WO2022114953A1

WO2022114953A1 - Crane for handling a cable-suspended load, method of manufacturing such a crane and use of such a crane

Info

Publication number: WO2022114953A1
Application number: PCT/NL2021/050716
Authority: WO
Inventors: Jan Prins
Original assignee: Prince Lifting Devices (Pld) B.V.
Priority date: 2020-11-24
Filing date: 2021-11-24
Publication date: 2022-06-02
Also published as: NL2026970B1

Abstract

Crane for handling a cable-suspended load comprising a crane structure with a boom; a lifting system for lifting or lowering the cable-suspended load, comprising a lifting wire which suspends a rotary element from a second end of the boom, said rotary element being provided with an attachment element for holding the load; and further comprising a winch, a wire of said winch having a Y-shaped distal end and being with both ends of the Y-shaped distal end attached to the rotary element, said ends of the Y-shaped distal end being spaced apart in a horizontal plane, said winch being adapted to be controlled together with the lifting system and being fixedly attached to the crane structure at a height such that througout lifting and lowering the cable-suspended load the wire of the winch is under an angle between +/- 45° with respect to a horizontal plane through said winch.

Description

Crane for handling a cable-suspended load, method of manufacturing such a crane and use of such a crane.

Field of the invention

[0001] The present invention relates to a crane for handling a cable-suspended load comprising: a crane structure with a boom, which boom is with a first end connected to the crane structure at a boom point; a lifting system for lifting or lowering the cable-suspended load, comprising a lifting wire and a rotary element, which lifting wire is arranged to suspend the rotary element from a second end of the boom, said rotary element being provided with an attachment element for holding the load and comprising a rotor for rotating the attachment element around an axis which is substantially parallel to a section of lifting wire with which the rotary element is suspended from the second end of the boom.

[0002] The invention further relates to a method of manufacturing such a crane and the use of such a crane for lifting a load.

Background art

[0003] When turning over a load suspended from a rope by means of a crane or excavator, pendulum movements of the load occur. The loads lifted normally have a rather high weight, up to about 50 metric tonne. Putting such a considerable weight into motion and moving it to a desired position requires a lot of power and braking power, which is transmitted by the crane to the load via the vertical lifting cables. The pendulum vibrations of the load are highly undesirable, impacting both accuracy and safetly of lifting. This problem exists for cranes of various designs and various attempts have been made to reduce or suppress the pendulum vibrations.

[0004] From EP1628902 A1 , such a crane is known. The crane comprises a continuous control system whose output values are directly or indirectly used for input values for adjusting the position or speed of the crane, the control guiding values being generated in the continuous control system in such a way that the amplitude of pendulum swing of the load is minimised.

[0005] Even with the continuous control system present in the crane, the correct positioning of the load is highly dependent on the experience and estimating ability of the crane operator. In order to minimise the pendulum vibrations from the powering up and braking of each lifting motion, each movement must be slowly started and slowly brought to a halt, thus relatively slow and timeconsuming movement of the crane is required. Although the presence of the continuous control system lowers the demand on the crane operator’s experience and estimating ability to reduce pendulum swing of the load, the motions carried out by the crane still need to be rather slow. [0006] Often, crane operators speed up their operations and use surrounding structures to provide additional braking effect by knocking the load against it. This, however, results in a lot of damage. This is especially seen in habours and yards, where containers and other sizeable loads are to be loaded, offloaded, stacked and stored, thereby reducing the lifecycles of shippingcontainers significantly. [0007] It is an aim of the invention to provide a crane with an improved load positioning control system wherein pendulum movements are significantly reduced, in order to enable faster and safer lifting operations with a reduced risk of damage.

[0008] It is a further aim of the invention to provide an improved load positioning control which can be retrofitted to existing cranes.

Summary of the invention

[0009] According to the present invention, a crane as defined above is provided, which further comprising a winch, a wire of said winch having a Y-shaped distal end and being with both ends of the Y-shaped distal end attached to the rotary element, said ends of the Y-shaped distal end being spaced apart and an axis exdending through both ends of the Y-shaped distal end being horizontal, said winch being adapted to be controlled together with the lifting system and being fixedly attached to the crane structure at a height such that throughout lifting and lowering the cable-suspended load the wire of the winch is under an angle between +/-45⁰ with respect to a horizontal plane through said winch.

[0010] Through the attachment of the winch to the winch structure at a height such that throughout lifting and lowering the cable-suspended load the wire of the winch is under an angle of 45° or less with respect to a horizontal plane through said winch, the winch wire is arranged to exert a horizontal force onto the rotary element throughout lifting and lowering operations. Through this horizontal force, the winching wire limits the freedom of movement of the rotary element in a horizontal plane, thereby preventing the load to swing in a plane parallel to both the winching wire and the lifting wire. Additionally, any rotation of the rotary element around a vertical axis is prevented by the spaced apart ends of the Y-shaped distal end being attached to the rotary element in the horizontal plane. Thus the presence of the winch succesfully significantly reduces unwanted movement of the rotary element and thereby of the load suspended therefrom. Neither movements of the crane itself, such as the turning of the crane, nor wind have a significant effect on the movement of the cable- suspended load due to the presence of the winch.

[0011] Angles larger than 45° are undesirable, as a vertical component of the load exerted by the winch wire onto the rotary element then becomes larger than a horizontal component thereof, such that the winch becomes less effective in counteracting unwanted movement in the horizontal plane. [0012] By providing the control of the winch with the control of the lifting system, a crane operator may operate both the lifting system and the winch wire simultaneously, and thereby effecting a controlled lift of the load. The length of winch wire extending between the winch and the crane block can be varied in dependence of the lifting height of the load, such that the lifting wire is maintained in a vertical position whilst no slack being present in the winch wire.

[0013] The winch is a relatively cheap component, which can even be added to existing cranes without requiring modifications of the crane structure or lifting system. Through the attachment of the distal end of the winch wire to the rotary element, no adjustments are required to said connection when changing the attachment element over to hold a different load. The ends of the Y-shaped distal end preferably are spaced apart over a distance of at least 0,4 m. On conventional crane blocks, a maximum distance of 0,8m may be achieved. The crane block may be adapted to achieve larger spacings, by adding, for example, a horizontal beam structure to the crane block.

[0014] The crane structure comprises either a main boom or a mast to which the boom is connected.

[0015] In an embodiment, the winch is attached to the crane structure at or below the boom point. This placement ensures that the winch wire does not coincide with the boom throughout lifting and lowering cable-suspended loads and generally offers positions complying with the maximum angle for the winch wire with respect to the horizontal plane through the winch. The attachment of the winch at or below the boom point of the crane structure, such that throughout lifting and lowering the cable-suspended load the wire of the winch is under an angle between +/-45⁰ with respect to a horizontal plane through said winch means that the winch is preferably attached to the main boom or mast.

[0016] In another embodiment, a height at which the winch is attached to the crane structure between 4m and 25m from a ground surface on which the crane is positioned, more preferably between 8 m and 21 m, most preferred between 15m and 20m from the ground surface. The height depends on the size of the crane and is determined on a maximum lifting height and boom length thereof. For example, a crane with maximum lifting height of 45 m and a boom length of 58 m requires the winch being attached to the crane structure at a height of at least 4 m, while a crane with maximum lifting height of 42 m and a boom length of 35 m requires the winch being attached to the crane structure at a height of at least 17.25 m, in order to ensure the winch wire remains within the +/- 45° angle limits. At smaller angles, the horizontal load component of the winch wire acting on the rotary element is larger, such that a slightly higher placement of the winch is preferable.

[0017] In an embodiment, the attachment element is one of a grabber, for lifting dry bulk, or a spreader, for lifting loads of fixed dimensions such as container loads. Depending on the attachment element of the crane, the rotary element may either be a crane block or a rotary system for a grabber. The cranes may for example be cranes used on building sites or in silviculture or be mobile harbour cranes.

[0018] In a further embodiment, the winch wire is pretensioned to extend in a straight line between the winch and the rotary element whilst the lifting wire extending between the jib arm and the rotary element is in a vertical position when a load is held by the attachment element. The pretensioning prevents slack in the cable, even when operation of the winch is not perfectly synchronised with operation of the lifting system, ensuring a resistance against pendulum motions of the suspended load is present at all times. The pretensioning load is relatively low, compared to the weight of the suspended load, such as to maintain a vertical lifting trajectory of the suspended load with respect to the second end of the boom.

[0019] The pretensioning may be achieved by attaching a weight to the winch wire, either at the ends of the Y-shaped distal end or at a position near the winch. Alternatively, and preferably, the winch may be adapted to be pretensioned to roll-in the wire, for example by comprising a spring- mechanism. The pretensioning force may be equivalent to a relatively low weight of between 30 and 50 kg in order to be sufficient to pretension the winch wire. This is a low cost and simple solution for providing a constant tension, especially suitable for winches which are adapted for manual control by the crane operator.

[0020] In an embodiment, the winch comprises at least a sensor for monitoring a tension in the winch wire and a computerized control system adapted for operating the winch based on at least one of manual input, predetermined input values and/or sensed input values received from the at least one sensor. The computerized control may be in addition to manual contrail, assisting the crane operator, for example by maintaining a preset minimum tension value on the winch wire, as an alternative to the use of a physical weight for pretensioning said wire, and/or be preprogrammed to operate the winch, for example in dependence of the operation of the lifting system and/or depending on sensed tension values of the winch wire.

[0021] In an embodiment, the wire of the winch is a stretchable wire, preferably a synthetic winch rope, most preferably a wire comprising at least one of polyethylene and nylon. Through being stretchable, the wire suffers less wear and tear compared to regular steel cables used for hoisting and winching. The strech reduces the effect of sudden forcesfrom the suspended load acting on the winch and vice versa, lowering the risk of damage to the winch and lowering the risk of the wire snapping as a result of such forces. The stretchable cable preferably is a synthetic winch rope. Synthetic winch ropes have a significantly lower weight/higher strength compared to steel wires, making them easier to handle and allowing a relatively low power winch being used. Furthermore, synthetic winch wires suffer less wear and tear than steel wires and cause less wear to components of the winch, providing a more durable alternative. Most preferable, the winch wire comprises at least one of polyethylene and nylon.

[0022] In another embodiment, the winch is an electric winch. Such a winch can be powered with the crane's electric system. Due to the winch wire acting on the suspended load mainly with a horizontal load component, a relatively light winch may be used. A 24V winch may be sufficient for providing the required winching power if a synthetic winch rope is used.

[0023] In a further embodiment, the crane is a mobile harbour crane, wherein the lifting wire is arranged to suspend the rotary element via two spaced apart lengths of lifting wire from the second end of the boom. This configuration is especially used in mobile harbour cranes, where the rotary element is a crane block comprising a rotor, which is used to rotate a container held by the attachment element for manoeuvring during lifting and correct positioning prior to placement on a resting surface. The weight of the container may be between 15 and 50 tons. The two vertical lifting wires provide little horizontal resistance for efficient starting and stopping of the rotational movement. For this configuration, the presence of the winch wire with the Y-shaped distal end connected to the crane block is particularly advantageous, providing rotational resistance of the crane block around the axis parallel to the spaced apart lengths of lifting wire. It results in significantly improvements on both the accuracy with which the load can be positioned and the stability of said load during and immediately after rotation. The increased stability allows the movement being carried out faster without an increased risk of damage to the load and its immediate surroundings. The use of a mobile harbour crane according to the invention for the (un)loading of containers significantly reduces the time of each lifting cycle, such that up to 35 containers may be (un)loaded each hour by a single of such mobile harbour cranes compared to around 10 containers per hour when using a mobile harbour crane according to the prior art.

[0024] In an embodiment, the attachment element for holding the load is suspended from the rotary element via a wire or chain having a length between 2 and 20 meters, preferably between 8 and 15 meters, most preferred of 12 meters. The wire or chain from which the attachment element for holding the load is suspended from the rotary element provides clearance between the attachment element and the position at which the winch wire is attached to control the positioning of the rotary element in a horizontal plane, perpendicular to the lifting direction. As a result, the arrangement is also suitable for lifting and lowering loads, such as for example containers, in a controlled manner over other items, such as stacks of containers. This arrangement is thus particulary advantageous when provided to mobile harbour cranes, with the rotary element being a crane block and the attachment element being a spreader for holding containers or the like. Advantageously, thereby the crane can be used for loading and offloading vessels and yards without having to move the crane around a lot on the quay or yard and/or being forced to offload nearest items first and load them last.

[0025] Due to the weight of the load held by the attachment element and the relatively short length of the wire or cable with which it hangs from the crane block, the positioning of the attachment element with the load is substantially dependent on the positioning of the rotary element. Thus the presence of the cable or chain between the attachment element and the rotary element does not affect the controllability of the positioning of the load with the winch being attached to the rotary element.

[0026] In an embodiment, a camera is attached to the rotary element orto the attachment element, said camera comprising a wide-angle lens which is pointed towards a ground surface which is perpendicular to the section of lifting wire with which the rotary element is suspended from the second end (5) of the boom and being adapted to transmit, and wherein a display is provided at the winch control, said display being connected with an input to the camera and adapted for displaying live video footage of an area of the ground surface below the suspended load on said display. The camera provides the crane operator with a visual of an area below the rotary element. Through the wide angle lens, the video footage shows an area of the ground surface below the suspended load, allowing the crane operator to continuously verify the positioning of the load throughout lifting movements for accurate lifting and lowering without the load hitting any objects. This allows lifts being carried out without requiring personnel on the ground, in the lifting area, making lifting operations much safer.

[0027] Although the camera can be connected via wires running along the lifting wire to the crane’s power system and/or the display, preferably, the camera is adapted for wireless transmission and provided with a battery for powering said camera. This makes the camera easier to install and less susceptible to damage.

[0028] In a further embodiment, the rotary element, the attachment element and/or camera is provided with LED lighting, arranged to brighten the area of the ground surface below the suspended load when switched on. The lightning enables the crane operator to see the load even when dark(er), allowing controlled lifting operations to be carried out even throughout the night and during the nordic winters. Additionally, the lighting ensures continuous visibility for controlling the load during lifts with changing lighting conditions in the area below the rotary element or the attachment element, such as for example when loading or unloading the internal cargo space of a vessel.

[0029] Additionally or alternatively, the camera is a thermographic camera or wherein a second camera is provided, which second camera is a thermographic camera. A thermographic camera registers IR, thereby providing footage independent of lightening conditions.

[0030] According to a second aspect of the invention, a method of manufacturing a crane for handling a cable-suspended load is provided, comprising the steps of:

- providing a crane having a crane structure with a boom, which boom is with a first end connected to the crane structure at a boom point, and a lifting system for lifting or lowering the cable-suspended load, comprising a lifting wire and a rotary element, which lifting wire is arranged to suspend the rotary element from a second end of the boom, said rotary element being provided with an attachment element for holding the load;

- providing a winch with a winch wire, said winch wire having a Y-shaped distal end from the winch such that the winch wire has two free ends;

- rigidly attaching the winch to the crane structure, at or below the boom point, such that throughout lifting and lowering the cable-suspended load with the lifting system the wire of the winch is under an angle between +/-45⁰ with respect to a horizontal plane through said winch and providing a winch control with a control for the lifting system; and

- connecting the two free ends of the winch wire to the rotary element, such that the two free ends are spaced apart and such that an axis extending through both free ends is horizontal.

[0031] In an embodiment, the method further comprises the step of providing a wire or a chain between the attachment element for holding the load and the rotary element, such that during use the attachment element is suspended from the rotary element, the wire or chain having a length between 2 and 20 meters, preferably between 8 and 15 meters, most preferred of 12 meters. [0032] In a further embodiment, the method comprises the step of attaching a wide-angle camera to the rotary element or to the attachment element, with a lens of the camera pointed towards a ground surface which is perpendicular to a section of lifting wire with which the rotary element is suspended from the second end of the boom, said camera being adapted to wirelessly transmit live video footage of a area of the ground surface below the attachment element, and providing a display at the winch control.

[0033] According to a third aspect of the invention, use of a crane according to the first aspect of the invention for lifting a load.

Brief description of the drawings

[0034] The present invention will be discussed in more detail below, with reference to the attached drawings, in which: [0035] Figs. 1 A and 1 B respectively depict a side view of a mobile harbour crane according to the prior art and a detailed view of the configuration at the crane block;

[0036] Figs. 2A and 2B respectively show a side view of a mobile harbour crane according to an embodiment of the invention and a detailed view of the configuration at the crane block; and [0037] Fig. 3 shows a schematic top view of the winch as attached to the crane block of the mobile harbour crane depicted in Fig. 2A;

[0038] Fig. 4 shows a schematic side view of a mobile harbour crane according to an embodiment of the invention.

Description of embodiments

[0039] Fig. 1A depicts a side view of a mobile harbour crane 100 according to the prior art. The crane 100 is shown to comprise a carrier 10 with a crane structure, including a boom 3 which is provided with a lifting system. The crane structure is provided with a mast 2, in the form of a vertical cilinder, to which the boom 3 is connected with a first end, said connection forming a boom point 4. The carrier 10 has a slewing unit for rotating the boom 3 with respect to a position of the carrier and a contrail room for a crane operator to contrail the cranes movements from, including slewing and lifting motions. The lifting system comprises a winding durm (not shown), the lifting wire 20, 21 , 22 and a crane block 25 as rotary element with a container spreader as attachment element 26. The lifting wire 20 extends from the winding drum along the boom 3 up to an upper sheave 5 located at a free end of the boom 3, from which upper sheave 5 a first length of lifting wire 21 extends to the crane block 25 and a second length of lifting wire 22 extends from the crane block 25 to the free end of the boom 3. The winding drum is normally located in or onto the carrier or on the mast 2, holding a variable section of the lifting wire 20, said variable section having a length depending on the height with which the crane block is suspended from the upper sheave 5. The container spreader 26 of the mobile harbour crane 100 is holding a container 30. The crane has a vertical height HI of the upper sheave with respect to a ground surface, which is larger than a vertical height Hb of the boom point 4 with respect to the ground surface. The vertical height of the boom point 4 depends on the size of the crane and may be between 5 m and 30 m., with the maximum lifting height being determined by the vertical height HI of the upper sheave with respect to a ground surface onto which the crane is positioned, said vertical height HI being between 30 m and 70 m. The weight of the container is generally between 15 and 50 tonnes.

[0040] Details of the configuration at the crane block 25 and the attachment element 26 holding the container are shown in Fig. 1 B. The attachment element 26 is directly connected to a lower side of the crane block 25 and the first and second lengths of lifting wire 21 , 22 are connected to an upper side of the crane block 25, horizontally spaced apart over substantially the width of the crane block. The crane block 25 comprises a rotor 28, for rotating the attachment element 26 around a vertical axis, substantially parallel to the first and second lengths of lifting wire 21 , 22, for positioning of the container when for example lowering the container to be placed directly next to a stack of containers 31 , 32, 33. The two vertical lengths of lifting wire 21 , 22 provide little horizontal resistance for efficient starting and stopping of rotational movement of the rotor. The positioning of the container is a precision job, which is made difficult by pendulum swinging of the container suspended from the crane, caused by sudden crane movements and wind, as well as rotational motions resulting from braking of the rotor 28. In order to limit pendulum swinging and rotational motions of the container, all movements during lifting are to be carried out slowly. As a result, average lifting cycles of these mobile harbour cranes are around 6 min. per lift, enabling them to complete around 10 cycles per hour. In order to speed up the lifting cycles, crane operators often use the already present stack of containers 31 , 32, 33 to stabilise the container 30 suspended from the crane. This, however, results in damage to the containers 30, 31 , 32, 33.

[0041] Fig. 2A shows a side view of a mobile harbour crane 200 according to an embodiment of the invention. The crane 200 has a similar configuration to the crane 100 of the prior art, but further comprises a winch 40 and a chain 45. The winch 40 is fixedly attached to the mast 2, below the boom point 4 and holds a winch wire 41 which is with a distal end attached to the crane block 25. The winch 40 is attached to the mast 2 at a height such that an angle a of the winch wire 41 with respect to a horizontal plane through the winch 40 is between +45° and -45° throughout lifting and lowering of the container 30. The chain 45 is with a first end connected to a lower side of the crane block 25 and with a second end connected to the attachment element 26, such that the attachment element 26 is suspended from the crane block 25 by the chain 45. The chain 45 has a length c, which is chosen such that a load may be positioned with the crane reaching over another object, preventing the winch cable 41 attached to the crane block from colliding with this other object. In the mobile harbour crane as depicted, the length c of the chain equals approximately the height of one container 30, but preferably the length c of the chain equals the height of a maximum container stack height. Preferably, the chain 45 may have a length c between 2 and 20 meters, preferably between 8 and 15 meters, most preferred of 12 meters.

[0042] Details of the configuration at the crane block 25 and the attachment element 26 holding the container 30 are shown in Fig. 2B. Contrary to the configuration shown in Fig. 1 B, the attachment element 26 is connected to a lower side of the crane block 25 via a chain, which in Fig. 2B is shown as having two lengths of chain 45a, 45b, but may alternatively be a single length. The crane block 25 comprises a rotor 28, for rotating the attachment element 26 around a vertical axis, substantially parallel to the first and second lengths of lifting wire 21 , 22, for positioning of the container when for example lowering the container to be placed directly next to a stack of containers 31 , 32, 33. The attachment of the winch wire 41 directly to the crane block 25 provides additional rotational resistance for efficient starting and stopping of rotational movement of the rotor 28. This is further enhanced by providing the end with which the winch wire 41 is attached to the crane block 25 with a Y-shape, as shown in more detail in the schematic top view of Fig. 3.

[0043] Fig. 3 shows a schematic top view of the winch 40 as attached to the crane block 25 of the mobile harbour crane depicted in Fig. 2A. The winch 40 holds the winch wire 41 , which winch wire is provided with a Y-shaped distal end 43, having two ends 44a, 44b, which are attached to the crane block 25. The ends 44a, 44b of the Y-shaped distal end are spaced apart over a distance substantially equal to a widht of the crane block 25. On conventional crane blocks, a maximum distance w of 0.8 m may be achieved. The crane block may be adapted to achieve larger spacings, by adding, for example, a horizontal beam structure to the crane block. Any rotation of the crane block around a vertical axis, paralel to the first and second lengths of lifting wire 21 , 22 is prevented by the spaced apart ends of the Y-shaped distal end being attached to the crane block in the horizontal plane. In Fig. 3, an imaginary horizontal axis extending through the ends 44a, 44b of the Y-shaped distal end is shown to be parallel to an imaginary horizontal axis extending through the first and second lengths of lifting wire 21 , 22, but the skilled person will understand that any orientation of both imaginary axes with respect to each other in the horizontal plane is suitable for providing the additional rotational resistance and therefore fall within the scope of the invention. [0044] The winch 40 and chain 45 can be added to existing mobile harbour cranes without requiring modifications of the crane boom or lifting system. The winch 40 is fixed to the crane boom at the boom point 4. Preferably the winch 40 is an electric winch, this being a relatively light weight winch which can feed of existing power supplies of the crane. Through the attachment of the distal end of the winch wire to the crane block, no adjustments are required to said connection when changing the attachment element over to hold a different load.

[0045] The winch 40 is operable from the carrier 10 by the crane operator, simultaneously with the lifting system. The length of the winch cable 41 is adapted in dependence of the first and second length of lifting wire 21 , 22, and prevents the crane block 25 from swinging away from the boom, thereby effectively stopping pendulum swinging motions thereof. The winch may be adapted for manual control by the crane operator, or be fully or partially operated by a computer which operates based on sensor values sensing loads acting on the winch wire and/or lifting wire.

[0046] In order to allow the crane operator to perform lifts without ground support, which otherwise may result in one or more persons being present in an area of the ground below the container, the system further comprises a camera (not shown), which may be attached to either the rotary element or the attachment element and pointed towards the ground below the container, and a display at the contrails of the lifting system and winch, to which an image captured by the camera is directly transmitted.

[0047] In fig. 4 a schematic side view of a mobile harbour crane according to an alternative embodiment of the invention is shown. Rather than being provided with a crane block 25 as rotary element with a container spreader as attachment element 26, as shown in Fig. 2a, the crane 200 is provided with a rotor 25’, having a grabber 26’ for lifting dry bulk directly attached thereto. The winch wire 41 is attached to the rotor 25’ and works according to the same principle as explained for the set-up of the crane in Fig 2a.

[0048] The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. It is understood that modifications and alternative implementations of some parts or elements are possible and are included in the scope of protection as defined in the claims set forth hereunder.

Claims

1 . A crane (200) for handling a cable-suspended load (30) comprising: a crane structure with a boom (3), which boom (3) is with a first end connected to the crane structure at a boom point (4); a lifting system for lifting or lowering the cable-suspended load, comprising a lifting wire (20) and a rotary element (25; 25’), which lifting wire is arranged to suspend the rotary element (25; 25’) from a second end (5) of the boom, said rotary element (25; 25’) being provided with an attachment element (26; 26’) for holding the load (30; 30’) and comprising a rotor (28) for rotating the attachment element (26; 26’) around an axis which is substantially parallel to a section of lifting wire (21 , 22) with which the rotary element is suspended from the second end (5) of the boom; and further comprising a winch (40), a wire (41) of said winch (40) having a Y-shaped distal end (43) and being with both ends (44a, 44b) of the Y-shaped distal end attached to the rotary element (25; 25’), said ends of the Y-shaped distal end being spaced apart and an axis exdending through both ends of the Y-shaped distal end being horizontal, said winch (40) being adapted to be controlled together with the lifting system and being fixedly attached to the crane structure at a height such that throughout lifting and lowering the cable-suspended load the wire (41) of the winch is under an angle (a) between +/-45⁰ with respect to a horizontal plane through said winch (40).

2. The crane (200) according to claim 1 , wherein the winch (40) is attached to the crane structure at or below the boom point (4).

3. The crane (200) according to claim 1 or 2, wherein a height at which the winch (40) is attached to the crane structure between 4m and 25m from a ground surface on which the crane is positioned, more preferably between 8 m and 21 m, most preferred between 15m and 20m from the ground surface.

4. The crane (200) according to claim 1 or 2, wherein the attachment element (26; 26’) is one of a grabber (26’), for lifting dry bulk, or a spreader (26), for lifting loads of fixed dimensions such as container loads.

5. The crane (200) according to any one of the preceding claims, wherein the winch wire (41) is pretensioned to extend in a straight line between the winch (40) and the rotary element (25; 25’) whilst the lifting wire extending between the jib arm (3) and the rotary element (25; 25’) is in a vertical position when a load (30; 30’) is held by the attachment element (26; 26’).

6. The crane (200) according to any one of the preceding claims, wherein the winch (40) comprises at least a sensor for monitoring a tension in the winch wire (41) and wherein the winch comprises a computerized control system adapted for operating the winch based on at least one of manual input, predetermined input values and/or sensed input values received from the at least one sensor.

7. The crane (200) according to any one of the preceding claims, wherein the wire (41) of the winch is a stretchable wire, preferably a synthetic winch rope, most preferably a wire comprising at least one of polyethylene and nylon.

8. The crane (200) according to any one of the preceding claims, wherein the winch is an electric winch.

9. The crane according to any one of the preceding claims, said crane being a mobile harbour crane, wherein the lifting wire (20) is arranged to suspend the rotary element (25; 25’) via two spaced apart lengths of lifting wire (21 , 22) from the second end (5) of the boom (3).

10. The crane according to any one of the preceding claims, wherein the attachment element (26; 26’) for holding the load is suspended from the rotary element (25; 25’) via a wire or chain (45a, 45b) having a length (c) between 2 and 20 meters, preferably between 8 and 15 meters, most preferred of 12 meters.

11 . The crane according to any one of the preceding claims, wherein a camera is attached to the rotary element or to the attachment element, said camera comprising a wide-angle lens which is pointed towards a ground surface which is perpendicular to the section of lifting wire (21 , 22) with which the rotary element is suspended from the second end (5) of the boom and being adapted to transmit, and wherein a display is provided at the winch control, said display being connected with an input to the camera and adapted for displaying live video footage of an area of the ground surface below the suspended load on said display.

12. The crane according to claim 11 , wherein the rotary element (25; 25’), the attachment element (26; 26’) and/or camera is provided with LED lighting, arranged to brighten the area of the ground surface below the suspended load when switched on.

13. The mobile harbour crane according to claim 11 or 12, wherein the camera is a thermographic camera or wherein a second camera is provided, which second camera is a thermographic camera.

14. Method of manufacturing a crane for handling a cable-suspended load, comprising

- rigidly attaching the winch to the crane structure, at or below the boom point, such that throughout lifting and lowering the cable-suspended load with the lifting system the wire (41) of the winch is under an angle (a) between +/-45⁰ with respect to a horizontal plane through said winch (40) and providing a winch control with a control for the lifting system; and - connecting the two free ends of the winch wire to the rotary element, such that the two free ends are spaced apart and such that an axis extending through both free ends is horizontal.

15. The method of manufacturing according to claim 14, further comprising the step of providing a wire or a chain between the attachment element for holding the load and the rotary element, such that during use the attachment element is suspended from the rotary element, the wire or chain having a length between 2 and 20 meters, preferably between 8 and 15 meters, most preferred of 12 meters.

16. The method of manufacturing according to claim 14 or 15, further comprising the step of attaching a wide-angle camera to the rotary element or to the attachment element, with a lens of the camera pointed towards a ground surface which is perpendicular to a section of lifting wire (21 , 22) with which the rotary element is suspended from the second end (5) of the boom, said camera being adapted to wirelessly transmit live video footage of a area of the ground surface below the attachment element, and providing a display at the winch control.

17. Use of a crane according to any one of claims 1 to 11 for lifting a load.