Patent Application
20190218075
The invention relates to an extendable lattice type boom for a crane. In many fields of construction and maintenance there is a demand for ever larger cranes capable of hoisting loads at increasing heights. This requires the use of a longer boom, or an extension attached to a boom, such as a jib. Increasing the length of the boom will inevitably introduce a hindrance for transportation of the crane.
Cranes with a telescopic boom have been developed to achieve relatively large lifting heights while being able to quickly retract the boom to transportable dimensions. Such telescopic booms usually have two or more sections with decreasing dimensions, the larger section enclosing the inserted part of the smaller section. The loads on the boom, such as the weight of the boom and the hook load, will result in a bending or overturning moment in the boom and therefore between the sections, which will result in large forces being transferred through the guides between the telescoping sections, requiring significant material strength at the guides.
In general, a longer boom requires a heavier construction to be able to withstand not only the increased forces and bending moment induced by a hook load at a larger outreach of the crane, but also to support its own increased weight. When increasing the length of a conventional tubular type telescopic boom, such tubular boom may become too heavy for certain applications such as off-shore applications when taking into account the required material strength at the guides.
Application of a lattice type boom can reduce the weight of the boom significantly in view of the tubular type boom. A telescoping boom with lattice type sections has been disclosed, but connecting and/or locking the telescopic boom sections remains problematic. Also, load transfer to the telescopic boom sections may remain difficult.
In the field of wind turbine installation, it is expected that the required lifting height for installing the turbine on top of the tower will increase to 140-160 m, or beyond, in the near future. For onshore installation of wind turbines, for which usually conventional mobile cranes with telescopic boom are used, this lifting height would require the largest available conventional mobile telescopic cranes with additional lattice jib and luffing systems.
For offshore installation of wind turbines, jack-up platforms carrying lattice boom type cranes with boom hoist wires are generally used. The expected lifting heights for future installations exceed the current capabilities of the available cranes on existing installation jack-up platforms. If a lattice boom of such a lattice boom type crane were extended with an additional section, the longer boom would then protrude from its original boom rest in a transit position and the crane block would not fit its original support. This could result in increased bending moment in the boom during transit. Also, the protruding boom may not fit within the footprint of the jack-up platform any more and may extend outwardly thereof, which may cause stability problems during transit of the platform and/or may result in an increased bending moment in the boom. Additionally, the protruding boom can also cause logistic problems on the platform itself, such as the boom blocking the helicopter platform.
It is an objective to provide for an extendable lattice boom which obviates at least one of the above mentioned drawbacks.
There is disclosed an extendable lattice type boom for a crane comprising a base boom section and at least one telescopic boom section including the features of claim 1. The extendable lattice type crane boom comprises a lattice type base boom section and at least one lattice type telescopic boom section. A lattice type boom section generally comprises a plurality of longitudinal chords interconnected with trusses. The chords generally form the corners of the boom's cross-section, which may have a triangular, rectangular, or square shape, or any other desired, usually polygonal, cross-sectional shape. The at least one telescopic boom section is adjustable with respect to the base boom section between a retracted position, in which the telescopic boom section is substantially inside of the base boom section, and an extended position, in which the telescopic boom section is at least partly outside of the base boom section. The extended position can be a maximally extended position, in which there is only a minimal overlap between the base boom section and the telescopic boom section, or can also be any other intermediate extended position, in which a larger part of the telescopic boom section is still inside the base boom section. The extendable crane boom further comprises a locking system configured to lock the at least one telescopic boom section with respect to the base boom section in at least the extended position. Said locking system includes a plurality of pins, each pin being configured to extend, in at least the extended position of the boom, at least partly through a corresponding pin receiving aperture provided in one of the base boom section and the at least one telescopic boom section. In an inventive way, a size of at least one of said pin receiving apertures is substantially larger than a cross-sectional dimension of a corresponding one of said plurality of pins to be received in the pin receiving aperture.
The pin receiving aperture can have various forms, e.g. a substantially round hole, or a slotted hole, or an egg-shaped hole, or any other variant of a hole in which in at least one radial direction, the dimension of the hole is substantially larger than a cross-section of the corresponding pin as to provide sufficient play in the connection.
In particular, in at least one radial direction of the pin receiving aperture the dimension of the pin receiving aperture is substantially larger than a cross-section of the pin. For example, the pin receiving aperture can be a slotted hole, that in at least one direction, i.e. in longitudinal direction of the hole, is substantially larger than a cross-section of the pin. Substantially larger is understood to be larger than normal tolerances available to allow a pin to be received in a hole. For example, the additional dimension, i.e, the size of the pin receiving aperture that is larger than the cross-section of the pin, resulting in additional play, in the at least one direction can be about 10 mm to about 40 mm, Advantageously, the additional dimension, or the difference in size between the length of the pin receiving aperture and the cross-section of the pin in a certain direction, is provided at both sides of the pin at a position where the pin is inserted in the aperture to allow for easy insertion. For example the additional dimension can be between about 10 mm to about 40 mm at each side. More preferably, the additional dimension can be between about 15 mm to about 35 mm. The additional dimension is advantageously independent of the size and/or cross-sectional shape of the pin, but allows for easy insertion independent of the size and/or cross-sectional shape, e.g. circular or square, of the pin. The additional dimension can be provided in one direction, e.g. resulting in a slotted hole or an oval hole or an egg-shaped hole, or can be provided in more than one radial direction with respect to the cross-section of the pin, or can be provided in all radial directions of the hole, resulting in an enlarged hole with respect to the cross-sectional dimension of the pin.
In this way, an extendable crane boom can be obtained, which can be solidly locked in an extended position in a relatively quick and easy way, while still remaining transportable as it is a retractable and relatively light-weight structure. Also, the locking and/or unlocking of the telescopic boom section from the base boom section can be done relatively simple and fast, reducing time between subsequent working operations. In particular when the crane with the extendable crane boom is installed on a jack-up platform that is working on subsequent installation sites offshore, such as for example in a wind-mill park, a relatively short retracting and/or extending of the telescopic boom section is advantageous reducing the turnaround time between subsequent installation sites.
Advantageously, an at least one primary pin can be provided that is adapted to be received in a corresponding primary pin receiving aperture and an at least one secondary pin can be provided that is adapted to be received in a corresponding secondary pin receiving aperture. Preferably, the primary pins are inserted first into the corresponding apertures. The corresponding primary pin receiving apertures are preferably slotted or egg-shaped, or droplet shaped such that the pin can be received at the larger part of the egg-shaped aperture and then, upon further locking of the connection, the pin moves to the smaller part of the egg-shaped opening as to align and lock the pin in the aperture. To provide for the movement and alignment, the egg-shaped hole has oblique sides with respect to a longitudinal direction of the hole, approximately with an angle between about 2 deg to about 10 deg with respect to the longitudinal direction of the aperture. The primary pin and the corresponding primary pin receiving aperture can be provided at an upper chord of the base boom section and the telescopic section and/or at a lower chord of the base boom section and the telescopic section. The pin can thus be firmly received in the smaller part of the egg-shaped or droplet-shaped aperture such that load, e.g. axial and/or transverse, can be transferred. These primary pins may be provided in an upper chord, when boom hoist wires are connected to the telescopic section. To optimize load transfer, the shape of the smaller part of the egg-shaped opening mainly corresponds to the cross-sectional shape of the pin to be received in the aperture. In an embodiment, there may be primary pins provided in a lower chord as well, when boom hoist wires are connected to the telescopic section. Such primary pins may be subject to axial loading only. These primary pins may have for example a rectangular shape and the corresponding pin receiving aperture may have a rectangular shape as well that has a size that is substantially larger than the cross-sectional dimension of the pin, e.g. the pin receiving aperture may be in two perpendicular dimensions, i.e. transverse to the sides of the rectangle, at both sides of the rectangle, larger than the cross-section of the pin with an additional dimension of between about 10 mm to about 40 mm to allow easy insertion. In use, a side of the pin abuts against a side of the aperture to allow load transfer.
In a further embodiment, there may be provided at least one secondary pin with a corresponding at least one pin receiving aperture. Such a secondary pin may be provided in a lower chord as well, when boom hoist wires are connected to the telescopic section. The secondary pin may be subject to axial loading only. Also, such a secondary pin may advantageously be of a rectangular cross-section with a corresponding rectangular shaped pin receiving aperture. The secondary pin may provide for axial locking of the base boom section with the telescopic boom section together with the primary pin in the, in this embodiment, lower chord.
Various embodiments and combinations are possible. For example, the boom hoist wires may be connected to the base boom section and to the telescopic section. In this embodiment, the at least one secondary locking pin with corresponding pin receiving aperture may be provided in lower chords of the base boom section and the telescopic section. Additionally, an at least one primary pin and corresponding pin receiving aperture may be provided in the lower chords, together providing for axial locking. While an at least one primary pin and corresponding pin receiving aperture can be provided in the upper chords of the base boom section and the telescopic section. In another embodiment, the boom hoist wires are connected to the telescopic section only. In this embodiment, an at least one secondary pin and corresponding pin receiving aperture may be provided in the lower chords, similar to the previous embodiment. In another embodiment, the boom hoisting wires are connected to the base boom section only. In this embodiment, an at least one secondary pin and corresponding pin receiving aperture may be provided in the upper chords. Additionally, in the upper chords an at least one primary pin and corresponding primary pin receiving aperture can be provided, together providing for axial locking of the base boom section and the telescopic boom section. An at least one primary pin with corresponding primary pin receiving aperture is then provided in the lower chords. Said locking system can comprise a support structure from which the plurality of pins extend. Said support structure is preferably provided at a distal end of the base boom section. Alternatively, the support structure could also be provided at a proximal end of the telescopic boom section. In the latter case, the pins extend outwardly to be received in corresponding apertures in the base boom section. In the former case, the pins extend inwardly to be received in corresponding apertures in the telescopic boom section. The support structure can have a shape that is similar to a cross-section of the crane boom, for example a rectangular shape or any other desired shape. The corners of said support structure can be in line with the longitudinal chords of the boom. The support structure can for example be a solid and reinforced structure, or alternatively an open structure including chords and trusses with local reinforcement elements, e.g. to transfer loads from the pins to the chords and/or trusses. The support structure can provide a relatively solid locking system of the extendable boom. In order to further reinforce the solidity of the locking system of the extendable boom, the corresponding pin receiving aperture may advantageously be provided at a chord of the telescopic boom section, preferably at a proximal end of the telescopic boom section, more preferably at a proximal end of every chord of the telescopic boom section. As an example, in case of an extendable boom with a substantially rectangular cross-section, the locking system can comprise four main pins extending at least partly into four main pin receiving apertures, i.e. one aperture in each of the four longitudinal chords of the telescopic boom section, each receiving one of the four main pins. A size of at least one of said four apertures is larger than a cross-section of the pin to be received, and preferably, a size of all four apertures is larger than the cross-section of the pin to be received.
More advantageously, the locking system can comprise a secondary set of pins and corresponding pin receiving apertures provided at a lower side of the base boom section and of the telescopic boom section, wherein preferably at least one of the pin receiving apertures has a size which is substantially larger than a cross-sectional dimension of the corresponding pin to be received. The corresponding pin receiving apertures for the set of secondary pins may be the same, or part of, the pin receiving apertures for the primary pins, or may be separate pin receiving apertures. When the pin receiving aperture for the secondary pin and the pin receiving aperture for the primary pin is the same, in fact a large aperture is provided in which the primary pin and the secondary pin can be received. The primary pin and the secondary pin preferably are each provided at opposite ends of the combined primary and secondary pin receiving aperture to provide for axial or chordwise locking.
A lower side of the extendable boom is a side which is turned downwards when the extendable boom is retracted and in a transport position. When the extendable boom, as part of a crane, is brought into a working position, which is a substantially upright but still slightly tilted position of the boom, said lower side is also the side on which loads can be hoisted. Said secondary set of pins and corresponding apertures can firmly lock the telescopic boom section to the base boom section substantially without play and can thus improve load transmission via the pins to the chords of the base boom section.
The extendable lattice type crane boom can further comprise a guiding system configured to guide a movement of the telescopic boom section along the base boom section. Said guiding system may for example include guide rails and guide elements configured to be guided along the guide rails, or any other guiding system. Said guiding system can advantageously be provided on a chord of the base boom section and/or the telescopic boom section under an angle with respect to an upper or a lower side of the boom, preferably the angle is about 45°. Said angle allows an efficient guiding system which can be made relatively compact. An example of a guiding system will be discussed in more detail in the figures.
The extendable lattice type crane boom may further comprise a measuring system configured to detect a position of the telescopic boom section with respect to the base boom section. Such measuring system can for example include a camera for visual inspection, or a closed circuit TV system, or any other suitable measuring system. The measuring system can send feedback of its measurements to a control system, which may control the extension or retraction of the extendable boom, in a partly or entirely automated way, or under control of a human operator.
The extendable lattice crane boom can further comprise a telescopic system arranged to adjust the at least one telescopic boom section between said retracted position and said extended position, wherein said telescopic system comprises at least one reeving system. The reeving system can comprise a wire rope tackle system with a winch. The wire rope can be reeved between sheaves mounted inside the base boom section and sheaves mounted on a telescopic boom section. Pulling the wire rope in with the winch can for example result in the telescopic boom section being pulled out of the base boom section, thus extending the boom, while moving along the guides. During retraction of a telescopic boom section, the winch can be operated to release the wire rope allowing the telescopic boom section to move inside of the base boom section, typically moving down as a result of gravity. In alternative embodiments, the telescopic system may comprise a hydraulic cylinder or a rack & pinion system, instead of a reeving system. The telescopic system can preferably comprise two reeving systems, each provided on an opposite side of the base boom section, preferably on lateral sides of the base boom section, which is advantageous for a balanced load distribution. Preferably there is a single winch for the two reeving systems such that the two reeving systems in fact form a single combined telescopic system provided at both sides of the base boom section.
There is also disclosed a locking system for an extendable lattice type crane boom, including the features of claim 11. Such a locking system can provide a solid locking of an extendable boom in at least an extended position, and is relatively easy and quick in operation. An extendable lattice type crane boom can also comprise a plurality of telescopic boom sections, wherein each telescopic boom section is lockable with a contiguous telescopic boom section via such a locking system. In this way, a still larger and/or compacter extendable crane boom can be provided.
According to an aspect of the invention, a crane is disclosed according to the features of claims 13-15. The crane comprises an extendable lattice type crane boom as described above. Said lattice type boom is movable between a transit position, in which said lattice type boom is in a substantially retracted and substantially horizontal position, and a working position, in which the lattice type boom is extended. The crane also comprises a crane base to which said extendable lattice type boom is pivotably connected, such that the crane boom can be rotated around a substantially horizontal axis between said transit position and said working position. The crane base can optionally also be made rotatable around a substantially vertical axis. The crane further comprises a boom hoisting system arranged to rotate the extendable boom between said transit position and said working position, and a load hoisting system configured to hoist a load. The boom hoisting system can preferably be connected to a distal end of the base boom section as well as to a distal end of the telescopic boom section, which can provide a relatively stable, well-balanced and reliable crane. Alternatively, the boom hoisting system may also be connected to one of a distal end of the base boom section and a distal end of the telescopic boom section. The boom hoisting system may also be configured to be controlled by a control unit during operation of the telescopic system to follow the telescopic system to facilitate the movement of the telescopic boom section. As such, the telescopic system acts as a master system, while the boom hoisting system acts as a slave system that follows the operation of the master system to facilitate the movement of the telescopic system. Thus, the crane operator may only need to operate the telescopic system while the boom hoisting system follows automatically, controlled by a control unit, to facilitate movement of the telescopic boom section. As such, an optimal angle of about 80° of the crane boom can be kept during the telescopic operation. Also, providing the boom hoisting system as a slave system to the master system, at least during telescopic operation, provides for a more easy operation of the crane by the crane operator, as the operator then has to operate the telescopic reeving system only. This may reduce the risk on failures and/or mistakes.
Advantageously, a measurement system can be provided to determine the actual position of the telescopic crane boom section with respect to the base boom section. The measurement can provide feedback on the actual position to the crane operator who can adapt the crane operations on that information. Also, the measurement system can be configured to control a speed reduction of the telescopic system upon approaching a desired extended position. This may assist the crane operator in approaching the desired extended position and may reduce the risk on failures or damages.
The control unit for controlling the operation of the boom hoisting system in dependency of the operation of the telescopic reeving system can be part of the measurement system of may be provided as a separate control unit. In a preferred embodiment, a measurement system is provided that is configured to control the operations of the crane and provide output on measured parameters, such as telescopic boom speed to an output unit, e.g. the user interface of the crane operator.
In a preferred embodiment of the crane, the crane base can be mountable around a leg of a jack up platform. Such a crane can provide a relatively compact yet efficient crane, even in a harsh off-shore environment. The crane base may also be mountable on a standard pedestal with a slewing bearing arrangement. However, providing the crane base around a leg of the jack-up platform provides for a space efficient solution for the use of the space on a deck of the jack-up platform.
According to a further aspect of the invention, there is disclosed in claims 16-22 a method for operating a crane including an extendable lattice type crane boom, providing one or more of the above-mentioned advantages.
According to a further aspect of the invention, the features of claims 23-24 disclose a jack up platform comprising a crane according to an aspect of the invention, providing one or more of the above-mentioned advantages.
According to an alternative embodiment of the invention, an extendable or telescopic boom with a base boom section and at least one telescopic boom section is proposed. As previously described, the sections are of a lattice type construction with a square, rectangular or possibly triangular cross section, with longitudinally extending chords in each corner of the cross-section which are connected to each other with trusses. The telescopic section has smaller cross-sectional dimensions in comparison with the base boom section, which base boom section at least partly encloses the inserted part of the telescopic boom section. The telescopic section can be moved relative to the base boom section in order to extend or shorten the boom. The telescopic boom section is adjustable with respect to the base boom section between a retracted position, in which the telescopic boom section is substantially inside of the base boom section, and an extended position, in which the telescopic boom section is substantially outside of the base boom section. The telescopic boom section is preferably locked with respect to the base boom section in at least an extended position, but may also be lockable in intermediate positions and/or in a retracted position.
Typically, the extendible boom is provided with hoisting elements to which a hoisting system can be mounted that is connectable to a crane base, preferably to winches at the crane base. In a mounted position, when the boom is mounted to a crane base, one or more chords of the boom are upper chords at the side where the boom is provided with the hoisting elements. The chords at an opposite side thereof are, in mounted condition, the lower chords.
The extendable boom may also comprise multiple telescopic boom sections with decreasing dimensions, preferably with decreasing cross-sectional dimensions, and/or with similar or decreasing longitudinal dimensions, each being movable relative to the other in order to extend or retract the boom. Guides are provided for guiding the movement of the telescopic boom section along the base boom section. Guide rails can be provided on the chords of the telescopic boom section and corresponding guides can be positioned inside the base boom section. Alternatively, the guides can be provided on the chords of the telescopic boom section and the corresponding guide rails can be positioned inside the base boom section. In case the extendable boom has multiple sections, the same guiding configuration is applied between each successive sections. The guides may be used for moving each telescopic boom section with respect to the base boom section, or preceding boom section.
The extendable boom is preferably equipped with a telescopic system arranged to extend or retract each telescopic boom section out of and/or into a preceding telescopic boom section or the base boom section. The telescopic system may comprise a reeving system, as previously described.
In case the boom has multiple telescopic boom sections, each telescopic boom section may be provided with an additional telescopic system between the telescopic boom sections, or a single telescopic system may be configured to extend and/or retract multiple telescopic boom sections. The telescoping system can be arranged to extend the telescopic boom sections simultaneously and/or sequentially.
The extendable boom is preferably provided with a locking system arranged for connecting and/or locking the chords of the telescoping part to the base boom section, or a preceding telescopic boom section, in order to provide for a firm connection between the respective telescopic boom sections such that boom load can be transferred through the chords. The locking system may comprise a support structure at a distal end of the base boom section or the preceding telescopic boom section, which support structure is provided with locking pins. The locking pins are positioned to align with apertures in the chords of the telescopic boom section that is at least partly inserted in the base boom section. The telescopic boom section is provided with apertures arranged in or integrated with the chords to receive the locking pins. The locking pins can be engaged with hydraulic or electric actuating means. The support structure can be provided at the distal end of the base boom section with the locking pins connected thereto and extending therefrom towards a chord of the telescopic boom section. Alternatively, the support structure can be provided at the proximal end of the telescopic boom section with the locking pins connected thereto and extending therefrom towards a chord of the base boom section, or preceding telescopic boom section. Alternatively, the support structure can be provided at the distal end of the base boom section with the locking pins connected to the telescopic boom section, e.g. at the chords of the telescopic boom section, and extending therefrom towards the support structure.
The telescopic boom section can be locked with respect to the base boom section in at least an extended position. However, locking in the retracted position and/or in intermediate positions may also be possible. Alternative to locking of the telescopic boom section in the retracted position, there may be a stop element provided against which the telescopic boom section may abut as to position the telescopic boom section in the retracted position.
To enable locking at these positions, the telescopic boom section may be provided with multiple apertures arranged for receiving a locking pin from the locking system. The apertures of the telescopic boom section are preferably provided at predetermined positions on the chords thereof, such that they can receive a locking pin in a required position of the telescopic boom section.
The locking pins are engageable in the retracted and/or extended and/or intermediate position of the telescopic boom section with respect to the base boom section. When at least one locking pin is engaged, the guides can be retrieved from the guide rails to undo the contact between the guides and the guide rails. As such, the boom load may be directly transferred via the locking pins through the chords and no or minimal load transfer may go through the guides of the guiding system. So, the guide rails may not support the load in the extended position of the boom. This is advantageous for the mechanical structure of the boom for which less or reduced reinforcement may be required, allowing the mechanical structure to become lighter in view of prior art structures. When the locking pins are engaged, the telescopic system need not be actuated anymore, so load transfer is mainly done via these locking pins through the chords, instead of via the guides and/or via the telescopic system. Basically, the guides and/or the telescopic system may not be subject to boom loads in the extended position.
In case the boom has multiple telescopic boom sections, a locking system is provided at each transition between successive telescopic boom section, with the support structure and locking pins at the top end of each telescopic boom section.
For example, the extendable crane may have boom hoist wires connected to the boom tip. The upper chords, i.e. the chords of the boom sections at the side of the boom sections provided with hoisting elements, may then be under compression. The apertures in the upper chord for receiving the locking pins may be slotted holes to allow easy insertion of the upper locking pins during extending. Alternatively, the boom hoist wires can be connected to the base boom section. The telescopic part may now be subject to an additional bending moment resulting in the lower chords, i.e. the chords of the boom sections at a side opposite of the upper chords, being under compression. In this case the apertures in the lower chords for receiving the lower locking pins may be slotted for easy insertion during extending.
It is noted that the apertures arranged on the chords of a telescopic boom section which correspond with the retracted position of the telescopic boom section may have the form of a slotted hole to provide for easy insertion of the locking pins during extension, if locking in a retracted position is provided.
In order to enable insertion of a locking pin into a pin receiving aperture on the telescopic boom section, the base boom section and the telescopic boom section are preferably properly aligned. During extension and/or retraction of the telescopic boom section with respect to the base boom section, the guides are in contact with the guide rails for guiding the telescopic boom section during the telescopic movement. Due to the contact of the guides and the guide rails, the bending moment of the boom is transferred via the guides to the telescopic boom section during telescoping. By providing a locking system with locking pins, the chords of successive sections can be connected and locked in order to transfer boom loads via the pins through the chords. Upon locking of the locking pins, the contact between the guides and the guide rails can be undone, so as to transfer the load via the locking pins and such that the guides can become unloaded. The extendable boom is advantageously provided with an alignment system arranged to align the telescopic boom section with the base boom section as to enable proper locking of the telescopic boom section with respect to the base boom section in the determined position. The aligning system is arranged to push, or pull, the telescopic boom section in a direction transverse to the longitudinal chord direction, at the proximal end of the telescopic boom section such that a longitudinal center line of the telescopic boom section aligns with a longitudinal center line of the base boom section. A stop may be provided at an opposite end of the alignment system against which the telescopic boom section can abut during alignment, preferably the stop is retrievable such that, after alignment, there is no contact with the telescopic boom section. The alignment system may comprise at least an actuator, such as a hydraulic cylinder or electric actuator, mounted to the base boom section, or telescopic boom section, preferably at the side where, in an extended position, there is contact between the sections due to the bending moment of the base boom section and/or telescopic boom section. The alignment system, for example the actuator is capable of pushing, or pulling, the proximal end of the telescopic boom section away from the guides to undo the contact between the guides and the guide rails. This way the guides can be unloaded and the centerline of the telescopic boom section can be brought in alignment with the centerline of the base boom section.
Due to the alignment of the telescopic boom section with respect to the base boom section, the telescopic boom section may rotate around an axis transverse to its center line. Preferably, at least one aperture is provided as a slotted hole to allow the alignment rotation of the telescopic boom section when the locking pin is already engaged. Once the alignment is completed, the opposite locking pin may be engaged into a corresponding aperture. The opposite pin-and-aperture set may have mating dimensions such that the pin closely fits in the aperture, but preferably, all apertures in the chords of the telescopic boom section are not closely fitting apertures.
In the above, the telescopic boom section is explained as being extendible and/or retractable with respect to the base boom section. It is to be understood, that in case the boom has multiple telescopic boom sections, that a more distal telescopic boom section is extendible and/or retractable with respect to its preceding telescopic boom section in the same or similar manner.
In case the boom has multiple telescopic boom sections, an alignment system is provided at each transition between successive telescopic boom sections, with the alignment system mounted to the preceding telescopic boom section and arranged to align the distal telescopic boom section with respect to its preceding telescopic boom section.
Methods for operating an extendable boom are also proposed.
A first method comprises the sequence of operational steps during extension of the boom, using a locking system involving a crane with boom hoist wires attached to the boom tip and at least a telescopic boom section of which the upper chords are provided with apertures for receiving the locking pins which may be in the form of slotted holes, comprising the steps:
A second method comprises the sequence of operational steps during extending the boom, using a locking system involving a crane with boom hoist wires attached to the top of the base boom section and at least a telescopic boom section of which at least the lower chords are provided with apertures for receiving the locking pins which are in the form of slotted holes, comprising the steps:
A third method comprises the sequence of operational steps during retracting the boom comprising the steps of:
In case the boom has multiple telescopic boom sections, the method can be repeated for each consecutive telescopic boom section.
The disclosure will further be elucidated on the basis of exemplary embodiments given by way of non-limitative description and illustration. It is noted that the figures are only schematic representations of embodiments of the disclosure that are given by way of non-limiting example. Various modifications, variations, and alternatives are possible, as well as various combinations of the features described. The specifications, drawings and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense. Embodiments according to the disclosure will, by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings:
In
The boom 2 is in retracted position when the distal telescopic boom sections 2b are stored in the base boom section 2a. In the retracted position the boom 2 can be upended by means of the boom hoist system 5. For normal lifting purposes, the crane 1′ can be used in the retracted position, as the crane is then stronger (more capacity) and/or more flexible and/or easier to use than with an extended boom 2. In the upended or working position the boom 2 can be extended when large lifting height is required, for example when installing a wind turbine on top of a tower.
Guide rails 19′ are connected on the chords 15 of the telescopic boom section 2b. In the base boom section 2a the lower and upper guides 20′ are mounted. The guide system can be arranged vice versa as well, for example with the guide rails 19′ on the base boom section 2a and the guides 20′ on the telescopic boom section 2b.
The locking system 23′ comprises a support structure 9′ that is provided in the head of the base boom section 2a. The support structure 9′ is embodied here as a reinforced ‘box-like’ structure, of which the sides are provided as plate structure to which the locking pins are mounted. For reasons of simplicity, the side plates are not shown in
In
The procedure for operating the extendable boom with boom hoist wires connected to the boom top is shown in
Step 1: With the winch of the telescopic system the telescopic boom section 2b can be extended. The telescopic boom section 2b can be extended a little bit “too” far. The upper pin 24 can be easily inserted in the slotted hole 25. The own weight bending moment in the boom can still be transferred by the guiding system. After the upper pin insertion the telescopic system 12 can lower the telescopic boom section 2b a little bit until the upper pin 24 is in contact with the corresponding slotted aperture 25 of the telescopic boom section 2b. The telescopic system 12 does not need to be actuated anymore, and the actuator can be decoupled and/or unloaded from the telescopic system, so the telescopic system does not transfer load in the extended position. The slotted hole dimensions will be designed in such a way that it can take over the compression load but it also allow alignment of the telescopic boom section and can unload the upper guides, after alignment.
Step 2: With the hydraulic jacks 31 of the alignment system the telescopic boom section 2b can be rotated over a small angle with respect to the upper pin connection to undo the contact of the lower guide 20′ from its corresponding guide rail 19′. The telescopic boom section 2b can now be accurately aligned with the base boom section 2a. When both the telescopic boom section 2b and the base boom section 2a are in line, the locking pin 26 and aperture 25b of the lower part will be in line as well and the lower pin 26 can be inserted.
Step 3: The final step can be to insert the lower locking pin 26 and to release the hydraulic jacks 31 of the alignment system. All the guides 20′ are retrieved now and not in load transferring contact anymore with the respective guide rail. The boom loads can be transferred through the locking pins. When the locking pins are engaged the winch of the telescopic system may be unloaded to be sure that all the load transfer is via these locking pins.
In
The procedure for operating the extendable boom crane 1″ with boom hoist wires (luffing wires) connected to the top of the base boom section is shown in
Step 1: With the winch of the telescoping system the telescopic boom section 2b can be extended. The telescopic boom section 2b will be extended a little bit “too” far. The lower pin can 24 be easily inserted in the slotted hole 25. The own weight moment in the boom will still be transferred by the guiding system. After the lower pin insertion the telescopic system 12 may lower the telescopic boom section 2b a little bit until the upper pin 24 is in contact with the corresponding aperture 25 of the telescopic boom section 2b. The actuator of the telescopic system can be unloaded, so to relieve the telescopic system from load transfer. The slotted hole dimensions are preferably designed in such a way that it can take over the compression load but it also may also allow alignment of the telescopic boom section.
Step 2: With the hydraulic jacks of the alignment system the telescopic boom section 2b can be rotated over a small angle with respect to the lower pin connection to undo the load transferring connection between the upper guide and the corresponding guide rail. The telescopic boom section 2b can now be accurately aligned with the base boom section 2a. When both the telescopic boom section 2b and the base boom section 2a are in line, the pin 26 and aperture 25b of the upper part may be in line as well and the upper pin 26 can be inserted.
Step 3: The final step may be to insert the upper locking pin 26 and to release the hydraulic jacks of the alignment system. All the guides are free from their corresponding guide rail, so load transfer between the guide and the guide rail may be obviated. Preferably, the guide and the guide rail are not in contact anymore. The boom loads may be transferred through the locking pins. When the locking pins are engaged the actuator of the telescopic system can be unloaded as well to ensure that all the load transfer is via these locking pins and not via the telescopic system.
A crane 1 with extendable boom 2, comprising of lattice type sections, has several advantages when utilized on offshore installation jack-up platforms. The crane boom 2 may be retracted when in transit positions which means that the boom, capable of large lifting height as required for installing wind turbines, may not protrude from the boom rest, which obviates the problems that occur when utilizing a longer fixed boom.
It is to be noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. The mere fact that certain features are recited does not indicate that a combination of these features cannot be used to an advantage. Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017498 | Sep 2016 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NL2017/050370 | 6/6/2017 | WO | 00 |
