This hydraulic pump system includes: a hydraulic pump having a discharge flow rate that is changeable; a regulator device that adjusts the discharge flow rate of the hydraulic pump; an operation device including an operation tool; a lock switching input unit that unlocks the operation tool; an unloader valve that adjusts a discharge pressure of the hydraulic pump by changing the opening area of the unloader valve; and a control device that controls movement of the unloader valve. When a predetermined actuation condition is satisfied, the control device causes the unloader valve to reduce the opening area to increase the discharge pressure of the hydraulic pump. The regulator device increases the discharge flow rate after the control device causes an increase in the discharge pressure of the hydraulic pump. The actuation condition includes a condition that the lock switching input unit has unlocked the operation tool.

A hydraulic system for a working vehicle includes a first hydraulic pump to deliver pilot fluid to a control valve for a hydraulic actuator whose highest load pressure acts on a first fluid passage, and a second hydraulic pump to deliver hydraulic fluid whose pressure acts on a second fluid passage. A hydraulic controller is operable to control a load-sensing (LS) differential pressure between the highest load pressure and a delivery pressure of the hydraulic fluid from the second hydraulic pump. A third fluid passage to which the second hydraulic pump delivers the hydraulic fluid branches to a fourth fluid passage for flow of the pilot fluid. A solenoid valve is operable to change a pilot pressure of the pilot fluid for the hydraulic controller, and a controller is configured or programmed to control the solenoid valve to adjust the pilot pressure to change the LS differential pressure.

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.

This hydraulic drive system includes: a hydraulic pump that supplies a working fluid to a hydraulic actuator; a meter-in control valve that controls a flow rate of the working fluid flowing from the hydraulic pump to the hydraulic actuator; a meter-out control valve that controls a flow rate of the working fluid being drained from the hydraulic actuator into a tank; and a regeneration valve that supplies, to the hydraulic actuator, the working fluid drained from the hydraulic actuator. The meter-out control valve is connected to the hydraulic actuator in parallel with the regeneration valve.

Provided is a hydraulic machine including an actuator, a first pump and a second pump configured to supply pressurized fluid to the actuator, a driving motor configured to drive the first and second pumps, a first operator input device through which an operator's desire to operate the actuator is input, and a controller. The controller determines displacements of the first and second pumps corresponding to the operator's desire and a speed of rotation of the driving motor and controls the first pump, the second pump, and the driving motor to operate according to the displacements of the first and second pumps and the speed of rotation of the driving motor finally determined in the determination of the displacements of the first and second pumps.

A control system for a work machine includes a plurality of hydraulic pumps that discharge hydraulic oil, a hydraulic cylinder that moves a working equipment element, a plurality of flow rate control valves that are respectively connected to the hydraulic pumps and adjust a flow rate of the hydraulic oil supplied to the hydraulic cylinder, a plurality of supply flow paths respectively connected to the of flow rate control valves, a meter-in flow path that connects a collective part of the supply flow paths and an inlet of the hydraulic oil in the hydraulic cylinder, a plurality of discharge flow paths respectively connected to the flow rate control valves, a meter-out flow path that connects a collective part of the discharge flow paths and an outlet of the hydraulic oil in the hydraulic cylinder, and a throttle disposed in the meter-out flow path.

A hydraulic apparatus comprises first and second manifolds each of which is connected to a plurality of actuators via corresponding actuator valves connected in parallel and operated responsive to inputs to regulate the flow of fluid to the actuators. A plurality of working chambers are connectable to either the first or second manifold and have a net flow which is controlled responsive to a negative feedback signal. The negative feedback signal is determined in response to a calculated pressure or flow rate in virtual fluid flow paths extending from the first and second manifolds.

A machine control system can store model weights determined via machine learning using a training dataset correlating preset hydraulic valve displacements to measured movement parameters of a machine component. The machine control system can receive an input command for the component and machine state data from machine sensors. A control mapping model can use the model weights to map a combination of the input command and the machine state data into a predicted displacement of the hydraulic valve that causes movement of the component in response to the input command.

A hoist valve assembly for a work machine cylinder includes a main control valve, a counterbalance valve and a counterbalance shutoff valve. A main control valve raise position connects a head end of the cylinder with a pressurized fluid source and a rod end of the cylinder to a low pressure reservoir to extend the cylinder. The counterbalance valve is between the rod end and the main control valve, is biased to a closed position and has an open position connecting the rod end to the low pressure reservoir. Rod end and head end pressure signals apply force to the counterbalance valve toward the open position. The counterbalance shutoff valve is positioned between the head end and the counterbalance valve, and has a normal position to apply the head end pressure signal to the counterbalance valve and a shutoff position that blocks the head end pressure signal from the counterbalance valve.

A hydraulic system of a construction machine includes: control valves interposed between a variable displacement main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: a regulator that changes a displacement of the main pump; and a second solenoid proportional valve connected to an auxiliary pump by a primary pressure line, the second solenoid proportional valve outputting a secondary pressure to the regulator through a secondary pressure line. A switching valve is interposed between the auxiliary pump and the first solenoid proportional valves, and includes a pilot port that is connected to the secondary pressure line by a pilot line.