A hydraulic system for a vehicle includes a first hydraulic pump including a first displacement actuator and a first pressure port, a first load sense system fluidly coupled to the first displacement actuator, a second hydraulic pump including a second displacement actuator and a second pressure port, a second load sense system fluidly coupled to the second displacement actuator, and a crossover pressure controller coupled between the first pressure port and the second pressure port. The crossover pressure controller reconfigurable between (a) a combined pressure configuration providing fluid communication between the first pressure port and the second pressure port and (b) a separate pressure configuration inhibiting fluid communication between the first pressure port and the second pressure port. The crossover pressure controller is actuatable independent of the first load sense system and the second load sense system.

A work machine includes an electric drive system. The work machine includes a prime mover, a machine controller, and a hydraulic control system. The hydraulic control system includes a pump, a control valve and a retarding control valve. The pump is configured to supply pressurized fluid to the hydraulic control system via a supply line. The control valve is fluidly coupled to the pump via the supply line, and includes a pressure relief valve. The retarding control valve is fluidly connected to the pump and the control valve. The retarding control valve includes a solenoid valve, an orifice and a check valve. The solenoid valve is coupled to the machine controller, the orifice restricts a flow of the pressurized fluid through the supply line, and the check valve is coupled to a discharge line, which branches from a point along the supply line between the solenoid valve and the orifice.

A work vehicle includes a hydraulic actuator, a hydraulic pump, an operation member, a control valve, an angular velocity corresponding value sensing unit, a notification component, and a controller. The actuator changes a steering angle based on a supplied fluid. The pump supplies fluid to the actuator. The operation member is operated by an operator when the steering angle is changed. The valve controls flow of fluid supplied from the pump to the actuator based on an amount the operation member is operated. The sensing unit senses a corresponding value corresponding to a steering angular velocity changed based on the flow of fluid. The notification component notifies that the corresponding value has reached a threshold value preset based on an upper limit of the steering angular velocity. The controller causes the notification component to perform a notification when it is detected that the corresponding value has reached the threshold value.

An open center (OC)-open center load sense (OCLS) conversion valve and hydraulic circuits therewith configured to control flow from a hydraulic pump to multiple hydraulic functions. The conversion valve includes cartridge, load sense, pump, first function supply, first function return, and downstream ports. When an OC cartridge is inserted in the cartridge port, regardless of load sense, the pump and first function supply ports are connected and the first function return and downstream ports are connected. When an OCLS cartridge is inserted in the cartridge port and load sense is detected, the pump and first function supply ports are connected and the first function return and downstream ports are connected. When an OCLS cartridge is inserted in the cartridge port and load sense is not detected, the pump, first function return and downstream ports are connected.

An open center (OC)-open center load sense (OCLS) conversion valve and hydraulic circuits therewith configured to control flow from a hydraulic pump to multiple hydraulic functions. The conversion valve includes cartridge, load sense, pump, first function supply, first function return, and downstream ports. When an OC cartridge is inserted in the cartridge port, regardless of load sense, the pump and first function supply ports are connected and the first function return and downstream ports are connected. When an OCLS cartridge is inserted in the cartridge port and load sense is detected, the pump and first function supply ports are connected and the first function return and downstream ports are connected. When an OCLS cartridge is inserted in the cartridge port and load sense is not detected, the pump, first function return and downstream ports are connected.

The present invention provides an engineering machinery hydraulic system with compensation differential pressure controllable, uses an electronic pressure compensating valve to solve the problem of flow mismatch under conditions of pressure over-limit and flow saturation, and realizes proportional shunt control and high-precision flow distribution of the system. The engineering machinery hydraulic system disclosed in the present invention has the advantages of low energy consumption, fast response speed, and high flow control precision.

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.

Modular directional valve with two or more crossing elements (E1 . . . En) able, acting only on the entry side, to manage a variable displacement pump (PA) of the load sensing type. In particular, this management allows in a single drive, unlike the conventional crossing distributors, to make the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads. A compensated flow rate regulator is placed in the entry side so as to act only on the bypass line LC upstream of the first element (E1 . . . En) while a proportional choke is placed on the load line consisting of a 2-way 2-position tray.

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.

A hydraulic system for a work machine includes a first control valve including a first direction switch to switch a direction in which the operation fluid is to flow through a first hydraulic actuator and a pressure compensator to maintain a differential pressure to a constant pressure, the differential pressure being a difference between a pressure of the operation fluid to be inputted to the pressure compensator and a pressure of the operation fluid to be outputted from the pressure compensator. And, the hydraulic system includes a second control valve including a second direction switch to switch a direction in which the operation fluid is to flow through a second hydraulic actuator and a flow rate prioritizer to prioritize a flow rate of the operation fluid to be outputted to the second hydraulic actuator.