Provided is an assembly method for a crane, by which method a crane including a strut can be assembled easily. The assembly method for the crane includes a strut coupling step of coupling a base end of a strut, a cylinder connecting step of extending a cylinder unit having one end supported by the strut, the cylinder unit being capable of extending/contracting, to connect the other end of the cylinder unit to the boom, a strut raising step of causing the cylinder unit to contract to raise the strut, and a strut supporting step of stretching a stretching member, such as a rear side guy line or a luffing cable, between a front end of the strut and a base end of the boom to support the strut in a raised state.

A system for detecting a type of hydraulic device. The system includes a hydraulic device. The system also includes a power supply having an engine and a controller. The controller is configured to detect a voltage of a signal from the hydraulic device, to categorize the signal as a type of signal of multiple types of signals based on the voltage, and to control a hydraulic output based on the voltage and the type of the signal.

A system for detecting a type of hydraulic device. The system includes a hydraulic device. The system also includes a power supply having an engine and a controller. The controller is configured to detect a voltage of a signal from the hydraulic device, to categorize the signal as a type of signal of multiple types of signals based on the voltage, and to control a hydraulic output based on the voltage and the type of the signal.

It is aimed to enable an easier attachment of a lower spreader to a machine main body. The mast 30 is tiltably attached to the machine main body 13, and operable to lie over the machine main body 13. The lower spreader retainer 40 is fixedly attached to the machine main body 13, and adapted for retaining the lower spreader 50. The connector 60 connects the mast 30 and the lower spreader 50 with each other so that the mast 30 holds the lower spreader 50. The lower spreader 50 and the lower spreader retainer 40 are arranged at a position that allows the lower spreader retainer 40 to retain the lower spreader 50 in a state where the mast 30 holding the lower spreader 50 is lowered.

A work vehicle includes: an operation tool that is operated by an operator; and a controller that determines a target flow rate for hydraulic oil fed to a hydraulic device on a basis of the amount of operation of the operation tool. The controller calculates a bleed-off target flow rate on a basis of the flow rate of hydraulic oil fed from a hydraulic oil pump and the target flow rate for hydraulic oil fed to the hydraulic device, calculates a bleed-off throttle differential pressure on a basis of a pressure of hydraulic oil fed from the hydraulic oil pump and a pressure of hydraulic oil in a hydraulic oil tank, calculates a bleed-off target opening area on a basis of the bleed-off target flow rate and the bleed-off throttle differential pressure, and controls a hydraulic oil control valve such that the bleed-off target opening area is achieved.

A telescoping crane boom having a rotary locking mechanism. A motor drives a rotating element about an axis parallel to the axis of the crane boom. The rotation of the rotating member causes a pin to selectively lock and unlock sections of the telescoping crane boom.

A telescoping crane boom having a rotary locking mechanism. A motor drives a rotating element about an axis parallel to the axis of the crane boom. The rotation of the rotating member causes a pin to selectively lock and unlock sections of the telescoping crane boom.

A work state monitoring device for a work vehicle is provided, such that an operator can perform the work without receiving a warning. The work state monitoring device acquires a current work state of a crane using work posture detectors. A calculator calculates at least a predetermined work state corresponding to a warning load factor based on the current work state acquired by the work posture detectors. A monitor informs an operator of the predetermined work state calculated by the calculator.

The invention employs a folding arm conveyor that rotates horizontally. The folding arm conveyor is mainly composed of an undercarriage mounted on the ground of a stockyard, a tower body mounted on the undercarriage, a balance arm, a conveying arm, a tower top, and other main components, wherein the balance arm, the conveying arm, and the tower top are mounted on the tower body. The conveying arm is provided with two portal frames (I) and (II) and an unloading trolley. The tower body is provided with a gyration apparatus and a hopper. The balance arm is provided with a balance trolley. The folding arm conveyor can rotate horizontally, and the conveying arm can be folded and retraced by controlling the wind rope by the windlass, so that the folding arm conveyor can be prevented from colliding with other devices or buildings during the rotation.

A mobile crane is configured so that a boom is raised by a derrick cylinder in response to a raise signal output from a derrick lever and the derrick cylinder is stopped in response to the derrick angle of the boom reaching the maximum angle γ corresponding to the hoisted-down length of a rope.