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(11) | EP 3 375 747 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | TOWER CRANE |
| (57) A tower crane (100) is described, comprising: a tower (105), a pivoting structure
(125) installed at the top of the tower (105), a fifth wheel (130) adapted to allow
the movable structure to rotate around a vertical rotation axis (Y), and a luffing
jib (145) having one end articulated to the pivoting structure (125) according to
a horizontal articulation axis (X), where the pivoting structure (125) comprises:
actuating means (159) adapted to rotate the luffing jib (145) around the articulation
axis (X) up to a vertical position, and a cage (135) adapted to accommodate at least
one portion of the luffing jib (145), when the luffing jib (145) is located in said
vertical position.
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Field of the invention
[0001] The present invention relates to a tower crane and, in particular, a tower crane and luffing jib of the type commonly known by the name of luffer crane.
Background art
[0002] It is known that a tower crane is a widespread lifting device that is primarily used for the handling of loads within construction sites.
[0003] A tower crane generally comprises a vertical structure, conventionally called "tower", which is firmly anchored to the ground and at the top carries a pivoting structure which, due to the interposition of a special fifth wheel, is adapted to move with respect to the tower by rotating around a vertical rotation axis. The pivoting structure generally comprises a protruding jib intended for load handling, usually called "rise", and a counter jib, or "counter rise", which protrudes from the diametrically opposite side with respect to the jib and which carries the ballasts necessary for the static balance of jibs and loads.
[0004] In tower cranes and luffing jib, the jib adapted to handle loads is constrained to the pivoting structure by means of a horizontal articulation axis and is associated with special hydraulically operated jacks, which are adapted to rotate it around said articulation axis so as to vary the inclination thereof with respect to the ground.
[0005] In this way, the luffing jib can be rotated between a minimum tilting position, in which the arm is lowered so as to bring the loads to the maximum radial distance from the tower, to a maximum tilting position, in which the arm is raised so as to bring the loads to the minimum radial distance from the tower.
[0006] To allow mounting the crane, the tower generally consists of a plurality of prefabricated lattice elements, the first of which is firmly anchored to the ground. A cage is applied around this first tower element, usually referred to as "telescoping cage", on which the pivoting structure including the luffing jib, the counter jib and the load handling devices, is then mounted.
[0007] The telescoping cage is provided with suitable hooking and lifting members, for example with one or more hydraulically operated jacks, allowing it to progressively "climb" on the tower element both in ascent and in descent.
[0008] By means of these hooking and lifting members, once the pivoting structure has been assembled, the telescoping cage is made to move upwards, so as to distance the pivoting structure from the top of the first tower element by an extent equal to or slightly greater than the height of a second tower element. By using the load handling devices located on the luffing jib, this second tower element is then lifted to height and inserted laterally between the pivoting structure and the top of the first tower element to which it is firmly fitted.
[0009] At this point, the telescoping cage is made to move up along the second tower element to allow the fitting of a third tower element, and so on until a tower having the desired height is obtained.
[0010] Once the desired height has been achieved, the pivoting structure is attached to the top of the tower and the telescoping cage can be removed or left in place for subsequent dismantling of the crane.
[0011] In this regard, the dismantling of the crane is carried out by using the telescoping cage in a manner substantially opposite to what is described above, i.e. so as to remove one tower element at a time starting from the top and then gradually making the pivoting structure descend to the ground where it is dismantled.
[0012] A drawback of this solution consists in that the movement of the luffing jib during the mounting and dismantling steps of the pivoting structure generally requires the use of large vehicles and powerful mobile cranes.
[0013] These large vehicles and mobile cranes, in turn, require the availability of large site access ways and extremely large clearances, which are not always available, especially when the site is located in a highly urbanized environment.
Description of the invention
[0014] One object of the present invention is to solve the above drawback of the prior art by providing a tower crane with luffing jib that can be dismantled more easily and in much smaller spaces than the cranes currently known.
[0015] Another object of the invention is to achieve the above object with a simple, rational and relatively cost-effective solution.
[0016] These and other objects are achieved with the features of the invention set out in the independent claim 1. The dependent claims describe preferred and/or particularly advantageous aspects of the invention.
[0017] In particular, an embodiment of the present invention provides a tower crane comprising:
- a tower,
- a pivoting structure installed at the top of the tower,
- a fifth wheel adapted to allow the pivoting structure to rotate around a vertical rotation axis, and
- a luffing jib having one end articulated to the pivoting structure according to a horizontal articulation axis,
- actuation means adapted to rotate the luffing jib around the articulation axis up to a vertical position, and
- a cage adapted to accommodate at least one portion of the luffing jib when the luffing jib is in said vertical position.
[0018] By virtue of the ability to orient the luffing jib in a perfectly (or nearly) vertical direction and due to the presence of a cage containing it at least partially, the luffing jib can be efficiently mounted and dismantled directly on site and aboard the crane itself, without the need for further cranes and therefore with reduced clearances.
[0019] In this regard, one aspect of the invention provides that the luffing jib can be longitudinally divided into a plurality of prefabricated elements joined together by means of removable fixing means.
[0020] In this way, the mounting and dismantling of the luffing jib are greatly simplified, as these operations only require the assembly and disassembly of a reduced number of prefabricated elements.
[0021] According to another aspect of the invention, the pivoting structure may comprise at least one hydraulically operated jack, which is constrained to the cage and can be constrained to the luffing jib when the luffing jib is in vertical position.
[0022] With this solution, as the luffing jib is mounted or dismantled, the upper part of the luffing jib can be effectively raised or lowered, respectively, to make space for new elements to be assembled or to dismantle the elements still present, similar to what happens during the mounting and dismantling of the tower with the telescoping cage.
[0023] According to a further aspect of the invention, the pivoting structure may comprise one or more service platforms placed outside the cage and at different heights.
[0024] These platforms are intended to safely support the operators in charge of mounting and dismantling the luffing jib.
[0025] A different aspect of the invention provides that the articulation axis of the luffing jib may be coplanar to the rotation axis of the pivoting structure.
[0026] In this way, when it is in vertical position, the luffing jib is perfectly aligned with the underlying tower, thus improving the static stability of the crane.
[0027] According to another aspect of the invention, the actuation means adapted to rotate the luffing jib may comprise a system of pulleys connected between the luffing jib and at least one hydraulically operated jack mounted aboard the cage.
[0028] This aspect provides a very simple and rational solution to vary the inclination of the luffing jib.
[0029] In particular, the jack may be articulated to the cage according to an articulation axis placed at a higher height than the articulation axis of the luffing jib.
[0030] In this way, the jack designed to rotate the luffing jib may be the same that is used for dismantling, thus saving on equipment and costs.
Brief description of the drawings
[0031] Further features and advantages of the invention will become apparent from the following description, provided by way of non-limiting example with the aid of the figures shown in the accompanying drawings.
Figure 1 is a lateral view of a tower crane according to an embodiment of the present invention, shown with the luffing jib in lowered position.
Figure 2 is the detail indicated with A in figure 1, shown in enlarged scale.
Figure 3 is the view indicated with B in figure 2.
Figure 4 is a lateral view of the tower crane in figure 1 shown with the luffing jib in raised position.
Figure 5 is detail C in figure 4, shown in enlarged scale.
Figures 6 to 9 are the view in figure 4 during subsequent steps of the procedure for removing the luffing jib.
Detailed description
[0032] The present invention relates to a tower crane 100 and more in particular, a tower crane with luffing jib of the type commonly known by the name of luffer crane.
[0033] Crane 100 comprises a vertical structure, usually referred to as "tower" and indicated as a whole with reference numeral 105, which may have the overall shape of a parallelepiped extending according to a vertical central axis starting from a lower end towards a top.
[0034] The lower end of tower 105 is firmly anchored to the ground, for example by means of a resting base 110 on which a ballast 110 is loaded having a stabilization function.
[0035] Tower 105 may consist of a lattice structure, typically a metal lattice, which may for example comprise four vertical uprights connected together by a plurality of horizontal and diagonal crosspieces, thus defining an empty inner space in which a ladder and any platforms may be accommodated.
[0036] From a construction point of view, tower 105 may be longitudinally divided into a plurality of prefabricated elements or segments having a predetermined height, such as between 2 and 12 metres, which are coaxially stacked on top of each other and fitted together by means of removable fasteners, for example by means of bolts, up to obtain a tower 105 having desired height.
[0037] Tower 105 may be mounted and disassembled directly on site by means of a telescoping cage 120, according to the outlined ways in the introduction of the present discussion.
[0038] Crane 100 further comprises a pivoting structure 125, which is installed at the top of tower 105 by the interposition of a fifth wheel 130 which allows said pivoting structure 125 to rotate about a vertical rotation axis Y.
[0039] The rotation axis Y of the pivoting structure 125 is preferably coincident with the central axis of tower 105, so as to improve the stability of crane 100.
[0040] The fifth wheel 130 generally comprises a fixed ring connected to tower 105 and a rotatable ring connected to the pivoting structure 125, which is rotatably coupled to the fixed ring through the interposition of rolling elements, such as one or more rows of balls.
[0041] The actuation in rotating of the pivoting structure 125 may be achieved by means of one or more motors, such as an electric or hydraulic motor, which is adapted to actuate in rotation the rotatable ring of the fifth wheel 130 with respect to the fixed ring. For example, the motor may be installed aboard the pivoting structure 125 and be adapted to actuate a pinion that meshes on a toothed crown coaxially anchored to the fixed ring of the fifth wheel 130.
[0042] The pivoting structure 125 comprises a cage 135, which can be shaped as a parallelepiped tower that extends with a vertical central axis starting from a lower end connected to the fifth wheel 130 towards an upper top end.
[0043] Cage 135 may consist of a lattice structure, such as a metal lattice, and is internally hollow so as to define an empty inner channel which extends along the central axis of cage 135 up to the top.
[0044] Preferably, the central axis of cage 135 coincides with the rotation axis Y of the pivoting structure 125 and thus with the central axis of the underlying tower 105.
[0045] The pivoting structure 125 further comprises a luffing jib 145, which has a free end and an opposite end that is articulated at the base of cage 135 according to a horizontal articulation axis X.
[0046] The luffing jib 145 is generally shaped as an elongated body which extends mainly along a longitudinal axis Z substantially orthogonal to the articulation axis X.
[0047] The luffing jib 145 may consist of a lattice structure, typically a metal lattice, which may for example comprise four longitudinal members oriented parallel to the longitudinal axis Z and connected together by a plurality of horizontal and diagonal crosspieces.
[0048] From a construction point of view, the luffing jib 145 may be longitudinally divided into a plurality of prefabricated elements or segments 150 having a limited length, such as between 2.5 and 6 metres, which are coaxially arranged in a succession and fitted together by means of removable fasteners, for example by means of bolts, up to obtain a luffing jib 145 having the desired length.
[0049] In particular, the prefabricated elements 150 may be fitted one after the other starting from a connecting element 155, shaped as a pinnacle, which is directly connected to the pivoting structure 125 by means of a joint that defines the articulation axis X.
[0050] By rotating around the articulation axis X, the luffing jib 145 can vary its inclination with respect to the rotation axis Y of the pivoting structure 125 between a lowered position (see fig. 1) and a completely raised position (see fig. 4).
[0051] In the lowered position, the luffing jib 145 protrudes transversely, i.e. substantially cantilevering, with respect to the rotation axis Y of the pivoting structure 125, forming an angle close to 80° therewith and thus being nearly horizontal with respect to the ground.
[0053] Preferably, the articulation axis X of the luffing jib 145 is substantially coplanar to the central axis of cage 135, so that when the luffing jib 145 is in the raised (vertical) position, at least the lower portion of the luffing jib 145 is accommodated within the inner channel of cage 135.
[0054] In particular, the height of cage 135 is selected so as to accommodate at least the first two prefabricated elements 150, i.e. the first prefabricated element directly fitted on the connecting element 155 and the second prefabricated element 150 directly fitted on the first one.
[0055] Of course, in order to allow the luffing jib 145 to enter into the inner channel of cage 135, one of the sides of cage 135 parallel to the articulation axis X must be left open (i.e. left devoid of horizontal and/or oblique crosspieces), or it must be opened before lifting the luffing jib 145.
[0056] As shown in figures 2 and 3, the oscillation of the luffing jib 145 around the articulation axis X may be obtained by means of a pair of hydraulically operated jacks 159 mounted aboard cage 135, preferably on the opposite side with respect to the luffing jib 145.
[0057] In particular, jacks 159 are oriented essentially vertically and comprise each a lower cylinder 160 from which a sliding stem 161 protrudes superiorly. Cylinders 160 are articulated to cage according to an articulation axis X' parallel to the articulation axis X of the luffing arm 145, while the free ends of the sliding stems 161 are fixed to a single movable crosspiece 162.
[0058] Preferably, the articulation axis X' of jacks 159 may be placed at a higher height than the articulation axis X of the luffing boom 145.
[0059] The movable crosspiece 162 is coupled with a system of pulleys 163 which are positioned at the top of cage 135 and whose ropes 164 are directly connected to the luffing jib 145, in particular to the free end thereof (see fig. 1). The pulley system 163 is configured so that a shortening of jacks 159 corresponds to a pull of ropes 164 downwards, and thus a lifting of the luffing jib 145 and vice versa, a lengthening of jacks 159 corresponds to a release of ropes 164 and thus a lowering of the luffing jib 145.
[0060] In particular, the pulley system 163 is configured so as to multiply the displacement of the movable crosspiece 162, i.e. so that a predetermined linear displacement of the movable crosspiece 162 corresponds to a greater sliding of ropes 164, for example a sliding equal to three times the linear movement of the movable crosspiece 162.
[0061] In this way, despite having a limited length, jacks 159 are effectively able to lift the luffing jib 145 up to reach a perfectly vertical position.
[0062] Although two jacks 159 have been described in this embodiment, it is not excluded that other embodiments use a single jack 159 or alternatively a number of jacks 159 higher than two.
[0063] As shown in figure 2, cage 135 is also associated with two mutually overlapping counter jibs, of which a lower counter jib 165 which can be placed substantially at the same height as the articulation axis X of the luffing jib 145, and an upper counter jib 170 placed at a higher height, for example substantially at the same height as the articulation axis X' of jacks 159.
[0064] Each of these counter jibs 165 and 170 is attached substantially cantilevering to cage 135 so as to protrude horizontally with respect to it, and thus with respect to the rotation axis Y of the pivoting structure 125, on the diametrically opposite side with respect to the luffing jib 145 when in the lowered position. In order to improve the stability of crane 100, the upper counter jib 170 may have a slightly greater horizontal extension than that of the lower counter jib 165.
[0065] In any case, the horizontal extension of both counter jibs 165 and 170 is preferably rather limited, such as between 3 and 5 metres.
[0066] It is noted herein that the term "horizontal extension" refers to the maximum cantilever dimension of the counter jibs with respect to the rotation axis Y, measured along a horizontal direction and coplanar to the longitudinal axis Z of the luffing jib 145.
[0067] From a construction point of view, each counter jib 165 and 170 can be shaped like a platform that is attached outside cage 135 and that defines a horizontal loading platform.
[0068] On both counter jibs 165 and 170, preferably in the vicinity of the free ends thereof, groups of ballasts 175 may be installed with the function of counterbalancing the weight of the luffing jib 145 and of the loads connected to it. Each ballast 175 may consist of a steel block, which has a specific weight greater than conventional reinforced concrete blocks, thereby providing the same counterweight with a smaller footprint.
[0069] A lifting winch 180 may be installed on the upper counter jib 170, generally comprising a motor, such as an electric or hydraulic motor, and a drum adapted to be set in rotation by the motor, possibly through the interposition of a gearbox.
[0070] A rope is wrapped around the drum of the lifting winch 180 which, guided by suitable return wheels placed at the top of cage 135, is connected to a pulley 185 placed at the free end of the luffing jib 145 to fasten the loads.
[0071] A hydraulic group 190 may be installed on the lower counter jib 165, which comprises one or more hydraulic pumps which, driven by suitable electric motors, are adapted to deliver oil under pressure towards the various utilities installed on crane 100, including for example the motor (if hydraulic) of the lifting winch 180, jacks 159 that actuate the movement of the luffing jib 145 and the motor (if hydraulic) that drives the rotation of the entire pivoting structure 125. The lower counter jib 165 may also accommodate an electrical panel 195 whose purpose is to power and optionally disconnect, in case of breakdown or maintenance, the electrical utilities of crane 100, including for example the motor (if electric) of the lifting winch 180 and the motor (if electric) which drives the rotation of the entire pivoting structure 125.
[0072] A peculiarity of crane 100 described above is that the luffing jib 145 can be disassembled piece by piece, without the need for external devices or machines.
[0073] To perform this disassembly, the luffing jib 145 is first brought into the raised position shown in figure 4 and 5, in which it is oriented vertically and in which the lower portion thereof is accommodated into the inner channel of cage 135. At this point, jacks 159 may be detached from the pulley system 163 to be directly connected to the luffing jib 145 which is located in the raised position. This connection (not shown in the figures) can be achieved by means of the movable crosspiece 162, which can be released from the pulley system 163 to be subsequently anchored to corresponding abutment elements of the luffing jib 145.
[0074] In particular, the movable crosspiece 162 can be anchored to the second prefabricated element 150 of the luffing jib 145 (the second one starting from the connecting element 155, and thus from below), for example by engaging one of the horizontal beams thereof.
[0075] In this way, the first prefabricated element 150 of the luffing jib 145, which is contained within cage 135, can be released from the connecting element 155 (which is directly articulated to cage 135) and from the second prefabricated element 150 (to which the movable crosspiece 162 has been attached), for example by removing the mutual connection bolts.
[0076] At this point, jacks 159 may be actuated so as to slightly raise the second prefabricated element 150 and with it the entire upper portion of the luffing jib 145, which can then be anchored to cage 135.
[0077] In this way, the first prefabricated element 150 is completely free and can be pulled out sideways from cage 135 (see fig. 6), for example with the aid of special carriages provided with a movement in the horizontal direction. Once this first prefabricated element 150 is placed outside and next to cage 135, the same can be attached to pulley 185 that comes down from the end of the luffing jib 145, to be lowered to the ground with the lifting winch 180.
[0078] At this point, jacks 159 may be actuated so as to lower the remaining portion of the luffing jib 145, until the second prefabricated element 150 is brought substantially at the same height previously occupied by the first prefabricated element 150, such as resting on the connecting element 155 (see fig. 7). Once this position has been reached, the luffing jib 145 can be anchored to cage 135, so that the movable crosspiece 162 can be released from the second prefabricated element 150 and, after appropriate extension of jacks 159, be anchored to the fourth prefabricated element 150.
[0079] At this point, the second prefabricated element 150 can be released from the fourth prefabricated element 150 and extracted from cage 135 in the same way as described for the first prefabricated element 150 (see fig. 8).
[0080] The remaining part of the luffing jib 145 is then lowered as shown in figure 9 and the procedure is repeated up to the complete disassembly of the luffing jib 145.
[0081] The assembly of the luffing jib 145 can be carried out with the aid of jacks 159 by simply by reversing the steps described above.
[0082] To facilitate the disassembly/assembly operations, the pivoting structure 125 may be provided with some service platforms 210 attached externally with respect to cage 135 and placed at different heights, each of which is adapted to provide a support surface for the operators in charge of the above activities. Crane 100 can finally be completed by a driver cab 215 which can be attached to, for example, the pivoting structure 125, for example at a height between the fifth wheel 130 and the lower counter jib 165.
1. A tower crane (100) comprising:
- a tower (105),
- a pivoting structure (125) installed at the top of the tower (105),
- a fifth wheel (130) adapted to allow the movable structure to rotate around a vertical rotation axis (Y), and
- a luffing jib (145) having one end articulated to the pivoting structure (125) according to a horizontal articulation axis (X),
where the pivoting structure (125) comprises:- actuating means (159) adapted to rotate the luffing jib (145) around the articulation axis (X) up to a vertical position, and
- a cage (135) adapted to accommodate at least one portion of the luffing jib (145), when the luffing jib (145) is located in said vertical position.
2. A tower crane (100) according to claim 1, wherein the luffing jib (145) is longitudinally
divided into a plurality of prefabricated elements (150) joined together by means
of removable fasteners.
3. A tower crane (100) according to anyone of the preceding claims, wherein the pivoting
structure (125) comprises at least a hydraulically actuated jack (159), which is constrained
to the cage (135) and can be constrained to the luffing jib (145), when the luffing
jib (145) is located in vertical position.
4. A tower crane (100) according to anyone of the preceding claims, wherein the pivoting
structure (125) comprises one or more service platforms (210), located outside the
cage (135) and at different heights.
5. A tower crane (100) according to anyone of the preceding claims, wherein the articulation
axis (X) of the luffing jib (145) is coplanar to the rotation axis (Y) of the pivoting
structure (125).
6. A tower crane (100) according to anyone of the preceding claims, wherein said actuating
means comprise a system of pulleys (163), connected between the luffing jib (145)
and at least one hydraulically actuated jack (159), mounted aboard cage (135).
7. Tower crane (100) according to claim 6, wherein said jack (159) is articulated to
the cage (135) according to an articulation axis (X'), located at higher height than
the articulation axis (X) of the luffing jib (145).