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 method for controlling a work vehicle includes driving a first hydraulic pump and a second hydraulic pump by an engine to supply hydraulic fluid to a first hydraulic motor and a second hydraulic motor, respectively, to drive a first traveling device and a second traveling device, respectively. An operation state of a direction input device to operate a traveling direction of the work vehicle is detected. Based on the operation state detected, whether or not a traveling state of the work vehicle is a turning state. When it is determined that the traveling state is the turning state, a rotation command to decrease a target rotational speed of the engine from a first rotational speed to a second rotational speed is output.

A mobile machine includes an internal combustion engine operatively connected to a plurality of propulsion devices for travel over a work surface. The mobile machine can include an electronic controller that receives condition data signals indicative of the operating state or condition of the mobile machine from a plurality of condition input sensors. The electronic controller compares the condition data signals with condition threshold to determine whether to operate the internal combustion engine in accordance with rated engine speed range or an adjusted engine speed range.

A shovel enabled to set an engine revolution speed to revolution speeds including a revolution speed for a running operation and a revolution speed for an idling running operation that is lower than the revolution speed for the running operation includes an engine provided as a driving source of the shovel, an operating part configured to be driven by a driving force of the engine, an operation component configured to operate the operating part, a detecting device configured to detect a position of a movable portion of an operator and a position of the operation component, an operation determining part configured to determine a positional relationship between the movable portion and the operation component, and a control part configured to set the engine revolution speed of the engine based on the positional relationship between the movable portion and the operation component that is determined by the operation determining part.

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.

An electrically powered hydraulic system for a working machine includes: an electric motor to power a working hydraulic pump. A flow of hydraulic fluid generated by the hydraulic pump is controlled by the operation rotational speed of the electric motor. An electronic control unit is configured to: when an operator input device is in a first operating range, maintain the electric motor at a constant rotational speed, and control a variation in flow of hydraulic fluid to the hydraulic function with an electronically controlled control valve, and when the operator input device is in a second operating range, control a variation in flow of hydraulic fluid by varying the electric motor rotational speed and by controlling the control valve, according to displacement of the operator input device.

A controller may receive a first input indicating that a machine is performing a lifting operation. The controller may determine that the machine is operating in a first lifting mode associated with a first lifting capacity during the lifting operation. In the first lifting mode, a pressure of a hydraulic pump of the machine is between a first value and a second value that exceeds the first value. The controller may receive sensor data indicating a current value for the pressure, during the lifting operation. The controller may determine that the current value is approaching the second value. The controller may receive a second input indicating that the machine is continuing to perform the lifting operation. The controller may cause, based on the second input, the machine to transition from operating in the first lifting mode to operating in a second lifting mode associated with a second lifting capacity.

A working machine includes a controller that performs shift shock reduction control when shift-down switching from a second state to a first state, in which a motor speed can be increased up to a first maximum speed lower than a second maximum speed available in the second state, is performed. The controller includes a first processor configured to, based on a drop amount that is a difference between target and actual numbers of revolutions of a prime mover, compute a first reduction amount for reducing an amount of hydraulic fluid supply from a traveling pump to a traveling motor, a second processor configured to compute a second reduction amount based on a degree of straight traveling of a machine body, and a reduction controller configured to, based on the first or second reduction amount, whichever is larger in absolute value, perform the shift shock reduction control.

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.

When a machine-control ON/OFF switch is switched to the ON position, a controller outputs either a first control signal generated by an operation lever or a second control signal that operates a boom cylinder in accordance with a predetermined condition; when the ON/OFF switch is switched to the OFF position, the controller outputs the first control signal; when a control signal has been switched from one of the first control signal and the second control signal to the other control signal by the operation of the ON/OFF switch, the controller applies a rate limit to the control signal, and controls the boom cylinder on the basis of the control signal obtained after the limitation.