The present invention relates to a hydraulic system for a hydraulically actuable work machine that comprises a switching valve block having a plurality of valve block inputs for a respective connection to a pressure output of one or more hydraulic fluid pumps; having a plurality of valve block outputs for outputting a pressurized hydraulic fluid; and having at least one valve that is arranged between valve block inputs and valve block outputs and that is adapted to selectively produce a fluid connection between a first valve block input and a first valve block output or between the first valve block input and a second valve block output; a plurality of pressure sources, preferably a plurality of separately controllable pressure sources of which each one is connected to a respective valve block input; and a plurality of hydraulic consumers of which each one is connected to a respective valve block output. The system is characterized in that the first valve block output furthermore already has a fixed fluid connection, preferably a fixed exclusive fluid connection, to a second valve block input and in that the steering is connected to the first valve block output.

A direction control valve group for a construction machine that controls an amount of pressure oil supplied to a hydraulic actuator from a hydraulic pump that discharges the pressure oil is provided. The direction control valve includes a cylinder port that supplies the pressure oil to the hydraulic actuator, a bridge passage that is switchably connected and disconnected to the cylinder port according to a change in position of a first spool, and an internal passage that supplies the pressure oil discharged from the hydraulic pump to the bridge passage. The first spool is provided in the internal passage.

A drive control method of a hydraulic actuator of a construction machine includes: determining whether a rotation operation lever and a working device operation lever are operated; calculating the required pressure of a hydraulic cylinder fix a working device according to the operation amount of the rotation operation lever; calculating the required flow rates of a swing motor and the hydraulic cylinder for the working device, the required flow rates corresponding to the operation amounts of the working device operation lever and the rotation operation lever; calculating the opening areas of the first and second proportional solenoid valves of an inlet side and an outlet side by using the calculated required pressure and required flow rates of the hydraulic cylinder for the working device and the swing motor; and calculating current values to be inputted into the first and second proportional solenoid valves of the inlet side and the outlet side according to preset data values or a table in comparison with the calculated opening areas of the first and second proportional solenoid valves of the inlet side and the outlet side.

The present disclosure relates to a load-sense system such as a load-sense steering system that operates in a static load-sense mode for low flows and operates in a dynamic load-sense mode for high flows.

Agricultural implements and hydraulic circuits for agricultural implements are disclosed herein. An agricultural implement includes a fluid source, a plurality of fluid demand devices, a delivery control valve, and a priority valve. The fluid source is configured to supply hydraulic fluid. The plurality of fluid demand devices are each configured to receive hydraulic fluid supplied by the fluid source during operation of the agricultural implement. The delivery control valve is fluidly coupled between the fluid source and a first fluid demand device. The delivery control valve is configured to selectively deliver hydraulic fluid supplied by the fluid source to the first fluid demand device during operation of the agricultural implement. The priority valve is fluidly coupled between the delivery control valve and the first fluid demand device.

A working machine includes: a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator whose hydraulic pressure for actuation thereof is lower than that of the high-load hydraulic actuator; a plurality of direction switching valves each of which switches a direction of a hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator; and a dummy-load forming unit that forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly.

A pressure supply device for prioritised volume flow splitting, in particular in mobile working machines, includes at least one adjusting pump (2) controllable by an LS signal as main pump, a constant-displacement pump (4) as an auxiliary pump, and two pressure balances. A system is supplied primarily, in particular in the form of steering hydraulics (PL), which outputs an LS signal. A system is supplied secondarily, which outputs a further LS signal, in particular in the form of working hydraulics (PA). A further system is supplied hydraulically, in particular in the form of brake hydraulics (PB). One pressure balance (DW1) is used to supply the system (PL) to be supplied primarily and/or the further hydraulic system (PB), the other pressure balance (DW2) is used to supply the system (PL) to be supplied primarily and/or the system (PA) to be supplied secondarily, The respective pressure balance (DW1, DW2) can be activated by an LS signal in such a way that the constant-displacement pump (4) is also used to supply the system (PA) to be supplied secondarily.

A hydraulic system for a vehicle includes a hydraulic monitoring control unit configured to receive an operational signal from a sub-system of the vehicle and control flow of hydraulic fluid to actuators of components based on the operational signal. The hydraulic monitoring control unit is configured to bypass the flow of the hydraulic fluid in relation to a subset of the actuators in response to the operational signal indicating an altered operational state of the sub-system.

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.

The invention relates to a construction machine, road milling machine, stabiliser, recycler, surface miner, and a to method for controlling a construction machine. The construction machine has a machine frame 2 supported by a chassis 1 and a plurality of hydraulic systems 15, 16, each of which has at least one hydraulic component 18, 22, at least one hydraulic pump 17, 21 for conveying hydraulic fluid for the at least one hydraulic component and at least one hydraulic line 28, 31 for transporting the hydraulic fluid from the at least one hydraulic pump to the at least one hydraulic component. The drive device of the construction machine comprises at least one internal combustion engine 24. A power transmission device 44 is provided for transmitting at least part of the drive power from the internal combustion engine 24 to the hydraulic pumps 17, 21. The construction machine according to the invention is characterised by a hydraulic control device 26, which is assigned to two hydraulic systems 15, 16 of the plurality of hydraulic systems. The hydraulic control device 16 is designed such that, in a special operating mode, at least part of the hydraulic fluid delivered by the hydraulic pump 17 of the one hydraulic system 15 is supplied to the other hydraulic system 16.