A crane includes a jib which is mounted on the crane structure so as to be rotatable about a bearing point, a counterweight arrangement which can be positioned variably in relation to the bearing point, and a hoisting cable which runs out from a hoisting winch and is guided via the jib. A counterweight adjustment device, which is coupled to the counterweight arrangement, includes a lever element mounted rotatably about a pivot point, a hoisting cable guide arranged in the course of the hoisting cable between the hoisting winch and an upper jib section, with a first deflecting pulley arrangement mounted on the jib and a second deflecting pulley arrangement mounted on the lever element, wherein the hoisting cable is guided in an alternating manner via the first and the second deflecting pulley arrangement, and a coupling element acting on the lever element and connected to the counterweight arrangement.

A crane includes a jib which is mounted on the crane structure so as to be rotatable about a bearing point, a counterweight arrangement which can be positioned variably in relation to the bearing point, and a hoisting cable which runs out from a hoisting winch and is guided via the jib. A counterweight adjustment device, which is coupled to the counterweight arrangement, includes a lever element mounted rotatably about a pivot point, a hoisting cable guide arranged in the course of the hoisting cable between the hoisting winch and an upper jib section, with a first deflecting pulley arrangement mounted on the jib and a second deflecting pulley arrangement mounted on the lever element, wherein the hoisting cable is guided in an alternating manner via the first and the second deflecting pulley arrangement, and a coupling element acting on the lever element and connected to the counterweight arrangement.

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.

A crane characterized in that it comprises a lower vertical boom (10) and an upper horizontal boom (12), mutually connected through a joint element (20), in that the lowest part of the vertical boom is connected through a pedestal (14), the pedestal further comprising a slew ring for rotating of the crane about a vertical axis (16), and a tension rod (22) is arranged between the pedestal and the joint element in a distance from the vertical boom and mainly parallel to this in a normal position of the crane.

A crane characterized in that it comprises a lower vertical boom (10) and an upper horizontal boom (12), mutually connected through a joint element (20), in that the lowest part of the vertical boom is connected through a pedestal (14), the pedestal further comprising a slew ring for rotating of the crane about a vertical axis (16), and a tension rod (22) is arranged between the pedestal and the joint element in a distance from the vertical boom and mainly parallel to this in a normal position of the crane.