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 (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic actuator (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and first and second blocking valves (350, 450). A net load (90) is supported by a first chamber (116, 118) of the hydraulic actuator, and a second chamber (118, 116) of the hydraulic actuator may receive fluctuating hydraulic fluid flow from the second control valve to produce a vibratory response (950) that counters environmental vibrations (960) on the boom. The first blocking valve prevents the fluctuating hydraulic fluid flow from opening the first counter-balance valve. The first blocking valve may drain leakage from the first counter-balance valve.

A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.

A multi-control valve device includes: a valve block including a plurality of valve holes; a plurality of spools movably housed in the plurality of valve holes in a one-to-one correspondence; one or more attachment parts provided on the valve block; and a plurality of solenoid valves provided on the one or more attachment parts in a one-to-one correspondence with the plurality of spools and each of which reduces a primary pressure, outputs a secondary pressure to a corresponding one of the plurality of spools, and moves the spool. The valve block includes a primary pressure supply passage through which the primary pressure is supplied to each of the plurality of solenoid valves.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A pilot hydraulic system may include a pilot pressure source, a pilot pressure return tank, a pilot valve, a pilot pressure supply line connecting the pilot pressure source to the pilot valve, and a pilot pressure return line connecting the pilot pressure return tank to the pilot valve. A main control valve may include a pilot chamber. A pilot pressure control line connects the pilot valve to the pilot chamber. A hydraulic sub-system is provided for modifying pilot pressure provided to the pilot chamber of the main control valve. The hydraulic sub-system may include a variable orifice valve disposed in the pilot pressure control line, a pilot pressure bypass line communicating the pilot pressure control line downstream of the variable orifice valve with the pilot pressure return line, and an electrohydraulic pressure reducing valve (EHPRV) disposed in the pilot pressure bypass line.

A load sense pressure regulating system is provided. The load sense pressure regulating system can be operable between a flow regulation mode and a pressure limiting mode. When the load sense pressure control system is in the flow regulation mode, flow between a load sense inlet and a pilot vent are metered by a main poppet. The load sense pressure regulating system can also include a control valve downstream from the pilot vent that is configured to control a relief setting of a relief valve to regulate the load sense pressure within a desired operating range.

A method is for controlling an actuation force exerted by an actuating device having a first working chamber and a second working chamber supplied with pressurized air from a source of pressurized air by a first pressure regulator and a second pressure regulator. The method includes calculating, by an optimization algorithm based on a dynamic model of the actuating device and of the first and second pressure regulators, desired values for control signals for the first and second pressure regulators to generate an actuation force equal to a desired value for the actuation force. An estimated value for the actuation force, estimated values for pressures inside the first and second working chambers and for first derivatives of the pressures, are determined by a state observer based on a measured value for the actuation force and on measured values for the pressures in the first and second working chambers.

A hydraulic control system includes a first hydraulic cylinder, a second hydraulic cylinder, a fluid supply apparatus, a first control valve bank, a second control valve bank, a third control valve bank, and a first check valve. The first control valve bank is configured to independently control the first hydraulic cylinder; the second control valve bank is configured to independently control the second hydraulic cylinder; and the third control valve bank is configured to synchronously control the first hydraulic cylinder and the second hydraulic cylinder. Synchronous volume control is implemented through series connection of the hydraulic cylinders, and has quite high synchronization precision, which is measured to be up to two percent.

A system for controlling hydraulic fluid flow within a work vehicle includes a load sense valve configured to adjust the pressure of a bleed flow within a load sense conduit. Moreover, the system includes a computing system 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 device is configured to control an operation of the load sense valve to selectively adjust the pressure of the bleed flow within the load sense conduit based on the determined pressure.