A method of operating a mobile industrial machine including an electric motor and a hydraulic motor for driving a common load may include receiving a desired drive request for the electric motor to drive the common load, driving the electric motor based on the desired drive request, sensing that the electric motor is unable to provide the full amount of the desired drive request, and driving the hydraulic motor to fulfill the full amount of the desired drive request.

A prime mover and hydraulic actuators, a hydraulic machine having a rotatable shaft engaged with the prime mover and having a plurality of working chambers, a hydraulic circuit extending between a group of working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine having a low-pressure and a high-pressure valve regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine controlling the low-pressure valves of the group of working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of working chambers, responsive to a demand signal, the apparatus further having a controller calculating the demand signal responsive to a measured property of the hydraulic circuit or an actuator.

A preselection valve is for a hydraulic valve assembly with a switching element, a pressure input line, a first pressure output line and a first load pressure line with a load pressure inlet and output. The switching element is switchable from neutral to a first switching position. The pressure input line is connected to the first pressure output line in the first position. The preselection valve has a second and third load pressure line and a load pressure increasing device. The second load pressure line branches off the pressure input line upstream of the switching element. The load pressure increasing device is connected to the third load pressure line, which connects the pressure increasing device to the first load pressure line. The second load pressure line is connected to the pressure increasing device in the first switching position and the second load pressure line is blocked in the neutral position.

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.

A hydraulic system includes a pump in communication with a fluid reservoir and powered by a motor. A pressure compensator is adapted to adjust a position of a variable displacement mechanism of the pump. A load sensing line is adapted to communicate a highest load sensing pressure from a plurality of valves to the pressure compensator. The pressure compensator adjusts the variable displacement mechanism of the pump based on the highest load sensing pressure for maintaining a constant pressure drop across one or more work ports in each of the plurality of valves. The plurality of valves each include a load sense port having an integrated check valve that includes a metering orifice.

To improve operability and work efficiency while achieving reduction of the number of parts and simplification of circuit structure, in a hydraulic control system equipped with hydraulic actuators whose hydraulic power sources are both the first, second hydraulic pumps. The hydraulic control system is provided with the stick directional switching valve; the main-side, sub-side supply oil passages connecting the hydraulic pumps to the stick directional switching valve; and the stick flow rate control valve which is placed in the sub-side supply oil passage, and controls the supply flow rate from the hydraulic pump when the supply flow rate to the stick cylinder requires the supply flow rates from both the hydraulic pumps, wherein the stick directional switching valve is configured such that the discharge flow rate control is performed in the entire area of the spool stroke, and the supply flow rate control is performed at the first region of the former half of the spool stroke, but not performed at the second region of the latter half of the spool stroke.

A hydraulic system having a hydraulic pump, having a plurality of hydraulic loads and having a plurality of load-sensing valves for adjusting the pump performance of the hydraulic pump. An association unit is arranged between the hydraulic pump and the hydraulic loads and in a first switched state defines a first hydraulic path between the hydraulic pump and the hydraulic loads and in a second switched state defines a second hydraulic path between the hydraulic pump and the hydraulic loads. The system comprises a controller, which processes a state value of a hydraulic load as an input variable and which determines a control signal for the switched state of the association unit. The invention also relates to a method for controlling a hydraulic system.

To achieve reduction of fuel consumption and enhancement of operability, in a hydraulic control circuit provided with a bypass oil passage formed by being branched from a discharge line of a hydraulic pump and extending to an oil tank, and a bypass valve having variable opening area for controlling a flow rate of the bypass oil passage, and to accurately perform pump pressure control through opening area control of the bypass valve without being affected by a condition of each time. The hydraulic control circuit is configured to perform closed-loop control of the opening area of the bypass valve so that the pump pressure is maintained at a set pressure, during nonoperation of the operation lever; on the other hand, to perform open-loop control for reducing the opening area of the bypass valve depending on the operation input of the operation lever, during an operation of the operation lever, and further configured to correct on the basis of the opening area of the bypass valve during the closed-loop control, the correspondence relationship between the operation input of the operation lever and the opening area of the bypass valve during the open-loop control.

A load sensing valve maintains a differential pressure at a set pressure by controlling a regulator in accordance with a differential pressure between a discharge pressure of a hydraulic pump and a load pressure of hydraulic actuators. A set pressure control device controls the set pressure. A controller controls the set pressure control device to reduce the set pressure more than when the work implement is being operated, when a predetermined determination condition that includes the work implement not being operated is satisfied.

A system for operating a work vehicle includes a hydraulic control assembly and a controller. The hydraulic control assembly includes a pump, accumulator, boom hydraulic cylinder, pin hydraulic cylinder, pin control valve, and ride control valve assembly. The boom hydraulic cylinder moves a boom of the work vehicle. The pin hydraulic cylinder moves a pin on the boom. The ride control valve assembly includes a charge valve and discharge valve. The charge valve is in fluid communication with the pump and the accumulator. The discharge valve is in fluid communication with the accumulator and a reservoir. The controller operates the work vehicle in a ride control mode and pin actuation mode. The pin actuation mode includes opening the charge valve with the discharge valve closed, and directing hydraulic fluid through the pin control valve.