A hydraulic system having a hydraulic pump, having a plurality of hydraulic loads and having a plurality of load-sensing valves for adjusting the pump performance of the hydraulic pump. An association unit is arranged between the hydraulic pump and the hydraulic loads and in a first switched state defines a first hydraulic path between the hydraulic pump and the hydraulic loads and in a second switched state defines a second hydraulic path between the hydraulic pump and the hydraulic loads. The system comprises a controller, which processes a state value of a hydraulic load as an input variable and which determines a control signal for the switched state of the association unit. The invention also relates to a method for controlling a hydraulic system.

A hydraulic drive system includes a hydraulic pump, a boom-dedicated control valve, a turning-dedicated control valve, a boom-dedicated operation unit, a turning-dedicated operation unit, and a driving control unit. If an operating amount of the turning-dedicated operating portion where a concurrent operation is performed and a single operation is performed are the same, the driving control unit adjusts a turning driving command, that an opening area between the hydraulic pump and a turning motor where the concurrent operation is performed is less than the opening area between the hydraulic pump and the turning motor where the single operation is performed, the concurrent operation wherein the turning operation command is outputted from the turning-dedicated operation unit and a boom operation command is outputted from the boom-dedicated operation unit, the single operation wherein the turning operation command is outputted, but the boom operation command is not outputted from the boom-dedicated operation unit.

A control system for construction machinery, includes a hydraulic pump, first and second actuators connected to the hydraulic pump through first and second parallel lines respectively, first and second control valves installed in the first and second parallel lines respectively and configured to control operations of the first and second actuators, first and second spool displacement adjusting valves configured to control displacement amounts of the spools of the first and second control valves, and a controller configured to output a control signal to the first and second spool displacement adjusting valves corresponding to a manipulation signal of an operator, and configured to limit a spool displacement amount of the second control valve according to the manipulation signal for the first actuator when the manipulation signal for a multiple operation of the first and second actuators is received.

A hydraulic circuit of a construction machine includes: a first pump line that connects a delivery port of a pump to a pump port of a first direction-switching valve; a second pump line that is branched off from the first pump line and is connected to a pump port of a second direction-switching valve; and a priority valve provided on the second pump line. The priority valve is configured to: fully open the second pump line when a pressure difference between a delivery pressure of the pump and a load pressure of a first actuator is greater than a setting value; and decrease an opening degree of the second pump line in accordance with decrease in the pressure difference when the pressure difference is less than the setting value.

A hydraulic system includes a first fixed displacement pump having a first pump output and a second fixed displacement pump having a second pump output. A first actuator requires a first required flow rate to perform a first function. A second actuator requires a second required flow rate to perform a second function. A combined flow control valve is controllable between a first state connecting fluid communication between the first fixed displacement pump and the tank so that only the second pump output is directed to the second actuator, and a second state disconnecting fluid communication between the first fixed displacement pump and the tank to combine the first pump output and the second pump output such that the combined first pump output and the second pump output is directed to the first actuator.

A hydraulic control arrangement for simultaneously supplying at least two hydraulic consumers with predefinable individual pressure medium flow rates includes a hydraulic pump having an adjustable swept volume, and at least two valve arrangements each including a variable metering restrictor and a pressure balance arranged downstream of the variable metering restrictor. Each pressure balance is configured to be acted on in an opening direction by pressure downstream of the respective variable metering restrictor and to be acted on in a closing direction by a highest load pressure or by a pressure derived therefrom. Each valve arrangement is arranged between a pump line, which leads away from the hydraulic pump, and a consumer of the at least two hydraulic consumers. The arrangement further includes an electronic control device, by which the hydraulic pump is actuatable such that it conveys a sum of the predefinable individual pressure medium flow rates.

A hydraulic system controller is disclosed. The hydraulic system controller may determine a maximum active circuit pressure of a set of active hydraulic circuits of the hydraulic system, wherein the hydraulic system includes a hydraulic pump to cause fluid to flow throughout the set of active hydraulic circuits; determine a circuit pressure of a hydraulic circuit of the hydraulic system; determine, based on a hydraulic flow command for the hydraulic circuit and the circuit pressure, a desired circuit delta-pressure for the hydraulic circuit; determine, based on the desired circuit delta-pressure and a pressure difference between the maximum active circuit pressure and the circuit pressure, a circuit valve setting for a circuit valve of the hydraulic circuit; and cause a control device to set a position of the circuit valve according to the circuit valve setting.

An actuation pressure to actuate one or more hydraulic actuators may be determined based on a load on the one or more hydraulic actuators of a robotic device. Based on the determined actuation pressure, a pressure rail from among a set of pressure rails at respective pressures may be selected. One or more valves may connect the selected pressure rail to a metering valve. The hydraulic drive system may operate in a discrete mode in which the metering valve opens such that hydraulic fluid flows from the selected pressure rail through the metering valve to the one or more hydraulic actuators at approximately the supply pressure. Responsive to a control state of the robotic device, the hydraulic drive system may operate in a continuous mode in which the metering valve throttles the hydraulic fluid such that the supply pressure is reduced to the determined actuation pressure.

Disclosed embodiments include power machines, and hydraulic systems for power machines, in which a controller is configured to monitor the power in each of an implement circuit and a drive circuit and to adjust pump flow to manage engine power consumption.

A dual mode control system for a work vehicle includes a hydraulic system configured to drive a loader assembly and a dozer assembly coupled to the work vehicle. The hydraulic system includes a fluid delivery system comprising a plurality of flow paths fluidly coupled to a hydraulic pump. The hydraulic system includes a valve assembly configured to regulate diversion of fluid into a first and a second hydraulic cylinders coupled to the fluid delivery system to adjust the loader assembly, or into a third cylinder coupled to the fluid delivery system to adjust the dozer assembly. The dual mode control system also includes a controller operably coupled to the valve assembly, and one or more user interfaces coupled to the controller to enable an operator to provide inputs to cause the controller to adjust the valve assembly, and to thereby adjust the loader assembly or the dozer assembly.