A hydraulic control system for blowout preventers systems, frack valves and chokes, and related wellhead and control equipment used in oil and gas well drilling operations. The hydraulic control system can include one or more hydraulic control valves or pressure regulators including an internal, linear slider and pairs of seal rings. Lapped and polished surfaces of the seal rings and sliders can form a dynamic metal-to-metal seal within the hydraulic control valves or pressure regulators.

Various embodiments of the present disclosure provide a rotorcraft-assisted system and method for launching and retrieving a fixed-wing aircraft into and from free flight. The launch and retrieval system includes a modular multicopter, a storage and launch system, an anchor system, a flexible capture member, and an aircraft-landing structure. The multicopter is attachable to the fixed-wing aircraft to facilitate launching the fixed-wing aircraft into free, wing-borne flight. The storage and launch system is usable to store the multicopter (when disassembled) and to act as a launch mount for the fixed-wing aircraft by retaining the fixed-wing aircraft in a desired launch orientation. The anchor system is usable with the multicopter, the flexible capture member, and the aircraft-landing structure to retrieve the fixed-wing aircraft from free, wing-borne flight.

Method of adjusting the pressure balance or a control device, in particular of a servo valve, the requisite adjusting movement being applied by a disc translator.

The system is an improved valve/actuator architecture using a 4-way blocked-port architecture and area asymmetry providing numerous advantages over the conventional practice. The system uses fewer control circuits and provides for reduced component parts—it reduces hose, tubing and fitting requirements (lower cost, improved packaging, less installation labor and less leakage due to fewer connections). It also eliminates the need for a spring for static load support and other suspension control components (such as a sway bar). The system simplifies the mechanical design thereby reducing cost, aids in packaging, eliminates hysteresis losses of the spring and reduces moving mass thereby lowering response time. The system further allows regeneration of hydraulic power thereby increasing overall efficiency. The system further eliminates one half of throttling loss in a servo-valve.

The invention relates to a pressure oil filter system for a hydraulic transmission, in particular for a motor vehicle transmission, comprising at least one oil pump which can be actuated as required and which has a pressure side and a suction side, a pressure line to a consumer and at least a first oil filter which is arranged at the pressure side of the oil pump in the pressure line, wherein means for damping pressure surges during intermittent operation of the oil pump are provided in the pressure line upstream of the first oil filter in the flow direction of the oil.

A spool valve device includes: a housing with channels; a spool moving to change channel connection statuses; an electric actuator including an electric motor and linear-motion conversion mechanism, the motor rotating an output shaft by torque corresponding to a drive current supplied to the motor, the mechanism converting rotational output shaft movement into straight movement and applying thrust corresponding to the torque to the spool to change position; a biasing member applying biasing force to the spool against the actuator thrust; an angle detector detecting an motor output shaft angular position; a driving portion driving the motor by controlling drive current flow supplied to the motor based on a position command input and the angular position detected by the angle detector; and an abnormality determining portion calculating the spool position based on the detected angular position and determine presence or absence of operation spool abnormality.

A hydraulic component includes a component housing and a connection block. The component housing has an outer surface and an axial bore. At least one connecting channel extends from the outer surface to the axial bore. The connection block has a housing side with at least one connection bore, where the connection bore is in fluidic connection with the at least one connection channel. The outer surface of the component housing has a non-planar shape at least in the area of the at least one connecting channel, where at least one connecting bushing with a through hole is received in the at least one connecting channel and extends into the at least one connecting bore.

The subject matter of this specification can be embodied in, among other things, a fluid valve assembly that includes a first fluid port, a second fluid port, a third fluid port, a valve spool configured to be positioned at a first position, a second position away from the first position, a third position away from the first position opposite the second valve position, the valve spool defining a first fluid duct configured to fluidly connect the first fluid port to the second fluid port in the first valve position, a second fluid duct configured to fluidly connect the first fluid port to the third fluid port in the second valve position, and a third fluid duct configured to fluidly connect the first fluid port to the second fluid port in the third valve position.

An example valve includes: a first port, a second port, and a load-sense port; a valve piston configured to block fluid flow from the first port to the second port when the valve piston is in a neutral position; a reverse flow spring applying a first biasing force on the valve piston in a proximal direction; and a pressure compensation spring disposed in a spring chamber and applying a second biasing force on the valve piston in a distal direction, wherein when pressure level of fluid at the second port is higher than pressure level of fluid at the load-sense port, fluid flows from the second port to the spring chamber and the load-sense port, and wherein when pressure level of fluid at the load-sense port is higher than pressure level of fluid at the second port, fluid of the load-sense port is provided to the spring chamber.

A hydraulic circuit includes a pump connected to a tank for supplying hydraulic liquid under pressure to a component via a directional control slide valve provided with a feed port connected to an inlet of the component and with a return port connected to an outlet of the component. The hydraulic circuit further includes a pressure limiter connected to the inlet of the component and the tank, and a feed control system for the hydraulic component including a pressure sensor installed upstream of the hydraulic component downstream of the feed port for supplying information about the pressure of the hydraulic liquid and a setpoint pressure. The feed control system further including an actuator for controlling the movement of the directional control slide valve, and a control unit for generating a control signal for the actuator based on information about the pressure measured at the feed port.