A working-fluid supply system includes: a first pump and a second pump driven by an engine; a first switching valve capable of switching a supply target of the second pump to either one of the discharge side and the suction side of the first pump; a first switching control unit configured to perform a switching control of the first switching valve; and a first pressure control unit configured to perform a control such that pressure on the suction side of the first pump becomes a predetermined first pressure when the first switching valve is switched such that the supply target of the second pump becomes the suction side of the first pump.

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.

A system, including: a fluidic actuator which can be acted upon by a pressurized fluid and has an actuator member, a pressurized fluid provision device which is adapted to carry out a position control of the actuator member and, within the position control, to act upon the fluidic actuator with the pressurized fluid in order to move the actuator member into a prescribed position, and a hose arrangement, including at least one hose via which the fluidic actuator is fluidically connected to the pressurized fluid provision device, wherein the pressurized fluid provision device is adapted to carry out the position control taking into account a system model describing the hose arrangement, the actuator and/or the pressurized fluid provision device.

A device for varying the swept volumes of first and second hydraulic machines, whose swept volumes depends upon pivoting positions of adjustable axes thereof which can be connected to one another by first and second lines. The axes can be coupled to a piston-cylinder device which is adjustable by a control valve unit for pivoting the axes. Pressures in the area of the hydraulic machines can be limited by the control valve unit. The control valve unit can be coupled to a respective first or second line with the highest pressure. A device for determining an existing actual pressure is located upstream of the control valve unit, at least in the area of one of the first and the second lines that connects with the first and the second hydraulic machines. The control valve unit can be actuated based on the actual pressure value determined by the device.

A hydraulic device 10 includes a hydraulic pump 20, a tool 70, an oil passage 30, 32, 50, 52 for sending the pressure oil generated by the hydraulic pump 20 to the tool 70 and returning return oil from the tool 70 to the hydraulic pump 20, a handle 90 configured to be held by one hand of a worker, a switching part 88 disposed at the oil passage 30, 32, 50, 52 and configured to switch a path for at least one of the pressure oil and the return oil, and an operation part 80 for operating the switching part 88. The operation part 80 is disposed at a position that allows the operation part 80 to be operated with the hand of the worker holding the handle 90, or with a finger of the hand holding the handle 90.

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 herein are methods and systems of robust electrohydraulic pressure control with distributed damping. The system includes a two-stage pilot operated electrohydraulic pressure reducing-relieving valve have a valve body with a high-pressure port, a low-pressure port, and a variable working pressure port. A valve spool is disposed within the valve body to direct oil flow into and out of a working volume, and a pilot subassembly is also disposed within the valve body to generate a pilot pressure and create a hydraulic motive force to operate the valve spool. A linear electromagnetic actuator is operatively coupled to the pilot subsystem to generate an electromotive force to operate the pilot assembly. The system further includes a fluid path that restrictively communicates a common fluid pressure to a volume of fluid defined by a position of the linear electromagnetic actuator.

A work vehicle includes a valve for switching between a merging position for causing a first oil passage for driving a bucket and a second oil passage for driving an arm to communicate with each other, and a diverging position for separating the first oil passage and the second oil passage. The work vehicle is adapted to switch the valve from the merging position to the diverging position, when one of a pump pressure in the first pump and a pump pressure in the second pump comes to be equal to a predetermined value during an excavation operation. The work vehicle is adapted to control both pumps, such that the amount of the oil discharged from the first pump is larger than the amount of the oil discharged from the second pump, when the pump pressure in the first pump is equal to or more than the predetermined value.

A method and control system operable to control movement of a work implement of a work vehicle. The control system includes a reservoir that retains fluid, a pump in fluid communication with the reservoir, and an actuator in fluid communication with the pump. The actuator has a first side and a second side. A control valve is fluidly positioned between the pump and the actuator, a first proportional relief valve is fluidly positioned between the pump and the first side of the actuator, and a second proportional relief valve is fluidly positioned between the pump and the second side of the actuator. The first proportional relief valve is configured to permit flow of fluid from the first side of the actuator to the reservoir when a pressure at the first side of the actuator exceeds a pressure set point.

A hydraulic work machine is provided in which left and right hydraulic motors are driven independently of each other by two hydraulic pumps and in which an anomaly of any of the left and right track devices can be detected with high accuracy. The hydraulic work machine includes a first pressure sensor 13 configured to detect a first pump pressure that is a delivery pressure of a first hydraulic pump 11 and a second pressure sensor 23 configured to detect a second pump pressure that is a delivery pressure of a second hydraulic pump 21. When a controller 2 decides, from detection results of a travel operation detector 5 and work operation detectors 3 and 4, that a work implement 103 is not operated but travel operation devices 6 and 7 are operated and besides left and right track devices 50 and 60 are straightly traveling, the controller 2 calculates an anomaly decision evaluation value based on a pressure difference value obtained by subtracting one from the other of the first pump pressure and the second pump pressure and decides, based on a result of comparison between the anomaly decision evaluation value and a predetermined decision reference value 84, that one of the left and right track devices has an anomaly.