A hydraulic work system can include a continuously variable displacement hydraulic pump that is powered by an engine and is in communication with a hydraulic actuator. A run-time displacement of the hydraulic pump for movement of the hydraulic actuator can be controlled based on a speed of the engine.

A method for automatically adjusting the position of an implement of a lift assembly of a work vehicle includes determining a tilt transition boom angle for the lift assembly, determining a closed-loop control signal associated with controlling movement of the implement based at least in part on the tilt transition boom angle, generating a valve command signal based at least in part on the closed-loop control signal, and controlling an operation of at least one valve associated with the implement based at least in part on the valve command signal to maintain the implement at a target implement angle as a boom of the lift assembly is being moved across a boom travel range.

A hydraulic excavator having a plurality of front implement members, including a bucket, has a controller that controls the work implement by using: excavation assistance control that controls the work implement such that the bucket moves along a predetermined target excavation surface; and deviation prevention control that prevents deviation of the work implement from a predetermined work area by decelerating or stopping operation of a subject front implement member that is included in the plurality of front implement members and that can deviate the work implement from the work area. The controller controls the work implement such that when the controller controls the work implement by using both the excavation assistance control and the deviation prevention control, an operation direction of the bucket approximates to an operation direction of the bucket that is to be generated when the work implement is controlled by using only the excavation assistance control.

A work machine comprises: a work implement; a hydraulic cylinder; a hydraulic pump that supplies the hydraulic oil to the hydraulic cylinder via a hydraulic circuit; a relief valve that can set a relief pressure of the hydraulic circuit to either a first set pressure or a second set pressure higher than the first set pressure; a detection unit that detects at least one of a pressure of the hydraulic oil in the hydraulic circuit and a speed of the work implement; and a relief pressure changing unit that changes a relief pressure of the relief valve from the first set pressure to the second set pressure based on a detection value of at least one of the pressure of the hydraulic oil in the hydraulic circuit and the speed of the work implement when the controlled state of the work implement is the excavation state.

The present disclosure relates to a hydraulic-electric coupling driven multi-actuator system and control method, and belongs to technical fields of hydraulic transmission and electro-mechanical transmission. The hydraulic-electric coupling driven multi-actuator system comprises one or more hydraulic-electric hybrid driven actuators, first inverters, control valves, centralized hydraulic units and control units, wherein the number of the first inverters and the number of the control valves are the same as that of the hydraulic-electric hybrid driven actuators; each hydraulic-electric hybrid driven actuator is correspondingly connected with one first inverter and one control valve; the centralized hydraulic units are connected with the control valves and configured to supply oil for the hydraulic-electric hybrid driven actuators and to perform power compensation; and the control units are respectively connected with the hydraulic-electric hybrid driven actuators, and each control unit is configured to control output torque of a first motor of the corresponding hydraulic-electric hybrid driven actuator based on pressure information of the hydraulic-electric hybrid driven actuator, such that pressure of driving cavities of the hydraulic-electric hybrid driven actuators is equal, which greatly reduces throttling loss caused by the load differences of the actuators.

An operation control device for a working vehicle comprises a hydraulic actuator to drive the hydraulic working device, operating oil supply source for driving the hydraulic actuator, an operating oil supply control device that performs control to supply operating oil to the hydraulic actuator, an operating device to be operated to make the hydraulic actuator work and a working gain setting device that sets a gain of working speed of the hydraulic actuator corresponding to the operation of the operating device. The operating oil supply control device controls operating oil supply from the operating oil supply source to the hydraulic actuator based on the operation output signal from the operating device and the working speed gain set by the working gain setting device.

A hydraulic system for a machine includes an implement pump, a valve, and an implement valve subsystem. The implement pump includes a load sensing control, and the valve controls the flow of hydraulic fluid to the implement pump. The implement valve subsystem includes one or more implement control subsystems to control movement of an implement. The valve is an electrohydraulic proportional relief valve and includes a solenoid configured to adjust the pressure of hydraulic fluid delivered to the implement pump proportionally to a current delivered through the solenoid.

A working machine includes a prime mover, a rotation-speed operation actuator, a rotation detector, a hydraulic pump, a hydraulic unit, an operation valve capable of changing a pilot pressure of a pilot fluid supplied from the hydraulic pump to the hydraulic unit in accordance with an operation of an operation member, an actuation valve operating in accordance with a control signal and capable of changing a primary pressure as the pilot pressure of the pilot fluid supplied from the hydraulic pump to the operation valve, and a controller that outputs the control signal based on a difference between target and actual rotation speeds to the actuation valve to control an opening thereof. The controller has a mode including calculating the control signal based on the difference, correcting the calculated control signal, and increasing or decreasing a target primary pressure value set in accordance with the control signal.

A working machine includes first and second traveling pumps, an acquirer to acquire the number of revolutions and the rotation direction of each of first and second traveling motors, a determiner to, based on the acquired number of revolutions and the acquired rotation direction, determine whether a machine body is in a straight traveling state or a turn traveling state, and a controller configured or programmed to, when switching from a first state allowing rotation speeds of the first and second traveling motors to increase up to a first maximum speed, to a second state allowing the rotation speeds to increase up to a second maximum speed higher than the first maximum speed, or vice versa, is performed, reduce an amount of hydraulic fluid supply from the pumps to the motors according to the straight traveling state or the turn traveling state of the machine body.

A control system for controlling a moveable device includes at least one hydraulic actuator associated with the moveable device, at least one position sensing device to determine the position of the moveable device or the actuator, or both, and a hydraulic control system, including an electronic control unit, for controlling the actuator. For performing a control method, the hydraulic control system is configured to deliver pressurized hydraulic fluid to the actuator, the hydraulic fluid being pressurized at most to a predetermined maximum pressure, and the control system is adapted to regulate the predetermined maximum pressure based on the determined position. According to an example, the moveable device is a boom of a working machine. According to a further example, the actuator is a hydraulic cylinder or motor.