Abstract: This work machine includes: a first hydraulic cylinder and a second hydraulic cylinder that telescope a telescopic boom on the basis of hydraulic oil supply and discharge, a switching valve that is disposed on a pressure relief circuit for connecting the first hydraulic cylinder and the second hydraulic cylinder to a tank, and a control unit that causes the switching valve to connect the first hydraulic cylinder to the tank and releases the pressure in the first hydraulic cylinder when contracting or extending the second hydraulic cylinder in a condition in which the first hydraulic cylinder is contracted.

Abstract: An informing device is an informing device mounted on a work vehicle that includes a lower base body, and a swivel body swivelably provided at the lower base body. The informing device includes a first detection unit that detects the actual amount of rotation of a drive device which swivels the swivel body or a driven part driven by the drive device, and a notification unit that issues a notification regarding information corresponding to the amount of rotation detected by the first detection unit.

Abstract: This hydraulic system is provided with: a hydraulic pump; a pilot-type control valve; an electromagnetic proportional valve; a controller; and a pilot pressure switching unit which is capable of switching the electromagnetic proportional valve supply pressure to a first pressure during a normal operation, or to a second pressure lower than the first pressure. The control valve is provided with a bleed-off passage, and is capable of controlling the operating oil pressure supplied to the actuator, according to the opening area thereof. During an emergency operation, the electromagnetic proportional valve supply pressure is switched from the first pressure to the second pressure, the electromagnetic proportional valve is brought into a fully opened state, and the operating oil discharge amount from the hydraulic pump increases and decreases, and the operating oil pressure increases and decreases, and thus the operating speed of the actuator is controlled.

Abstract: The failure detection device is a failure detection device of a pilot circuit, the pilot circuit including: a pilot pressure source; a pilot pressure supply unit that supplies pilot pressure to a control valve; a pilot oil path that connects the pilot pressure source and a pilot pressure supply unit; and a pressure control unit that controls a pressure of the pilot oil path, the failure detection device including: a pressure sensor that measures the pressure on a downstream side in a pilot pressure supply direction of the pressure control unit; and a controller that controls the pressure control unit to sequentially switch the pressure of the pilot oil path and performs a failure diagnosis based on a measurement result of the pressure sensor at this time, as an operation lever which receives an operation for operating the actuator returns to a neutral state.

Abstract: Provided is a crane capable of allowing an operator to recognize an error in work information or in a number of windings set in a safety device. A main tension of a main wire rope is calculated from a main output torque of a main winch, a sub output torque of a sub winch, a main drum winding radius of the main winch, and a sub drum winding radius of the sub winch. An estimated hanging load, which is calculated from the main tension, a sub tension of a sub wire rope and the number of windings of the wire rope set in a safety device, is compared with an actual hanging load calculated from fluctuating thrust force and boom information. Thus, the suitability of a work kind or a winding number set in the safety device is determined.

Abstract: This hydraulic system is provided with a hydraulic pump, a control valve, and a pilot pressure supply unit. The pilot pressure supply unit has: an electromagnetic proportional valve that has a detent-type emergency manual operation function with which a pilot oil passage can be opened manually and generates pilot pressure for a control valve; a controller that controls the degree of opening of the electromagnetic proportional valve in accordance with the operation of an operation lever; and a pilot pressure switching unit that switches the oil pressure state of the pilot pressure supply unit between an on-loading state and an unloading state. The pilot pressure switching unit performs control to implement the unloading state when the electromagnetic proportional valve is being opened manually and performs control to implement the on-loading state after the electromagnetic proportional valve has been opened manually.

Abstract: A crane 1, the hook (main hook 24) of which is stored on the lower end of a boom 7, and the winch (main winch 9) of which can be moved by a hydraulic motor 37, said crane being provided with a pressure sensor 55 capable of detecting the pressure of hydraulic fluid being delivered to the hydraulic motor 37, and a controller 61 capable of recognizing changes in the pressure of the hydraulic fluid on the basis of a signal from the pressure sensor 55, and also being provided with an anomaly warning means Mi capable of providing warning of anomalies pertaining to the storage of at least the hook (24), the controller 61 activating the anomaly warning means Mi when it is determined that the pressure of the hydraulic fluid when the hook has been stored is below a minimum value.

Abstract: The unload circuit includes a pump oil passage that connects between a hydraulic pump and a direction control valve, a tank oil passage that connects between the direction control valve and a hydraulic tank, a pressure compensating flow control valve interposed between the pump oil passage and the tank oil passage, a pilot operated relief valve interposed between the pump oil passage and the tank oil passage, and an unloading solenoid valve interposed in a vent oil passage of the pilot operated relief valve. The failure diagnosis device includes a pressure sensor that measures a pressure of the pump oil passage, and a controller that receives a pressure signal from the pressure sensor. The controller performs failure diagnosis of the unload circuit based on a differential pressure between a first pump oil passage pressure during unloading and a second pump oil passage pressure during on-loading.

Abstract: This hydraulic system is provided with: a hydraulic pump; a pilot-type control valve; an electromagnetic proportional valve; a controller; and a pilot pressure switching unit which is capable of switching the electromagnetic proportional valve supply pressure to a first pressure during a normal operation, or to a second pressure lower than the first pressure. The control valve is provided with a bleed-off passage, and is capable of controlling the operating oil pressure supplied to the actuator, according to the opening area thereof. During an emergency operation, the electromagnetic proportional valve supply pressure is switched from the first pressure to the second pressure, the electromagnetic proportional valve is brought into a fully opened state, and the operating oil discharge amount from the hydraulic pump increases and decreases, and the operating oil pressure increases and decreases, and thus the operating speed of the actuator is controlled.

Abstract: The failure detection device is a failure detection device of a pilot circuit, the pilot circuit including: a pilot pressure source; a pilot pressure supply unit that supplies pilot pressure to a control valve; a pilot oil path that connects the pilot pressure source and a pilot pressure supply unit; and a pressure control unit that controls a pressure of the pilot oil path, the failure detection device including: a pressure sensor that measures the pressure on a downstream side in a pilot pressure supply direction of the pressure control unit; and a controller that controls the pressure control unit to sequentially switch the pressure of the pilot oil path and performs a failure diagnosis based on a measurement result of the pressure sensor at this time, as an operation lever which receives an operation for operating the actuator returns to a neutral state.

Abstract: An actuator control device performs a reception process in which designations of a minimum operation amount and maximum operation amount of an operation unit for driving an actuator, and a maximum driving speed which is the actuator driving speed corresponding to the maximum operation amount are received. It also performs a determination process in which a function representing a characteristic line that links a first point, which corresponds to the minimum operation amount and the driving speed of 0, and a second point, which corresponds to the maximum operation amount and the maximum driving speed, is stored in a storage unit as a drive control characteristic and a drive control process in which, in response to operation of the operation unit, the actuator is driven at a driving speed corresponding to the operation amount specified by the drive control characteristic stored in the storage unit.

Abstract: Provided is a crane capable of allowing an operator to recognize an error in work information or in a number of windings set in a safety device. A main tension of a main wire rope is calculated from a main output torque of a main winch, a sub output torque of a sub winch, a main drum winding radius of the main winch, and a sub drum winding radius of the sub winch. An estimated hanging load, which is calculated from the main tension, a sub tension of a sub wire rope and the number of windings of the wire rope set in a safety device, is compared with an actual hanging load calculated from fluctuating thrust force and boom information. Thus, the suitability of a work kind or a winding number set in the safety device is determined.

Abstract: A crane 1, the hook (main hook 24) of which is stored on the lower end of a boom 7, and the winch (main winch 9) of which can be moved by a hydraulic motor 37, said crane being provided with a pressure sensor 55 capable of detecting the pressure of hydraulic fluid being delivered to the hydraulic motor 37, and a controller 61 capable of recognizing changes in the pressure of the hydraulic fluid on the basis of a signal from the pressure sensor 55, and also being provided with an anomaly warning means Mi capable of providing warning of anomalies pertaining to the storage of at least the hook (24), the controller 61 activating the anomaly warning means Mi when it is determined that the pressure of the hydraulic fluid when the hook has been stored is below a minimum value.

Abstract: The unload circuit includes a pump oil passage that connects between a hydraulic pump and a direction control valve, a tank oil passage that connects between the direction control valve and a hydraulic tank, a pressure compensating flow control valve interposed between the pump oil passage and the tank oil passage, a pilot operated relief valve interposed between the pump oil passage and the tank oil passage, and an unloading solenoid valve interposed in a vent oil passage of the pilot operated relief valve. The failure diagnosis device includes a pressure sensor that measures a pressure of the pump oil passage, and a controller that receives a pressure signal from the pressure sensor. The controller performs failure diagnosis of the unload circuit based on a differential pressure between a first pump oil passage pressure during unloading and a second pump oil passage pressure during on-loading.

Abstract: This hydraulic system is provided with a hydraulic pump, a control valve, and a pilot pressure supply unit. The pilot pressure supply unit has: an electromagnetic proportional valve that has a detent-type emergency manual operation function with which a pilot oil passage can be opened manually and generates pilot pressure for a control valve; a controller that controls the degree of opening of the electromagnetic proportional valve in accordance with the operation of an operation lever; and a pilot pressure switching unit that switches the oil pressure state of the pilot pressure supply unit between an on-loading state and an unloading state. The pilot pressure switching unit performs control to implement the unloading state when the electromagnetic proportional valve is being opened manually and performs control to implement the on-loading state after the electromagnetic proportional valve has been opened manually.

Abstract: [Problem] To provide an actuator control device with which desired drive control characteristics can be obtained by means of a simple operation.