A fluid circuit includes a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source , a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source , and a discharge amount control mechanism configured to control the output pressure of the pressure fluid source such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator configured to accumulate part of return fluid from the actuators.

A dual pressure margin priority circuit and method for controlling flow from a pump to steering valve and low priority inlets. A steering pressure valve controls flow from pump to steering valve inlets, and provides a steering valve load sense pressure. A priority valve controls flow from pump to low priority inlets. A load sense cutoff valve has a first inlet receiving the steering valve load sense pressure. The load sense cutoff valve controls flow through the priority valve based on steering valve load sense pressure at the first cutoff valve inlet. The cutoff valve can include a second inlet coupled to tank, and a load sense input coupled to the steering valve load sense pressure. The cutoff valve can be a pressure limiter valve. The priority and steering pressure valves can be 2-way proportional flow spool valves with bias springs, and contributing and opposing load sense inputs.

Provided is a construction machine capable of driving each hydraulic actuator at a suitable speed while suppressing delivery flow rate of a hydraulic pump, both at a single operation time of driving each hydraulic actuator respectively singularly and at a combined operation time of simultaneously driving a plurality of hydraulic actuators. A controller is configure to compute a first required pump flow rate for each of operation amounts of a plurality of operation devices, compute a second required pump flow rate greater than the first required pump flow rate for the same operation amount for each of the operation amounts of the plurality of operation devices, select as a final required pump flow rate either smaller one of a sum total value of the first required pump flow rates computed for the operation amounts of the plurality of operation devices and a maximum value of the second required pump flow rates computed for the operation amounts of the plurality of operation devices, and control a regulator in such a manner that the delivery flow rate of the hydraulic pump and the final required pump flow rate will be equal.

The present disclosure relates to a hydraulic circuit, comprising: a hydraulic displacement unit for driving an implement; a hydraulic machine fluidly connected or selectively fluidly connected with the hydraulic displacement unit the hydraulic machine having a fixed hydraulic displacement; an electric machine drivingly engaged or selectively drivingly engaged with the hydraulic machine; a hydraulic pump fluidly connected or selectively fluidly connected with the hydraulic displacement unit, the hydraulic pump having a variable hydraulic displacement; and an electric motor drivingly engaged or selectively drivingly engaged with the hydraulic pump.

A work machine and method for a work machine with an open center hydraulic system for controlling actuation of an implement includes an implement control valve, an electro-hydraulically controlled pump, a hydraulic circuit coupled to the implement actuator, and a pressure transducer positioned for measuring a pressure in the hydraulic circuit between the pump and the implement control valve. A calibration system for calibrating the pump includes a controller having a non-transitory computer readable medium having a program instruction for causing a processor to calibrate a first threshold for the pump in a pump-flow curve wherein the first threshold including a minimum current command to actuate the pump; determine a hysteresis band in the pump-flow curve; and calibrate a second threshold for the pump in the pump-flow curve wherein the second threshold including a maximum current command to actuate the pump below a relief setpoint.

A hydraulic system for a machine includes an implement pump, a valve, and an implement valve subsystem. The implement pump includes a load sensing control, and the valve controls the flow of hydraulic fluid to the implement pump. The implement valve subsystem includes one or more implement control subsystems to control movement of an implement. The valve is an electrohydraulic proportional relief valve and includes a solenoid configured to adjust the pressure of hydraulic fluid delivered to the implement pump proportionally to a current delivered through the solenoid.

A variator includes an epicyclic gear set that has at least three nodes. The variator includes a pumping unit connected to a first node of the epicyclic gear set. The variator includes a clutch connected to a second node of the epicyclic gear set. The clutch is selectively movable between three positions. When in the first position, the clutch allows the second node to freewheel. When in the second position, the clutch connects the second node to a fixed surface. When in the third position, the clutch connects the second node to an electric motor. The variator includes a receiver connected to the third node of the epicyclical gear set. The receiver is configured to receive a drive shaft.

A system for controlling hydraulic fluid flow within a work vehicle includes a pilot conduit fluidly configured to receive a pilot flow of the hydraulic fluid from a fluid supply conduit such that an operation of a compensator valve is controlled based on a pressure of the pilot flow. Furthermore, the system includes a pilot conduit valve configured to adjust the pressure of the pilot flow within the pilot conduit. A computing system is configured to determine the pressure of the hydraulic fluid within the fluid supply conduit downstream of the flow control valve based on the data captured by a pressure sensor. Furthermore, the computing system is configured to control an operation of the pilot conduit valve to selectively adjust the pressure of the pilot flow within the pilot conduit based on the determined pressure.

Systems and apparatuses include a primary hydraulic pump including a primary displacement actuator and a primary pressure port, a primary load sense system fluidly coupled to the primary displacement actuator, a secondary hydraulic pump including a secondary displacement actuator and a secondary pressure port, a secondary load sense system fluidly coupled to the secondary displacement actuator, and a crossover pressure controller coupled between the primary pressure port and the secondary pressure port and including: a selectively energizable crossover pressure solenoid, and a crossover pressure spool movable by the crossover pressure solenoid between a combined pressure position providing fluid communication between the primary pressure port and the secondary pressure port, and a separate pressure position inhibiting fluid communication between the primary pressure port and the secondary pressure port.

The invention relates to a system for a work machine. The power system comprises a power-split continuously variable transmission for propulsion of the work machine and a hydraulic system for work hydraulics. The power-split continuously variable transmission has a hydrostatic branch and a mechanical branch. The hydrostatic branch comprises a first hydraulic machine and a second hydraulic machine. The hydrostatic branch comprises a first control valve fluidly connected to the first hydraulic machine and to the second hydraulic machine for controlling the flow of hydraulic fluid between the first hydraulic machine and the second hydraulic machine. The hydraulic system comprises at least one hydraulic actuator fluidly connected to a first port of the first hydraulic machine, and a second control valve for controlling the flow of hydraulic fluid to said at least one hydraulic actuator.