WO2024003167A1

WO2024003167A1 - Connection device for connecting jib segments of a jib of a tower crane

Info

Publication number: WO2024003167A1
Application number: PCT/EP2023/067700
Authority: WO
Inventors: Thomas Heidrich; Björn-Philipp Hessenmüller; Steffen Hildenbrand; Wolfgang Ingelfinger; Stefan Reinhard; Patrick WITTECK
Original assignee: Wolffkran Holding Ag
Priority date: 2022-06-30
Filing date: 2023-06-28
Publication date: 2024-01-04

Abstract

The invention relates to a connection device, in particular for connecting jib segments (1) of a jib of a tower crane, comprising: - at least one connection bolt (6) with a first securing part (9, 10, 63, 64) for securing to a first pressure plate (5, 5a, 5b, 5c) of a first jib segment (1) and with a second securing part (61, 62) for securing to a second pressure plate (5, 5a, 5b, 5c) of a second jib segment (1), wherein the first securing part (9, 10, 63, 64) is provided with a releasable non-rotating connection device for securing to the first pressure plate (5, 5a, 5b, 5c), and the second securing part (61, 62) is provided with a centering pin for securing to the second pressure plate (5, 5a, 5b, 5c), said centering pin having a securing groove (69), in particular a continuous securing groove, for receiving a radial plug-in wedge (8); and - a centering sleeve (7) for inserting into a corresponding through-opening in the second pressure plate (5, 5a, 5b, 5c), said through-opening having an inner cross-section in order to receive the second securing part (61, 62) in a form-fitting manner.

Description

Connecting device for connecting boom segments of a boom of a tower crane

Description

Technical area

The present invention relates to a boom of a tower crane, in particular a boom in the design of a crane element known in specialist circles as a trolley boom or trolley jib. The invention further relates to lower chord connections for connecting boom segments for such a boom.

Technical background

Booms of tower cranes usually consist of individual boom segments that are detachably connected using connecting devices. Such booms have, among other design features, at least one lower chord and at least one upper chord. Lower chords are preferably made from steel tubes with a square profile, upper chords from flat steel, steel tubes with a square profile or from steel tubes with a round profile. The at least one upper chord serves primarily to absorb forces resulting from tensile loads and is located in the head area of a boom segment. The at least one lower chord serves primarily to absorb forces resulting from pressure loads and is located in the foot area of a boom segment. The boom segments have connecting devices in the areas in which they are connected to one another. These connecting devices form the front end of the at least one upper chord or the at least one lower chord for the boom segment in question.

Certain versions of tower crane booms are referred to as trolley jibs or trolley jibs because they have a track (track) and a lateral guide for include a deflection device for a hoist rope, known in specialist circles as a trolley or cat.

Such booms can also be used within steel construction structures, e.g. in mobile steel hall or festival hall construction, or in booms of other types of cranes, such as mobile harbor cranes or semi-stationary storage yard cranes, insofar as such steel construction structures or crane booms are made of steel constructions connected by means of a connecting device. or have cantilever segments that are based on a truss or lattice structure.

The individual boom segments of a tower crane jib are usually connected to each other, i.e. assembled, preferably on the ground before the crane is put into operation. In exceptional cases, boom segments are added to the boom of a tower crane that is already in operation using detachable connection techniques in order to extend it. Detachable connections must therefore be suitable for both installation scenarios and be structurally designed accordingly.

The connection techniques used to build such a boom from boom segments generally include a few easy-to-use, maintenance-free, play-free and low-wear connecting elements.

A boom of a tower crane is known, for example, from EP 1 728 756 B1. This has a connecting device formed from pins and centering pins between two cantilever elements, separate recesses that accommodate these pins and centering pins, and fixing elements, which are in operative connection with one another and with one another, on the one hand fixing the cantilever segments to one another and, on the other hand, releasably connecting them to one another. In specialist circles, this connection device is also known as Liebherr LiConnect (see “LIEBHERR ECB LiConnect”, website brochure p.18). With such a connecting device for lower chords of boom segments, a first disadvantage is that, due to its arrangement, the connecting device can only absorb the forces over the limited area of the end faces of the lower chords. The trusses of the ECB boom located between the bottom chords do not transmit any forces within the front connection area of the segments because these trusses in the connection area are not directly tied to one another in the steel construction, in other words they are mechanically directly coupled to one another. The wear pattern of a using the concept of The connecting device designed by LiConnect is correspondingly strong because the transmitted forces are introduced exclusively in a limited area via the surfaces of the end faces that are located outside the pin. The resulting contact pattern is characterized by locally extremely high forces and corresponding stress peaks.

Furthermore, transverse forces generated by the rotation of the tower crane in the foot area of the boom and the resulting moments cannot be completely absorbed by a connecting device designed in this way, or local counter moments can be generated in particular by the pin, which permanently leads to incremental deformations of the boom segment in its foot area. but in particular the connecting device can lead. The cantilever construction must therefore be made of solid steel in the lower chords and with regard to the integration of these into the truss structure of the cantilever segment. In this context, another disadvantage that should be mentioned is the relatively complex structure of the connecting device, especially in the area of the front ends of the lower flanges (so-called joints) as well as the edging of the pin, as well as the pin itself, in order to ensure a so-called sealing caulking, i.e. ensuring a permanent seal To achieve positive locking of the connecting elements and thus the joints between each other. Despite this high level of steel construction effort, opening the joints during crane operation cannot be permanently avoided. In addition, the pin wears within its receptacle due to friction and dynamic bearing play, which cannot be subsequently adjusted or compensated for and which is why the tolerances of the receptacle and the pin must be designed tightly from the start.

From EP 1 468 955 A1 a tower crane boom is known, the front end plates of the lower chords are designed as cross members and extend transversely to the longitudinal axis of the boom. The cross members have round cutouts (holes), a first cutout of which accommodates a clamping bolt, which is fixed by a plug-in wedge. The plug-in wedge, which is not fixed in its position, is secured against slipping out using a plug-in lock (spring pin). A second round cutout (hole) in the cross member accommodates a centering bolt in the front area of the lower chords. Within the front ends of the lower chords, centering bolts are placed on the cross member of a lower chord to be connected, which engage in a complementary manner in round cutouts in the front ends of the cross member of another lower chord to be connected. These centering bolts are designed as cylinders with a stepped section and two directly on top of each other following, conically shaped areas with different flank pitches, the cylindrical part within the front end taking on the function of a sealing section.

The releasable connection device between the lower chords is represented by a locking unit which consists of several links, the locking unit being in spatial proximity but at a distance from the respective front centering bolt. Each connecting unit comprises a clamping bolt which is mounted so as to be displaceable in the longitudinal direction of the boom segment, parallel to the lower chord, along a carriage welded to the cross member. The respective connecting effect between the lower chords is achieved by sliding the clamping bolt along the carriage into the round cutout of the front cross member of the other boom part and inserting a locking wedge into the head of the clamping bolt. With a connecting device for boom parts designed in this way, a first disadvantage is that the connecting unit can only inadequately absorb the forces and moments that occur. Another disadvantage is that the end trusses located between the bottom chords on the foot side can only absorb local and limited forces within the front connection area of the segments, because these end traverses are not directly coupled to one another over a large area in the steel construction in the connection area. Due to its arrangement at a distance from the end face of the lower flanges, the connecting device primarily absorbs axial bending moments and only to a small extent transverse forces, without being able to generate corresponding bearing forces or counter moments. The forces acting on the lower chord connection are transferred between the locations of the frontal fixation and the locations of the connection, which in turn results in greater steel construction effort in order to be able to absorb these redirected forces without deforming the foot-side boom area and the connecting elements. Another disadvantage is the relatively complex structure of this connecting device, which has many elements that must be secured against loss.

It is the object of the present invention to develop a detachable connection of boom segments in such a way that, on the one hand, it consists of a few elements and is simple and, on the other hand, it is suitable for absorbing large forces, as well as moments acting on the boom elements during crane operation. The forces and moments that change during crane operation should ideally be counteracted by creating local, adjustable bearing forces and counter-torques. Disclosure of the invention

This object is achieved by a connecting device for a boom segment with the features of claim 1 and the dependent claims.

Further refinements are specified in the dependent claims.

According to a first aspect, a lower chord connection is provided with a connecting device, in particular for connecting boom segments of a boom of a tower crane, comprising:

- at least one connecting bolt with a first fastening part for fastening to a first pressure plate of a first boom segment and with a second fastening part for fastening to a second pressure plate of a second boom segment,

- wherein the first fastening part is provided with a detachable, anti-twist connecting device for fastening to the first pressure plate,

- wherein the second fastening part is provided with a centering mandrel for fastening to the second pressure plate, which has a radial, in particular continuous securing groove for receiving a plug-in wedge;

- At least one centering sleeve for insertion into a corresponding through opening in the second pressure plate, which has an internal cross section in order to receive the second fastening part in a form-fitting manner.

In particular, the at least single first through opening located in the first pressure plate can be designed in such a way as to accommodate the connecting bolt in a form-fitting manner, particularly in the axial and radial directions of a through opening. In particular, the through opening located in the second pressure plate can be designed in such a way as to accommodate the centering sleeve in a positive and frictional manner in the axial and radial directions of the through opening in the second pressure plate.

Consequently, the connecting device according to the invention is characterized in particular by the fact that its elements have the function of a fixed screw connection with the function of a Detachable plug connection is advantageously combined with one another by means of adjustable centering and fixing elements.

The proposed connecting device puts predominantly standard parts into active connection with a few special parts, which results in a high degree of standardization and predictability in the design of the individual elements and thus ultimately a high functional reliability of the boom.

To increase the rigidity in the lower chord area, it has also proven to be advantageous if the lower chords of the boom segment are connected to one another on the front side, preferably via at least two pressure plates. By creating a flat contact between the at least two pressure plates, which close the end faces of the boom segments in their foot areas, they take on the function of two mechanically connected cross beams. The lower chords are tied together using a steel structure using these cross beams, which can have the same external geometry and can therefore double the force and moment-absorbing cross sections in the foot area of the boom segments. The construction of the boom segments is thereby stiffened in an area in which maximum bending and transverse forces as well as moments act on the lower chords.

Through the pressure plates integrated into the front foot area of the boom segment, a maximum effective transfer surface can be formed, via which the connection between the lower chord areas of two boom segments is established and which is not only located in the limited area of the surfaces directly in the area of the front ends of the lower chords, but over a maximum front foot area, which extends in a plane that is transverse or angled to the longitudinal axis of the boom.

Furthermore, it is advantageous if the connecting device comprises at least one connecting bolt, which is preferably designed in one piece and rotationally symmetrical, a first through opening located in a first pressure plate and receiving the connecting bolt, a centering sleeve arranged between the connecting bolt and a second through opening of a second pressure plate, and a plug-in wedge.

The elements of the connecting device mounted on the boom segments to be connected complement each other. For this purpose, a first boom segment points in the foot area of the front end has a first pressure plate. This first pressure plate accommodates the connecting device, by means of which a second pressure plate present in a second boom segment to be connected is connected. The first and second pressure plates connected by the connecting device lie primarily against one another; any frictional connection that occurs between the first and second pressure plates can be neglected when determining the connecting forces generated between the boom segments by means of the connecting device.

It can be provided that the first fastening part has a second cylindrical lateral surface section, which in particular directly adjoins the second fastening part. In particular, the first fastening part can have a screw thread section which adjoins the second cylindrical lateral surface section in order to fasten the first fastening part to the first pressure plate by screwing. The second cylindrical lateral surface section can be provided with an anti-rotation device, which is in particular designed with a centering pin protruding from the second cylindrical lateral surface section.

In order to accommodate several connecting bolts in the same direction according to a preferred embodiment of the connecting device, it has proven to be advantageous if the first pressure plate has a plurality of first through-openings and the second pressure plate has a plurality of corresponding second through-openings. Co-rotating recording then means the identical (preferably parallel with respect to their longitudinal directions) orientation of the mounted connecting bolts, in such a way that the connecting bolts located in and on the pressure plates point in the same direction.

It can be provided that at least one further connecting bolt is provided with a first fastening part for fastening to the second pressure plate of the second boom segment and with a second fastening part for fastening to the first pressure plate of the first boom segment, the first fastening part having a releasable connecting device for fastening is provided on the second pressure plate, the second fastening part being provided with a centering mandrel for fastening to the first pressure plate, which has a radial, in particular continuous securing groove for receiving a plug-in wedge, and a centering sleeve is provided for insertion into a corresponding through opening in the first pressure plate is, which has an internal cross section in order to accommodate the second fastening part in a form-fitting manner. In order to accommodate several connecting bolts alternately according to a further conceivable embodiment of the connecting device, it has proven to be advantageous if the first and second pressure plates each have at least one first through-opening and at least one second through-opening. Alternating mounting means the orientation of the connecting bolts in such a way that at least two of the connecting bolts located in and on the pressure plates point in opposite directions.

The at least one first through opening can be widened in the form of a groove in its upper region in order to accommodate a centering pin, which advantageously fixes the connecting bolt against rotation while it is screwed to the pressure plate. This ensures that the insertion of the plug-in wedge into a locking groove located in the head of the connecting bolt can always be done vertically from above, which is an advantage when installing the boom segments on the floor on the construction site and in particular when installing the boom segments during crane operation, in a partly airy manner height. The connecting bolt is provided on one end in a first section (screw thread section, characterized by a first cross section, in particular with a metric thread of normal pitch.

A second section of the connecting bolt has a first shoulder immediately adjacent to the first section (screw thread section), from which the first cross section of the connecting bolt widens towards a second cross section of the connecting bolt. The first and second sections form the first fastening part of the connecting bolt. A first contact surface is formed between the first cross section of the connecting bolt and the second cross section of the connecting bolt, which can also have a non-round shape and which has a first chamfer in its upper region. This chamfer makes it easier to thread the connecting bolt into the at least one first through opening of the first pressure plate, which is particularly beneficial for mounting the connecting bolt.

The second section (second cylindrical lateral surface section) of the connecting bolt is characterized by a first lateral surface into which a hole is embedded for receiving a centering pin. This centering pin is used when threading the connecting bolt accommodated in a groove, which serves to radially fix the connecting bolt in an extension of the at least one existing first through opening in the first pressure plate.

During assembly, the first and second sections of the connecting bolt are inserted into the at least one first through opening of the first pressure plate. A lock washer is placed on the part of the first section (screw thread section) protruding from the mounting side of the first pressure plate and ensures that a castle nut screwed onto the screw thread section rests flatly on the mounting side of the first pressure plate. This advantageously ensures that the screwing forces are applied uniformly and predictably to the mounting side of the first pressure plate over a large cross section.

The lateral surface of the second section of the connecting bolt ends at a second shoulder and, due to its full-surface contact in the at least one first through opening of the first pressure plate, ensures, on the one hand, a radial fixation of the connecting bolt in the first pressure plate and, on the other hand, a low-play connection between the connecting bolt and the first pressure plate.

Starting with the second paragraph, a third section (first cylindrical lateral surface section) of the connecting bolt extends, from which the second cross section of the connecting bolt widens to a third cross section of the connecting bolt. A second contact surface is formed between the second cross section of the connecting bolt and the third cross section of the connecting bolt, which rests directly on the end face of the first pressure plate. By means of this second contact surface, both an axial contact of the connecting bolt and a transfer of the axial preload forces generated by the connecting bolt to the end face of the first pressure plate take place.

The third section (first cylindrical lateral surface section) of the connecting bolt is characterized by a second lateral surface. This lateral surface merges into a fourth section of the connecting bolt, which is referred to as the head area. The third and fourth sections form the second fastening part of the connecting bolt.

Furthermore, the connecting bolt can have a section in its head area that tapers in the direction of the second fastening part and is adjacent to a first cylindrical section Connect the lateral surface section, wherein the first cylindrical lateral surface section can be received in the centering sleeve, in particular in a form-fitting manner, in an assembled state.

The tapering section located in the head area of the connecting bolt can be characterized by a third lateral surface, which is designed as a cone and thus forms a centering mandrel. The centering mandrel ends in a second chamfer, which also forms the other end of the connecting bolt.

The second chamfer, together with the surface of the cone of the centering mandrel of the connecting bolt, facilitates the introduction of the connecting bolt and the centering sleeve into the at least one second through opening of the second pressure plate. This makes the assembly of boom segments to be connected considerably easier, which particularly benefits safe handling and assembly of the same.

Another advantage of the new connecting device for a lower belt connection is given in particular by the introduction of a centering sleeve. For this purpose, it can be provided that the centering sleeve has a completely or partially circumferential flange, which can be provided at an axial end of the centering sleeve and, in an assembled state, is arranged in the direction of the second fastening part. This centering sleeve can thus be designed as a collar bushing and is characterized by a first sleeve section which has the shape of a tube, which does not necessarily have to be round, and an inner wall and an outer wall with an intermediate surface, which is not necessarily an annular surface must be trained. At a first end of the first sleeve section, a chamfer can be arranged between the surface and the inner wall, which, as an insertion aid, makes it easier to insert the centering sleeve onto the second lateral surface of the connecting bolt, complementary to the cone of the centering mandrel of the connecting bolt.

At a second end of the first sleeve section of the centering sleeve there is an undercut, which is followed by a second sleeve section of the centering sleeve. This second sleeve section is characterized by a circumferential flange with an inner and outer flange surface. The flange surfaces of the flange thus have a first and a second contact surface as well as an inner diameter and an outer diameter and thereby give this second sleeve section the shape of a collar. This collar is cut off on one side at the outer cross section, which leaves more scope in the structural steel design of the boom segment.

The centering sleeve is, as described above, arranged between the lateral surface of the first cylindrical lateral surface section of the connecting bolt and the wall of an at least single second through opening, which is located in the second pressure plate. For this purpose, the centering sleeve is dimensioned in the axial and radial directions so that it achieves full-surface support over a maximum contact surface on the one hand for the second lateral surface of the connecting bolt and on the other hand for the wall of the at least single second through opening of the second pressure plate. By means of an undercut between the first and the second sleeve section of the centering sleeve, a flat and step-free contact of the centering sleeve can be created by an inwardly directed undercut radius between the first and the second sleeve section of the centering sleeve.

Both the centering sleeve and the at least one second through opening of the second pressure plate can be structurally designed in their cross-sections or diameters in such a way that they work together to achieve a clearance fit. As a result, these two elements ensure, on the one hand, an optimal transmission of the radial forces acting on the centering mandrel and, on the other hand, the absorption of the moments acting on the length of the centering mandrel clamped in the second pressure plate. When producing the centering sleeve as a turned part, tight tolerances should be applied to the dimensions of the outer wall of the first sleeve section of the centering sleeve so that it has minimized play in its installed position relative to the wall of the at least one second through opening.

A further advantage of the connecting device can be, in particular, the axial force input via the engaging inner and outer contact surfaces of the centering sleeve in the second sleeve section, by means of which the axial preload caused by the centering mandrel and the plug-in wedge ensures a uniform and maximum surface pressure between the first and the second printing plate allows. In cooperation with the rigid centering bolt, the elastic centering sleeve as well as the elastic pressure plates result in improved bending, transverse force and moment absorption as well as optimized restoring behavior of the connecting device. A further advantage of the centering sleeve can consist in particular in its design of a completely or partially circumferential flange, which can be designed as a collar as described above. The collar located in the second sleeve section is characterized in particular by an inner and outer flange surface. The contact surface that forms between the inner diameter and the outer diameter of the collar can be designed depending on the area and thus the area-related resistance of the first and second pressure plates. Due to its radial and surface contact in the first and second sleeve sections, the centering sleeve ensures a large-area introduction and uniform distribution of the axial and radial preload forces into the second and/or first pressure plate, which are generated by the tensioning of the plug-in wedge within the securing groove of the centering mandrel. Due to the possibility of adapting the outer cross section of the centering sleeve in the second sleeve section, i.e. the collar or its flange, on the one hand a maximized inner flange surface for the full-surface contact of the centering sleeve on the mounting side of the second and / or first pressure plate and on the other hand the largest possible outer flange surface can be created for the full-surface contact of a second contact surface of the plug-in wedge.

Furthermore, it can be provided that the flange of the centering sleeve is provided with one or more fastening devices for secure fastening to the first and/or second pressure plate.

A plug-in wedge is used to secure the connecting device, which is inserted in particular into a securing groove located in the conical centering mandrel of the connecting bolt, preferably from above. The plug-in wedge can be designed in different lengths, so that its contact surface can be adapted to the outer flange surface of the second sleeve section of the centering sleeve.

Another advantage of the connecting device is that it is designed to be adjustable. The adjustment is achieved in particular by means of the plug-in wedge, which can be adjusted within limits.

After pushing the connecting bolt through the at least one second through opening in the second pressure plate and after inserting the centering sleeve, the plug-in wedge is inserted into the free space formed between the second lateral surface of the connecting bolt and the wall of the at least one second through opening Continuous locking groove located in the conical area of the centering mandrel of the connecting bolt is inserted.

The plug-in wedge is solid and can have different outer contours in its respective contact surfaces. The outer contour of a first contact surface forms the head-side termination and absorbs the clamping forces, preferably introduced by hammer blows, during assembly of the connecting device. When the connecting device is assembled, the outer contour of a second contact surface lies directly on the outer flange surface of the centering sleeve and introduces axial and radial clamping forces into it by means of positive locking. The outer contour of a third contact surface can have a rounded shape. By rounding the outer contour, a full-surface contact of the third contact surface of the plug-in wedge against the outer wall of the locking groove of the centering mandrel can be achieved, thereby generating maximum compression of the plug-in wedge within the centering mandrel.

This third contact surface can form an angle with respect to the second contact surface and, within the securing groove of the connecting bolt, causes the plug-in wedge to be forced against the inner and outer walls of the securing groove.

When assembled, the plug-in wedge can be secured against upward migration by a safety plug, which can be designed in the form of a spring clip (standard part). Depending on the insertion depth of the plug-in wedge within the locking groove, the safety plug can be inserted into at least one locking hole in the lower leg area of the plug-in wedge in order to secure the plug-in wedge in its respective position within the locking groove. As a result, a permanent fixation of the plug-in wedge and thus ensuring sufficient tension forces of the plug-in wedge can be permanently guaranteed, on the one hand within the securing groove of the connecting bolt and on the other hand against the outer contact surface of the centering sleeve and thus against the mounting side of the first and / or second pressure plate.

Depending on the wear of the lower chord connection, which depends on the duration of use of the crane and the associated deformations of the individual boom segments, the strength of the lower chord connection can be permanently high due to the plug-in wedge slipping due to its own weight or by mechanical readjustment of the plug-in wedge, in particular by means of hammer blows level are maintained. In the case of the lower chord connection, the connecting device can be modeled on a fixed bearing. According to a further aspect, it has proven to be advantageous, in a preferred embodiment, to relieve the load on the connecting device according to the invention, in its form as a fixed bearing, by means of a further cantilever connection. A further cantilever connection can be formed by an additionally introduced fixing device, which can be designed as a floating bearing in addition to the fixed bearing of the connecting device. The fixed bearing can be located outside the front end of the lower chords. The floating bearing can be arranged on or within the front end of the lower chords. The end faces of the lower chords are understood to be the contact surfaces which form directly in the joints above the ends of the lower chord tubes, transversely to the longitudinal axis of the boom. Through the interaction of the fixed bearing and the floating bearing, the lower chords of two boom segments to be connected and in particular the joints above the ends of the lower chord tubes are, on the one hand, fixed in position to one another and to one another and, on the other hand, permanently and releasably connected to one another by means of adjustable connecting forces.

A movable trolley can be arranged to be movable along the substructure. During crane operation, loads hanging on the trolley can exert a maximum bending moment on the pressure plates in the front end area of the lower chords (boom chords) while the trolley is traveling over the areas of the boom connections, i.e. the boom joints. This can lead to permanent, local deformations of the frontal areas of the boom joints, in such a way that at least one step can be formed between the oppositely positioned and adjacent boom joints. Since the lower belts usually have running surfaces for the trolley, such steps can lead to mechanical shocks during trolley travel under load.

According to a further aspect, the above lower chord connection is provided with the connecting device, wherein the lower chord connection connects two lower chords of the boom segments, ie a lower chord of the first boom segment and a corresponding lower chord of the second boom segment, with one another on the front side of each of the two lower chords Fixing device is provided to secure the lower chords against displacement transversely to their axial direction. It has therefore proven to be advantageous if a fixing device additionally introduced in the highly loaded lower flange area of the pressure plate can support the centering effect of the connecting device. This local support provided by the fixing device leads to additional relief of the connecting device and to a permanent and low-wear fixation of the lower chords to one another and to one another in the area of the joints, which are located in the immediate area above the front ends of the lower chord tubes. The fixing device can in particular be arranged centered in the surfaces of the front ends, i.e. the joints of the lower chords. Further arrangements of the fixing device within the lower chord connection are conceivable, for example in an area above or below or to the side of the structural center of the respective lower chord.

Furthermore, the fixation device can include:

- at least one screw mandrel with a first fastening section for fastening to the first pressure plate and with a second fastening section for fastening to the second pressure plate, the second fastening section having a lateral surface section for fastening the screw mandrel to the second pressure plate, with a socket for insertion into a through opening is provided in the second pressure plate, wherein the bushing has an inner wall in order to receive the lateral surface portion of the second fastening portion in the through opening.

Furthermore, the first fastening section can be provided with a threaded section for fastening the screw mandrel to a threaded hole in the first pressure plate.

It can be provided that the lateral surface section of the second fastening section is received in the through opening in a form-fitting and friction-locking manner.

Thus, in addition to the connecting device according to the invention, at least one further fixing device can be provided, comprising:

- at least one screw mandrel with a first fastening section

Attachment to a first pressure plate of a first boom segment and with a second fastening section for fastening to a second pressure plate of a second boom segment, the first fastening section being provided with a threaded section for fastening the screw mandrel to a threaded hole in the first pressure plate, the second fastening section having a lateral surface section for fastening the screw mandrel to the second pressure plate, - at least one bushing for insertion into a corresponding through opening, the through opening being located in the second pressure plate, the bushing having an inner wall in order to accommodate the lateral surface portion of the second fastening portion in a positive and frictional manner.

A further advantage of the new lower flange connection is the introduction of an additional fixing device. The elements of the fixing device mounted on the boom segments to be connected complement each other. For this purpose, a first boom segment has a first pressure plate in the foot area of its front end. This first pressure plate accommodates the previously described connecting device and the fixing connection, by means of which a second pressure plate present in a second boom segment to be connected is connected. The first and second pressure plates connected by the connecting device and by the fixing device lie against each other predominantly in a form-fitting manner and over the entire surface; any frictional connection that occurs between the first and the second pressure plate can be neglected when determining the connecting forces generated between the boom segments by means of the connecting device and the fixing device.

Furthermore, it is advantageous if the at least one fixing device has a preferably one-piece and rotationally symmetrical screw mandrel with a first and a second fastening section, a threaded hole located in a first pressure plate and receiving the first fastening section, and a further through opening located in the second pressure plate and receiving the second fastening section and a socket arranged between the second fastening section and the further through opening. It can be provided that the first fastening section of the fixing device has a threaded section which is located directly on a preferably cylindrically formed lateral surface section of the second fastening section of the fixing device. In particular, the first fastening section can be fastened by means of the threaded section by screwing into a threaded hole located in the first pressure plate. In the second fastening section of the fixing device, a lateral surface section and a head region can be formed, wherein the lateral 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 lateral surface section and the head area can have a polygonal, for example triangular, square or pentagonal shape. A chamfer can be formed between the head area and the lateral surface section of the second fastening section. The chamfer can facilitate the insertion of the lateral surface section of the second fastening section into a socket with a complementary geometry.

The fixing device can comprise a socket, which can be arranged within a corresponding through opening in a second pressure plate. This through opening can in particular be designed as a bore, which in particular can have a round profile. The bushing can in particular be designed as a replaceable bushing, and can in particular have the shape of a tube, which does not necessarily have to be round 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 socket, a chamfer can be arranged between the surface and the inner wall, which serves as an insertion aid complementary to the chamfer of the screw mandrel and makes it easier to thread the lateral surface of the screw mandrel during assembly. A second end of the bushing can be arranged directly in front of a stiffening plate and can find a spatial stop there. By means of this spatial stop, the bushing is secured in its longitudinal direction against migration into the rear area of the lower flange. The stiffening plate serves, in the manner of a bulkhead, on the one hand to stiffen the lower chord in the indirect area of the connection between two lower chords and, on the other hand, to close the lower chord against penetrating water and the associated corrosion of the rear area of the lower chord.

In order to accommodate several centering mandrels and several screw mandrels in the same direction according to a preferred embodiment, it has proven to be advantageous if the first pressure plate has a plurality of first through-openings and the second pressure plate has a plurality of second through-openings corresponding to the first through-openings and one has another through opening. Co-rotating recording then means the identical (preferably parallel with respect to their longitudinal directions) orientation of the mounted connecting bolts and screw mandrels, in such a way that the connecting bolts and screw mandrels located in and on the pressure plates point in the same direction.

It can therefore be provided that at least one further screw mandrel is provided with the first fastening section for fastening to the second pressure plate of the second cantilever segment and with the second fastening section for fastening to the first pressure plate of the first cantilever segment, the first fastening section of the further screw mandrel in particular with is provided with a metric thread of normal pitch for fastening to the first pressure plate, the second fastening section of the further screw mandrel being provided with a lateral surface section for releasable fastening in a further through hole in the second pressure plate, and a bushing for insertion into the further through opening in the second Pressure plate is provided, which has an internal cross section with a corresponding shape in order to accommodate the lateral surface portion of the second fastening portion of the screw mandrel in a positive and frictional manner.

Brief description of the drawings

Further details of the invention are explained in more detail using an exemplary embodiment shown in the accompanying drawings. Identical multiple references of a component in one and the same figurative representation include both the singular and plural of the element represented. Show in it:

Figures 1a, 1b perspective overview representations of frontal embodiments of the tower crane boom segment in the unassembled state;

Figures 2a, 2b, 2c perspective overview representations of the foot area of two boom segments connected by means of the lower chord connection according to one embodiment;

Figure 2d shows a perspective overview representation of the foot area of two boom segments connected by means of the lower chord connection according to a further embodiment; Figures 3a, 3b perspective representations of printing plates according to one

Embodiment, wherein the pressure plates are detached from the truss or lattice structure of the boom segment in individual perspective;

Figure 3c shows a side view and perspective view of a printing plate according to a further embodiment, the printing plate being seen in individual perspective from the truss or lattice structure of the

Boom segment is detached;

Figure 4 shows a perspective overview representation of elements of the lower chord

Connection (exploded drawing), as well as two printing plates to be connected to each other;

Figure 5a shows a perspective view of the elements of the lower chord connection according to a preferred embodiment as well as the pressure plates connected by means of the lower chord connection of a preferred embodiment;

Figure 5b is a perspective view of the elements of the lower chord connection according to a further embodiment as well as the pressure plates connected by means of the lower chord connection of a further embodiment;

Figure 6 shows a sectional view of the assembled elements of the lower chord connection as well as the lower chords and the pressure plates;

Figure 7 shows a side and perspective view of the connecting bolt;

Figure 8 shows a side and perspective view of the centering sleeve; and

Figure 9 is a perspective view of the plug-in wedge;

Figures 10a, 10b perspective overview representations of the end faces of preferred embodiments of the tower crane boom segment in the unassembled state; Figure 11a shows a sectional representation of the foot area of two boom segments connected by means of the connecting device and the fixing device according to a preferred embodiment;

Figure 11b shows a section of the assembled elements of the fixing device and the connecting device according to a preferred embodiment of the lower chord connection as well as the lower chords and the pressure plates;

Figure 12 shows a sectional view of the assembled elements of the fixing device according to a preferred embodiment of the lower chord connection, as well as the lower chords and the pressure plates;

Figures 13a, 13b perspective representations of printing plates according to a preferred

Embodiment of the lower chord connection, whereby the pressure plates are separated from the truss or lattice structure of the boom segment in an individual perspective.

Description of embodiments

Figures 1a, 1b show connection areas of two embodiments of a boom segment 1, which include an upper chord 2, a final upper chord connection 21a and an end face of a pressure plate 5 connecting and closing the lower chords 3. The illustrated elements of the upper chord connection 21a of a first boom segment 1 are connected to a complementary element of an upper chord connection 21b of a second boom segment 1b (not shown). At least one lower chord connection with a connecting device 4a of a first boom segment 1a is attached to the pressure plate 5 for transport purposes.

The elements of the at least one lower chord connection are located in the foot area of the front end of the boom segment 1a and outside a front end 51 of the lower chords 3.

Figures 2a, 2b, 2c show the foot area of two boom segments 1a, 1b connected to each other by means of the lower chord connection and the integration of these foot areas into the truss or lattice structure of the respective boom segment 1a, 1b in different ways spatial perspectives. The pressure plates 5a, 5b lie directly against one another with their end faces 53 and are flush with one another at the end ends 51 (not visible in the assembled state in this illustration) of the lower chords 3. The at least one lower chord connection of this preferred embodiment is mounted on the pressure plates 5a or 5b and is located in spatial proximity to the lower chord 3 in the foot area of the boom segment 1a, 1b. 2a and 2b, the heads of locking screws (standard screws) are indicated, which are located on the outer flange surface 75 of the flange 70 of the centering sleeve 7 in bores 78 (not shown) and by means of which the centering sleeve 7 is on the mounting side 52 of the pressure plate 5a located standard threads (not shown) and thus secure them against loss and / or twisting. In Figure 2c, the castle nut 10 and the washer 9 are shown as elements of the lower flange connection 4, which are located on the mounting side 52 of the pressure plate 5b.

Figure 2d shows the foot area of two boom segments 1a, 1b connected to each other by means of the lower chord connection and the integration of these foot areas into the truss or lattice construction of the respective boom segment 1a, 1b in a spatial perspective. The pressure plates 5c lie directly against one another with their end faces 53 and are flush with one another at the end ends 51 (shown in dashed lines) of the lower chords 3. The elements of the at least one lower chord connection of this further embodiment are mounted on the pressure plates 5c on the mounting side 52 and are located in the spatial proximity of the lower chord 3 in the foot area of the boom segment 1a, 1b.

Figure 3a shows a pressure plate 5a detached from the truss or lattice construction of the respective boom segment 1b, 1b, according to the preferred embodiment. The second through openings 56 located in the pressure plate 5a each receive centering sleeves 7 (not shown) on their walls.

Figure 3b shows a pressure plate 5b detached from the truss or lattice construction of the respective boom segment 1a, 1b according to the preferred embodiment. The first through openings 54 located in the pressure plate 5b are each widened in the form of a groove in their upper region by a recess 55. The first through openings 54 located in the pressure plate 5b receive the lateral surfaces 63 (second lateral surface section) of the connecting bolts 6 (not shown) on their walls. The pressure plate 5b represents a contact surface for the lock washer 9 (not shown) on the mounting side 52. Figure 3c shows a pressure plate 5c detached from the truss or lattice structure of the respective boom segment 1a, 1b, according to a further embodiment. A first through opening 54 located in the pressure plate 5c is widened in the form of a groove by a recess 55 in its upper region. The first through opening 54 located in the pressure plate 5c receives the lateral surface 63 (second lateral surface section) of the connecting bolt 6 (not shown) on its wall. A second through opening 56 located in the pressure plate 5c receives the centering sleeve 7 (not shown) on its wall. The pressure plate 5c represents a contact surface for the lock washer 9 (not shown) on the mounting side 52.

In Figures 3a, 3b and 3c, the front end areas 51 represent the outer end areas of the pressure plate 5a, 5b and 5c, which lie in the front end area of the lower chords 3 (not shown).

Figure 4 shows elements of the lower chord connection 4a detached from the truss or lattice construction of the respective boom segment 1a, 1b in the unassembled state (exploded view) outside of their engagement in the respective pressure plate 5a, 5b or 5c. The first fastening part of the connecting bolt 6, which can be inserted into the first through opening 54 and the groove-like extension 55 on the end face 53 of the first pressure plate 5b or 5c, is inserted during the subsequent assembly on the mounting side 52 of the pressure plate 5b or 5c by means of the screw thread section 64 (not shown) as well the washer 9 and the castle nut 10 are screwed. The second fastening part of the connecting bolt 6, which can be inserted into the second through opening 56 of the second pressure plate 5a or 5c, is inserted during the subsequent assembly on the mounting side 52 of the second pressure plate 5a or 5c by means of the centering sleeve inserted into the second through opening 56 on the mounting side 52

7 and the plug-in wedge located in the securing groove 69 later in the assembly process

8 (not shown) and a spring pin (not shown) located in a securing hole 84 (not shown) of the plug-in wedge 8 (not shown).

Figure 5a shows the preferred embodiment removed from the truss or lattice construction of the respective boom segment 1a, 1b with connecting devices 4a of the lower chord connection and the different pressure plates 5a and 5b in the assembled state. It can be seen that the connecting devices 4a are mounted in the same direction on the respective pressure plate 5a and 5b and elements of the lower belt Connections 4a protrude from the respective mounting side 52 of the pressure plate 5a. The end faces 53 (not visible) of the pressure plates 5a and 5b lie against one another over the entire surface, whereby the connection of the pressure plates 5a and 5b achieves a high degree of tightness by means of positive and frictional connection between the end faces 53.

Figure 5b shows a further embodiment detached from the truss or lattice structure of the respective boom segment 1a, 1b with lower chord connections and two identical pressure plates 5c in the assembled state. It can be seen that the lower flange connections are mounted alternately on the respective pressure plate 5c and elements of the lower flange connections protrude from the respective mounting side 52 of the pressure plates 5a and 5c. The end faces 53 (not visible) of the pressure plates 5c lie against one another over the entire surface, whereby the connection of the pressure plates 5c achieves a high degree of tightness by means of positive and frictional connection between the end faces 53.

Figure 6 shows a section through the connecting device 4a of the lower flange connection in its installed position, within the pressure plates 5 connected to one another by this (in embodiments 5a, 5b or 5c). The end faces 53 of the pressure plates 5 (in embodiments 5a, 5b or 5c) lie against one another over the entire surface. The connecting bolt 6 is screwed to the first pressure plate 5b or 5c on the mounting side 52 by means of its screw thread section 64 and the attached washer 9 and the castle nut 10. To secure the position while the connecting bolt 6 is screwed to the first pressure plate 5b or 5c, a centering pin 613 lies in the groove-shaped extension 55 of the first through opening 54.

The centering sleeve 7 receives the lateral surface 62 (first lateral surface section) of the connecting bolt 6 in the radial direction on the inner wall 71 of the first sleeve section. In the axial direction of the centering sleeve 7, the plug-in wedge 8 rests on the outer flange surface 75 of the second sleeve section.

The centering sleeve 7 transmits the axial preload forces generated by the connecting bolt 6 and the plug-in wedge 8 located in the securing groove 69 by means of the flange 70 formed in its second sleeve section via its outer flange surface 75 and its inner flange surface 76 to the mounting side 52 of the second pressure plate 5 (in the embodiments 5a or 5c). In addition, the centering sleeve 7 transmits the pressure from the connecting bolt 6 via its lateral surface

62 (first lateral surface section), radial prestressing forces introduced by means of the inner wall 71 and the outer wall 72 of its first sleeve section onto the wall of the second through opening 56 of the second pressure plate 5 (in embodiments 5a or 5c).

Figure 7 shows the details of the connecting bolt 6. In particular, the lateral surface

63 (second lateral surface section) and the lateral surface 62 (first lateral surface section) as well as the first contact surface 65 and the second contact surface 66 represent the surfaces via which the axial and radial prestressing forces of the lower flange connection 4 generated by the connecting bolt 6 onto 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).

Figure 8 shows details of the centering sleeve 7. A tubular first sleeve section of the centering sleeve is delimited by an inner wall 71 and an outer wall 72 as well as by a surface 73 between the inner wall 71 and the outer wall 72 and ends in an undercut 79. A second The sleeve section of the centering sleeve begins from the undercut 79 and represents a circumferential flange 70 in the form of a collar. The circumferential flange 70 has an outer flange surface 75 and an inner flange surface 76 as well as a side end 77. Take the holes 78 located in the flange 70 Standard screws (not shown) to secure the centering sleeve 7 on the mounting side 52 of the pressure plate 5a or 5c. These locking screws (not shown) are screwed to the pressure plate 5a or 5c on the mounting side 52 using standard threads located in the pressure plate 5a or 5c (not shown) and serve to secure the centering sleeve 7 against loss and / or twisting.

Figure 9 shows the details of the plug-in wedge 8. The plug-in wedge 8 lies in the mounted or inserted position (not shown) within the locking groove 69 (not shown), which is in the lateral surface 61 (third lateral surface section, not shown) of the conical centering mandrel of the connecting bolt 6 is located (not shown). The outer contour 82 of the plug-in wedge 8 represents, on the one hand, the contact surface to the inwardly directed wall 610 (not shown) of the locking groove 69 (not shown) and, on the other hand, to the outer flange surface 75 (not shown) of the centering sleeve 7 (not shown). The outer contour 83 represents the contact surface of the plug-in wedge 8 to the outward-facing wall 611 (not shown). Locking groove 69 (not shown) of the connecting bolt 6 (not shown). The outer contour 81 serves as a receiving surface for hammer blows, which are entered within the locking groove 69 (not shown) to fix and, if necessary, reposition the plug-in wedge 8.

The at least one securing hole 84 located in the lower region of the plug-in wedge 8 can accommodate a spring pin (standard part, not shown) for securing the plug-in wedge 8. The at least one securing hole 84 lies in the inserted and set or repositioned position of the plug-in wedge 8 in a space below the securing groove 69 (not shown) of the connecting bolt 6 (not shown).

Figures 10a and 10b show the connection areas of two boom segments 1a, 1b according to a preferred embodiment, each of which comprises an upper chord 2, final upper chord connections 21a, 21b and the end faces 53 of a pressure plate 5 connecting and closing the lower chords 3. The illustrated elements of an upper chord connection 21a of a first boom segment 1a are connected to a complementary element of an upper chord connection 21b of a second boom segment 1b. Two fixing devices 4b and two connecting devices 4a of a first boom segment 1a are attached to the pressure plate 5. There is one screw mandrel 40 for the fixing connections 4b in the foot area of the boom segment 1a in the front end 51 for each of the lower chords 3. The at least one through opening 56 is located within the pressure plate 5 in the foot area of the boom segment 1b and between the front ends 51.

At least one through opening 57 for receiving the screw mandrel 40 is located in the pressure plate 5 in the foot area of the boom segment 1b and within the front end area 51.

Figure 11a shows the foot area of two boom segments 1a, 1b connected to one another by means of the lower chord connections 4a and 4b according to a preferred embodiment in a sectional view (top view). The pressure plates 5a, 5b lie directly against one another with their end faces 53. The connecting devices 4a and the fixing devices 4b are mounted on the pressure plates 5a and 5b and are located in the spatial proximity of the lower chords 3 in the foot area of the boom segment 1a, 1b. Figure 11b shows a section of the foot area of two boom segments 1a, 1b connected to one another by means of the connecting device 4a and the fixing device 4b according to a preferred embodiment in a sectional view (top view). The connecting device 4a and the fixing device 4b are mounted on the pressure plates 5a and 5b and are located in the spatial proximity of the lower chord 3 in the foot area of the boom segment 1a, 1b.

The fixing device 4b comprises a bushing 45 which is arranged in the corresponding through opening 57 within the pressure plate 5a, the bushing 45 and the through opening 57 preferably having no play with one another. This ensures that the bushing 45 is, on the one hand, firmly mounted within the through opening 57 and, on the other hand, can preferably be pulled out and replaced by means of a bushing pulling tool placed on the inner wall 46 of the bushing 45.

Figure 12 shows a section of two boom segments 1a, 1b connected to one another by means of the fixing device 4b according to a preferred embodiment in a sectional view (side view). The screw mandrel 40 has a threaded section 41 in a first fastening section. The threaded section 41 is screwed into a threaded hole 58, the threaded hole 58 being arranged in the front end region 51 of the pressure plate 5b. The screw mandrel 40 has a lateral surface section 42 in a second fastening section, which directly adjoins the threaded section 41. In the assembled state, the lateral surface section 42 of the screw mandrel 40 is located directly above the end face 53 of the pressure plate 5b and lies against the inner wall 46 of the bushing 45 in a form-fitting and friction-locking manner. A chamfer 44 can be located between the head 43 of the screw mandrel 40 and the lateral surface section 42 of the screw mandrel 40 and can make it easier to thread the screw mandrel 40 into the socket 45. The head 43 can in particular be hexagonal in shape for receiving a tool, which can be designed as an open-end wrench.

The outer wall 47 of the socket 45 rests directly on the wall of the through opening 57 within the pressure plate 5a. In the assembled state, the bushing 45 lies directly in front of the stiffening plate 31, which delimits the rear end area within the lower flange 3. The bushing 45 is fixed in the rear end area neither to the through opening 57 nor to the stiffening plate 31, but rather to its outer wall 47 has a small excess size compared to the diameter of the through opening 57 and is releasably mounted within the rear end area by means of a press fit.

Figure 13a shows a pressure plate 5a detached from the truss or lattice construction of the respective boom segment 1b, 1b, according to a preferred embodiment. The through openings 56 located in the pressure plate 5a each receive centering sleeves 7 (not shown) on their walls. The through openings 57 located in the pressure plate 5a each receive bushings 45 (not shown) on their walls.

Figure 13b shows a pressure plate 5b detached from the truss or lattice construction of the respective boom segment 1a, 1b according to a preferred embodiment. The through openings 54 located in the pressure plate 5b are each widened in the form of a groove in their upper region by a recess 55. The through openings 54 located in the pressure plate 5b receive the lateral surfaces 63 (second lateral surface section) of the connecting bolts 6 (not shown) on their walls. Metric internal threads (not shown) are embedded in the threaded holes 58 located in the pressure plate 5b, which each receive the metric external threads of the screw mandrels 40 (not shown) located in the threaded sections 41.

Reference symbol list

1a, 1b boom segment

2 top strap

21a,21b Top chord connection

3 bottom belt

31 stiffening plate

4a connecting device

4b fixation device

40 screw mandrel

41 threaded section of the screw mandrel

42 lateral surface section of the screw mandrel

43 head area

44 bevel

45 socket

46 inner wall of the socket 45

47 Outer wall of the socket 45

5 pressure plate (pressure plate 5a, 5b, 5c)

51 Front end area above the bottom chord ends

52 Mounting side of the pressure plate 5a, 5b, 5c

53 front side of the pressure plate 5a, 5b, 5c

54 First through opening within the pressure plate 5b, 5c

55 Groove-shaped extension of the first through opening 54

56 Second through opening within the pressure plate 5a, 5c

57 through opening within the pressure plate 5a, 5c

58 threaded hole within the pressure plate 5b

6 connecting bolts

61 lateral surface (cone) of the centering mandrel of the connecting bolt (third

lateral surface section)

62 lateral surface (cylinder) of the connecting bolt (second lateral surface section)

63 lateral surface (cylinder) of the connecting bolt (first lateral surface section)

64 screw thread section

65 first contact surface of the connecting bolt

66 second contact surface of the connecting bolt

67 chamfer (between jacket section 1 and jacket section 2) Chamfer (between jacket section 1 and jacket section 2)

Locking groove in the centering pin of the connecting bolt (fourth section)

Inner wall of the locking groove (contact surface of the outer contour 1 of the plug-in wedge 8) Outer wall of the locking groove (contact surface of the outer contour 2 of the plug-in wedge 8) Hole in the lateral surface 63 of the connecting bolt

Centering pin for centering the connecting bolt in the groove-shaped extension 55 centering sleeve

Flange (second sleeve section of the centering sleeve, collar)

Inner wall of the first sleeve section of the centering sleeve

Outer wall of the first sleeve section of the centering sleeve

Area between the inner and outer walls of the first sleeve section of the centering sleeve

Chamfer between the surface and the inner wall of the first sleeve section of the centering sleeve

Outer flange surface of flange 70, outer contact surface of the second

Sleeve section of the centering sleeve (support surface for the second contact surface of the plug-in wedge)

Inner flange surface of flange 70, inner contact surface of the second

Sleeve section of the centering sleeve (contact surface for the mounting side of the pressure plate) Lateral end of the centering sleeve

Holes to accommodate locking screws

Undercut between the first and second sleeve sections of the centering sleeve

plug-in wedge

Outer contour of a first contact surface of the plug-in wedge

Outer contour of a second contact surface of the plug-in wedge

Outer contour of a third contact surface of the plug-in wedge

Locking hole for accommodating a spring pin (standard part)

Disc (standard part)

Castle nut (standard part)

Claims

Expectations

1. Lower chord connection with a connecting device (4a), in particular for connecting boom segments (1) of a boom of a tower crane, comprising:

- at least one connecting bolt (6) with a first fastening part (9, 10, 63, 64) for fastening to a first pressure plate (5, 5a, 5b, 5c) of a first boom segment (1a) and with a second fastening part (61, 62 ) for attachment to a second pressure plate (5, 5a, 5b, 5c) of a second boom segment (1b), the first fastening part (9, 10, 63, 64) having a detachable, anti-twist connecting device for attachment to the first pressure plate (5 , 5a, 5b, 5c), the second fastening part (61, 62) being provided with a centering mandrel for fastening to the second pressure plate (5, 5a, 5b, 5c), which has a radial, in particular continuous, securing groove (69) for receiving a plug-in wedge (8);

- a centering sleeve (7) for insertion into a corresponding through opening (54, 56) in the second pressure plate (5, 5a, 5b, 5c), which has an internal cross section in order to receive the second fastening part (61, 62) in a form-fitting manner.

2. Lower flange connection with a connecting device (4a) according to claim 1, wherein the centering mandrel has a section which tapers in the direction of the second fastening part (61, 62) and adjoins a first cylindrical lateral surface section which, in an assembled state, in the Centering sleeve can be received in particular in a form-fitting manner.

3. Lower flange connection with a connecting device (4a) according to claim 1 or 2, wherein the centering sleeve (7) has a completely or partially circumferential flange (70) with flange surfaces (75, 76) which is at an axial end of the centering sleeve (7 ) is provided and is arranged in an assembled state in the direction of the second fastening part (61, 62).

4. Lower flange connection with a connecting device (4a) according to claim 3, wherein the flange (70) with flange surfaces (75, 76) and bores (78) by means of one or a plurality of fastening devices for fastening and securing in a rotation-proof manner on the second pressure plate (5, 5a, 5b, 5c). Lower flange connection with a connecting device (4a) according to one of claims 1 to 4, wherein the first fastening part (63, 64) has a second cylindrical lateral surface section, which in particular directly adjoins the second fastening part (61, 62). Lower flange connection with a connecting device (4a) according to claim 5, wherein the second cylindrical lateral surface section (63) is adjoined by a screw thread section (64) in order to secure the first fastening part (63, 64) by screwing it to the first pressure plate (5, 5a, 5b, 5c). Lower flange connection with a connecting device (4a) according to one of claims 5 to 6, wherein the second cylindrical lateral surface section (63) is provided with an anti-rotation device, which is in particular designed with a centering pin (613) protruding from the second cylindrical lateral surface section. Lower belt connection with a connecting device (4a) according to one of claims 1 to 7, wherein the second pressure plate (5, 5a, 5b, 5c) has a continuous second through opening (56) for positive and frictional reception in the axial and radial directions the centering sleeve (7) is provided. Lower flange connection with a connecting device (4a) according to one of claims 1 to 8, wherein the first pressure plate (5, 5a, 5b, 5c) has a first through opening (54) for positively and frictionally receiving the second in the radial and axial directions Lateral surface section (63) is provided, wherein in an assembled state an axial end of a first lateral surface section (62) of the second fastening part (61, 62) rests on the first pressure plate (5, 5a, 5b, 5c). Lower flange connection with a connecting device (4a) according to claim 9, wherein the first lateral surface section (62) has an axial length which corresponds at least to the thickness of the second pressure plate (5, 5a, 5b, 5c), the securing groove (69) being so is arranged so that in an assembled state, in which the first and second pressure plates (5, 5a, 5b, 5c) rest against one another Inserting the plug-in wedge (8) a force is exerted in the direction of the second fastening part (61, 62) against the second pressure plate (5, 5a, 5b, 5c). Lower chord connection with a connecting device (4a) according to one of the claims

1 to 10, wherein at least one further connecting bolt (6) is provided with a first fastening part for fastening to the second pressure plate (5, 5a, 5b, 5c) of the second boom segment (1b) and with a second fastening part for fastening to the first pressure plate of the first boom segment (1a), the first fastening part (63, 64) being provided with a releasable connecting device for fastening to the second pressure plate (5, 5a, 5b, 5c), the second fastening part (61, 62) being provided with a centering mandrel for attachment to the first pressure plate (5, 5a, 5b, 5c), which has a radial, in particular continuous securing groove for receiving a plug-in wedge (8); a centering sleeve (7) for insertion into a corresponding through opening in the first pressure plate (5, 5a, 5b, 5c), which has an internal cross section in order to receive the second fastening part (61, 62) in a form-fitting manner. Lower chord connection with a connecting device (4a) according to one of claims 1 to 11, wherein the lower chord connection connects two lower chords (3) of the boom segments (1a, 1b) to one another, with a fixing device ( 4b) is provided to secure the lower chords (3) against displacement transversely to their axial direction. Lower flange connection with a connecting device (4a) according to claim 12, wherein the fixing device (4b) comprises:

- at least one screw mandrel (40) with a first fastening section for fastening to the first pressure plate (5, 5b, 5c) and with a second fastening section for fastening to the second pressure plate (5, 5a, 5c), the second fastening section having a lateral surface section ( 42) for fastening the screw mandrel (40) to the second pressure plate (5, 5a, 5c), a bushing (45) being provided for insertion into a through opening (57) in the second pressure plate (5, 5a, 5c), wherein the bushing (45) has an inner wall (46) to receive the lateral surface portion (42) of the second fastening portion. Lower flange connection with a connecting device (4a) according to claim 13, wherein the first fastening section is provided with a threaded section (41) for fastening the screw mandrel (40) to a threaded hole (58) in the first pressure plate (5, 5b, 5c). Lower flange connection with a connecting device (4a) according to claim 13 or 14, wherein the lateral surface section (42) of the second fastening section is received in the through opening (57) in a form-fitting and friction-locking manner.