A shovel includes a lower traveling structure, an upper swing structure swingably mounted on the lower traveling structure, a first hydraulic pump provided on the upper swing structure, an attachment attached to the upper swing structure, a first actuator, a second actuator, a first directional control valve corresponding to the first actuator, a second directional control valve corresponding to the second actuator, a first conduit connecting the first hydraulic pump and the first directional control valve, a second conduit connecting the first conduit and the second directional control valve, a control valve installed in the second conduit, and processing circuitry configured to control the opening area of the control valve according to information on work details.

An open center hydraulic system (100) includes a tank configured to hold hydraulic fluid, a pump configured to provide pressurized hydraulic fluid from the tank, and a shunt valve configured to adapt a first opening area between a first input port and a first output port of the shunt valve dependent on a first control signal. The first input port is coupled to the pump, and the first output port is coupled to the tank. A first actuator valve is coupled to the first input port and configured to adapt a second opening area of the first actuator valve dependent on a second control signal. A hydraulic valve control unit is configured to determine a first opening area value and a second opening area value based on user input data and a predetermined relation dependent on the user input data, sending the first control signal, indicative of the first opening area value and sending the second control signal indicative of the second opening area value.

This hydraulic drive system includes: a hydraulic pump capable of changing a discharge flow rate of a working fluid; a meter-in control valve that controls a meter-in flow rate of the working fluid flowing from the hydraulic pump to a hydraulic actuator; a meter-out control valve that is provided separately from the meter-in control valve and controls a meter-out flow rate of the working fluid being drained from the hydraulic actuator into a tank; an operation device that outputs an operation command; a first pressure sensor that detects a drainage pressure of the hydraulic actuator; and a control device that sets a target meter-out flow rate according to the operation command from the operation device and controls an opening degree of the meter-out control valve on the basis of the drainage pressure detected by the first pressure sensor and the target meter-out flow rate.

Provided is a construction machine which can promptly adjust the rotational speed of a swing motor to a target rotational speed. A controller calculates a target rotational speed of the swing motor based on input from an operation device, calculates a degree of deviation of a rotational speed detected by a rotational speed sensor from the target rotational speed, sets a target driving pressure of the swing motor according to a moment of inertia about a swing axis of a swing structure and a work device and controls a pressure adjusting device in such a manner as to reduce a difference between a driving pressure detected by a pressure sensor and the target driving pressure, when the degree of deviation is larger than a predetermined value, and controls the pressure adjusting device in such a manner as to reduce a difference between the rotational speed detected by the rotational speed sensor and the target rotational speed, when the degree of deviation is equal to or smaller than the predetermined value.

Provided is a work vehicle capable of excavating an excavation object efficiently and in various excavation patterns with appropriate fuel efficiency, regardless of the operator's skill level. The work vehicle includes a controller. The controller executes control including insertion control, acceleration control, and deceleration control. The insertion control keeps the tilt amount (stroke amount S2) of the bucket and increases the lift amount (stroke amount S1) of the lift arm in the insertion period Ph1 from the timing when the work vehicle meets an entry condition for object, where the acceleration α of the vehicle becomes negative, to the timing when the acceleration α first becomes positive. The acceleration control keeps the tilt amount and increases the lift amount if the acceleration condition that the acceleration α becomes positive is met in the lift period Ph2 from the timing when the work vehicle first meets the insertion condition to the timing when the end condition is met, where the lift amount and the tilt amount reach their specified values. The deceleration control keeps the lift amount and increases the tilt amount when the deceleration condition that the acceleration α becomes negative is met in the lift period Ph2.

The object of the invention of the present application resides in provision of a work machine that can be improved in operability at start of an action of a hydraulic actuator in a fine operation in which an operation lever is operated by a small amount. To this end, on the basis of a signal from a first timing sensor and a signal from a second timing sensor, a machine body controller controls, before the first timing is sensed, the pump delivery flow rate to a minimum delivery flow rate, controls, after the first timing is sensed but before the second timing is sensed, the pump delivery flow rate to a predetermined delivery flow rate that is greater than the minimum delivery flow rate, and controls, after the second timing is sensed, the pump delivery flow rate to a delivery flow rate according to an operation amount of the operation lever.

Provided is a work machine including a front work device, the work machine including a state amount sensor that senses a state amount relating to an action state of the work device and a controller that controls an action of the work machine on the basis of an operation signal transmitted from a remote device by radio communication. The controller assesses a communication status of the radio communication, and, when restricting the action of the work machine on the basis of a result of the assessment, eases the restriction on the action of the work machine, depending on a sensing result from the state amount sensor. As a result, it is possible to appropriately restrict action on the basis of a communication status, while suppressing worsening of workability.

A hydraulic drive system includes a hydraulic pump, a boom-dedicated control valve, a turning-dedicated control valve, a boom-dedicated operation unit, a turning-dedicated operation unit, and a driving control unit. If an operating amount of the turning-dedicated operating portion where a concurrent operation is performed and a single operation is performed are the same, the driving control unit adjusts a turning driving command, that an opening area between the hydraulic pump and a turning motor where the concurrent operation is performed is less than the opening area between the hydraulic pump and the turning motor where the single operation is performed, the concurrent operation wherein the turning operation command is outputted from the turning-dedicated operation unit and a boom operation command is outputted from the boom-dedicated operation unit, the single operation wherein the turning operation command is outputted, but the boom operation command is not outputted from the boom-dedicated operation unit.

A work machine includes hydraulic actuators that drive a work implement, and a controller configured to output a control signal for controlling each hydraulic actuator on the basis of a velocity command to each actuator computed at each computation cycle. When controlling an action of a first hydraulic actuator under a predetermined condition according to an action of a second hydraulic actuator, the controller computes a velocity command to the first hydraulic actuator at a current computation cycle, with use of an actual velocity of each hydraulic actuator at the current computation cycle computed on the basis of a sensing signal of a posture sensor and a history of past velocity commands to each hydraulic actuator computed at previous computation cycles before the current computation cycle, and outputs a control signal according to the velocity command to the first hydraulic actuator at the current computation cycle.

The invention of the present application intends to provide a work machine that can improve the work performance by keeping the work state of work equipment conforming to the intention of an operator in machine control for causing the work equipment to follow an excavation target surface. For this purpose, a controller determines the work state of the work equipment on the basis of an operation input amount inputted from an operation input device and the posture of the work equipment with respect to the target surface, computes a range of an action command value of actuators in which the work state determined is kept, and corrects, within the range, the action command value of the actuators to make the distance between the work equipment and the target surface small.