A construction machine that makes it possible for an operator to linearly push a bucket simply by operating an arm in a pushing direction is provided. A controller 50 is configured to, in a case where a straight locus is selected by a bucket locus selecting device 52, calculate a constant flow rate ratio α according to a boom initial angle that is an angle of a boom 2 sensed by a boom angle sensor 33 at a time point when an arm 4 is operated in a pushing direction by an operation device 51, and control the delivery flow rate of a first hydraulic pump 12 such that a hydraulic fluid is discharged from a cap chamber 1a of a boom cylinder 1 at a flow rate Qb obtained by multiplying a flow rate Qa of a flow supplied to a cap chamber 3a of an arm cylinder 3 by the flow rate ratio α while the arm 4 is operated in the pushing direction by the operation device 51 and there is not an instruction for operation of the boom 2.

A work machine includes a frame, a traction system supporting the frame, an implement system supported by the frame, and a hydraulic system. The hydraulic system includes a hydraulic oil tank, a control circuit, an oil cooler, and a cooler bypass valve assembly. The cooler bypass valve assembly is connected to the control circuit by a control circuit return line, and includes an unloading valve configured to allow hydraulic oil to flow from the control circuit return line to the hydraulic oil tank if a pressure of hydraulic oil in the control circuit return line exceeds a first threshold, a backpressure valve configured to allow hydraulic oil to flow from the return line to the oil cooler through an oil cooler inlet line if a pressure of hydraulic in the oil control circuit return line exceeds a second threshold, and an orifice configured to limit the flow of hydraulic oil through the backpressure valve.

A hydraulic system includes a first supply line connecting a boom control valve and a bottom side of a boom cylinder, a second supply line connecting the boom control valve and a rod side of the boom cylinder, a leveling switch valve having: a first operating position allowing a leveling operation of a working tool; and a first stopping position allowing the leveling operation to stop, a ride controller including: a ride-control switch valve connected to a branched fluid line branched from the first supply line; and an accumulator configured to perform an anti-vibrating operation for suppressing a pressure fluctuation of the boom cylinder, and a drain fluid line to discharge operation fluid in a downstream section extending from the leveling switch valve to the rod side of the boom cylinder in the second supply line when the leveling switch valve is switched to the first stopping position.

An inner subassembly for assembling a valve assembly includes a spool defining a central bore that extends axially through the spool forming a spool annular wall, and including a spool cone tip that is disposed at the first axial end, as well as a hydraulic activation ridge extending radially outwardly from the spool annular wall, and that is disposed axially between the second axial end and the first axial end. The spool may further define a first bypass bore. A stem defines a first flow bore that aligns with the first bypass bore.

Provided is a work vehicle which can prevent an engine from stalling regardless of type of a system mounted on a vehicle body. In a wheel loader 1 equipped with a loading work device 11 operated by an electric operation lever 19, first and second directional control valves 5, 6 include neutral positions 5N, 6N for causing hydraulic oil discharged from a hydraulic pump 12 to return to a hydraulic oil tank 10, respectively, and in the case where a discharge pressure P of the hydraulic pump 12 is a main relief pressure Pr or more and an engine rotational speed N is less than a low idle rotational speed NL, a controller 2, 2A restricts the output of control signals to first and second solenoid control valves 3, 4 so as to cause the first and second directional control valves 5, 6 to be switched to the neutral positions 5N, 6N, respectively.

Provided is a construction machine. The construction machine includes a boom cylinder driving a boom, a rotation motor rotating a rotary body, an arm cylinder driving an arm, a bucket cylinder driving a bucket, a first main pump supplying working fluid to the boom cylinder and discharging the working fluid in opposite directions, a second main pump supplying working fluid to the rotation motor and discharging the working fluid in opposite directions, and a third main pump supplying working fluid to the arm cylinder or the bucket cylinder.

A working machine comprises an operation member for operating a hydraulic device via a control valve. An oscillation calculator acquires a specific value corresponding to a feature representing oscillation of the operation member when the feature appears in variation of an control signal output according to an operation amount of the operation member within one of a sequence of predetermined periods, and calculates an evaluation value representing a degree of oscillation of the operation member by adding up the specific value or values obtained within one or more of the predetermined periods. A control signal generator generates a control signal for controlling the control valve based on the operation signal. The control signal generator decreases a value of the control signal per a unit value of the operation signal as the evaluation value gradually increases with the elapse of one or more of the sequence of the predetermined periods.

A working control device comprises an operation lever for making a boom cylinder (36), an arm cylinder (37) and others work to drive a shovel apparatus (30), and a delivered oil amount control device (a controller (150)). A working oil supply source includes a first electric motor (M1) and a first hydraulic pump (P1). When the operation lever is subjected to a single operation, a number of the motor revolution based on the lever operation is set to control the first electric motor. When the number of motor revolution is less than a necessary minimum number of revolutions, the necessary minimum number is set to control the first electric motor (M1). When the operation lever is subjected to a composite operation, a total number of motor revolutions based on the lever operations is set. When the total number is less than a necessary minimum number of revolutions, the necessary minimum number is set to control the first electric motor (M1).

A work vehicle includes computing system is configured to receive a first and seconds inputs associated with controlling an operation of first and second hydraulic loads. Furthermore, the computing system is configured to control the operation of the first or second flow control valve corresponding to the one of the first or second hydraulic loads associated with the greater hydraulic fluid pressure based on the corresponding received first or second input. Additionally, the computing system is configured to determine the first or second pressure of the hydraulic fluid being supplied to another of the first or second hydraulic loads. Moreover, the computing system is configured to control the first or second flow control valve corresponding to the other of the first or second hydraulic loads based on the corresponding received first or second input and the determined first or second pressure.

Both a control for limiting operation of a machine body and a control for raising engine speed are achieved when an obstacle is detected. To this end, a machine controller performs operation limiting control by conducting a control for reducing the speed of the engine when the machine body does not require engine speed increase control and an obstacle is sensed by obstacle sensors, and the machine controller performs supply flow rate reduction control for reducing the flow rates of the hydraulic fluid supplied to hydraulic actuators from a hydraulic pump when the machine body requires the engine speed increase control and an obstacle is sensed by the obstacle sensors.