A hydraulic system for controlling an implement on a work machine may include a hydraulic reservoir, a hydraulic pump in fluid communication with the reservoir, a central valve in fluid communication with the pump and configured for controlling the implement, a pressure relief system arranged in fluid communication with the hydraulic pump and the central valve, and a controller. The controller may be configured for controlling the hydraulic pump, the central valve and the pressure relief system and selecting between operating the hydraulic system at a first pressure and a second pressure based on a factor relating to implement position.

The disclosure relates to a method for damping a movably mounted attachment part of a machine, wherein the attachment part is movable by means of a hydraulic cylinder, wherein the hydraulic cylinder is actuated via a hydraulic pump, comprising: receiving a measured value of a pressure (P) in a load-side chamber of the hydraulic cylinder during a measurement phase, and controlling the hydraulic pump to adjust the pressure in the load-side chamber of the hydraulic cylinder to the measured value as a setpoint value during operation of the machine for damping the movably mounted attachment part.

A construction machine including a variable displacement pump, and a boom cylinder including a rod operable to extend and retract to move a boom of the construction machine. A first chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod extension while fluid is removed from a second chamber of the boom cylinder. The second chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod retraction while fluid is removed from the first chamber of the boom cylinder. The construction machine has an active ride control mode in which a valve between the boom cylinder and the pump remains open, and the pump is configured to actively damp pressure fluctuations in the boom cylinder by variation of a displacement setting.

A working machine includes a machine body, a first hydraulic actuator mounted on the machine body, a first control valve that controls the first hydraulic actuator, a controller that controls the first control valve, and a second hydraulic actuator that is different from the first hydraulic actuator. When the second hydraulic actuator and the first hydraulic actuator are operated in combination, the controller reduces the amount of change in the flow rate of a hydraulic fluid supplied from the first control valve to the first hydraulic actuator with respect to changes in a manipulation amount to operate the first hydraulic actuator to a value smaller than that when the first hydraulic actuator is solely operated.

Provided is a work machine which can increase the operation speed of an actuator by a regeneration function while securing the position control accuracy of the actuator. A controller is configured to calculate a regeneration flow rate on the basis of an input amount of an operation lever and a target actuator flow rate, subtract the regeneration flow rate from the target actuator flow rate to calculate a target actuator supply flow rate, calculate a target flow rate control valve opening amount on the basis of the target actuator supply flow rate, calculate a target pump flow rate that is equal to or higher than a total target actuator supply flow rate, control a selector valve on the basis of the input amount of the operation lever, control a flow rate control valve according to the target flow rate control valve opening amount, and control a hydraulic pump according to the target pump flow rate.

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.

An object of the present invention is to provide a construction machine that can use the return oil from a hydraulic actuator effectively. For this purpose, a controller computes a flow rate of the return oil from a first hydraulic actuator on the basis of an operation signal from a first operation device, computes a flow rate of oil to be supplied to a second hydraulic actuator on the basis of an operation signal from a second operation device, sets smaller one of the flow rate of the return oil and the flow rate of the oil to be supplied, as a regeneration flow rate that is a flow rate of oil to be regenerated in the second hydraulic actuator, sets a flow rate obtained by subtracting the regeneration flow rate from the flow rate of the return oil, as a recovery flow rate that is a flow rate of oil to be recovered to a pressure accumulating device, adjusts an opening degree of a first control valve 2 such that a flow rate of oil supplied from the first hydraulic actuator to the pressure accumulating device coincides with the recovery flow rate, and adjusts an opening degree of a second control valve such that a flow rate of oil supplied from the first hydraulic actuator to the second hydraulic actuator coincides with the regeneration flow rate.

A work machine control system is provided with an acquisition process unit and a limit process unit. The acquisition process unit acquires a detection result of an object around a machine body of a work machine in a state incapable of operating the work machine. The limit process unit creates a limit state capable of limitedly operating the work machine, when the detection result meets a predetermined condition and then a gate lock lever is so operated as to create a state capable of operating the work machine.

A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, a cab mounted on the upper turning body, an attachment including a boom attached to the upper turning body, a boom cylinder configured to drive the boom, a control device configured to control hydraulic oil flowable into the boom cylinder, and an information obtaining device configured to obtain information on the attachment. The control device is configured to increase the pressure of hydraulic oil flowable into the boom cylinder in accordance with the information on the attachment before a boom raising operation is performed.

A hydraulic system according to one aspect of the present disclosure includes: control valves interposed between a main pump and hydraulic actuators; and solenoid proportional valves connected to pilot ports of the control valves. Among the solenoid proportional valves, a first solenoid proportional valve and a second solenoid proportional valve are connected to a pair of pilot ports of a particular control valve, respectively. The first solenoid proportional valve and the second solenoid proportional valve are directly connected to an auxiliary pump. The solenoid proportional valves except the first solenoid proportional valve and the second solenoid proportional valve are connected to the auxiliary pump via a switching valve. The switching valve includes a pilot port that is connected, by a switching pilot line, to a first pilot line between the first solenoid proportional valve and the particular control valve.