A crane includes a jib posture retention device that retains a jib in a frontward tilt posture to a boom. The jib posture retention device includes a jib mast that holds a rope connection part at a tensioning position separate from a jib proximal end and a boom distal end backward thereof to render a jib-side support rope and a boom-side support rope linearly tensioned with the jib in the frontward tilt posture. The jib mast is shiftable to a tension form of holding the rope connection part at a tensioning position in an uprise posture and a looseness allowing form of locating the rope connection part at a looseness allowing position closer to the boom distal end than the tensioning position and closer to the jib proximal end than the tensioning position to allow the jib-side support rope and the boom-side support rope to be loosened.

A rotary tower crane with a tower, which carries a jib and a counterjib, with a jib stay being guided from a tower top to the jib and to the counterjib. The jib stay tensions only an inner jib portion, the length of which is less than 40% of the total length of the jib, and an outer portion, the length of which is more than 60% of the total length of the jib, forms an untensioned bending beam jib which includes at least one jib piece which tapers in height and which is adjoined on the inner side by at least one jib part of greater height and on the outer side by a jib piece of smaller height.

A rotary tower crane with a tower, which carries a jib and a counterjib, with a jib stay being guided from a tower top to the jib and to the counterjib. The jib stay tensions only an inner jib portion, the length of which is less than 40% of the total length of the jib, and an outer portion, the length of which is more than 60% of the total length of the jib, forms an untensioned bending beam jib which includes at least one jib piece which tapers in height and which is adjoined on the inner side by at least one jib part of greater height and on the outer side by a jib piece of smaller height.

A crane includes a crane main body, a boom, a jib, a boom driving unit, a jib driving unit, a manipulation unit, a drive control unit, a suspension device, a determination unit, and an operation regulating unit. The determination unit determines whether a jib boom angle condition is established or not. The operation regulating unit allows the crane to change a posture between a fall posture and a work posture according to a determination result of the determination unit.

To reduce the number of places where dimension control regarding an attachment position of a coupling portion to a structure is required. A first coupling portion includes a first pin receiving portion into which a coupling pin can be inserted, and a load transmitting portion integrally provided with the first pin receiving portion. A second coupling portion includes a second pin receiving portion into which the coupling pin can be inserted, and a load receiving portion integrally provided with the second pin receiving portion. The first pin receiving portion and the second pin receiving portion match with each other so as to detachably attach the coupling pin in a state where the load transmitting portion and the load receiving portion are in contact with each other.

To reduce the number of places where dimension control regarding an attachment position of a coupling portion to a structure is required. A first coupling portion includes a first pin receiving portion into which a coupling pin can be inserted, and a load transmitting portion integrally provided with the first pin receiving portion. A second coupling portion includes a second pin receiving portion into which the coupling pin can be inserted, and a load receiving portion integrally provided with the second pin receiving portion. The first pin receiving portion and the second pin receiving portion match with each other so as to detachably attach the coupling pin in a state where the load transmitting portion and the load receiving portion are in contact with each other.

A changing device easily and safely changes the posture of the backstop of a crane between a support posture and a storage posture. The backstop posture changing device is provided with a first support member, a second support member, a push-up mechanism, and a connection member. The first support member and the second support member are rotationally connected to a backstop and a lower boom respectively. When a cylinder rod of the push-up mechanism is extended with respect to a cylinder body, a push-up member pushes up the first support member and the posture of the backstop is changed from a storage posture on the lower boom to a support posture in which it is possible to support a boom while the crane is in a working posture.

A changing device easily and safely changes the posture of the backstop of a crane between a support posture and a storage posture. The backstop posture changing device is provided with a first support member, a second support member, a push-up mechanism, and a connection member. The first support member and the second support member are rotationally connected to a backstop and a lower boom respectively. When a cylinder rod of the push-up mechanism is extended with respect to a cylinder body, a push-up member pushes up the first support member and the posture of the backstop is changed from a storage posture on the lower boom to a support posture in which it is possible to support a boom while the crane is in a working posture.

Provided is a periphery monitoring device for a work machine that displays an overhead image of the work machine and surroundings of the work machine, the device including: a detector that detects a distance to a surrounding object with respect to the work machine; and a display that displays the object in the overhead image with the distance between the work machine and the object reflected, in which a display range of the display for the object is a range obtained by extracting a portion of a detection range of the detector.

Providing energy to an energy consuming piece of equipment and/or tool during offshore operations. Use is made of a crane including a substructure, a boom mounted on the substructure, one or more hoist winches and cables, as well as an object suspension device suspended from the boom by the cables. A piece of equipment or tool is suspended from the object suspension device. An energy storage unit is provided on the object suspension device and has an input connector. The boom may be provided with an output connector of an energy charging unit and in a lower supply position of the object suspension device it is disconnected from the input connector of the energy storage unit. The piece of equipment or tool is then run on energy supplied by the energy storage unit. Moving the object suspension device to a charging position thereof by employing the hoist assembly of the crane brings the input connector of the energy storage unit in close proximity of the output connector of the energy charging unit which are then interconnected to charge the energy storage unit from a separate energy source.