The invention relates to a method of monitoring the safety of a crane, in particular of a revolving tower crane having a revolving deck, wherein the crane has a sensor system and a crane control, and wherein furthermore at least one tilt sensor is provided. In accordance with the invention, the at least one tilt sensor is attached to the revolving deck of the revolving tower crane, with the monitoring of the crane safety taking place at least during the putting up and/or taking down of the revolving tower crane.

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.

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.

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 vehicle crane comprising a jib that is raised and lowered by at least one main tensile connector, and a counter jib, where the main tensile connector extends between a first connecting point in the region of a jib head and a second connecting point in the region of a counter jib head. To reduce loading on the jib, in particular during raising and lowering and increase its bearing load overall, the jib has a third connecting point between the first connecting point and its foot opposite the head, and a secondary tensile connector extends between the third connecting point and a fourth connecting point in the region of the head of the counter jib, or the secondary tensile connector extends between the third connecting point via a seventh connecting point on the main tensile connector and a fourth connecting point in the region of the main jib foot.

The present invention relates to a crane having a boom at which at least one load receiving means is arranged in a raisable and lowerable manner, wherein an overload protection device has detection means for detecting the outreach and the load on the at least one load receiving means, and wherein a monitoring device for monitoring the overload protection device is provided and has determination means for determining a tensioning force holding the boom and/or induced in a guy cable. The invention furthermore also relates to a method for monitoring the overload protection device of such a crane. Provision is made in accordance with the invention that the monitoring device determines online in crane operation a tensioning torque from the continuously determined tensioning force, determines a lifting torque from the continuously detected outreach and the continuously detected load, determines a dead torque while making use of stored crane data, compares the sum of the named lifting torque and the named dead torque with the named tensioning torque and then, if a difference found in the comparison exceeds a tolerance threshold, emits an error signal and/or shutdown signal.

A lift crane includes a carbody; a rotating bed comprising a counterweight support frame; a boom; a counterweight unit supported on the counterweight support frame in a moveable relationship with respect to the counterweight support frame; and a counterweight unit movement device connected between the rotating bed and the counterweight unit to move the counterweight unit toward and away from the boom. The crane is configured such that during crane operation, the moment generated by the counterweight unit acts on the rotating bed predominantly through the counterweight support frame. Alternatively, the crane can include a mast. In some embodiments the same basic crane is configured to be set-up with two different counterweight options, i) a counterweight unit directly supported on the counterweight support frame and ii) a counterweight support beam moveably connected to the remainder of the rotating bed and a counterweight unit supported on the counterweight support beam.

A crane control system for actuating positioners of a crane is configured to receive target position data which describe a predefined target position of at least one positioner, in particular at least one crane superstructure positioner; receive clearance data which describe a user input for clearing a movement of the at least one positioner into the predefined target position; and output control data which describe control signals to be output to the at least one positioner in order to move the at least one positioner into the predefined target position.

A double jib slewing pedestal crane includes a main jib and a secondary jib, and a secondary jib positioning device to support and position the secondary jib with respect to the main jib and actuate the pivotal movement of the secondary jib. The secondary jib positioning device includes a secondary jib positioning cable; a spoke structure fixed to the secondary jib and extending radially outward; a tension chain connected at one end to the secondary jib positioning cable and at the other end to the secondary jib and/or to the spoke structure, wherein the spoke structure is adapted to support the tension chain.

A double jib slewing pedestal crane includes a main jib and a secondary jib, and a secondary jib positioning device to support and position the secondary jib with respect to the main jib and actuate the pivotal movement of the secondary jib. The secondary jib positioning device includes a secondary jib positioning cable; a spoke structure fixed to the secondary jib and extending radially outward; a tension chain connected at one end to the secondary jib positioning cable and at the other end to the secondary jib and/or to the spoke structure, wherein the spoke structure is adapted to support the tension chain.