Extendable lattice crane boom and method of operating a crane including an extendable boom

Abstract

An extendable lattice-type crane boom (2) for a crane (1), the boom comprising a lattice-type base boom section (2a) and at least one lattice-type telescoping boom section (2b), the at least one telescoping boom section being adjustable relative to the base boom section between a stowed position in which the telescoping boom section is generally inboard of the base boom section and an extended position in which the telescoping boom section is at least partially outboard of the base boom section, the base boom section having a distal end mounted with a first guide system (21) configured to guide movement of the telescoping boom section along the base boom section, and a proximal end of the telescoping boom section having a second guide system (30) configured to guide movement of the telescoping boom section along the base boom section.

Description

[Technical field]

[0001] The present invention relates to an extendable lattice boom for a crane. In many areas of construction and maintenance, there is a demand for ever larger cranes capable of lifting loads to increased heights. This requires longer booms or boom-mounted extensions such as jibs. The increased length of the boom necessarily impedes the transport of the crane. [Background technology]

[0002] Cranes with telescoping booms have been improved to reach relatively high lifting heights while allowing the boom to be quickly retracted to transportable dimensions. Such telescoping booms usually have two or more sections with reduced dimensions, with a larger section surrounding the inserted portion of the smaller section. Loads on the boom, such as the weight of the boom and the load of the hook, generate bending or overturning moments on the boom, and therefore large forces are transmitted between the sections through the guides between the telescoping sections, requiring special material strength in the guides.

[0003] Generally, a longer boom requires a heavier structure capable of supporting the increased weight as well as withstanding the increased forces and bending moments caused by the hook load at the longer reach of the crane. If the length of a conventional tubular telescopic boom is increased, such a tubular boom may become too heavy for a given application, such as an offshore application, given the material strength of the guides required.

[0004] The application of a lattice boom allows a significant reduction in the weight of the boom compared to a tube boom. Telescopic booms with lattice sections are known, but the extension of the sections is relatively time consuming. Stable guidance of the telescopic boom sections and the load transfer between the sections also appear to remain difficult.

[0005] In the field of wind turbine installation, the lifting height required to mount a turbine on top of a tower will increase from 140m to 160m or even more in the near future. For onshore installation of wind turbines using conventional mobile cranes with telescopic booms, this lifting height requires the largest available conventional mobile telescopic cranes with additional lattice jib and luff systems.

[0006] For offshore installation of wind turbines, jack-up platforms carrying lattice boom cranes with boom hoisting wires are commonly used. The expected lifting height for future installation exceeds the current capacity of the available cranes of the existing installation jack-up platforms. If the lattice boom of such lattice cranes is extended with an additional section, the longer boom will protrude from its original boom rest in the transport position and the crane block will not fit the original support. This may increase the bending moment of the boom during transportation. The protruding boom may no longer fit within the footprint of the jack-up platform and may extend outside it, causing stability problems during transportation of the platform and / or increasing the bending moment of the boom. The protruding boom may also potentially come into contact with water in case of bad weather during transportation. In addition, the protruding boom may also cause various logistics problems for the platform itself, such as the boom becoming an obstacle for helicopter platforms.

[0007] A telescoping boom can partially solve the above problems, however, the larger the height-capable lattice boom crane, the more time it takes to erect and extend the crane, which is lost time in terms of crane operation and increases costs. Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to overcome or alleviate one or more of the problems set forth above. In particular, it is an object of the present invention to provide an improved extendable lattice crane boom that allows for relatively rapid positioning of the crane boom in a safe and stable manner. [Means for solving the problem]

[0009] To this end, according to a first aspect of the invention, an extendable lattice crane boom is provided, characterized by the features of claim 1. In particular, an extendable lattice crane boom for a crane is provided, the boom comprising a lattice base boom section and at least one lattice telescopic boom section. The at least one telescopic boom section is adjustable relative to the base boom section between a stowed position, in which the telescopic boom section is generally inside the base boom section, and an extended position, in which the telescopic boom section is at least partially outside the base boom section. The distal end of the base boom section comprises a first collar on which a first guide system is mounted, which guide system may be configured to guide the movement of the telescopic boom section along the base boom section. The guide system may comprise a guide rail and a guide element, for example configured to be guided along the guide rail. The proximal end of the telescopic boom section comprises a second guide system configured to guide the movement of the telescopic boom section along the base boom section. In an inventive manner, the base boom section comprises a third guide system configured to guide the movement of the telescopic boom section along the base boom section, the third guide system being spaced from the first guide section by a distance corresponding to the length of the portion of the telescopic boom section remaining inside the base boom section in the extended position of the telescopic boom section. The third guide system can provide increased stability during extension and erection of the crane boom. When the telescopic boom section extends from the stowed position to the extended position, the telescopic boom section can be initially supported and guided by the first and second guide systems, while the third guide system is substantially unloaded. The third guide system can then take over guiding from the second guide system, whereby the telescopic boom section is supported by the first and third guide systems, while the second guide system is no longer loaded.The third guide system allows the crane boom to be extended and erected in a relatively quick manner while maintaining a relatively stable overall operation. The guide system may comprise a guide rail and a guide element configured to be guided along the guide rail, the guide rail being provided on one of the base boom section and the telescopic boom section, and the guide element being provided on the other of the base boom section and the telescopic boom section. In that way, the guide system comprises cooperating parts, i.e. the guide element and the guide rail, provided on the cooperating section, i.e. the base boom section or the telescopic boom section, whereby the guide element can be guided along the guide rail. For example, the first guide system comprises a guide element provided on the base boom section and a guide rail provided on the telescopic boom section, the guide element of the first guide system being mounted on the base boom section at the position of the first collar. The guide element may be a roller, a shoe, or a guide, or may be otherwise embodied. The positions of the guide element and the guide rail may also be reversed, with the guide rail provided on the base boom section and the guide element of the first guide system provided on the telescopic boom section. Advantageously, the collar is provided on the section to which the guide element is attached, so that when the guide element is attached to the base boom section, the base boom section is provided at least at an axial position with a first collar to which the guide element is attached. The second guide system also comprises a guide element on one of the base boom section and the telescopic boom section, and a cooperating guide rail on the other of the base boom section and the telescopic boom section. Similarly, the third guide system comprises a guide element on one of the base boom section and the telescopic boom section, and a cooperating guide rail on the other of the base boom section and the telescopic boom section. The third guide system is provided on the base boom section at a distance from the first guide system.Thus, the third guide system of the base boom section may be provided with a guide element cooperating with a corresponding guide rail of the telescopic boom section, or vice versa. Advantageously, a second collar may be provided at the location of the guide element to reinforce the section to which the guide element is attached. The first guide system and the third guide system are mounted on the same section of the telescopic crane, the base boom section or the telescopic boom section, advantageously on the base boom section. As an example, the second guide system is mounted on one of the base boom section and the telescopic boom section to which the first and third guide systems are attached. As another example, the second guide system is mounted on one of the base boom section and the telescopic boom section to which the first and third guide systems are attached, other than the one to which the first and third guide systems are attached.

[0010] The base boom section may preferably include a second collar on which the third guide system is mounted, the second collar stiffening the base boom section and capable of transferring loads from the third guide system to the base boom section.

[0011] The first and / or third guide system may comprise guide elements on all four cords of the base or telescopic boom section, respectively, on which the guide elements are mounted. The guide elements may be rollers, xy guides, or radial guides, or guide shoes, etc. The guide elements of the first guide system are mounted at the same axial position along the base or telescopic boom section. The guide elements of the third guide system are also mounted at the same axial position along the base or telescopic boom section. By providing guide elements on all cords of the base boom on the first and second collars, a sturdy, stable and reliable connection between the base boom and the telescopic boom may be obtained. Such a connection may make the extension and erection process easier, in addition, the extension and erection may be partially performed simultaneously. The second guide system comprises guide elements only on the lower cord of the telescopic boom section. Alternatively, the second guide system may comprise guide elements on the lower and upper cords of the base boom section of the telescopic boom section or vice versa.

[0012] The collar may be provided at an axial location where a guide element of the first guide system and / or the third guide system is mounted. The collar may comprise a brace connecting at least two cords at an axial location of the guide system. Thus, the collar may comprise two braces connecting two pairs of opposing braces. Alternatively, the collar may comprise four braces connecting four cords at an axial location of the guide system. The collar may be provided for reinforcement of the base boom section in one example.

[0013] The second guide system advantageously includes at least one rail attached to at least one chord of the base boom section, the length of the rail being approximately shorter than the length of the portion of the telescoping boom section that is configured to extend from the base boom section in the extended position of the telescoping boom section, such as when the telescoping boom section is approximately halfway between the stowed position and the fully extended position, the relatively short length of the rail allowing the guide of the telescoping boom section to be moved from the second guide system to the third guide system when the telescoping boom section is approximately halfway between the stowed position and the fully extended position.

[0014] It is preferred that the first guiding system is an xy guiding system, which includes guiding along two generally transverse directions substantially simultaneously and may for example include first guide rollers configured to guide movement of the telescoping boom section along the base boom section along a first direction x and second guide rollers configured to guide movement of the telescoping boom section along the base boom section along a second direction y that is substantially transverse to the first direction x, both directions being preferably substantially transverse to the longitudinal axis of the crane boom.

[0015] It is preferred that the third guide system is an xy guide system, which allows a relatively stable guiding of the telescopic boom section, especially in the extended position and / or at relatively high boom angles, in particular because an xy guide system makes it possible to prevent rotation about the longitudinal axis, which is not the case with radial guide systems.

[0016] More preferably, the first and / or third guide system may include at least one rail attached to or integrated into at least one chord of the telescopic boom section, the rail being shaped, for example, to guide both the x and y guide rollers of the xy guide system, the rail having, for example, a substantially rectangular cross section, whereby two adjacent sides of the rail are capable of guiding both the x guide roller along a first side of the rail and the y guide roller along a second side adjacent to the first side.

[0017] The telescopic boom section may advantageously comprise a cord having a generally rectangular cross section. Rails, for example guide rails of the first guide system or the third guide system, may be relatively easily mounted on such a generally rectangular cord. Alternatively, the cord may have a generally round cross section.

[0018] The base boom section may suitably comprise chords having a generally circular cross section, which are relatively easy to manufacture.

[0019] Advantageously, the second guide system is a radial guide system, which is provided on the chord of the base boom section and / or the telescopic boom section at an angle of approximately 45° to the upper or lower side of the boom. The radial guide system may comprise, for example, at least one, preferably two, guide rollers connected to the lower chord of the telescopic boom section in a substantially horizontal position of the boom. The at least one radial guide roller is configured to be in rolling or sliding contact with the lower chord of the base boom section at an angle of approximately 45°. The chord is provided with rails to guide the rolling or sliding contact of the guide roller on the chord. Other configurations of the radial guide system are possible.

[0020] The underside of the extensible boom is the side that faces down when the extensible boom is in the stowed and transport position, and is also the side from which a load can be lifted when the extensible boom as part of a crane is brought into a working position in which it is generally upright but with a slight boom tilt.

[0021] The extensible lattice crane boom may further comprise a locking system configured to lock at least one telescopic boom section relative to the base boom section at least in the extended position, whereby the boom load can be transferred through the cord. Such a locking system can provide a robust locking of the extensible boom at least in the extended position and can be operated relatively easily and quickly. The telescopic boom section can be locked relative to the base boom section at least in the extended position. However, locking in the stowed position and / or in intermediate positions can also be made possible. Alternatively, to lock the telescopic boom section in the stowed position, a stop element can be provided against which the telescopic boom section can abut and position the telescopic boom section in the stowed position. To enable locking in these positions, the telescopic boom section can be provided with a number of openings arranged to receive, for example, locking pins from the locking system. The openings of the telescopic boom section are provided in predetermined positions of its cord, whereby the openings can receive the locking pins in the required positions of the telescopic boom section.

[0022] The locking system preferably includes a plurality of pins, each of which extends at least partially through a corresponding pin receiving opening in one of the first collar and the telescopic boom section, at least in the extended position of the boom, the size of the pin receiving opening being at least 10 mm larger than the cross-sectional dimension of the corresponding pin. The pin receiving openings may have a variety of shapes, for example, roughly round holes, or slotted holes, or oval holes, or other variety of holes, and in at least one radial direction the dimension of the hole is at least 10 mm, preferably 20 mm, more preferably at least 30 mm larger than the cross-sectional dimension of the corresponding pin, to provide sufficient play or clearance in the connection to ensure relatively easy insertion or disengagement of the pin. The additional dimension may be provided in one direction, for example as a result of a slotted or oval hole or oval hole, or in one or more radial directions relative to the cross-sectional dimension of the pin, or in all radial directions of the hole, for example as a result of the hole being enlarged relative to the cross-sectional dimension of the pin.

[0023] The locking system may comprise a support structure at a distal end of the base boom section, to which the locking pin may be attached and extend from the support structure towards the cord of the telescoping boom section. When the telescoping boom section is in the extended position, the locking pin is positioned to align with a pin receiving opening in the cord of the telescoping boom section. The telescoping boom section is provided with a pin receiving opening disposed in or integral with the cord and configured to receive the locking pin. The locking pin may engage, for example, with a hydraulic or electric actuation means. The locking pin may engage with the base boom section in the retracted and / or extended and / or intermediate positions of the telescoping boom section. When the locking pin is engaged, the guides of the first and third guide systems remain in contact with their respective guide rails. As such, axial boom loads may be transferred directly through the locking pin through the cord. When the pin is engaged, shear or lateral loads may be transferred through the guides of the guide system. When the locking pins are engaged, the telescopic system does not need to be actuated any further and the axial load transmission is mainly performed through these locking pins through the cords instead of through the guides and / or through the telescopic system. Essentially, the guides of the first and third guide systems and / or the telescopic system can bear the axial boom loads in the extended position, but can bear the side loads.

[0024] Alternatively, the support structure can be provided at a proximal end of the telescoping boom section and the locking pin can be coupled to the proximal end and extend therefrom towards the chord of the base boom section or a prior telescoping boom section. Alternatively, the support structure can be provided at a distal end of the base boom section and the locking pin can be coupled to the telescoping boom section, e.g. the chord of the telescoping boom section, and extend therefrom towards the support structure.

[0025] The locking system advantageously includes the same number of pins as the number of cords the telescoping boom section includes, with each cord being configured to receive only one pin. The base boom section and the telescoping boom section may include, for example, four cords. Then, only four pins may be required to safely lock the telescoping boom section to the base boom section. Due to the third guide system, no further additional locking pins are required to counteract bending loads on the telescoping boom section, as is the case with prior art extendable booms.

[0026] The extendable lattice crane boom preferably further comprises a telescopic system arranged to adjust at least one telescopic boom section between the aforementioned stowed and extended positions, the telescopic system comprising at least one reeve system. The reeve system may comprise a wire rope tackle system with a winch. The wire rope may be threaded between a sheave mounted inside the base boom section and a sheave mounted on the telescopic boom section. Retraction of the wire rope by the winch may, for example, result in the telescopic boom section being retracted outside the base boom section, thereby moving along the guide and extending the boom. During retraction of the telescopic boom section, the winch may be operated to release the wire rope and allow the telescopic boom section to move inside the base boom section, typically downwards by gravity. In alternative embodiments, the telescopic system may comprise a hydraulic cylinder or a rack and pinion system instead of a reeve system. The telescopic system preferably comprises two reeve systems, each on opposite sides of the base boom section, preferably on the sides of the base boom section, to advantageously balance the load distribution. Preferably there is a single winch for the two reeve systems, so that the two reeve systems actually form a single combined telescopic system on either side of the base boom section.

[0027] The extensible lattice crane boom may further include a measurement system configured to detect the position of the telescoping boom section relative to the base boom section. Such a measurement system may include, for example, a camera for visual inspection, or a closed circuit TV system, or any other suitable measurement system. The measurement system may feed back its measurement results to a control system, which may control the extension or retraction of the extensible boom in a partially or fully automatic manner, or under the control of a human operator.

[0028] Instead of a single telescoping boom section, the extensible crane boom may comprise multiple telescoping boom sections of reduced dimensions, preferably reduced cross-sectional dimensions and / or similar or reduced vertical dimensions, each of which may also be movable relative to one another for extending or retracting the boom. A similar guide system between two adjacent telescoping boom sections may also be used between the telescoping boom section and the base boom section. The locking and telescoping systems may also be modified and / or multiplied for multiple telescoping boom sections.

[0029] According to another aspect of the invention, there is provided a crane with the features of claims 15 to 18. Such a crane may provide one or more of the aforementioned advantages. The crane comprises an extendable lattice crane boom as described above. The lattice crane boom is movable between a transport position in which the lattice boom is generally stowed and in a substantially horizontal position, and a working position in which the lattice boom is extended. The crane also comprises a crane base to which said extendable lattice boom is pivotally connected, such that the crane boom is capable of rotating about a substantially horizontal axis between said transport position and said working position. The crane base may optionally also be configured to be rotatable about a substantially vertical axis. The crane further comprises a boom lifting system arranged to rotate the extendable boom between said transport position and said working position, and a load lifting system configured to lift a load. The boom lifting system can be suitably coupled to the distal end of the base boom section and to the distal end of the telescopic boom section to provide a relatively stable, well-balanced, and reliable crane. Alternatively, the boom lifting system can also be coupled to one of the distal end of the base boom section and the distal end of the telescopic boom section. The boom lifting system can also be configured to be controlled by the control unit during operation of the telescopic system, and the telescopic system follows to facilitate the movement of the telescopic boom section. Thus, the crane operator only needs to operate the telescopic system, while the boom lifting system can automatically follow, controlled by the control unit, to facilitate the movement of the telescopic boom section. In this way, the optimum angle of the crane boom, which is about 80°, can be maintained during telescopic operation.

[0030] Advantageously, a measurement system can be provided to determine the actual position of the telescoping crane boom section relative to the base boom section. The measurement results can provide feedback of the actual position to the crane operator, who can adapt the crane operation to that information. The measurement system can also be configured to control the deceleration of the telescoping system upon approaching the desired extended position. This can assist the crane operator in approaching the desired extended position and can reduce the risk of failure or damage.

[0031] A control unit for controlling operation of the boom lifting system in response to operation of the telescopic reeve system can be part of a measurement system which may be provided as a separate control unit. In a preferred embodiment, the measurement system is arranged and provided to control operation of the crane and provide output of measured parameters, such as the telescopic boom speed, to an output unit, for example a user interface for a crane operator.

[0032] An extendable crane boom can typically be provided with a lifting element, a lifting system can be mounted on the lifting element, and the lifting element can be connected to a crane base, preferably to a winch at the crane base. In the mounted position, when the boom is mounted on the crane base, the side of the boom on which the lifting element is mounted is the upper cord, and the opposite cord is the lower cord in the mounted state.

[0033] In a preferred embodiment of the crane, the crane base can be mounted around the legs of the jack-up platform. Such a crane can provide a relatively compact and efficient crane even in harsh offshore environments. The crane base can also be mounted on a standard pedestal with slewing bearing means. However, providing the crane base around the legs of the jack-up platform provides a space efficient solution to use the space on the deck of the jack-up platform.

[0034] According to a further aspect of the invention there is provided a jack-up platform having the features of claims 18 and 19. Such a jack-up platform provides one or more of the aforementioned advantages.

[0035] According to yet a further aspect of the present invention, there is provided a method of operating a crane having the features of claims 20 to 23. Such a method may provide one or more of the aforementioned advantages. In a preferred embodiment of the method, operation of the telescopic system is initiated when the extendable lattice boom reaches a boom angle of at least about 30°, preferably at least about 50°, more preferably at least about 55° relative to a substantially horizontal position. The method may further comprise fixing a length of a boom lifting wire of the boom lifting system. As a result of fixing the length of the boom lifting wire by the boom lifting system at a boom angle of, for example, or around, about 50° relative to a substantially horizontal position, operation of the telescopic system may raise the extendable boom through fixing the length of the boom lifting wire of the boom lifting system.

[0036] The invention will be further elucidated with reference to the figures of exemplary embodiments, in which corresponding elements are indicated by corresponding reference symbols. [Brief description of the drawings]

[0037] [Figure 1]1A-1D are side views of a first embodiment of a crane including an extendable crane boom according to the present invention in different positions; [Diagram 2] FIG. 2 is a perspective view of the distal end of the base boom section of the extendable boom of the crane shown in FIG. [Diagram 3] FIG. 2 is a perspective view of the proximal end of the telescoping section of the extendable boom of the crane shown in FIG. [Figure 4] FIG. 2 is an enlarged perspective view of a third guide system of the extensible boom of FIG. 1. [Diagram 5] FIG. 2 is an enlarged perspective view of the base boom section of the extendable boom of the crane shown in FIG. [Figure 6] FIG. 2 is a perspective view of a portion of the extensible boom of FIG. 1 in a first intermediate position. [Figure 7] FIG. 2 is a perspective view of a portion of the extensible boom of FIG. 1 in a second intermediate position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] FIG. 1 shows a side view of a first embodiment of a crane 1 including an extendable crane boom 2 according to the invention in different positions. The crane 1 comprises a crane base 3, to which the aforementioned extendable lattice crane boom 2 is rotatably connected. The crane base 3 can be mounted around a leg 4 of a jack-up platform, for example as a slewing platform, but alternatively, for example, on a standard base with slewing bearings, on a jack-up platform or on any other structure where a crane of this type is required. The lattice boom 2 is movable between a transport position T, in which the lattice boom 2 is substantially stored and in a substantially horizontal position, and a working position W, in which the telescopic boom 2b is in an extended position E, through intermediate positions I. To carry out the aforementioned movements of the crane boom, the crane 1 also comprises a boom lifting system 5 arranged to move the extendable boom 2 between the aforementioned transport position and the aforementioned working position. The boom lifting system comprises at least one, preferably two, boom lifting winches 11 mounted on the crane base. The boom lifting system 5 may include two parallel wire rope and pulley systems, both of which may be coupled to the distal end of the extendable boom and / or to the distal end of the base boom section 2a. The crane 1 further includes a load lifting system 6 configured to lift a load. The load lifting system 6 may include at least one main lifting winch 10, a head assembly 7 mounted on the distal end of the extendable crane boom 2, and an additional secondary lifting system 8 including an auxiliary lifting winch, which may be configured to lift smaller loads higher and faster than the main load lifting system. The main lifting system may be configured to lift loads of up to about 2500 tonnes, for example, to a height of about 115 m above ground / deck, or loads of up to about 1250 tonnes to a height of about 156 m above ground / deck. Such a configuration allows for the installation of offshore wind turbines of up to about 16 MW. It will be appreciated that this is just one example and that smaller or larger configurations are possible.The extendable boom 2 comprises a lattice-type base boom section 2a and at least one lattice-type telescopic boom section 2b. The lattice-type base boom section 2a and the lattice-type telescopic boom section 2b each include a vertically elongated cord 15, in particular four cords 15, which are interconnected with a truss 16 at each corner of the boom sections 2a, 2b. The diameter of the cord 15a of the base boom section 2a is generally larger than the diameter of the cord 15b of the telescopic boom section 2b. The telescopic boom section 2b is adjustable relative to the base boom section 2a between a stowed position R, in which the telescopic boom section 2b is substantially inside the base boom section 2a, and an extended position E, in which the telescopic boom section 2b is at least partially outside the base boom section 2a. In the above-mentioned example of a lifting system configured to lift a load of up to 2500 tons, the overall boom length can be, for example, around 95 m in the stowed position, while the overall boom length in the fully extended position can be, for example, around 135 m, or longer or shorter. The boom lifting system 5 is connected to the distal end of the base boom section 2a and the distal end of the telescopic boom section 2b, more specifically to the head assembly 7 of the telescopic boom section 2b and the support structure 9 of the distal end of the base boom section 2a. In the working position W as shown, when the process of extension of the telescopic boom section 2b is completed, the crane boom 2 forms an angle in the range of about 75° to 85°, preferably about 80°, with the substantially horizontal transport position of the crane boom 2. This position can be considered as the starting position for lifting a load, and this boom angle can be readjusted to a lower boom angle if necessary. The transport position and the working position can determine the upper side 17 and the lower side 18 of the extensible boom 2, the lower side 18 being the side on which the extensible boom 2 faces downwards in the transport position, and the upper side 17 being the side on which the extensible boom 2 faces opposite the lower side 18. The boom lifting system 5 is at least partially mounted to an upper side 17 of the extensible boom 2 , while a load is lifted along an underside 18 of the extensible boom 2 .The extensible crane boom 2 also comprises a telescopic system 12 arranged for adjusting at least one telescopic boom section 2b between a stowed position and an extended position. The telescopic system 12 comprises at least one reeve system, preferably two reeve systems, each provided on opposite sides of the base boom section 2a, preferably on the sides of the base boom section 2a (see FIG. 4). The telescopic system 12 can be configured to relatively quickly extend the telescopic boom 2 from the stowed position (R) to the extended position (E). The telescopic system 12 includes at least one telescopic winch 13. The reeve system can be configured such that retraction of the wire rope 14 by the winch 13 can, for example, retract the telescopic boom section 2b at least partially outside the base boom section 2a, thereby extending the boom while moving along the guide system. During retraction of the telescopic boom section 2b, the winch 13 can be operated to release the wire rope to allow the telescopic boom section to move into the base boom section. To increase the operating speed, which may be important in harsh offshore environments, it is desirable to start extending the telescopic boom section 2b when the extensible boom 2 is raised, i.e. when the extensible boom 2 moves from the transport position T to the working position W, or when the telescopic boom section 2b starts to retract into the base boom section 2a, so that the boom 2 moves from the working position W to the transport position T. In prior art extensible boom cranes, such combined actions of extending the telescopic boom section and raising the boom may cause distortion and sagging, especially at low boom angles. According to the present invention, the combination of an innovative three-guide system makes it possible to start extending the telescopic boom section even at relatively low boom angles, as will be further described below.

[0039] FIG. 2 is a perspective view of the distal end of the base boom section 2a of the extendable boom 2 of the crane 1 shown in FIG. 1. The distal end of the base boom section 2a comprises a first collar 20 to which a first guide system 21 is attached. The first collar 20 comprises a cross-sectional reinforcement structure of the lattice boom section, which allows the collar to bear the load of an additional structure attached to the collar, such as the first guide system. The first guide system 21 is configured to guide the movement of the telescopic boom section 2b along the base boom section 2a. In addition, the first guide system can comprise a set of guide elements 22 on the base boom section 2a and corresponding guide rails on the telescopic boom section 2b, or vice versa (see FIG. 4). The guide elements 22 or guides 22, for example embodied as rollers, are configured to perform a guiding movement, for example a rotating or sliding movement, on or along the corresponding guide rails of the telescopic boom section. The first guide system 21 can comprise, for example, a set of guides 22 per cord. A corresponding rail of the first guide system can be attached to or integrated into each of the longitudinal chords of the telescopic boom section. The first guide system can advantageously be an xy guide system, with each set of guides comprising at least two guides, for example rollers, arranged to guide the movement of the telescopic boom along two substantially lateral directions. In an innovative manner, the base boom section 2a comprises a third guide system 24 arranged to guide the movement of the telescopic boom section 2b along the base boom section 2a. The third guide system can also comprise a set of guide elements or guides 25 in the base boom section 2a and corresponding guide rails in the telescopic boom section 2b, or vice versa. This third guide system 24, in particular the set of guides 25 of the third guide system, is spaced from the first guide system 21 by a distance corresponding to the length of the portion of the telescopic boom section 2b remaining in the base boom section 2a in the extended position of the telescopic boom section 2b.The base boom section 2a preferably comprises a second collar 26, on which a third guide system 24, in particular a set of guides 25 of the third guide system 24, is mounted. The second collar 26 may comprise one or more cross-section trusses, preferably the same number of cross-section trusses as the number of chords of the base boom section, for example four. The third guide system 24 is also preferably an xy guide system. The first guide system and the third guide system are preferably identical. As such, both the first guide system 21 and the third guide system 24 of the base boom section 2a, in particular the respective guide elements of the first guide system 21 and the third guide system 24, may share the same guide rail provided on the telescopic boom section 2b, as will be further described hereinafter. The extensible crane boom may further comprise a locking system 27 configured to lock at least one telescopic boom section 2b relative to the base boom section 2a at least in the extended position. Additionally, the locking system 27 includes a number of pins, each of which is configured to extend at least partially through a corresponding pin receiving opening 28 in one of the first collar 20 and the telescopic boom section 2b, at least in the extended position of the boom. When a number of pins extend from the first collar, the size of the pin receiving opening 28 in the telescopic boom section 2b can advantageously be at least 10 mm larger than the cross-sectional dimension of the corresponding pin, so that locking and unlocking of the pins can be performed relatively easily without frictional forces preventing the movement of the pins into and / or out of the pin receiving opening 28. Alternatively, a number of pins can extend from the telescopic boom section, while the pin receiving openings are formed in the first collar. Again, the size of these pin receiving openings can be at least 10 mm larger than the cross-sectional dimension of the corresponding pin. The locking system can preferably include as many pins as the number of cords that the telescopic boom section comprises, each cord being configured to receive only one pin.As further shown, the telescoping boom section 2b in this embodiment includes four cords 29 such that the first collar 20 includes four pin-receiving openings 28, each configured to receive a pin to lock the position of the telescoping boom section 2b relative to the base boom section 2a.

[0040] FIG. 3 is a perspective view of the proximal end of the telescopic boom section 2b of the extendable boom 2 of the crane 1 shown in FIG. 1. The proximal end of the telescopic boom section is provided with a second guide system 30 configured to guide the movement of the telescopic boom section 2b along the base boom section 2a. The second guide system also includes a set of guides and corresponding rails, the guides being provided on the telescopic boom section 2b and the rails being provided on the base boom section 2a or vice versa. Unlike the first and third guide systems, the second guide system can be a radial guide system. In this embodiment, the set of guides 31, in particular the rollers, are provided on the cords 32, in particular the lower cord 32a, of the telescopic boom section 2b at an angle of approximately 45° to the upper or lower side of the boom. Guides can also be provided on the upper cord of the telescopic boom section, although this is not necessary. The guide rails of the second guide system 30 are provided on a portion of the length of the cord of the base boom section 2a and can preferably have a substantially circular cross section. The guide rails are correspondingly mounted at a 45° angle to the top or bottom of the boom. Alternatively, the guides and guide rails may be interchanged.

[0041] FIG. 4 is a perspective view showing details of the third guide system of the extendable boom of FIG. 1. Contrary to the base boom section, the telescopic boom section 2b preferably comprises a cord with a substantially rectangular cross section. A guide rail 33 of the first guide system 21 and / or the third guide system 24 can be attached to or integrated into the cord 32 of the telescopic boom section 2b. This rail 33 can be shaped like a guide for both the x-guide roller and the y-guide roller of the xy-guide system. In particular, this guide rail 33 can include two adjacent guide sides that are substantially transverse to each other. Such a guide rail 33 can then be placed on the outer edge of the cord of the telescopic boom section 2b with a substantially rectangular cross section. The guide rail 33 on the cord of the telescopic boom section 2b can preferably engage with both the corresponding guides of the first guide system 21 and the third guide system 24.

[0042] FIG. 5 is a perspective view of the base boom section 2a of the extendable boom 2 of the crane 1 shown in FIG. 1. As shown in the previous figures, the lattice trusses between the longitudinal chords 29 are not shown for the purpose of clarity. The second collar 26 may also comprise two additional cross-sectional trusses or reinforcing structures. As shown previously, the base boom section 2a includes a chord 29 having a substantially circular cross-section. The second guide system 30 also includes at least one rail 34, preferably at least two rails 34, mounted on at least one chord 29 of the base boom section 2a, preferably on the lower chord 29a of the base boom section 2a. The guide rail 34 is preferably mounted at an angle of approximately 45° to the upper or lower side of the boom, so that the guide rail can engage with the guide 31 of the radial guide system. The length of this guide rail 34 may be approximately shorter than the length of the telescopic boom section portion configured to extend from the base boom section 2a in the extended position E of the telescopic boom section 2b. The guide rail 34 may extend from a proximal end 35 of the base boom section 2a along the chord 29 of the base boom section 2a, for example, less than half the length of the base boom section 2a.

[0043] Figure 6 is a perspective view of a portion of the extendable boom of Figure 1 in a first intermediate position. When moving the extendable boom from a stowed position R (as shown in Figure 1) where the telescopic boom section 2b is generally inside the base boom section 2a to an extended position E where the telescopic boom section is at least partially outside the base boom section, as shown in the intermediate position of Figure 6, the telescopic boom section 2b is initially guided by the first guide system 21 and by the second guide system 30. The guide 25 of the third guide system 24 may engage with the guide rail 33, but the third guide system 24 is substantially unloaded. At this stage of the extension of the telescopic boom, the crane boom is not statically determined.

[0044] FIG. 7 is a perspective view of a part of the extendable boom of FIG. 1 in a second intermediate position. If the telescopic boom section 2b is extended further after the first intermediate position shown in FIG. 6, the guide 31 of the second guide system 30 will go beyond the length of the corresponding guide rail 34 of the second guide system 30 at a predetermined position, whereby the second guide system stops guiding. The movement of the telescopic boom section 2b is then guided by the first guide system 21 and the third guide system 24. The second guide system 30 is no longer loaded at all. The telescopic boom section 2b reaches its extended position E when the guide 31 of the second guide system 30 has approximately reached the third guide system 24 and / or the second collar 26. The outward extension of the telescopic boom section 2b of the base boom section 2a is feasible when the extensible crane boom 2 is in an approximately upright position, in particular when the extensible crane boom 2 has a boom angle of approximately 80° with respect to the horizontal plane. However, the invention also allows for earlier extension of the telescopic crane boom, in particular starting from a boom angle α of approximately 30° or, more preferably, from a boom angle α of approximately 50°. More specifically, according to the invention, part of the raising of the crane boom from the transport position T to the working position W can be performed by fixing the length of the boom lifting wire of the boom lifting system 5, the length of the boom lifting wire being measured from the boom lifting winch 11 to the crane boom. The boom lifting system 5 can be activated for example to lift the crane boom from the transport position T to a first intermediate position, for example at a boom angle α in the range of approximately 30° to approximately 55° relative to the horizontal plane. The boom lifting system 5 can then be configured to maintain the lifting wire at a constant length, for example by braking the boom lifting winch 11. The locking pin of the locking system 27 can then be disengaged from the pin receiving opening 28, and the locking system 27 maintains the telescopic boom 2 in the storage position R. The telescopic system 12 can then be activated and extension of the telescopic boom can begin.Initiation of the extension of the telescopic boom, combined with a boom lifting system configured to maintain the hoisting line at a constant length, continues the raising of the crane boom towards the working position of the crane boom. Thus, by performing at least partial extension of the telescopic boom during the raising of the crane boom, or even better, by performing at least partial raising of the crane boom through the extension of the telescopic boom, it is possible to save time to prepare the crane for a lifting operation, while keeping these raising and extending operations relatively stable and safe due to the improvement of the extensible crane boom.

[0045] Although for purposes of clarity and conciseness of description, features are described herein as part of the same or separate embodiments, it will be understood that the scope of the invention may include embodiments having all or any combination of the described features. The illustrated embodiments may be understood to have the same or similar components, except where they are described as different.

[0046] In the claims, reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprises" does not exclude the presence of other features or steps than those recited in the claim. Furthermore, the words "a" and "an" shall not be construed as being limited to "only one" but are instead used to mean "at least one" and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. All variations are understood to be included within the scope of the present invention as defined in the following claims. [Explanation of symbols]

[0047] 1. Crane 2. Crane boom 2a Base boom section 2b Telescopic boom section 3. Crane base 4...legs 5. Boom lifting system 6. Luggage lifting system 7 Head Assembly 8. Secondary Lifting System 9...Support structure 10. Main lifting winch 11. Boom lifting winch 12 Telescopic system 13 Telescopic winch 14 Wire rope 15. Code 16 Truss 17 Upper side 18...lower side 20 First Color 21. First guide system 22 Guide elements 24. Third Guide System 25 Guide 26 Second Color 27 Locking system 28 Pin receiving opening 29 Code 29a Lower cord 30 Secondary guide system 31 Guide 32 Code 32a Lower cord 33, 34 Guide rail

Claims

1. An extendable lattice-type crane boom for a crane, the boom comprising a lattice-type base boom section and at least one lattice-type telescoping boom section; the at least one telescoping boom section is adjustable relative to the base boom section between a stowed position, in which the telescoping boom section is generally inboard of the base boom section, and an extended position, in which the telescoping boom section is at least partially outboard of the base boom section; a distal end of the base boom section including a first guide system configured to guide movement of the telescoping boom section along the base boom section; a proximal end of the telescoping boom section comprising a second guide system configured to guide movement of the telescoping boom section along the base boom section; 1. An extendable lattice crane boom, wherein the base boom section includes a third guide system configured to guide movement of the telescoping boom section along the base boom section, the third guide system being spaced from the first guide system by a distance corresponding to a length of a portion of the telescoping boom section remaining inside the base boom section in an extended position of the telescoping boom section.

2. 2. The extendable lattice crane boom of claim 1, wherein the first, second, and / or third guide systems comprise a guide rail and a guide element configured to be guided along the guide rail, the guide rail being provided on one of the base boom section and the telescoping boom section, and the guide element being provided on the other of the base boom section and the telescoping boom section.

3. 3. The extendable lattice crane boom of claim 1 or 2, wherein the base boom section includes a first collar to which the first guide system is attached, and / or the base boom section includes a second collar to which the third guide system is attached.

4. 4. The extendable lattice type crane boom of claim 1, wherein the second guide system includes at least one rail attached to at least one chord of the base boom section, the length of the rail being approximately less than a length of a portion of the telescoping boom section configured to extend from the base boom section in an extended position of the telescoping boom section.

5. 5. The extendable lattice type crane boom of claim 2, wherein the first guide system and / or the third guide system comprises guide elements on each chord of the base boom section, the guide elements of the first guide system and / or the third guide system being provided at the same axial distance along the base boom section.

6. The extendable lattice type crane boom of any one of claims 1 to 5, wherein the first guide system is an xy guide system.

7. The extendable lattice type crane boom of any one of claims 1 to 6, wherein the third guide system is an xy guide system.

8. 8. The extendable lattice type crane boom of claim 6 or 7, wherein each of the first guide system and the third guide system comprises at least one rail attached to or integrated into at least one chord of the telescoping boom section, the rail being configured to guide both x and y guide rollers of an x-y guide system.

9. 9. The extendable lattice type crane boom of claim 1, wherein the telescoping boom section includes chords having a generally rectangular cross-section.

10. 10. The extendable lattice type crane boom of claim 1, wherein the base boom section includes a chord having a generally circular cross-section.

11. 11. The extendable lattice crane boom of any one of claims 1 to 10, wherein the second guide system is a radial guide system and is provided on the chords of the base boom section and / or the telescoping boom section at an angle of approximately 45 degrees to the upper or lower side of the boom.

12. 12. The extendable lattice type crane boom of claim 1, further comprising a locking system configured to lock the at least one telescoping boom section relative to the boom section at least in the extended position.

13. 13. The extendable lattice crane boom of claim 12, wherein the locking system includes a plurality of pins, each pin configured to extend at least partially through a corresponding pin receiving opening in one of the base boom section and the telescoping boom section, at least in an extended position of the boom, the size of the pin receiving opening being at least 10 mm larger than a cross-sectional dimension of the corresponding pin.

14. 14. The extendable lattice crane boom of claim 13, wherein the locking system includes a number of pins equal to the number of cords provided on the telescoping boom section, each cord being configured to receive only one pin.

15. 15. The extendable lattice type crane boom of claim 1, further comprising a telescoping system arranged to adjust the at least one telescoping boom section between the stowed position and the extended position, the telescoping system comprising at least one reeve system.

16. 16. The extendable lattice type crane boom of claim 15, wherein the telescoping system comprises two reeve systems, each reeve system being provided on opposite sides of the base boom section, preferably on a side of the base boom section.

17. 17. An extendable lattice crane boom according to any one of claims 1 to 16, wherein the extendable lattice crane boom is movable between a transport position in which the lattice crane boom is substantially stored and in a substantially horizontal position, and a working position in which a load can be lifted; a crane base to which the extendable lattice type crane boom is rotatably connected; a boom lifting system arranged to move the extendable crane boom between the transport position and the working position; a load lifting system configured to lift a load; A crane equipped with a

18. 18. The crane of claim 17, wherein the boom hoisting system is coupled to a distal end of the base boom section and a distal end of the telescoping boom section.

19. 19. The crane of claim 17 or 18, wherein the crane base is mountable about legs of a jack up platform.

20. A jack-up platform including a crane as claimed in any one of claims 17 to 19.

21. 21. The jack up platform of claim 20, wherein the crane base is mounted about a leg of the jack up platform.

22. A method of operating a crane, preferably a crane as claimed in any one of claims 17 to 19, said crane comprising an extendable lattice type crane boom, preferably as claimed in any one of claims 1 to 16, said extendable lattice type boom comprising a lattice type base boom section and at least one telescoping boom section, said method comprising the steps of: bringing the extendable lattice boom from a transport position to a working position; operating a telescoping system to adjust the at least one telescoping boom section relative to the base boom section from a stowed position in which the telescoping boom section is generally inboard of the base boom section to an extended position in which the telescoping boom section is generally outboard of the base boom section; Including, A method of operating a crane, wherein operating the telescoping system and bringing the extendable lattice boom from a transport position to a working position are performed at least partially simultaneously.

23. 23. The method of operating a crane as described in claim 22, wherein operation of the telescoping system is initiated when the extendable lattice boom reaches a boom angle of at least about 30°, preferably at least about 50°, and more preferably at least about 55° relative to a substantially horizontal position.

24. 24. A method of operating a crane as claimed in claim 22 or 23, wherein preferably a length of a boom hoisting wire of the boom hoisting system is fixed when the extendable lattice boom reaches a boom angle of at least about 30°, preferably at least about 50°, more preferably at least about 55° relative to a substantially horizontal position.

25. 25. The method of operating a crane as claimed in any one of claims 22 to 24, further comprising the step of locking the telescoping boom section relative to the base boom section in the extended position of the telescoping boom section by substantially simultaneously inserting a plurality of pins through corresponding pin receiving openings in one of the cords of the telescoping boom section and the base boom section.

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