cylindrical structures and first piston form an outer chamber that receives a first fluid. The inner cylindrical structure, the first piston, and the second piston, which is nested within the first piston, form an inner chamber, which holds a second fluid comprising a gas. A volume of the inner chamber changes when at least one of the first and second pistons moves. The third piston is positioned between the outer cylindrical structure and the first piston. The first, second, and third pistons move in a direction parallel to an axis through the housing.