Patent Publication Number: US-6655539-B2

Title: Tower crane with composite structure, self-assembling, with folding and telescoping tower, and arm made up of several sections

Description:
This patent refers to a tower crane with composite structure, self-assembling, with folding and then telescoping tower, and arm made up of several folding and unfolding sections. 
     Cranes are already known which have a self-assembling composite structure in which the vertical element, known as “tower”, is composed of a pair of structural sections hinged together, and the horizontal element, known as “arm”, is similarly composed of one or more sections hinged together. The sections of the vertical element are, when the crane is down, horizontal and laid down one on top of the other, while with the crane assembled they are vertical and in line with each other so as to form the crane&#39;s tower. The sections of the horizontal element are likewise, when the crane is in the down position, horizontal and folded upon each other, and on top of the sections of the vertical element, while when the crane is assembled they are horizontal and in line with each other to form the arm of the crane. 
     There are various systems for passing from the position where the crane is down and the tower and arm sections are folded and horizontal to that in which the crane is assembled, with the tower sections in line and vertical and the arm sections in line and horizontal; the maximum height that the tower&#39;s upper end, and consequently the arm attached to that end, can reach is in any case equal to the maximum length of the two tower sections hinged together. 
     This limits the use of a crane constructed in this way, since there is no way of reaching heights greater than the sum of the lengths of the tower sections. At the same time, considerations of transporting the disassembled crane prevent the arm sections being much longer than the tower sections, while the cumulative total height of the tower sections and arm sections laid one upon the other cannot, in view of the same considerations, exceed a certain height, thus limiting the number or height of the individual arm sections to be placed one upon the other. 
     In the case of cranes already known, the raising of the arm into its working position from its position with the crane down is carried out during the stage of lining up and erecting of the tower by means of a suitable relay of struts and tie rods; this generates considerable bending forces in the two tower sections and in the various types of component that may be used for erection of the tower. Furthermore, in known cranes at least one of the hydraulic actuators, preferably installed for the deployment and folding of the crane and of the arm, has a structural function in the deployed machine and cannot, therefore, be replaced in the event of failure while the crane is assembled. 
     One purpose of the present invention is therefore to create a crane with a self-assembling foldable and telescoping tower and a multi-section arm, to avoid the above-described technical problems. 
     Another purpose of the present invention is to create a crane of the above type which is particularly simplified in structure and construction, and which would be equally simple and effective in use. 
     Yet another purpose is to create a crane capable of performing the tasks required of it while still being particularly simple to use. 
     These purposes have been achieved in this invention with the creation of a crane with a self-assembling foldable and telescoping tower and multi-section arm as set out in the attached claim 1. 
     Further salient particular characteristics of this invention are covered by the dependent claims. 
     In particular, the crane in the present invention has a tower of composite structure made of at least one pair of hinged sections consisting of structural members, box girders of square or rectangular cross-section, and a third section inserted into the upper section of the hinged pair, this third section being composed of a single structural member or box girder of square or rectangular cross-section which can be telescoped once the two hinged sections are vertical and lined up, so that the upper end of the tower so formed can reach a greater height than that reachable by the hinged pair of sections alone. Furthermore, the particular small height of the individual arm sections allows a sufficient number of them to be placed one upon the other, when the crane is folded, for the arm to be of considerable length, and longer than can be achieved with other known cranes of the same type, when the crane is assembled. 
     Furthermore, since in the case of the crane created by this invention the telescoping of the third tower section takes place after the alignment in the vertical position of the pair of hinged sections, and it is only at that stage of telescoping that the arm is raised to its working height, progress is made towards the aim of reducing the bending stresses in the two hinged tower sections and the components used for erecting the tower. 
    
    
     The features, and the advantages, of a crane with self-assembling foldable and telescoping tower and multi-section arm as in this invention will become clearer and more evident from the following description, which is provided merely as an example, and without liming purposes, of an embodiment with reference to the attached drawings, in which: 
     FIGS. 1 to  5  are schematic elevation side views of the self-assembling crane according to the invention, in which the assembling of the tower is essentially shown; 
     FIGS. 6 to  8  are schematic elevation side views showing the unfolding of the upper arm of the crane shown in FIG. 1; 
     FIG. 9 is an elevation side view on a smaller scale of the crane in the fully assembled position; 
     FIGS. 10 and 11 show the linkages between the first primary arm section, the intermediate element and the second primary arm section, respectively at a half-aligned stage and at the fully aligned stage. 
    
    
     It should be made clear first of all that the tower, notwithstanding that it is an integral part of the present invention, is the subject of two Italian patent applications, MI2000A002661 and MI2000A001062, which illustrate two embodiments thereof. The unfolding and re-folding arrangement that operates between the second and third primary arm sections, described below, likewise makes use of the finding described in the Italian Utility Model No. 218897. 
     Once that is clear, it may be noted that a crane has been constructed with a tower as described above and a multi-section arm with sections of limited height supported by struts and tie rods in such a way that no fewer than three arm sections can, when the crane is disassembled and the tower and arm are folded, be laid one on another and all together on top of the two hinged tower sections, in such a way that the overall height of the disassembled and folded crane is relatively low and not such as to hinder its transport. The finding that is the subject of this present invention, as well as allowing a considerable height to be reached and providing the other advantages inherent in the tower&#39;s particular features, also makes it possible, when all arm sections are deployed, to reach a considerable arm length, which increases the machine&#39;s capabilities of use to a significant extent. 
     In detail, it will be noted that in FIG. 1, the crane is in the fully folded state, with the base  10  resting on the ground. FIGS. 2 and 3 show the crane with the tower in various stages of erection, until in FIG. 4 we see the two tower sections aligned, with the third section as yet still fully inserted inside them. FIG. 5 then shows the two tower sections aligned and the third section now fully telescoped, while the arm sections are still partly folded up. FIGS. 6,  7  and  8  are schematic views of a self-assembling crane according to the present invention, with the arm, tie rods and booms shown at three successive stages of unfolding, until in FIG. 9 we can see the crane fully assembled in its working position. Lastly, FIGS. 10 and 11 show, as already said, the linkages between the first primary arm section, the intermediate element and the second primary arm section, at a half-aligned stage and at the fully aligned stage. 
     As can be seen from these figures, this invention refers to a crane with self-assembling tower with composite structure with sections hinged together with horizontal hinges, referenced with the numerals  11 ,  12 ,  13 ,  14 ,  15  and  16 . It is composed of a tower made up of two sections  20  and  21 , hinged together at  12 , and a third section  22  which is inserted into and can be telescoped from the upper section  21  of the two hinged sections. A load-bearing arm  50  is composed of a number of sections; it is made of a first primary section  23 , one end of which is hinged at  13  at its under surface to the upper end of the telescoping section  22  of the tower. There follows a relatively short secondary section  24 , one end of which is hinged at  14  at its under surface to the free end of the first primary section  23 ; then there is a second primary section  25 , one end of which is hinged at  15  at its under surface to the free end of the secondary section  24 ; and finally a third primary section  26 , one end of which is hinged at  16  at its upper surface to the free end of the second primary section  25 . All sections of the arm have a considerably reduced height so as to allow for the superimposition, when the crane is down, of at least three sections; only the first primary section  23  has, at its front end in the vicinity of its end hinge  14 , a greater vertical height so as to accommodate the motor, with motor reducer, that moves the truck. 
     The lower part of the tower,  20 , is in turn hinged at its bottom end  11  to a base structure shown altogether as  27 , with a turntable  17 , this turntable being solidly attached to the base  10 . This base structure  27  has the usual controls for unfolding and re-folding the whole crane, not shown in detail, which act via a flexible tie rod  30  running up beside the tower essentially at the opposite side with respect to the arm, and flexible tie rods  31  and  32  running to the arm from above. 
     The tie rods, the parts of the base structure, and parts of the crane structure, form an articulated quadrangle. 
     The two hinged parts of the tower  20  and  21  move from their disassembled position shown in FIG. 1 horizontal and one above the other to a near-vertical and aligned position shown in FIG. 4, passing through a series of intermediate positions, two of which are shown in FIGS. 2 and 3. 
     In the intermediate position shown in FIG. 2, the flexible tie rod  30 , which may be made up of more than one length, is attached with a hinge at  28  to the base structure  27 , and passes over a large pulley  29  located at the end of a boom  40 . The boom is rigidly attached to the upper end of the third tower section  22 , and rests against a roller  41  hinged at the end of the first arm section  23  at its upper surface. As can be seen better in FIG. 3, the other end of tie rod  30  is hinged to tie rods  31  and  32  and to the end of another boom  42 , this boom being in turn hinged at  43  to the upper end of the tower  22 . As the two hinged tower sections  20  and  21  are raised by degrees, so tie rod  30  comes under progressively greater tension. 
     Before the raising of the two tower sections  20  and  21  can make tie rod  30  pull boom  42  so that it rotates around hinge  43 , the second and third arm sections  25  and  26  must be unfolded enough, moving them away from the first section  23  by a distance necessary and sufficient to allow boom  42  to turn around hinge  43  without the end of that boom  42  fouling the third arm section  26 . The arrangements for unfolding all the arm sections are described below. 
     The raising of the two tower sections  20  and  21  makes tie rod  30  pull boom  42  so that it rotates around hinge  43 , pulling tie rod  31  tight. This tie rod is made of three lengths: the first  44  is shorter and attached to boom  42  while the second  46  is roughly the same length as boom  42  and is attached at  45  to the first length of tie rod  44 ; a third length,  48 , is attached at  47  to the second length  46  and at its other end at  49  to the first primary arm section  23  at that section&#39;s upper surface. 
     When tie rod  31  is pulled by the rotation of boom  42 , the time comes for unfolding the second arm section  25  and the third arm section  26  until they lean on tie rod  33 . The unfolding of the two tower sections  20  and  21  continues, and when the two hinged sections  20  and  21  are in line and vertical or leaning slightly in the direction away from tie rod  30 , as shown in FIG. 4, the telescopic tower section  22  is still fully inside tower section  21 ; the load-bearing arm  50 , hinged at  13  to the upper end of tower section  22 , is vertical and almost entirely supported by tower sections  20  and  21 , with tie rods  30  and  31  both under tension. 
     In the final stage of the crane tower&#39;s erection, tower section  22  is telescoped from hinged tower section  21  as shown in FIG. 5, and the control devices for this telescopic operation are illustrated in the two patent applications mentioned above. As tower section  22  is telescoped, the tension of tie rods  30  and  31  makes the load-bearing arm  50  turn around the hinge  13  while the arm rises, until it reaches a position of horizontality or is slightly higher at the end further from the tower, as shown in FIG. 6, just as tower section  22  reaches its fullest telescoping from tower section  21 . Tower section  22  is fixed, by conventional means, in this position of maximum telescoping at which the crane can be used for lifting loads. 
     One end of a strut  54  is hinged at  66  onto the upper part of the secondary section  24  of the arm  50 , while the other end of strut  54  is hinged at  55  to the end of flexible tie rod  33  and to the end of flexible tie rod  32 , which consists of a metal cable. Approximately two thirds of the way along its total length, tie rod  32  is fixed to the end  51  of a strut  52 , whose other end is hinged at  53  to length  48  of tie rod  31 . Details of the device for aligning the second primary arm section  25  and the secondary arm section  24  with the first primary arm section  23  can be seen more readily in FIGS. 10 and 11. 
     The end of a connecting rod  57  is attached by a hinge  58  to the secondary arm section  24 , hinge  58  being located half-way along the under side of section  24 , between hinges  14  and  15  and close to its under side; the rotation of rod  57  is restricted by a restrainer cable fixed with some degree of clearance at the other end of rod  57  by a loose hinge  67  which is fixed to the upper part of the secondary arm section  24 . 
     A hydraulic actuator  60  is hinged at one end  61  on the structure above the first primary arm section  23  and at the other at  59  on the upper part of rod  57 . A second hydraulic actuator  62  is hinged at one end  64  on the second primary arm section  25  and at the other at  63  on the upper part of rod  57 . A pair of connecting rods of equal length  68  and  70  are hinged at  69 , the other end of rod  70  being hinged at  71  on the first primary arm section  23  and the other end of rod  68  being hinged at  67  on the upper part of the secondary section  24 . 
     FIG. 6 shows the initial stage of aligning the primary section  23 , the secondary section  24  and the primary section  25  of the arm  50 . Hydraulic actuator  60  operates to turn the secondary section  24  of the arm  50  around hinge  14 , which is at the end of the first primary section  23 ; hydraulic actuator  62  operates likewise to turn the second primary section  25  of the arm  50  around hinge  15 , which is at the end of the secondary section  24 . As the secondary section  24  of the arm turns around hinge  14 , rods  68  and  70  turn around hinge  69  which links them together, while the end of rod  68  attached at  67  to the upper part of arm section  24  moves in accordance with the turning of that secondary arm section  24  around hinge  14 . 
     FIG. 7 shows a later intermediate stage in the alignment of the primary sections  23  and  25  of the arm  50  and its secondary section  24  of the arm  50 . The flexible tie rod  33  is composed of an initial rigid length  56  slightly shorter than strut  54 , this length  56  being attached to strut  54  by a hinge at  55  and also to flexible tie rod  32 . At the other end of this first length  56  of tie rod  33  are two parallel longitudinal openings between which are two knuckle pins  81  and  82 ; a short plate  84  has a slot  83  within which the movement of knuckle pins  81  and  82  is constrained, thus allowing in a certain degree the sleeve slinding of the plate  84  in the direction of the axis of the first section  56 ; the other end of said plate  84  being hinged at  85  to a second portion  86  of the tie rod  33  of relatively considerable lenght. The movement of plate  84  onto knuckle pins  81  and  82  is designed to facilitate the unfolding and re-folding of the lengths of tie rod  33  during the unfolding and re-folding of the crane arm  50 . A relatively short secondary length  88  of tie rod  33  is hinged at  87  to the second portion  86  and is hinged in  89  to the third length  90  of tie rod  33 , this third length  90  being hinged at  91  to the upper surface of the second primary arm section  25  in the vicinity of its end and of hinge  16 . 
     An arm section  24  turn s around hinge  14  and section  25  turns around hinge  15 , tie rod  33  is brought into tension, and strut  54  is raised by the force of this tension in tie rod  33 , turning around hinge  66 ; as section  24  continues to turn around hinge  14 , and section  25  around hinge  15 , and strut  54  around hinge  66 , so the steel cable flexible tie rod  32  comes into tension, which in turn makes strut  52  turn around hinge  53 , since strut  52  is rigidly attached at point  51  to flexible tie rod  32 . 
     FIG. 8 shows the final position in which sections  23 ,  24  and  25  of the arm  50  are aligned, while FIG. 11 gives a clearer idea of the details of the sections  23 ,  24  and  25 , which are joined by hinges  14  and  15 . When hydraulic actuator  60  is on the point of reaching its end-of-stroke position, and the secondary arm section  24  is in line with the first primary section  23 , a bracket  70  linked by a hinge  71  to the first primary arm section  23 , and another bracket  68  linked by a hinge  67  to the secondary section  24 , the two brackets  70  and  68  being joined together by hinge  69 , are brought into tension, preventing any further turning of secondary section  24  around hinge  14 , and performing the function of supporting section  24 ; the attachment hinge  61  of hydraulic actuator  60  has a slightly elongated hole, allowing that actuator  60  to reach its end position without putting any force on the secondary section  24  and without doing any structural duty of supporting section  24 . 
     When hydraulic actuator  62  is on the point of reaching its end-of-stroke position, and the second primary arm section  25  is in line with the secondary section  24 , tie rods  32  and  33  are brought into tension. The tension of the tie rods  32  and  33 , via boom  54 , prevents any further turning of second primary arm section  25  around hinge  15 , so that tie rods  32  and  33  perform via boom  54  the function of supporting section  25 ; the attachment hinge  64  of hydraulic actuator  62  has a slightly elongated hole, allowing that actuator  62  to reach its end position without putting any force on second primary section  25  and without doing any structural duty of supporting section  25 . 
     Lastly, the turning of the third primary arm section  26  around hinge  16 , and the alignment of that section  26  with sections  23 ,  24  and  25  of the arm  50 , are achieved by means of devices already known, such as hydraulic actuators. 
     This completes the description of the procedure for erecting the crane with, first, complete deployment of the tower and then of the arm; it should be made clear that the crane which is the subject of this invention can be used either with the arm  50  fully deployed as explained above or with the third arm section  26  folded and resting against the pull of tie rod  33 , or even with the second arm section  25  and the third arm section  26  both folded and resting against the pull of tie rod  31 : this configuration is illustrated in FIG.  5 . 
     The procedure for disassembling the crane, with full folding first of the arm and then of the tower, involves carrying out the erection operations described, in reverse. 
     In this way a crane has been created with a composite tower and automatic erection, whose tower is composed of at least three sections and whose arm is composed of a number of sections which can be folded and unfolded in the same direction of rotation. 
     The advantages of a crane using the present invention are clear to see. The tower in at least three sections two hinged and the third telescopical, and the arm sections of which only the first is of smaller vertical height, hinged together and capable of being unfolded and of being placed one upon the other, make it possible to achieve the two-fold result of having a crane of considerable size when deployed and limited size when folded up in its transporting configuration. None of the hydraulic actuators used for the deploying of the machine&#39;s sections does any structural duty once the machine has been deployed; in the event of breakdown in any of the hydraulic actuators, therefore, these can be replaced even while the machine is assembled, using suitable means of access.