The electro-hydrostatic actuator system for raising and lowering aircraft landing gear (1) is provided with at least one hydraulic actuator (21, 22) that is constituted so as to perform retraction and deployment of landing gear (11), a hydraulic circuit (33), a hydraulic pump (32), an electric motor (31), a controller (4) constituted so as to control the operation of the electric motor upon receiving an instruction relating to retraction of the landing gear or an instruction relating to deployment of the landing gear, and a sensor (34) that detects the discharge pressure of the hydraulic pump. The controller feeds back the discharge pressure that the sensor has detected, and controls the operation of the electric motor so that the discharge pressure of the hydraulic pump becomes a target discharge pressure.

A throttle assembly for a pressure control system in a vehicle includes at least one throttle valve. The at least one throttle valve defines an assembly cross-section of the throttle assembly, the assembly cross-section specifies a flow resistance acting on a pressure medium entering the throttle assembly, and the at least one throttle valve includes at least one controllable throttle valve configured to be controlled in accordance with an upstream pressure. The assembly cross-section of the throttle assembly is configured to be set, by control of the at least one controllable throttle valve, in such a way that an inlet volume flow of the pressure medium entering the throttle assembly can be limited to a limit volume flow in accordance with the upstream pressure, in order to set, in accordance with the upstream pressure, a power consumption of a pneumatic load in the pressure control system.

A transmission system includes a transmission assembly having clutches to transmit power from an input shaft to an output shaft at a plurality of gear ratios. A traction motor drives the input shaft and propels the work vehicle, while a controller controls operation of the transmission assembly and the traction motor. A hydraulic circuit controls actuation of the clutches responsive to commands from the controller. The hydraulic circuit includes a hydraulic pump driven by the traction motor, an accumulator connected to the hydraulic pump and that holds hydraulic fluid therein under pressure, and an unloading valve positioned in a secondary fluid path running from an outlet of the hydraulic pump to a sump. The unloading valve operates in a closed state to direct hydraulic fluid from the hydraulic pump to the accumulator and operates in an open state to direct hydraulic fluid from the hydraulic pump to the sump.

A robotic device may traverse a path in a direction of locomotion. Sensor data indicative of one or more physical features of the environment in the direction of locomotion may be received. The implementation may further involve determining that traversing the path involves traversing the one or more physical features of the environment. Based on the sensor data indicative of the one or more physical features of the environment in the direction of locomotion, a hydraulic pressure to supply to the one or more hydraulic actuators to traverse the one or more physical features of the environment may be predicted. Before traversing the one or more physical features of the environment, the hydraulic drive system may adjust pressure of supplied hydraulic fluid from the first pressure to the predicted hydraulic pressure.

Disclosed are a hydraulic system for construction equipment and a method of controlling the same, and the hydraulic system for construction equipment includes: a plurality of pressure control-type hydraulic pumps driven by an engine provided in construction equipment; an actuator driven by working oil discharged from the hydraulic pump; a closed center-type main control valve provided between the hydraulic pump and the actuator, and bypassing a virtual flow rate; and a controller configured to control the hydraulic pump by receiving the bypassed virtual flow rate from the main control valve.

A refuse vehicle includes a chassis and a vehicle body. A variable displacement pump is positioned within the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit. A lifting system on the vehicle includes at least one actuator in fluid communication with the variable displacement pump, which delivers pressurized hydraulic fluid from the hydraulic fluid reservoir to the actuator through the high pressure line to adjust a position of the actuator. A valve is positioned downstream of the variable displacement pump. In a first valve position, the valve restricts flow outward from the high pressure line. In a second valve position, the valve directs fluid from the high pressure line into a lower pressure line to reduce a hydraulic pressure within the high pressure line and adjust an output parameter of the variable displacement pump.

A hydraulic system includes: hydraulic actuators; a control valve for controlling the hydraulic actuators; a tank for storing a hydraulic operation fluid; a variable displacement pump for supplying the hydraulic operation fluid to the hydraulic actuators; a regulator for controlling the variable displacement pump; a pilot pump for discharging a hydraulic pilot fluid; a load sensing system for maintaining a differential pressure to be a constant pressure, the differential pressure being obtained by subtracting a second signal pressure from a first signal pressure that is the discharge pressure of the variable displacement pump, the second signal pressure being the maximum one of the load pressures generated in the hydraulic actuators; a signal tube for sending the second signal pressure to the regulator; a throttle provided on the signal tube; and a warm-up circuit for supplying the hydraulic pilot fluid to a downstream side of the throttle.

Provided is a hydraulic driving apparatus including a calculation section calculating a temporary target engine rotation speed corresponding to an engine operation amount, a calculation section calculating a temporary target pump displacement volume based on first-control and second-control target pump displacement volumes corresponding to an actuator operation amount and a pump load pressure, and a command section calculating a final target engine rotation speed and a final target pump displacement volume to output commands. The command section calculates a target pump discharge amount from the temporary target engine rotation speed and the temporary target pump displacement volume, sets the final target pump displacement volume to one larger than the temporary target pump displacement volume, and sets the final target engine rotation speed to one being lower than the temporary target engine rotation speed and allowing a pump discharge amount equivalent to the target pump discharge amount to be obtained.

A travel control device is provided with hydraulic pumps of a variable capacity type that are driven by an engine; hydraulic motors that are driven by discharged oil from the hydraulic pumps; traveling devices that are rotation-driven by the hydraulic motors; a travel operation lever that is operated so as to instruct a traveling operation; a first control valve for generating a charged hydraulic pressure by adjusting the discharged oil from a charge pump and a second control valve for generating a capacity control hydraulic pressure in accordance with the operation of the travel operation lever. The first control valve is designed to pressure-adjust and generate a charged hydraulic pressure in accordance with the rotation speed of the engine, and the hydraulic pump is subjected to a variable capacity control process by a capacity control hydraulic pressure that is pressure-adjusted and generated by the second control valve.

A work machine, preferably a mobile work machine, has an attachment device, in particular a trench cutter. The attachment device has at least two adjustable hydraulic motors for driving independent, individually controllable loads. The hydraulic supply of the adjustable hydraulic motors takes place by a hydraulic drive unit arranged externally from the attachment device, in particular by a drive unit of the work machine. The at least two adjustable hydraulic motors of the attachment device are connected to a constant pressure network provided by the hydraulic drive unit.