Bottom chord connection structure comprising connection device for connecting cantilever sections of tower crane cantilever

Abstract

The invention relates to a bottom chord connecting structure comprising a connecting device for connecting cantilever sections of a tower crane cantilever, the connecting device comprising: at least one connecting bolt, a first fastening part for fastening with a first pressure plate of the first cantilever section and with a second fastening part for fastening with a second pressure plate of the second cantilever section, the first fastening part being provided with releasable anti-torsion connecting means for fastening to the first pressure plate, the second fastening part is provided with a centering spindle for fastening to the second pressure plate, the centering spindle having a radial, in particular continuous, fixing groove for receiving the plug-in component; and a centering sleeve for insertion into a corresponding through-opening in the second pressure plate, the opening having an internal cross-section for receiving the second fastening portion, the cross-sections or diameters of both the centering sleeve and the corresponding through-opening in the second pressure plate being structurally designed to be in a clearance fit. Therefore, detachable connection of the cantilever sections is provided.

Description

[0001] This application is a divisional application of an invention patent application with an application date of June 28, 2023, application number 202380010687.4 (PCT / EP2023 / 067700), and invention name “Connecting device for connecting cantilever sections of a tower crane cantilever”. Technical Field

[0002] The present invention relates to a jib of a tower crane, in particular a jib of the type known in the art as a crane element, such as a trolley jib or a trolley carriage. The invention also relates to a bottom chord connection structure for connecting jib sections of such a jib. Background Art

[0003] The boom of a tower crane usually consists of individual boom sections which are detachably connected together by means of connecting devices. Such a boom has at least one bottom chord and at least one upper chord, among other structural features. The bottom chord is preferably made of a steel tube with a square profile, and the upper chord is made of flat steel, a steel tube with a square profile or a steel tube with a round profile. At least one upper chord is mainly used to absorb the forces resulting from tensile loads and is located in the head region of the boom section. At least one bottom chord is mainly used to absorb the forces resulting from compressive loads and is located in the foot region of the boom section. The boom sections are characterized by having connecting devices in the region where they are connected to each other. These connecting devices form an end closure for at least one upper chord or at least one bottom chord of the respective boom section.

[0004] Certain layouts of tower crane jibs are referred to as trolley jibs or trolley carriages, since they comprise rails (raceways) and lateral guides for a deflection device for the hoisting ropes, which deflection device is called a trolley or winch among experts.

[0005] Such cantilevers can also be used in steel construction structures, for example for the construction of mobile steel halls or festival halls, or for cantilevers of other crane types such as mobile harbour cranes or semi-fixed storage yard cranes, as long as such steel construction structures or crane cantilevers have steel construction or cantilever sections which are connected together by means of connecting devices and which are based on a truss or lattice structure.

[0006] The individual boom sections of a tower crane boom are usually connected to each other, i.e. assembled together, preferably on the ground before commissioning the crane. In special cases, boom sections are added to the boom of an already operating tower crane with the aid of detachable connection technology in order to extend the boom. The detachable connection must therefore be suitable for both installation situations and the structure must be designed accordingly.

[0007] The connection technology for assembling such a boom from boom segments usually consists of only a few connecting elements that are easy to handle, maintenance-free, free of backlash and low in wear.

[0008] For example, a cantilever of a tower crane is known from EP 1 728 756 B1. The cantilever is characterized by a connecting device, which is formed by a trunnion and a centering pin between two cantilever elements, a separate recessed portion for receiving these pins and the centering pin, and a fixing element, which is operatively connected to each other and connected to each other, fixing the cantilever sections to each other on the one hand and detachably connecting the cantilever sections to each other on the other hand. This connecting device is also known as Liebherr LiConnect among experts (see "LIEBHERR ECB LiConnect", website brochure page 18). For the connecting device used for the bottom chord of this cantilever section, the first disadvantage is that, due to the arrangement of the connecting device, the connecting device can only absorb forces via a limited area of ​​the end face of the bottom chord. The cross-members between the bottom chords on the foot side of the ECB cantilever will not convey any force in the front connection area of ​​the section, because with respect to the steel structure, these cross-members are not directly connected to each other in the connection area, in other words, these cross-members are not directly mechanically connected to each other. Since the transmitted forces are introduced exclusively in a limited area via the area of ​​the end face located outside the trunnion, the wear pattern of the connection designed with the aid of the LiConnect concept is therefore significant. The resulting load-bearing pattern is characterized by extremely high local forces and correspondingly developing stress peaks.

[0009] Furthermore, the transverse forces generated by the rotation of the tower crane in the foot region of the boom and the moments generated therefrom cannot be completely absorbed by a connection device designed in this way, that is to say, local reaction moments cannot be generated in particular by the trunnions, which can permanently lead to incremental deformations of the boom section in its foot region and in particular of the connection device. Therefore, the boom construction must be made solid with regard to the steel construction in the bottom chord and the integration of these steel constructions in the truss of the boom section. In this case, a further disadvantage is the relatively complex construction of the connection device, in particular in the region of the end of the bottom chord (the so-called joint) and of the enclosure of the trunnion and of the trunnion itself, in order to achieve a so-called sealing caulking, i.e. to ensure a permanent form fit of the connection elements and therefore of the joints with each other. Despite great efforts in terms of the steel construction, opening of the joint cannot be permanently avoided during crane operation. In addition, due to friction and dynamic load play, the trunnion wears in its receiving range, which wear cannot be subsequently adjusted or compensated, and this is why the tolerances of the mounting and the trunnion must be strictly defined from the outset.

[0010] From EP 1 468 955 A1, a tower crane boom is known, the end face of the bottom chord of which is designed as a cross member, and the end face of the bottom chord extends transversely to the longitudinal axis of the boom. The cross member has a circular cutout (hole), wherein the first cutout accommodates a clamping bolt, which is fixed by a plug-in component. The plug-in component that is not fixed in place is fixed by means of a fixing catch (pin) to prevent sliding out. The second circular cutout (hole) in the cross member accommodates a centering pin in the end face area of ​​the bottom chord. In the end face end of the bottom chord, the centering pin is placed on the cross member of the bottom chord to be connected, and the centering pin complementarily engages in the circular cutout of the end face end of the cross member of the other bottom chord to be connected. These centering pins are designed as a cylinder, which has a stepped section and two directly continuous, conical regions with different side pitches, wherein the cylindrical component in the end face section assumes the function of the sealing part.

[0011] The detachable connection device between the bottom chords is represented by a locking unit comprising several links, which are spatially adjacent to the corresponding end centering pins, but at a certain distance from the corresponding end centering pins. Each link unit comprises a clamping bolt, which is mounted so as to be displaceable along a bracket welded to the cross member in the longitudinal direction of the boom section parallel to the bottom chord. The corresponding connecting action between the bottom chords is achieved by pushing the clamping bolt into the circular cutout of the end cross member of the other boom section by sliding along a slide and inserting the locking plug-in part into the head of the clamping bolt. For the connection device for the boom parts designed in the described manner, a first disadvantage is that the connection unit can only absorb the forces and moments that occur inadequately. Another disadvantage is that the end cross member between the bottom chords at the foot end can only absorb the forces locally and to a limited extent in the end connection area of ​​the section, because in steel structures, these end cross members are not directly connected to each other over a large area in the connection area. Since the connection device is arranged at a certain distance from the end face of the bottom chord, the connection device mainly absorbs axial bending moments and only to a small extent transverse forces, without generating corresponding bearing forces or reaction moments. The forces acting on the bottom chord connection structure generate forces between the front fixing point and the connection creation point, which in turn leads to greater strain on the steel structure in order to be able to absorb these transferred forces without deforming the foot-side cantilever area and the connection elements. Another disadvantage is the relatively complex structure of such a connection device, which has many elements that need to be fixed to prevent loss.

[0012] The object of the invention is to further develop a detachable connection of a boom section which, on the one hand, comprises few components and is simple in design and, on the other hand, is suitable for absorbing large forces and moments acting on the boom element during crane operation. Forces and moments which change during crane operation should ideally be counteracted by forming local, adjustable load-bearing forces and counter-moments. Summary of the invention

[0013] This problem is solved by the following connection arrangement for the boom sections.

[0014] According to a first aspect, a bottom chord connection structure is provided with a connection device, in particular for connecting boom sections of a tower crane boom, the connection device comprising:

[0015] at least one connecting bolt having a first fastening portion for fastening to a first pressure plate of a first boom section and having a second fastening portion for fastening to a second pressure plate of a second boom section,

[0016] - wherein the first fastening part is provided with releasable anti-twist connection means for attachment to the first pressure plate,

[0017] - wherein the second fastening part is provided with a centering mandrel for fastening to the second pressure plate, said centering mandrel having a radial, in particular continuous, fixing groove for receiving the plug-in component;

[0018] at least one centering sleeve for insertion into a corresponding through-opening in the second pressure plate, the centering sleeve having an inner cross section for receiving the second fastening part,

[0019] - wherein the cross-section or the diameter of both the centering sleeve and the corresponding through-opening in the second pressure plate can be designed structurally as a clearance fit.

[0020] In particular, the first through-opening in the first pressure plate occurs at least once, which first through-opening can be designed such that the connecting bolt can be received in a form-fitting manner, in particular in the axial direction and in the radial direction of the through-opening. In particular, the through-opening in the second pressure plate can be designed such that the centering sleeve can be received in a form-fitting and friction-locking manner in the axial direction and in the radial direction of the through-opening in the second pressure plate.

[0021] The connection device according to the invention is therefore particularly characterized in that its elements advantageously combine the function of a detachable plug-in connection with the function of a fixed screw connection by means of an adjustable centering element and a fixing element.

[0022] The proposed connection device uses predominantly standard components and a small number of special components in the operational connection, wherein a high degree of standardization and computability is achieved in the design of the individual elements and thus ultimately a high functional reliability of the cantilever.

[0023] In order to increase the stiffness in the area of ​​the bottom chord, it has also been found to be advantageous if the bottom chords of the cantilever segments are connected to each other at the ends, preferably via at least two pressure plates. By establishing a planar contact between the at least two pressure plates, which close the front side of the cantilever segment in the area of ​​its foot, the two pressure plates function as two mechanically connected cross-members. In the steel structure, the bottom chords are held together by means of these cross-members, which can have the same external geometry and can thus produce a replication of the cross section in the area of ​​the foot of the cantilever segments, thereby absorbing forces and moments. The construction of the cantilever segment is thus reinforced in the area where the maximum bending and shear forces and moments act on the bottom chord.

[0024] By means of a pressure plate integrated in the front foot area of ​​the cantilever section, a maximum effective conveying area can be formed, via which a connection is established between the bottom chord areas of the two cantilever sections, and which is not only positioned in a limited area of ​​the surface directly in the area of ​​the end face end of the bottom chord, but also via the maximum front foot area, which extends in a plane formed transversely to the longitudinal axis of the cantilever or in a plane formed at a certain angle to the longitudinal axis of the cantilever.

[0025] Furthermore, it is advantageous if the connecting device comprises at least one connecting bolt, preferably made in one piece and rotationally symmetrical, a first through-opening in the first pressure plate and accommodating the connecting bolt, a centering sleeve arranged between the connecting bolt and a second through-opening of the second pressure plate, and a plug-in component.

[0026] The elements of the connecting device mounted on the boom sections to be connected complement each other. For this purpose, the first boom section has a first pressure plate in the foot region of its front end. The first pressure plate receives the connecting device, by means of which a second pressure plate is connected, which is present in the second boom section to be connected. The first and second pressure plates connected together by the connecting device are predominantly in contact with each other, and any frictional contact between the first and second pressure plates can be neglected when determining the connecting force generated between the boom sections by means of the connecting device.

[0027] It can be provided that the first fastening part has a second cylindrical side surface section, which in particular directly adjoins the second fastening part. In particular, the first fastening part can have a threaded section adjoining the second cylindrical side surface section in order to fasten the first fastening part to the first pressure plate by a threaded connection. The second cylindrical side surface section can be provided with an anti-rotation device, which is in particular formed with a centering pin protruding from the second cylindrical side surface section.

[0028] According to a preferred embodiment of the connection device, in order to accommodate several connection bolts in the same direction, it proves to be advantageous if the first pressure plate has several first through-holes and the second pressure plate has several corresponding second through-holes. In this case, the same (preferably parallel with respect to their longitudinal direction) orientation of the installed connection bolts is understood to be simultaneously accommodated, so that the connection bolts located in and on the pressure plates point in the same direction.

[0029] It can be provided that at least one other connecting bolt is provided with a first fastening portion for fastening to the second pressure plate of the second cantilever section, and is provided with a second fastening portion for fastening to the first pressure plate of the first cantilever section, wherein the first fastening portion is provided with a releasable connecting device for fastening to the second pressure plate, wherein the second fastening portion is provided with a centering spindle for fastening to the first pressure plate, the centering spindle having a radial, in particular continuous fixing groove for receiving an insert-type component, and a centering sleeve is provided, which is used to be inserted into a corresponding through opening in the first pressure plate, the centering sleeve having an internal cross-section for receiving the second fastening portion in a shape-fitting manner.

[0030] According to another conceivable embodiment of the connecting device, in order to accommodate several connecting bolts in an alternating manner, it proves to be advantageous if the first pressure plate and the second pressure plate each have at least one first through-opening and at least one second through-opening. The term "alternatingly mounted" means that the connecting bolts are oriented such that at least two of the connecting bolts located in the pressure plate and on the pressure plate point in opposite directions.

[0031] At least one first through-opening can be widened in its upper region in the form of a slot in order to accommodate a centering pin which advantageously secures the connecting bolt against rotation during the screwing of the connecting bolt to the pressure plate. This ensures that the insertion of the plug-in component into the fixing slot in the head of the connecting bolt can always be carried out vertically from above, which is an advantage when assembling the boom segments on the ground side on a building site and, in particular, when assembling the boom segments during crane operation, sometimes at high altitude. The connecting bolt is provided at one end with a first section (thread section) which is characterized by a first cross-section, in particular a metric thread with a normal pitch.

[0032] The second section of the connecting bolt has a first shoulder adjacent to the first section (threaded section), from which the first cross section of the connecting bolt widens to the second cross section of the connecting bolt. The first section and the second section form a first fastening part of the connecting bolt. A first contact area is formed between the first cross section of the connecting bolt and the second cross section of the connecting bolt, which first contact area can also be of non-circular shape and has a first chamfer in its upper area. By means of this chamfer, the connecting bolt can be screwed into the at least one first through-opening of the first pressure plate more easily, which is particularly advantageous for the assembly of the connecting bolt.

[0033] The second section of the connecting bolt (second cylindrical side surface section) is characterized by a first side surface in which a hole for receiving a centering pin is provided. When the connecting bolt is screwed in, the centering pin is received in a groove for radially fixing the connecting bolt in the extension of the at least one first through-opening of the first pressure plate.

[0034] During assembly, the first and second sections of the connecting bolt are inserted into at least one first through-opening of the first pressure plate. The locking washer is placed on the portion of the first section (threaded section) that protrudes from the mounting side of the first pressure plate and ensures a flat contact of the crown nut screwed onto the threaded section on the mounting side of the first pressure plate. This advantageously ensures that the screwing force is applied uniformly and predictably to the mounting side of the first pressure plate over a large cross section.

[0035] The side surface of the second section of the connecting bolt ends at a second shoulder and, through full-surface contact with at least one first through-opening of the first pressure plate, ensures, on the one hand, radial fixation of the connecting bolt in the first pressure plate and, on the other hand, a low-clearance connection between the connecting bolt and the first pressure plate.

[0036] Starting from the second shoulder, the third section of the connecting bolt (the first cylindrical side surface section) extends, whereby the second cross section of the connecting bolt widens to the third cross section of the connecting bolt. A second contact area is formed between the second cross section of the connecting bolt and the third cross section of the connecting bolt, which directly abuts against the end face of the first pressure plate. By means of the second contact area, the axial contact of the connecting bolt and the transmission of the axial pretensioning force generated by the connecting bolt to the end face of the first pressure plate are achieved.

[0037] The third section (first cylindrical side surface section) of the connecting bolt is characterized by the second side surface. This side surface merges into the fourth section of the connecting bolt, which is called the head section. The third section and the fourth section form the second fastening part of the connecting bolt.

[0038] Furthermore, the connecting bolt can have in its head region a section which tapers towards the second fastening part and adjoins the first cylindrical side surface section which can be received in the centering sleeve in the mounted state, in particular in a form-fitting manner.

[0039] The tapered section in the head region of the connecting bolt can be distinguished by a third side surface which is designed to be conical and thus forms a centering pin. The centering pin leads to a second chamfer which also forms the other end of the connecting bolt.

[0040] The second chamfer, together with the surface of the cone of the centering pin of the connecting bolt, facilitates the insertion of the connecting bolt and the centering sleeve into the at least one second through-opening of the second pressure plate. This greatly facilitates the assembly of the boom sections to be connected, which is particularly advantageous for the safe handling and assembly of the boom sections.

[0041] A further advantage of the novel connection device for the bottom chord connection is provided in particular by the introduction of a centering sleeve. To this end, it can be provided that the centering sleeve has a complete or partial circumferential flange, which can be provided at an axial end of the centering sleeve and is arranged in the assembled state in the direction of the second fastening part. The centering sleeve can thus be designed as a collar sleeve and is characterized by a first sleeve section, which has the shape of a tube, which does not necessarily have to be circular and has an inner wall and an outer wall with an intermediate surface, which does not necessarily have to be designed as an annular surface. At the first end of the first sleeve section, a chamfer can be arranged between the surface and the inner wall, which serves as an insertion aid complementary to the cone of the centering pin of the connecting bolt, facilitating the insertion of the centering sleeve onto the second side surface of the connecting bolt.

[0042] At the second end of the first sleeve section of the centering sleeve there is an undercut, to which the second sleeve section of the centering sleeve is connected. The second sleeve section features a circumferential flange with an inner flange area and an outer flange area. The flange area of ​​the flange thus has a first and a second bearing surface as well as an inner diameter and an outer diameter, and thus gives the second sleeve section the shape of a collar. The collar is cut off on one side of the outer cross section, which allows more leeway in the structural steel design of the cantilever section.

[0043] As described above, the centering sleeve is arranged between the side surface of the first cylindrical side surface section of the connecting bolt and the wall of the at least one second through-opening in the second pressure plate. For this purpose, the centering sleeve is dimensioned in the axial direction and in the radial direction such that: on the one hand, full-surface support is achieved on the maximum contact area of ​​the second side surface of the connecting bolt and on the other hand, full-surface support is achieved on the maximum contact area of ​​the wall of the at least one second through-opening of the second pressure plate. By means of the undercut between the first sleeve section and the second sleeve section of the centering sleeve, a planar and shoulder-free contact of the centering sleeve can be produced by the inwardly directed undercut radius between the first sleeve section and the second sleeve section of the centering sleeve.

[0044] The cross-sections or diameters of both the centering sleeve and the at least one second through-opening of the second pressure plate are designed structurally such that they are designed to have a clearance fit when they interact. As a result, the two elements ensure, on the one hand, an optimal transmission of radial forces acting on the centering pin and, on the other hand, an absorption of moments acting on the length of the centering pin clamped in the second pressure plate. When the centering sleeve is manufactured as a rotating part, strict tolerances should be imposed on the outer wall dimensions of the first sleeve section of the centering sleeve so that the outer wall of the first sleeve section has a minimum clearance in its installed position relative to the wall of the at least one second through-opening.

[0045] Another advantage of the connection device can be that the axial prestressing generated by the centering pin and the plug-in component by means of the axial force applied in particular in the second sleeve section via the joined inner and outer contact areas of the centering sleeve results in a uniform and maximum surface pressure between the first and second pressure plates. The elastic centering sleeve and the elastic pressure plate in combination with the bending-resistant centering pin improve the absorption of bending forces, transverse forces and moments and optimize the recovery properties of the connection device.

[0046] A further advantage of the centering sleeve can be that in particular it is designed with a completely or partially circumferential flange, which, as mentioned above, can be designed as a collar. The collar located in the second sleeve section is characterized in particular by having an inner flange area and an outer flange area. The bearing surface formed between the inner diameter and the outer diameter of the collar can be designed depending on the area of ​​the first and second pressure plates and the surface-related resistances. Due to their radial and planar contact in the first and second sleeve sections, it is ensured that axial and radial pre-tensioning forces are introduced over a large area and evenly distributed into the second pressure plate and / or the first pressure plate, which pre-tensioning forces are generated by the tensioning of the plug-in component in the fixing groove of the centering mandrel. The outer cross-section of the centering sleeve can be adjusted in the second sleeve section (i.e. the flange of the ring or the second sleeve section), which can advantageously maximize the internal flange area of ​​the centering sleeve for full-surface contact with the mounting side of the second pressure plate and / or the first pressure plate, and on the other hand, can maximize the outer flange area used for full-surface contact with the second contact area of ​​the plug-in component.

[0047] Furthermore, it can be provided that the flange of the centering sleeve is provided with one or more fastening means for non-rotational fastening to the first pressure plate and / or the second pressure plate.

[0048] In order to fix the connection device, a plug-in component is used, which is particularly preferably inserted from above into a fixing groove in the conical centering pin of the connecting bolt. The plug-in component can be designed with different lengths so that its contact area can be adapted to the outer flange area of ​​the second sleeve section of the centering sleeve.

[0049] Another advantage of the connection device is that it is adjustable. This adjustability is achieved in particular by means of a plug-in component, the position of which can be varied within a limited range.

[0050] After the connecting bolt has been pushed through at least one second through-opening in the second pressure plate and after the centering sleeve has been inserted into the free space formed between the second side surface of the connecting bolt and the wall of the at least one second through-opening, the plug-in component is inserted into the continuous fixing groove in the conical area of ​​the centering pin of the connecting bolt.

[0051] The plug-in component is solid and can have different outer contours in its corresponding contact areas. The outer contour of the first contact area forms a head-side termination and absorbs the clamping forces preferably introduced by hammering during assembly of the connecting device. The outer contour of the second contact area directly abuts against the outer flange area of ​​the centering sleeve in the assembled state of the connecting device and introduces axial clamping forces and radial clamping forces into the outer flange area by means of a positive fit. The outer contour of the third contact area can have a circular shape. By means of the rounding of the outer contour, full-surface contact of the third contact area of ​​the plug-in component against the outer wall of the fixing groove of the centering mandrel can be achieved, thereby achieving maximum tightening of the plug-in component in the centering mandrel.

[0052] The third contact area may form a certain angle with respect to the second contact area, and in the fixing groove of the connecting bolt, the plug-in component is pressed against the inner wall and the outer wall of the fixing groove respectively.

[0053] When mounted, the plug-in component can be secured against upward movement by means of a fixing insert, which can be designed in the form of a spring pin (standard component). Depending on the insertion depth of the plug-in component in the fixing groove, the fixing insert can be inserted into at least one fixing hole provided in the region of the lower leg of the plug-in component in order to fix the plug-in component in its corresponding position in the fixing groove. In this way, a permanent fixing of the plug-in component can be permanently ensured and therefore sufficient tensioning of the plug-in component can be ensured on the one hand in the fixing groove of the connecting bolt and on the other hand towards the outer contact region of the centering sleeve and thus towards the mounting side of the first pressure plate and / or the second pressure plate.

[0054] Depending on the wear of the bottom chord connection, which depends on the duration of use of the crane and the associated deformations of the individual boom sections, the strength of the bottom chord connection can be permanently maintained at a high level by sliding the plug-in part due to its own weight or by mechanical readjustment of the plug-in part, in particular by means of hammering.

[0055] In the case of a bottom chord connection, the connection device can be modeled as a fixed bearing. According to another aspect, in a preferred embodiment, in the embodiment of the connection device as a fixed bearing, it has been shown to be advantageous to relieve the load on the connection device according to the invention by means of a further cantilever connection. The further cantilever connection can be formed by an additionally introduced fixing device, which can be designed as a floating bearing complementary to the fixed bearing of the connection device. In this case, the fixed bearing can be located outside the end face of the bottom chord. The floating bearing can be arranged on the end face of the bottom chord or arranged in the end face. The contact area formed in the connection part directly above the end of the bottom chord and transverse to the longitudinal axis of the cantilever should be understood as the end face end of the bottom chord. By the interaction of the fixed bearing and the loose bearing, the bottom chords of the two cantilever sections to be connected, and in particular the connection parts above the ends of the bottom chords, are fixed to each other and fixed to each other in the correct position on the one hand, and are permanently and detachably connected to each other by means of an adjustable connecting force on the other hand.

[0056] A movable trolley may be arranged along the lower boom. During crane operation, when the trolley travels in the boom connection area, i.e. above the boom joint, the load suspended from the trolley may exert a maximum bending moment on the pressure plate in the end face area of ​​the bottom chord (chord). This may lead to a permanent, localized deformation of the front area of ​​the boom joint, thereby forming at least one step between oppositely located and adjacent boom joints. Since the bottom chord usually has a trolley running surface, such a step may lead to mechanical shocks during the travel of the trolley under load.

[0057] According to another aspect, the above-mentioned bottom chord connecting structure is provided with a connecting device, which connects two corresponding bottom chords of the cantilever section to each other, that is, connects the bottom chord of the first cantilever section and the corresponding bottom chord of the second cantilever section to each other, wherein a fixing device is provided at the end surfaces of the two corresponding bottom chords to fix the bottom chords to prevent the bottom chords from being laterally displaced relative to their axial direction.

[0058] It is therefore advantageous if additional fixing means introduced in the highly loaded bottom chord region of the pressure plate can support the centering effect of the connection means. This local support by the fixing means leads to an additional lightening of the connection means and to a permanent and low-wear fixing of the bottom chords to one another and to one another in the region of the connection above the front end of the bottom chord. In particular, the fixing means can be located centrally at the end face end, i.e. the surface of the connection of the bottom chord. Other arrangements of the fixing means in the bottom chord connection are conceivable, for example in the region above or below the structural center of the respective bottom chord or in the lateral direction.

[0059] Additionally, fixtures may include:

[0060] at least one screw spindle having a first fastening portion for fastening to the first pressure plate and having a second fastening portion for fastening to the second pressure plate,

[0061] wherein the second fastening portion has a side surface section for fastening the screw spindle to the second pressure plate,

[0062] wherein a sleeve is provided for insertion into a through opening in the second pressure plate,

[0063] Therein, the sleeve has an inner wall for receiving a covering surface section of the second fastening part located in the through-opening.

[0064] Furthermore, the first fastening portion may be provided with a threaded section for fastening the screw spindle to the threaded hole in the first pressure plate.

[0065] It may be provided that a side surface section of the second fastening part is received in the through-opening in a form-fitting and friction-fitting manner.

[0066] Therefore, in addition to the connection device according to the invention, at least one further fixing device can be provided, said fixing device comprising:

[0067] at least one screw spindle having a first fastening portion for fastening to a first pressure plate of a first boom section and having a second fastening portion for fastening to a second pressure plate of a second boom section,

[0068] The first fastening portion is provided with a threaded portion for fastening the screw spindle to the threaded hole in the first pressure plate.

[0069] wherein the second fastening portion has a side surface section for fastening the screw spindle to the second pressure plate,

[0070] - at least one sleeve, which is intended to be inserted into a corresponding through-opening,

[0071] wherein the through opening is located in the second pressure plate,

[0072] Therein, the sleeve has an inner wall for receiving a side surface section of the second fastening part in a form-locking and friction-locking manner.

[0073] A further advantage of the novel bottom chord connection is thus provided, in particular, by the introduction of an additional fixing device. The elements of the fixing device mounted on the boom sections to be connected complement each other. For this purpose, the first boom section has a first pressure plate in the foot region of its front end. The first pressure plate accommodates the above-mentioned connecting device as well as the fixing device, by means of which the second pressure plate present in the second boom section to be connected is connected. The first and second pressure plates connected together by means of the connecting device and the fixing device are predominantly in positive contact with each other over their entire surface, and any frictional contact between the first pressure plate and the second pressure plate can be neglected when determining the connecting forces generated between the boom sections by means of the connecting device and the fixing device.

[0074] Furthermore, it is advantageous if at least one of the fixing devices comprises a preferably one-piece and rotationally symmetrically designed screw spindle with a first fastening portion and a second fastening portion, a threaded hole in the first pressure plate and receiving the first fastening portion, a further through-opening in the second pressure plate and receiving the second fastening portion, and a bushing arranged between the second fastening portion and the further through-opening. It can be provided that the first fastening portion of the fixing device has a threaded portion which directly adjoins a preferably cylindrically formed side surface section of the second fastening portion of the fixing device. In particular, the first fixing section can be fixed by means of the threaded section by screwing the threaded section into the threaded hole in the first pressure plate. In the second fastening portion of the fixing device, a side surface section and a head region can be formed, wherein the side surface section can in particular have a cylindrical shape and the head region can in particular have a hexagonal profile. It is also conceivable that the side surface section and the head region can have a polygonal shape, for example a triangular, square or pentagonal shape. A chamfer can be formed between the head region and the side surface section of the second fastening portion. This chamfer may facilitate the insertion of the side surface section of the second fastening part into a bushing of complementary geometrical design.

[0075] The fixing device may comprise a bushing which may be arranged in a corresponding through-opening in the second pressure plate. The through-opening may be designed in particular as a hole, wherein the hole may in particular have a circular profile. The bushing may in particular be designed as a replaceable bushing and may in particular have the shape of a tube which does not necessarily have to be circular and has an inner wall and an outer wall with an intermediate surface which does not necessarily have to be designed as an annular surface. At a first end of the bushing, a chamfer may be arranged between the surface and the inner wall, which serves as an insertion aid complementary to the chamfer of the screw spindle and facilitates the screwing in of the side surface of the screw spindle during assembly. The second end of the bushing may be arranged just in front of the reinforcement plate and finds a spatial stop there. By means of this spatial stop, the bushing is fixed in its longitudinal direction against migration into the rear region of the bottom chord. The reinforcement plate serves, in the manner of a diaphragm, on the one hand to reinforce the bottom chord in the indirect region of the connection between the two bottom chords and, on the other hand, to seal the bottom chord against penetrating water and associated corrosion in the rear region of the bottom chord.

[0076] In order to accommodate several centering trunnions and several threaded pins in the same direction according to a preferred embodiment, it has proven to be advantageous if the first pressure plate has several first through-holes and the second pressure plate has several second through-holes corresponding to the first through-holes and further through-holes. The same orientation of the installed connecting bolts and screw spindles (preferably parallel with respect to their longitudinal direction) is then understood to mean that the connecting bolts and screw spindles located in and on the pressure plate point in the same direction.

[0077] Therefore, it can be provided that at least one other screw spindle is provided with a first fastening portion for fastening to the second pressure plate of the second cantilever section and is provided with a second fastening portion for fastening to the first pressure plate of the first cantilever section, wherein the first fastening portion of the other screw spindle is particularly provided with a metric thread with a standard pitch for fastening to the first pressure plate, wherein the second fastening portion of the other screw spindle is provided with: a side surface section for releasable fastening in the other through opening in the second pressure plate, and a bushing arranged to be inserted into the other through opening in the second pressure plate, the bushing having an inner cross-section with a corresponding shape, which is used to receive the side surface section of the second fastening portion of the screw spindle in a form-locked and friction-locked manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Further details of the invention are explained in more detail with reference to the exemplary embodiments shown in the accompanying drawings. In the same graphical representation, the same multiple references to components include both the singular and the plural of the corresponding elements depicted, in the accompanying drawings:

[0079] Figure 1a , Figure 1bis a schematic perspective view of an end face embodiment of a tower crane boom section in a non-assembled state;

[0080] Figure 2a , Figure 2b , Figure 2c is a perspective diagrammatic illustration of the foot region of two cantilever sections connected by means of a bottom chord connection structure according to one embodiment;

[0081] Figure 2d is a three-dimensional diagram of the foot region of two cantilever sections connected by means of a bottom chord connection structure according to another embodiment;

[0082] Figure 3a , Figure 3b is a perspective view of a pressure panel according to an embodiment, wherein the pressure panel is separated from a truss or grid structure of a cantilever section when viewed from an isolated perspective;

[0083] Figure 3c are side and perspective views of a pressure panel according to another embodiment, wherein the pressure panel is separated from a truss or lattice structure of a cantilever section when viewed from separate perspectives;

[0084] Figure 4 is a three-dimensional diagram (exploded view) of the elements of the bottom flange connection and the two pressure plates to be connected to each other;

[0085] Figure 5a is a perspective view of an element of a bottom flange connection according to a preferred embodiment and a pressure panel connected by means of a bottom flange connection according to a preferred embodiment;

[0086] Figure 5b is a perspective view of an element of a bottom flange connection according to another embodiment and a pressure panel connected by means of a bottom flange connection according to another embodiment;

[0087] Figure 6 are assembly elements of the bottom chord connection structure and cross-sectional views of the bottom chord and the pressure plate;

[0088] Figure 7 It is a side view and a three-dimensional view of the connecting bolt;

[0089] Figure 8 are side and perspective views of the centering sleeve; and

[0090] Fig. 9 It is a stereogram of the inserted part;

[0091] Fig.10a , Fig.10b is a perspective schematic representation of an end face of a preferred embodiment of a tower crane boom section in a non-assembled state;

[0092] Fig.11a is a cross-sectional view of the foot region of two cantilever sections connected by means of a connecting device and a fixing device according to a preferred embodiment;

[0093] Fig.11b is a cross-sectional view of assembly elements of a fixing device and a connecting device, a bottom chord, and a pressure plate according to a preferred embodiment of a bottom chord connecting structure;

[0094] Fig.12 is a cross-sectional view of assembly elements of a fixing device and a bottom chord and a pressure plate according to a preferred embodiment of a bottom chord connection structure;

[0095] Fig.13a , Fig.13b is a perspective view of a pressure panel according to a preferred embodiment of a bottom chord connection structure, wherein the pressure panel is respectively separated from the truss or grid structure of the cantilever section when viewed from an individual perspective. DETAILED DESCRIPTION

[0096] Figure 1a , Figure 1b The connection area of ​​two embodiments of a boom section 1 is shown, the boom section 1 comprising a top chord 2, a top chord connection 21a and an end face of a pressure plate 5 connecting and terminating a bottom chord 3. The shown elements of the top chord connection 21a of the first boom section 1 are connected to complementary elements (not shown) of the top chord connection 21b of the second boom section 1b. At least one bottom chord connection structure with a connection device 4a of the first boom section 1a is attached to the pressure plate 5 for conveying purposes.

[0097] An element of the at least one bottom chord connection is positioned in the foot region of the end face of the boom section 1 a and outside the end face end 51 of the bottom chord 3 .

[0098] Figure 2a , Figure 2b , Figure 2c The foot regions of two cantilever segments 1a, 1b connected to each other by means of a bottom chord connection structure and the integration of these foot regions into the truss or grid structure of the respective cantilever segments 1a, 1b are shown in different spatial perspectives. The end faces 53 of the pressure plates 5a, 5b abut directly against each other and are nearly flush with each other at the end face ends 51 of the bottom chord 3 (not visible in this illustration in the assembled state). At least one bottom chord connection structure of this preferred embodiment is mounted on the pressure plate 5a or 5b and is positioned in the space near the bottom chord 3 in the foot region of the cantilever segments 1a, 1b. Figure 2a and Figure 2bThe figure shows the heads of locking screws (standard screws), which are positioned in holes 78 (not shown) on the outer flange area 75 of the flange 70 of the centering sleeve 7 and with the help of which the centering sleeve 7 is screwed into a standard thread (not shown) on the mounting side 52 of the pressure plate 5a, thereby fixing the centering sleeve 7 to prevent loss and / or rotation. Figure 2c The crown nut 10 and the washer 9 are shown positioned on the mounting side 52 of the pressure plate 5b as elements of the bottom flange connection 4.

[0099] Figure 2d The foot regions of two boom sections 1a, 1b connected to one another by means of a bottom chord connection structure and the integration of these foot regions into the truss or grid structure of the respective boom section 1a, 1b are shown in spatial perspective. The pressure plates 5c with their end faces 53 directly abut against one another and are nearly flush with one another at the end face ends 51 (shown in dashed lines) of the bottom chord 3. The elements of at least one bottom chord connection structure of another embodiment are each mounted on a pressure plate 5c on a mounting side 52 and are positioned spatially adjacent to the bottom chord 3 in the foot region of the boom section 1a, 1b.

[0100] Figure 3a A pressure plate 5a is shown separated from the truss or lattice structure of the respective boom section 1b, 1b according to the preferred embodiment. A second through-opening 56 in the pressure plate 5a receives a centering sleeve 7 (not shown) on its wall.

[0101] Figure 3b A pressure plate 5b is shown separated from the truss or lattice structure of the respective cantilever section 1a, 1b according to the preferred embodiment. The first through holes 54 in the pressure plate 5b are each widened in their upper region by a recess 55. The walls of the first through holes 54 in the pressure plate 5b each receive a side surface 63 (second side surface section) of a connecting bolt 6 (not shown). The mounting side 52 of the pressure plate 5b is a contact area for locking a washer 9 (not shown).

[0102] Figure 3c A pressure plate 5c is shown separated from the truss or lattice structure of the corresponding boom section 1a, 1b according to another embodiment. A first through-opening 54 in the pressure plate 5c is widened in its upper region by a recess 55. The wall of the first through-opening 54 in the pressure plate 5c receives the side surface 63 (second side surface section) of the connecting bolt 6 (not shown). The second opening 56 in the pressure plate 5c receives the centering sleeve 7 (not shown) on its wall. The mounting side 52 of the pressure plate 5c is a contact area for locking a washer 9 (not shown).

[0103] exist Figure 3a , Figure 3b and Figure 3c, the end face end 51 represents the outer end portion of the pressure panels 5a, 5b and 5c which is positioned in the end face end of the bottom chord 3 (not shown).

[0104] Figure 4 The bottom chord connection structure 4a is shown as a separate element from the truss or lattice structure of the respective boom section 1a, 1b in a non-assembled state without being joined to the respective pressure plate 5a, 5b or 5c (exploded view). The first fastening portion of the connection bolt 6, which can be inserted into the first through-opening 54 and the slot-shaped extension 55 on the end face 53 of the first pressure plate 5b or 5c, is screwed during the subsequent assembly on the assembly side 52 of the pressure plate 5b or 5c by means of the threaded section 64 (not shown) and the washer 9 and the crown nut 10. The second fastening portion of the connecting bolt 6, which can be inserted into the second through-opening 56 of the second pressure plate 5a or 5c, is subsequently fixed during assembly on the assembly side 52 of the second pressure plate 5a or 5c by means of a centering sleeve 7 inserted into the second through-opening 56 on the assembly side 52 and a plug-in component 8 (not shown) located in the fixing groove 69 and a spring connector (not shown) located in the fixing hole 84 (not shown) of the plug-in component 8 (not shown) during the subsequent assembly process.

[0105] Figure 5a A preferred embodiment is shown separated from the truss or lattice structure of the respective boom section 1a, 1b with the connection means 4a of the bottom chord connection structure and the different pressure plates 5a and 5b in the assembled state. It can be seen that the connection means 4a are mounted on the respective pressure plates 5a and 5b in the same direction and that the elements of the bottom chord connection structure 4a protrude from the respective mounting side 52 of the pressure plate 5a. The end faces 53 (not shown) of the pressure plates 5a and 5b abut against each other over their entire surface, wherein the connection of the pressure plates 5a and 5b achieves a high degree of tightness by means of the form and friction fit between the end faces 53.

[0106] Figure 5b Another embodiment is shown, in which the bottom chord connection structure is separated from the truss or grid structure of the respective boom section 1a, 1b and two identical pressure plates 5c are in the assembled state. It can be seen that the bottom chord connection structure is alternately mounted on the respective pressure plates 5c and that elements of the bottom chord connection structure protrude from the respective mounting sides 52 of the pressure plates 5a and 5c. The end faces 53 (not shown) of the pressure plates 5c abut against each other over their entire surface, wherein the connection of the pressure plates 5c achieves a high degree of tightness by means of the form and friction fit between the end faces 53.

[0107] Figure 6A section through the connecting device 4a of the bottom chord connection in its mounted position is shown in the pressure plates 5 (in the embodiment 5a, 5b or 5c) connected to each other by the connecting device 4a. The end faces 53 of the pressure plates 5 (in the embodiment 5a, 5b or 5c) bear against each other over their entire surface. The connecting bolt 6 is screwed to the first pressure plate 5b or 5c by means of its screw thread section 64 and the matching washer 9 and the crown nut 10 on the mounting side 52. In order to fix the position during the screwing of the connecting bolt 6 to the first pressure plate 5b or 5c, the centering pin 613 is positioned in the slot-shaped extension 55 of the first through-opening 54.

[0108] In radial direction, the centering sleeve 7 receives the side surface 62 (first side surface section) of the connecting bolt 6 on its inner wall 71 of the first sleeve section. In axial direction of the centering sleeve 7, the plug-in component 8 rests against the outer flange area 75 of the second sleeve section.

[0109] The centering sleeve 7 transmits the axial pretensioning force generated by the connecting bolt 6 and the plug-in component 8 located in the fixing groove 69 to the mounting side 52 of the second pressure plate 5 (in embodiment 5a or 5c) by means of the flange 70 formed in its second sleeve section via the outer flange area 75 of the flange 70 and the inner flange area 76 of the flange 70.

[0110] In addition, the centering sleeve 7 transmits the radial pretensioning force introduced by the connecting bolt 6 via its side surface 62 (first side surface section) to the wall of the second through opening 56 of the second pressure plate 5 (in embodiment 5a or 5c) by means of the inner wall 71 and the outer wall 72 of its first sleeve section.

[0111] Figure 7 Details of the connecting bolt 6 are shown. In particular, the side surface 63 (second side surface section) and the side surface 62 (first side surface section) as well as the first contact area 65 and the second contact area 66 represent the surfaces via which the axial and radial pretensioning forces of the bottom chord connection 4 generated by the connecting bolt 6 are introduced into the end face 53 (not shown) of the pressure plate 5a, 5b or 5c (not shown) and the inner wall 71 (not shown) of the centering sleeve 7 (not shown).

[0112] Figure 8Details of the centering sleeve 7 are shown. The tubular first sleeve section of the centering sleeve is delimited by an inner wall 71 and an outer wall 72 and by a surface 73 between the inner wall 71 and the outer wall 72, and ends in an undercut 79. The second sleeve section of the centering sleeve starts from the undercut 79 and is a circumferential flange 70 in the form of a collar. The circumferential flange 70 has an outer flange area 75 and an inner flange area 76 and a side end 77. Holes 78 located in the flange 70 receive standard screws (not shown) for fixing the centering sleeve 7 to the mounting side 52 of the pressure plate 5a or 5c. These locking screws (not shown) are screwed onto the mounting side 52 of the pressure plate 5a or 5c by means of a standard thread located in the pressure plate 5a or 5c (not shown) and are used to fix the centering sleeve 7 to prevent loss and / or rotation.

[0113] Fig. 9 A detail of a plug-in component 8 is shown. The plug-in component 8 is located in an assembly or insertion position in a fixing groove 69 (not shown), which is positioned in the side surface 61 (third side surface section, not shown) of the conical centering pin of the connecting bolt 6 (not shown). The outer contour 82 of the plug-in component 8 represents the contact area with the inwardly oriented wall 610 (not shown) of the fixing groove 69 (not shown) on the one hand and with the outer flange area 75 (not shown) of the centering sleeve 7 (not shown) on the other hand. The outer contour 83 represents the contact area of ​​the plug-in component 8 with the outwardly oriented wall 611 (not shown) of the fixing groove 69 (not shown) of the connecting bolt 6 (not shown). The outer contour 81 serves as a receiving surface for hammer strikes, which enter for fixing and, if necessary, readjusting the plug-in component 8 in the fixing groove 69 (not shown).

[0114] At least one fixing hole 84 in the lower region of the plug-in component 8 can receive a spring pin (standard component, not shown) for fixing the plug-in component 8. When the plug-in component 8 is in the inserted and set or readjusted position, the at least one fixing hole 84 is positioned in the space below the fixing groove 69 (not shown) of the connecting bolt 6 (not shown).

[0115] Fig.10a and Fig.10bThe connection area of ​​two boom sections 1a, 1b according to a preferred embodiment is shown, the boom sections 1a, 1b each comprising a top chord 2, terminating top chord connections 21a, 21b and an end face 53 of a pressure plate 5 connecting and terminating a bottom chord 3. The shown elements of the top chord connection 21a of the first boom section 1a are connected to complementary elements of the top chord connection 21b of the second boom section 1b. Two fixing means 4b and two connecting means 4a of the first boom section 1a are fixed to the pressure plate 5. In the end face end 51 of each of the bottom chords 3 a corresponding threaded pin 40 is located for the fixing connection 4b in the foot region of the boom section 1a. At least one through opening 56 is located in the pressure plate 5 in the foot region of the boom section 1b and between the end face ends 51.

[0116] At least one through-opening 57 for receiving the screw spindle 40 is positioned in the pressure plate 5 in the foot region of the cantilever section 1 b and within the face end 51 .

[0117] Fig.11a The foot region of two boom sections 1a, 1b connected to each other by means of a bottom chord connection 4a and 4b according to a preferred embodiment is shown in a cross-sectional view (top view). The pressure plates 5a, 5b bear directly against each other with their end faces 53. The connecting device 4a and the fixing device 4b are mounted on the pressure plates 5a and 5b and are positioned in the spatial vicinity of the bottom chord 3 in the foot region of the boom sections 1a, 1b.

[0118] Fig.11b The cross section of the foot region of two boom sections 1a, 1b connected to each other by means of a connecting device 4a and a fixing device 4b according to a preferred embodiment is shown in a sectional view (top view). The connecting device 4a and the fixing device 4b are mounted on pressure plates 5a and 5b and are positioned in the spatial vicinity of the bottom chord 3 in the foot region of the boom sections 1a, 1b.

[0119] The fixing device 4b comprises a bushing 45 arranged in a corresponding through-opening 57 in the pressure plate 5a, the bushing 45 and the through-opening 57 preferably having no play relative to each other. This ensures that the bushing 45 is firmly mounted in the through-opening 57 on the one hand and can be pulled out and replaced on the other hand, preferably by means of a bushing pulling tool applied to the inner wall 46 of the bushing 45.

[0120] Fig.12A cross section of two cantilever sections 1a, 1b connected to each other by means of a fixing device 4b according to a preferred embodiment is shown in a cross-sectional view (side view). The screw spindle 40 has a threaded section 41 in a first fixing section. The threaded section 41 is screwed into a threaded hole 58, which is arranged in the end face end 51 of the pressure plate 5b. In the second fastening section, the screw spindle 40 has a side surface section 42 directly adjoining the threaded section 41. In the assembled state, the side surface section 42 of the screw spindle 40 is positioned directly above the end face 53 of the pressure plate 5b and is in form-fitting and frictional contact with the inner wall 46 of the bushing 45. The chamfer 44 can be positioned between the head 43 of the screw spindle 40 and the side surface section 42 of the screw spindle 40 and facilitates screwing the screw spindle 40 into the bushing 45. In particular, the head 43 can be hexagonal in shape to receive a tool that can be in the form of an open-end spanner.

[0121] The outer wall 47 of the bushing 45 directly abuts against the wall of the through-opening 57 in the pressure plate 5a. In the assembled state, the bushing 45 is located directly in front of the reinforcing plate 31 which delimits the rear end region in the bottom chord 3. In the rear end region, the bushing 45 is not fixed to the through-opening 57 or the reinforcing plate 31, but the outer wall 47 of the bushing 45 has a slightly larger dimension than the diameter of the through-opening 57 and is detachably mounted in the rear end region by means of a press fit.

[0122] Fig.13a A pressure plate 5a is shown separated from the truss or lattice structure of the respective boom section 1b, 1b according to the preferred embodiment. The through opening 56 in the pressure plate 5a receives the centering sleeve 7 (not shown) on its wall. The through hole 57 in the pressure plate 5a receives the bushing 45 (not shown) on its wall.

[0123] Fig.13b A pressure plate 5b is shown separated from the truss or lattice structure of the respective boom section 1a, 1b according to the preferred embodiment. The through openings 54 in the pressure plate 5b are each widened in their upper region by a recess 55. The walls of the through openings 54 in the pressure plate 5b each receive a side surface 63 (second side surface section) of a connecting bolt 6 (not shown). The threaded holes 58 in the pressure plate 5b are provided with a metric internal thread (not shown) which receives a metric external thread of a screw spindle 40 (not shown) in the threaded section 41.

[0124] Reference numerals list

[0125] 1a, 1b cantilever section

[0126] 2 Top String

[0127] 21a, 21b top string connection

[0128] 3 Bottom String

[0129] 31 Reinforcement plate

[0130] 4a Connecting device

[0131] 4b Fixing device

[0132] 40 Screw spindle

[0133] 41 Threaded section of screw spindle

[0134] 42 Side surface section of screw mandrel

[0135] 43 Head area

[0136] 44 Chamfer

[0137] 45 Bushing

[0138] 46 Inner wall of bushing 45

[0139] 47 Outer wall of bushing 45

[0140] 5 Pressure Plates (Pressure Plates 5a, 5b, 5c)

[0141] 51 End of the end face above the end of the bottom chord

[0142] 52 Mounting side of pressure plates 5a, 5b, 5c

[0143] 53 End surfaces of pressure plates 5a, 5b, 5c

[0144] 54 First through opening in pressure plate 5b, 5c

[0145] 55 Slot-shaped extension of the first through opening 54

[0146] 56 Second through opening in pressure plate 5a, 5c

[0147] 57 Through openings in pressure plates 5a, 5c

[0148] 58 Threaded hole in pressure plate 5b

[0149] 6 Connecting bolts

[0150] 61 Side surface of the centering mandrel of the connecting bolt (conical) (third side surface section)

[0151] 62 Side surface of connecting bolt (cylindrical) (second side surface section)

[0152] 63 Side surface of connecting bolt (cylindrical) (first side surface section)

[0153] 64 Screw thread section

[0154] 65 First contact area of ​​the connecting bolt

[0155] 66 Second contact area of ​​the connecting bolt

[0156] 67 Chamfer (between side section 1 and side section 2)

[0157] 68 Chamfer (between side section 1 and side section 2)

[0158] 69 Fixing groove in the centering spindle of the connecting bolt (fourth section)

[0159] 610 Inner wall of the fixing groove (contact area of ​​the outer contour 1 of the plug-in component 8)

[0160] 611 Outer wall of the fixing groove (contact area of ​​the outer contour 2 of the plug-in component 8)

[0161] 612 Hole in the side surface 63 of the connecting bolt

[0162] 613 Centering pin for centering the connecting bolt in the groove-shaped extension 55

[0163] 7 Centering sleeve

[0164] 70 Flange (second sleeve section of centering sleeve, collar)

[0165] 71 Inner wall of the first sleeve section of the centering sleeve

[0166] 72 Outer wall of the first sleeve section of the centering sleeve

[0167] 73 Area between the inner wall and the outer wall of the first sleeve section of the centering sleeve

[0168] 74 Chamfer between the area of ​​the first sleeve section of the centering sleeve and the inner wall

[0169] 75 The outer flange area of ​​the flange 70, the outer contact of the second sleeve section of the centering sleeve

[0170] Area (contact area for the second contact area of ​​the plug-in component)

[0171] 76 The inner flange area of ​​the flange 70, the inner contact of the second sleeve section of the centering sleeve

[0172] Area (contact area available for the mounting side of the pressure plate)

[0173] 77 Lateral end of centering sleeve

[0174] 78 Hole for locking screw

[0175] 79 Gap between the first sleeve section and the second sleeve section of the centering sleeve

[0176] 8 Plug-in components

[0177] 81 Outer contour of first contact area of ​​plug-in component

[0178] 82 Outer contour of the second contact area of ​​the plug-in component

[0179] 83 Outer contour of the third contact area of ​​the plug-in component

[0180] 84 Fixing hole for receiving spring plug connector (standard part)

[0181] 9 Washer (standard part)

[0182] 10 Crown nut (standard part)

Claims

1. A bottom chord connection structure comprising a connection device (4a), the connection device (4a) being used to connect a cantilever section (1) of a cantilever of a tower crane, the connection device (4a) comprising: at least one connecting bolt (6) having a first fastening portion (9, 10, 63, 64) for fastening to a first pressure plate (5, 5a, 5b, 5c) of a first boom section (1a) and a second fastening portion (61, 62) for fastening to a second pressure plate (5, 5a, 5b, 5c) of a second boom section (1b), wherein the first fastening part (9, 10, 63, 64) is provided with a releasable anti-twist connection device for fastening to the first pressure plate (5, 5a, 5b, 5c), wherein the second fastening part (61, 62) is provided with a centering mandrel for fastening to the second pressure plate (5, 5a, 5b, 5c), the centering mandrel having a radial, continuous fixing groove (69) for receiving the plug-in component (8); a centering sleeve (7) for insertion into a corresponding through-opening (54, 56) in the second pressure plate (5, 5a, 5b, 5c), the centering sleeve (7) having an inner cross section for receiving the second fastening portion (61, 62), Therein, the cross-sections or diameters of both the centering sleeve and the corresponding through-opening in the second pressure plate can be designed structurally to be a clearance fit.

2. The bottom chord connection structure comprising a connection device (4a) according to claim 1, wherein: The centering mandrel has a section which tapers toward the second fastening portion (61, 62) and adjoins a first cylindrical side surface section which, in the assembled state, can be received in the centering sleeve in a form-fitting manner.

3. The bottom chord connection structure comprising a connection device (4a) according to claim 2, wherein: The centering sleeve (7) has a completely or partially circumferential flange (70) with a flange area (75, 76), which is provided at an axial end of the centering sleeve (7) and is arranged in the direction of the second fastening part (61, 62) in the assembled state.

4. The bottom chord connection structure comprising a connection device (4a) according to claim 3, wherein: The flange (70) is provided with flange areas (75, 76) and holes (78) for non-rotational fastening and fixing to the second pressure plate (5, 5a, 5b, 5c) by means of one or more fastening means.

5. A bottom chord connection structure comprising a connection device (4a) according to any one of claims 1 to 4, wherein: The first fastening portion (63, 64) has a second cylindrical side surface section directly adjacent to the second fastening portion (61, 62).

6. The bottom chord connection structure comprising the connection device (4a) according to claim 5, wherein: A threaded portion (64) abuts the second cylindrical side surface section (63) to fasten the first fastening portion (63, 64) to the first pressure plate (5, 5a, 5b, 5c) by threaded connection.

7. The bottom chord connection structure comprising the connection device (4a) according to claim 6, wherein: The second cylindrical side surface section (63) is provided with an anti-twist connection device, which is formed with a centering pin (613) protruding from the second cylindrical side surface section.

8. A bottom chord connection structure comprising a connection device (4a) according to one of claims 1 to 4, wherein: The second pressure plate (5, 5a, 5b, 5c) is provided with a continuous second through-opening (56) for receiving the centering sleeve (7) in the axial direction and in the radial direction in a form-locking and friction-locking manner.

9. The bottom chord connection structure comprising the connection device (4a) according to claim 5, wherein: The first pressure plate (5, 5a, 5b, 5c) is provided with a first through opening (54) for receiving the second cylindrical side surface section (63) in a radial direction and an axial direction in a form-locking and friction-locking manner, wherein, in an assembled state, the axial end of the first cylindrical side surface section (62) of the second fastening part (61, 62) abuts against the first pressure plate (5, 5a, 5b, 5c).

10. The bottom chord connection structure comprising the connection device (4a) according to claim 9, wherein: The first cylindrical side surface section (62) has an axial length at least equal to the thickness of the second pressure plate (5, 5a, 5b, 5c), wherein the fixing groove (69) is arranged so that in an assembled state where the first pressure plate (5, 5a, 5b, 5c) and the second pressure plate (5, 5a, 5b, 5c) are in close contact with each other, a force is applied to the second pressure plate (5, 5a, 5b, 5c) along the direction of the second fastening portion (61, 62) when the plug-in component (8) is inserted.

11. A bottom chord connection structure comprising a connection device (4a) according to any one of claims 1 to 4, wherein: at least one other connecting bolt (6) is provided with a first fastening portion for fastening to the second pressure plate (5, 5a, 5b, 5c) of the second boom section (1b) and a second fastening portion for fastening to the first pressure plate of the first boom section (1a), wherein the first fastening portion (63, 64) is provided with releasable connection means for fastening to the second pressure plate (5, 5a, 5b, 5c), wherein the second fastening portion (61, 62) is provided with a centering mandrel for fastening to the first pressure plate (5, 5a, 5b, 5c), the centering mandrel having a radial, continuous fixing groove for receiving a plug-in component (8); - a centering sleeve (7) for insertion into a corresponding through-opening in the first pressure plate (5, 5a, 5b, 5c), the centering sleeve (7) having an inner cross section for receiving the second fastening part (61, 62) in a form-fitting manner.

12. A bottom chord connection structure comprising a connection device (4a) according to any one of claims 1 to 4, in, The bottom chord connection structure connects the two bottom chords (3) of the cantilever sections (1a, 1b) to each other. A fixing device (4b) is provided at the end surface of each of the two bottom chords (3) so as to fix the bottom chord (3) to prevent displacement in a direction transverse to the axial direction of the bottom chord (3).

13. The bottom chord connection structure comprising the connection device (4a) according to claim 12, wherein: The fixing device (4b) comprises: at least one screw spindle (40) having a first fastening portion for fastening to the first pressure plate (5, 5b, 5c) and a second fastening portion for fastening to the second pressure plate (5, 5a, 5c), wherein the second fastening portion of the screw spindle (40) has a side surface section (42) for mounting the screw spindle (40) to the second pressure plate (5, 5a, 5c), wherein a bushing (45) is provided for insertion into a through opening (57) in the second pressure plate (5, 5a, 5c), The bushing (45) has an inner wall (46) for receiving the side surface section (42) of the second fastening portion of the screw spindle (40).

14. The bottom chord connection structure comprising the connection device (4a) according to claim 13, in, The first fastening portion of the screw spindle (40) is provided with a threaded portion (41) for fastening the screw spindle (40) to a threaded hole (58) in the first pressure plate (5, 5b, 5c).

15. The bottom chord connection structure comprising the connection device (4a) according to claim 14, wherein: The side surface section (42) of the second fastening part of the screw spindle (40) is received in the through-opening (57) in a form-fitting and friction-fitting manner.

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