A crane extension and installation device includes an extension device, a winch, a pulley and a cable. A main arm includes a vertical slide rail, the main arm is inclined relative to vertical, and three second pulleys at different heights of the slide rail are installed in the vertical direction of the slide rail, and the second pulley can slide vertically along the slide rail and can be fixed at a certain position of the slide rail. The extension device includes a number of cantilever beams connected end to end. The front end of the extension device is a cantilever beam, and a fixed pulley is installed on the lower peripheral surface of the extension device. The end face of the cantilever beam is equipped with a vertical lower arm through a joint, and the bottom end of the lower arm has a first pulley fixed by the joint.

A dual hoist crane is provided with a heave compensation system that can be used for both the main and for the auxiliary hoisting assembly. The heave compensation system includes a first set of sheaves for guiding the main hoisting cable and a second set of sheaves for guiding the auxiliary hoisting cable. The heave compensation system is configured to individually lock the first set of sheaves and the second set of sheaves to a heave compensation cylinder, for respectively providing the main hoisting assembly and the auxiliary hoisting assembly with heave compensation.

A dual hoist crane is provided with a heave compensation system that can be used for both the main and for the auxiliary hoisting assembly. The heave compensation system includes a first set of sheaves for guiding the main hoisting cable and a second set of sheaves for guiding the auxiliary hoisting cable. The heave compensation system is configured to individually lock the first set of sheaves and the second set of sheaves to a heave compensation cylinder, for respectively providing the main hoisting assembly and the auxiliary hoisting assembly with heave compensation.

Provided is a crane (1) comprising: a boom (7) capable of being raised, lowered, and telescoped; a wire rope (8) being suspended from the boom (7); a winch (9) for winding and unwinding the wire rope (8); and a hook (10) being raised and lowered by the winding and unwinding of the wire rope (8). The crane further comprises a spooling operation instrument (24) for enabling commanding an operation state of the winch (9). When the hook (10) is raised to a height at which the hanging length d is a prescribed value by an operation of the spooling operation instrument (24), the boom (7) is raised and extended while the wire rope (8) is unwound such that the prescribed hanging length d is maintained, thereby sustaining the elevation operation of the hook (10).

Provided is a crane (1) comprising: a boom (7) capable of being raised, lowered, and telescoped; a wire rope (8) being suspended from the boom (7); a winch (9) for winding and unwinding the wire rope (8); and a hook (10) being raised and lowered by the winding and unwinding of the wire rope (8). The crane further comprises a spooling operation instrument (24) for enabling commanding an operation state of the winch (9). When the hook (10) is raised to a height at which the hanging length d is a prescribed value by an operation of the spooling operation instrument (24), the boom (7) is raised and extended while the wire rope (8) is unwound such that the prescribed hanging length d is maintained, thereby sustaining the elevation operation of the hook (10).

Provided is a crane (1) comprising: a boom (7) capable of being raised, lowered, and telescoped; a wire rope (8) being suspended from the boom (7); a winch (9) for winding and unwinding the wire rope (8); and a hook (10) being raised and lowered by the winding and unwinding of the wire rope (8). The crane further comprises a spooling operation instrument (24) for enabling commanding an operation state of the winch (9). When the hook (10) is raised to a height at which the hanging length d is a prescribed value by an operation of the spooling operation instrument (24), the boom (7) is raised and extended while the wire rope (8) is unwound such that the prescribed hanging length d is maintained, thereby sustaining the elevation operation of the hook (10).

Provided is a crane (1) comprising: a boom (7) capable of being raised, lowered, and telescoped; a wire rope (8) being suspended from the boom (7); a winch (9) for winding and unwinding the wire rope (8); and a hook (10) being raised and lowered by the winding and unwinding of the wire rope (8). The crane further comprises a spooling operation instrument (24) for enabling commanding an operation state of the winch (9). When the hook (10) is raised to a height at which the hanging length d is a prescribed value by an operation of the spooling operation instrument (24), the boom (7) is raised and extended while the wire rope (8) is unwound such that the prescribed hanging length d is maintained, thereby sustaining the elevation operation of the hook (10).

A crane extension and installation device includes an extension device, a winch, a pulley and a cable. A main arm includes a vertical slide rail, the main arm is inclined relative to vertical, and three second pulleys at different heights of the slide rail are installed in the vertical direction of the slide rail, and the second pulley can slide vertically along the slide rail and can be fixed at a certain position of the slide rail. The extension device includes a number of cantilever beams connected end to end. The front end of the extension device is a cantilever beam, and a fixed pulley is installed on the lower peripheral surface of the extension device. The end face of the cantilever beam is equipped with a vertical lower arm through a joint, and the bottom end of the lower arm has a first pulley fixed by the joint.

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.