An excavator includes a hydraulic oil holding circuit that is provided in an oil passage between a bottom-side oil chamber of a boom cylinder and a control valve and is closed when the boom is not lowered, and a controller. The controller releases a closed state of the hydraulic oil holding circuit when the excavator is in a predetermined unstable state, and controls a released state so that an acting velocity in a lowering direction of the boom becomes less than or equal to a predetermined reference.

Provided are methods for controlling loading/unloading of a material (from a load-delivering unit to a load-receiving unit, wherein at least one of the load-delivering unit and the load-receiving unit is a working machine vehicle configured to transport a load of material from a first location to a second location, and wherein at least the load-delivering unit is provided with a control unit configured to control operation of the load-delivering unit. Methods include receiving a first signal indicative of the material associated with the load-delivering unit; receiving a second signal indicative of the material intended to be received by the load-receiving unit; and comparing material information related to the first signal with material information related to the second signal.

An electricity storage device (20) includes voltage detectors (25A) to (25C) detecting cell voltages (VcA) to (VcC) and a controller (26) controlling the cell voltages (VcA) to (VcC). The controller (26) includes a balancing control section (27) performing balancing control reducing deviations of the cell voltages (VcA) to (VcC), a maximum cell voltage calculating section (28) calculating a maximum cell voltage (Vmax) in the cell voltages (VcA) to (VcC), a minimum cell voltage calculating section (29) calculating a minimum cell voltage (Vmin) in the cell voltages (VcA) to (VcC), and an abnormality detecting section (34) detecting an abnormality of the electricity storage device (20) in accordance with whether or not a differential voltage (ΔV) between the maximum cell voltage (Vmax) and the minimum cell voltage (Vmin) is within a range of a reference differential voltage (ΔVstd1) calculated based on a history of the balancing control performed.

A method for determining a load in a working machine including a linkage to be connected to an implement includes determining pressure in a first hydraulic cylinder and pressure in a second hydraulic cylinder arranged to control the linkage and determining at least one link angle between at least two links in the linkage. The method further includes, for a selected linkage bearing, determining at least two perpendicular force components acting on the selected linkage bearing, based on the determined pressure in each of the first and second cylinders and the at least one link angle; and determining a load on the selected linkage bearing as a linear combination of the at least two perpendicular force components using predetermined constants for the linear combination.

A relay (25) connects and disconnects an electrical circuit to which an inverter (16) and an electricity storage device (19) are connected. A BCU (22) controls the electricity storage device (19). An HC (27) controls an electric motor (15), the inverter (16) and the BCU (22). The HC (27) and the BCU (22) respectively have FET switches (30, 31) for controlling supply and stop of the excitation current in the relay (25). When the electricity storage device (19) is determined to be in an abnormal state, the BCU (22) transmits an abnormal signal to the HC (27), and when a predetermined time has elapsed, turns off (opens) the first FET switch (30) of the BCU (22). The HC (27) executes stop processing based upon the abnormal signal received from the BCU (22) and then turns off (opens) the second FET switch (31) of the HC (27).

A vehicle (2) comprising at least one working unit (4) and a vehicle control system (6) comprising control units for controlling the vehicle to work in accordance with one or many working procedures. The vehicle is provided with a plurality of sensor units (12) configured to generate a sensor signal (14). Each control unit (8) is configured to determine control signals (18) to control its working unit (4), and the control unit designated to the vehicle is configured to determine control signals to control the vehicle, and also to determine control signals (18) for controlling at least one of the other working units (4) or the vehicle, and specifically to determine control signals (18) capable of controlling steps of a working procedure. At each point in time one of the control units is a master control unit being the control unit that is responsible for controlling its own working unit (4) and also at least one other working unit (4), and that at least two control units (8) are configured to be a master control unit. A determination procedure is provided to continuously determine if handover to another control unit, then being the new master control unit, should be made, and enabling the new master control unit to take control in accordance with the current working procedure if handover has been determined.

To provide a construction machine that can highly precisely control branch flows from a hydraulic pump to a plurality of hydraulic actuators without being affected by load conditions. A controller (100) has a meter-out valve control section (140) configured to calculate a target opening area of a second meter-out valve (65a) (65b) according to a pressure difference between a supply pressure and a second meter-in pressure, or calculate a target opening area of a first meter-out valve (55a) (55b) according to a pressure difference between the supply pressure and the first meter-in pressure.

Method for controlling a hydraulic system for a working machine, the system including a first electric machine connected to a first hydraulic machine the first hydraulic machine including an input side and an output side a second electric machine connected to a second hydraulic machine the second hydraulic machine including a high-pressure side and a low-pressure side the high-pressure side connected to the input side; a hydraulic consumer coupled to the output side via a supply line and configured to be powered by the first hydraulic machine; a first return line hydraulically coupling the hydraulic consumer to the input side and to the high-pressure side; wherein the method includes detecting a return flow from the hydraulic consumer through the first return line; and controlling the second hydraulic machine to maintain a pressure in the first return line at a pressure level higher than a predetermined minimum pressure level.

A system controls a work machine that loads materials onto a conveyance vehicle. The system includes a controller and a detection device. The controller controls the work machine in an automatic control mode in which work is performed automatically. The detection device detects an approach of the conveyance vehicle toward the work machine. The automatic control mode includes a loading mode in which the work machine is caused to move to perform loading work for loading onto the conveyance vehicle, and an other mode other than the loading mode. The other mode includes at least one of a mode for gathering fallen materials and a digging mode for further increasing the materials by digging. The controller causes the automatic control mode to transition from the other mode to the loading mode when the approach of the conveyance vehicle is detected.

In a work machine including a solenoid valve that generates a pilot pressure to drive a directional control valve with use of the delivery pressure of a pilot pump as a source pressure, a shut-off valve that shuts off a hydraulic operating fluid from the pilot pump to the solenoid valve, a first sensor that senses the amount of operation of an operation lever, and a second sensor that senses a state amount relating to operation of the solenoid valve, whether or not an abnormality of the second sensor exists is determined on the basis of a sensing signal of the second sensor. When it is determined that the second sensor is abnormal, on the basis of a sensing signal of the first sensor, an opening command is made to the shut-off valve if operation of the operation lever is sensed, and a closing command is made to the shut-off valve if the neutral state of the operation lever is sensed.