In a hydraulic system for a working machine, a controller is configured or programmed to increase an output-port pressure of one activation valve for one hydraulic device and an output-port pressure of another activation valve for another hydraulic device to a normal pressure higher than a preloading pressure from a state where the output-port pressure of the one activation valve is equal to the preloading pressure and the output-port pressure of the other activation valve is lower than the preloading pressure, by causing the output-port pressure of the one activation valve to be lower than the preloading pressure and increasing the output-port pressure of the other activation valve to the normal pressure.

To provide a work machine that can maintain the construction precision of semi-automatic control irrespective of excavation depths and differences in soil nature. A controller acquires soil-nature information on the basis of an operation command given to a work implement, a bucket-claw-tip position outputted from a bucket-position measuring device, and a drive load of the work implement outputted from a load measuring device; generates a soil-nature map on the basis of the bucket-claw-tip position, and the soil-nature information; calculates an estimated load that is an estimate of an excavation load on the basis of the soil-nature map and a bucket-claw-tip target position; and corrects the operation command in accordance with the estimated load.

A working control device comprises a hydraulic actuator such as the boom cylinder 36, the bucket cylinder 38, the operation device 160 that is operated by an operator to drive the hydraulic actuator, a hydraulic oil supply source consisting of the electric motor M1 and the hydraulic pump P1 that delivers hydraulic oil required to drive the hydraulic actuator; and a delivery oil amount control device (the controller for controlling rotation of the electric motor) that controls an amount of oil to be delivered from the hydraulic oil supply source in response to an operation of the operation device. The delivery oil amount control device is configured to perform a supplying oil amount control to deliver from the hydraulic oil supply source a required amount of oil for the hydraulic actuator to have a working speed corresponding to the operation of the operation device.

An engine control system controls a work machine including an engine, a fuel injection device that injects fuel into the engine, and a hydraulic pump that is driven by the engine. The rotation state amount specification unit specifies a rotation state amount related to rotation of the engine. The injection amount determination unit determines a fuel injection amount by the fuel injection device based on the rotation state amount.

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 working machine includes: a machine body provided thereon with a traveling pump and a traveling motor; a traveling change-over valve shiftable between a first state where a rotation speed of the traveling motor is set to a first speed and a second state where the rotation speed is set to a second speed; an actuation valve operable to control a flow of operation fluid to an operation valve that changes a pressure of operation fluid to be applied to the traveling pump according to operation of an operation member; and a controller to perform a shock-mitigation control for reducing an opening degree of the actuation valve when the traveling change-over valve is shifted from the first state to the second state. The controller determines a reduction amount of the opening degree of the actuation valve reduced by the shock-mitigation control, based on a straight-traveling degree of the machine body.

An arm load control system for a work vehicle including a controller comprising a memory and a processor. The controller is configured to determine whether a lift arm is in a maximum load configuration based on a position of the lift arm relative to a chassis of the work vehicle and output a control signal to a propulsion assembly of the work vehicle indicative of instructions to adjust a tractive effort of the work vehicle based on whether the lift arm is in the maximum load configuration.

A working machine includes a prime mover, a traveling motor a speed shifting valve configured to shift an output speed of the traveling motor between a first speed and a second speed faster than the first speed, an actuation valve to change a hydraulic pressure applied to the speed shifting valve, a brake shiftable between a braking state to brake the traveling motor and a braking releasing state to release the braking, and a controller configured or programmed to control the actuation valve and the brake, and being capable of activate a warm-up mode. The controller, when activating the warm-up mode, shifts the brake into the braking state, and controls the actuation valve so as to make the hydraulic pressure applied to the speed shifting valve equal to or greater than a value corresponding to the second speed.

A method for steering alignment calibration of an articulated machine having front and rear frames pivotally connected by an articulation joint to steer the machine may include displaying a steering alignment calibration screen with a target steering angle between the frames and a calculated steering angle. The calculated steering angle may be determined based on a sensed steering angle and a calibration steering angle. The machine is steered until the displayed calculated steering angle is equal to the target steering angle. If an actual steering angle of the machine is not equal to the target steering angle, further steering is performed until the actual steering angle is equal to the target steering angle. The calibration steering angle may be recalculated and stored for future use when the actual steering angle is equal to the target steering angle but the calculated steering angle is not equal to the target steering angle.

A construction machine is provided which is capable of detecting an operation state of an operation device even if the idle rotation speed for a prime mover is set to a low value and is capable of setting the idle rotation speed for the prime mover to a low value. A hydraulic excavator includes an operation device that generates a pilot pressure corresponding to an operation amount of an operation lever and switches a control valve with the generated pilot valve, and a controller that controls an electric motor such that the rotation speed of the electric motor becomes an idle rotation speed set in advance when a no-operation state of the operation device continues. The hydraulic excavator further includes a hydraulic pressure signal line that is connected between the discharge side of a pilot pump and a tank and in which the control valve is interposed, a fixed restrictor provided between the discharge side of the pilot pump and the control valve in the hydraulic pressure signal line, and pressure sensors that individually detect the hydraulic pressures on the upstream side and the downstream side of the fixed restrictor. The controller detects an operation state of the operation device on the basis of results of detection of the pressure sensors.