Crane having a truss girder with flattened braces

Abstract

The invention relates to a crane, particularly a bridge crane or gantry crane, including at least one crane girder extending horizontally and designed as a truss with a plurality of braces, on which girder a crane trolley with a lifting gear is movable. At least some of the braces have a flat shape. The flat-shaped braces each have a flat main surface that extends in each case transversely to a longitudinal direction of the crane girder.

Claims

1. A crane comprising at least one crane girder that extends horizontally and is designed as a truss with a plurality of braces, on which girder a crane trolley with a lifting gear is movable, wherein at least some of the braces are designed having a flat shape, wherein the flat-shaped braces each have a planar main surface that extends in each case transversely with respect to a longitudinal direction of the crane girder, wherein the flat-shaped braces have an elongated shape with longitudinal sides, and comprise in a region of the longitudinal sides of the braces in each case at least one folded auxiliary surface that adjoins the main surface, wherein the at least one auxiliary surface points transversely with respect to the longitudinal direction of the crane girder, the braces having opposite brace ends, wherein lower and upper recesses are provided in the main surfaces of the braces along respective laterally-outboard edges of the longitudinal sides of the braces, wherein the auxiliary surfaces are spaced longitudinally inwardly from the brace ends and between the lower and upper recesses, and wherein the length of the auxiliary surface extending between and outside the brace ends is in a range of about 40% to 70% of the total length of the respective brace.

2. The crane of claim 1, wherein all of the braces of the crane girder are designed having a flat shape.

3. The crane of claim 1, wherein the main surfaces of the braces extend over at least half the width of the crane girder.

4. The crane of claim 1, wherein the braces, as seen in the direction of their longitudinal axes, have an L-, U- or Z-shaped cross-section.

5. The crane of claim 1, further comprising an aperture provided on a lower narrow side of the braces, which narrow side extends between the longitudinal sides of the braces, and which apertures are arranged in each case in the region of a first or second brace end.

6. The crane of claim 1, wherein the crane girder comprises at least one upper boom that extends in a linear manner in the longitudinal direction thereof, and wherein the crane girder further comprises at least one lower boom arranged in parallel with the upper boom, wherein the upper boom and the lower boom are connected to one another by a plurality of the braces arranged along the longitudinal direction of the crane girder.

7. The crane of claim 6, wherein each of the auxiliary surfaces comprises respective opposite ends that are spaced below the upper boom and spaced above the lower boom.

8. The crane of claim 6, wherein the upper boom and the lower boom are connected to one another by a plurality of posts arranged along the longitudinal direction of the crane girder.

9. The crane of claim 8, wherein each of the posts is arranged next to at least one brace, wherein each of the braces forms with the corresponding post a setting angle of the same size.

10. The crane of claim 8, wherein the posts are designed having a flat shape.

11. The crane of claim 1, wherein the crane comprises two crane girders that are arranged in parallel and at a spaced interval from one another.

12. The crane of claim 8, wherein the flat-shaped braces and the posts are fastened to the upper boom and the lower boom by weld seams, wherein the weld seams are arranged exclusively on the longitudinal sides of the respective main surfaces.

13. The crane of claim 8, wherein the upper boom and the lower boom each have mutually facing limbs and the braces and the posts are welded exclusively to the inner sides of the limbs.

14. The crane of claim 1, wherein the crane girder comprises at least one upper boom that extends in a linear manner in the longitudinal direction thereof, and wherein the crane girder further comprises at least one lower boom arranged in parallel with the upper boom, wherein the upper boom and the lower boom are connected to one another by a plurality of the braces arranged along the longitudinal direction of the crane girder.

15. The crane of claim 14, wherein the upper boom and the lower boom are connected to one another by a plurality of posts arranged along the longitudinal direction of the crane girder.

16. The crane of claim 15, wherein each of the posts is arranged next to at least one brace, wherein each of the braces forms with the corresponding post a setting angle of the same size.

17. The crane of claim 16, wherein the posts are designed having a flat shape.

18. The crane of claim 17, wherein the crane comprises two crane girders that are arranged in parallel and at a spaced interval from one another.

19. The crane of claim 18, wherein the flat-shaped braces and the posts are fastened to the upper boom and the lower boom by weld seams, wherein the weld seams are arranged exclusively on the longitudinal sides of the respective main surfaces.

20. The crane of claim 19, wherein the upper boom and the lower boom each have mutually facing limbs and the braces and the posts are welded exclusively to the inner sides of the limbs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a is a top perspective view of a prior art bridge crane designed as a single-girder crane;

(2) FIG. 1b is a top perspective view of another prior art bridge crane designed as a double-girder crane;

(3) FIG. 2a is a top perspective view of a crane girder in accordance with the present invention, for a bridge crane generally in accordance with FIG. 1a;

(4) FIG. 2b is a top perspective view of two crane girders in accordance with the present invention, for a bridge crane generally in accordance with FIG. 1b;

(5) FIG. 3 is a cross-sectional view of the crane girder of FIG. 2a;

(6) FIG. 4a is a side elevation of an adapter at an end of the crane girder; and

(7) FIG. 4b is an end elevation of the adapter as seen in the longitudinal direction of the crane girder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) Referring now to the drawings and the illustrative embodiments depicted therein, a conventional first crane 1a is designed as a single-girder bridge crane (FIG. 1a). The first crane 1a includes a crane girder 2 that is designed as a box girder, is oriented horizontally and extends with a length L in its longitudinal direction LR. Fastened to opposite ends of the crane girder 2 are first and second travelling mechanisms 7, 8, so that a crane bridge which, in plan view, is substantially double-T-shaped is formed. By means of the travelling mechanisms 7, 8, the first crane 1a is movable on rails, not illustrated, in a horizontal direction of travel F transversely with respect to the longitudinal direction LR of the crane girder 2. The rails are typically arranged at a position above the ground and for this purpose can be elevated, for example, by means of a suitable support structure or can be fastened to opposite walls of a building. In order to move the first crane 1a or its crane girder 2, the first travelling mechanism 7 is driven by a first electric motor 7a and the second travelling mechanism 8 is driven by a second electric motor 8a. Suspended from the crane girder 2 is a crane trolley 9 having a lifting gear designed as a cable winch, the crane trolley being movable by means of travelling mechanisms, not illustrated, transversely with respect to the direction of travel F of the first crane 1a and along the longitudinal direction LR of the crane girder 2. The crane trolley 9 is movable along and on laterally protruding running surfaces 4c of a lower boom 4 of the crane girder 2. The first crane 1a also includes a crane controller 10 and a pendant control switch 11 that is connected thereto and by means of which the first crane 1a or the electric motors 7a, 8a and the crane trolley 9 having the cable winch can be controlled and operated separately from one another.

(9) A conventional second crane 1b is designed as a double-girder bridge crane and which, in contrast to the first crane 1a designed as a single-girder bridge crane, includes two crane jibs 2 (FIG. 1b). Fastened to the ends of the two crane girders 2 are, again, travelling mechanisms 7, 8, so that a frame is formed as seen in plan view. The second crane 1b also includes a crane trolley 9 having a lifting gear designed as a cable winch. However, the crane trolley 9 is not suspended from the lower booms 4 of the crane girders 2, but rather runs on upper booms 3 of the two crane girders 2. Accordingly, the crane trolley 9 arranged centrally between crane girders 2 can be moved along the longitudinal direction LR of the crane girders 2 and between the two crane girders 2. In this case, a load picking-up means of the cable winch arranged on the crane trolley 9 can be lowered or raised between the two crane girders 2.

(10) For the remainder, the statements made with respect to the first crane 1a apply accordingly to the second crane 1b. Although like reference numerals are used in some cases to describe a conventional box girder and related components as in FIGS. 1a and 1b, and also to describe the inventive truss girder and related components as in FIGS. 2a-4b, it will be understood with reference to the drawings and the following descriptions that the truss girders 2 of the present invention are intended to substitute for the conventional box girders 2 of the cranes 1a, 1b of FIGS. 1a and 1b. It will further be appreciated the explanations given hereinafter with reference to bridge cranes also apply accordingly to gantry cranes.

(11) In the illustrated embodiment of FIG. 2a, a crane girder 2 is provided for use with a crane 1a designed in accordance with FIG. 1a as a single-girder bridge crane. In this case, the crane girder 2 is not designed conventionally as a box girder (as in the girders 2 of FIGS. 1a and 1b), but rather as a truss.

(12) The truss construction of the crane girder 2 includes an upper boom 3, a lower boom 4, diagonally extending braces 5 and vertical posts 6 (FIG. 2a). The upper boom 3 and the lower boom 4 extend in each case linearly, in parallel and spaced apart from one another in the longitudinal direction LR of the crane girder 2 between the travelling mechanisms 7, 8. In this case, the upper boom 3 and the lower boom 4 are spaced vertically apart from one another. The upper boom 3 is composed of two first and second upper boom profiles 3d, 3e that are arranged in a horizontal plane and are spaced horizontally apart from one another.

(13) The two upper boom profiles 3d, 3e are formed by an L- or angle-profile girder. The lower boom 4 is formed by a flat profile 4b having two vertically upstanding limbs 4a, so that approximately a U-profile-shaped cross-section is provided. In this case, the flat profile 4b is extended laterally beyond the limbs 4a (see also FIG. 3). The lateral extensions of the flat profile 4b each form a running surface 4c for travelling mechanisms of the crane trolley 9. The spaced intervalas seen in the longitudinal direction LRbetween the outermost edges of the upper boom profiles 3d, 3e or of the flat profile 4b also produces a width B of the crane girder 2.

(14) The upper boom 3 and the lower boom 4 are connected to one another by means of a plurality of braces 5 designed having a flat shape and a plurality of posts 6 that are bar-shaped in one embodiment. In this case, the braces 5 are formed as a sheet metal profile having a main surface 5a with a substantially rectangular cross-section, wherein the longitudinal sides thereof are folded back at least in a central region in the form of auxiliary surfaces 5b in order to increase buckling strength.

(15) The truss construction of the crane girder 2 is terminated at the opposite ends of the upper boom 3 and of the lower boom 4 by means of an adapter 12 in each case. By means of these adapters 12, the upper boom 3 and the lower boom 4 are connected to form a frame. Since the lower boom 4 is, on the whole, shorter than the upper boom 3, the adapter 12 has a diagonal progression and the frame of the crane girder 2 is, on the whole, extended from the bottom to the top and is formed in a trapezoidal manner. Moreover, the adapter 12 includes, in the region of the upper boom 3 and on the side facing away from the upper boom 3, a connection plate 12a, to which one of the travelling mechanisms 7, 8 or the girder thereof is fastened.

(16) Starting from one of the two adapters 12 as seen in the longitudinal direction LR of the crane girder 2, a first brace 5 is connected to the lower boom 4 and extends in the longitudinal direction LR at a first setting angle 1 inclined in the direction of the upper boom 3 and is fastened at this location in an upper node point OK. In this case, the first setting angle 1 is formed by the first brace 5 and a post 6, which ends in the upper node point OK. Preferably, the first setting angle 1 is in a range of about 35 to 55 and in a particularly preferred manner is about 45. Then, adjoining in the upper node point OK is a second brace 5, which extends obliquely at the setting angle 1 downwards to the lower boom 4. This is repeated until the opposite end of the crane girder 2 is reached by the braces 5. In this case, an even number of braces 5 is always used, so that the last brace 5 ends at the lower boom 4. Depending upon the length L of the crane girder 2, the setting angle 1 is determined prior to assembly, so that an even number of braces 5 each having the same length and at the same setting angle 1 is used. Moreover, in the region of each upper node point OK, a post 6 is additionally also fastened, which extends vertically with respect to the lower boom 4 and is fastened at this location. As a consequence, the lower boom 4 that is used as a rail and for this purpose forms the running surface 4c is reinforced to prevent bending.

(17) The braces 5 are oriented within the truss construction of the crane girder 2 in such a manner that in each case their main surface 5a extends transversely with respect to the longitudinal direction LR of the crane girder 2. Moreover, the braces 5 are arranged with their lower first brace ends 5g between the upwardly pointing limbs 4a of the lower boom 4. At their upper second brace ends 5h, the braces 5 are arranged between the two upper boom profiles 3d, 3e, wherein the upper boom profiles 3d, 3e are welded to the braces 5 with the inner sides of their limbs 3a that are vertically oriented flush with the limbs 4a of the lower boom 4 (see FIG. 3). The bar-shaped posts 6 are also arranged between the limbs 4a of the lower boom 4 and the limbs 3a of the upper boom profiles 3d, 3e and are welded with the inner sides thereof. For instance, as seen transversely with respect to the longitudinal direction LR of the crane girder 2, only ever one brace 5 is arranged between the limbs 3a, 4a of the upper boom 3 or lower boom 4.

(18) Furthermore, it is apparent with reference to FIG. 2a that in each case two vertical posts 6 are arranged between two braces 5 that extend obliquely or diagonally in the manner of a pitched roof. The braces 5 and posts 6, which are allocated to each other in this manner, meet one another at a common node point OK on the upper booms 3, wherein each brace 5 forms, together with the associated post 6 in the region of the corresponding upper node point OK on the upper booms 3, a first setting angle 1 of the same size. Therefore, by reason of the even number of braces 5 arranged accordingly in pairs the last brace 5 descends towards the lower boom 4 at both ends of the crane girder 2.

(19) Furthermore, the crane girder 2 can be adjusted in a dimensionally accurate manner to the length L by means of adapters 12 (see also FIG. 4), in that the adapters 12 are slid onto the opposite ends of the upper boom 3 of the crane girder 2, are then displaced accordingly in the longitudinal direction LR of the crane girder and finally are welded to the crane girder 2.

(20) Optionally, and with reference to FIG. 2b, two crane girders 2 are designed in accordance with the invention as trusses, for a crane 1b designed in accordance with FIG. 1b as a double-girder bridge crane. Both crane girders 2 are adjusted to the desired length L by means of adapters 12 slid on at their opposite ends (see also FIG. 4), and are arranged spaced apart from one another in parallel. The travelling mechanisms 7, 8, which are also illustrated, are fastened to the ends of the two crane girders 2 by means of the adapters 12.

(21) The truss construction of the two crane girders 2 of the second crane 1b comprise, again, a lower boom 4 and an upper boom 3 longer than the lower boom, the booms being designed in each case in one piece in the same way as the lower boom 4 of the first crane 1a. Accordingly, the upper boom 3 of each crane girder 2 is also formed by a flat profile 3b having limbs 3a with an approximately U-profile-shaped cross-section. The downwardly directed limbs 3a of the flat profiles 3b of the upper booms 3 and the upwardly directed limbs 4a of the flat profiles 4b of the lower booms 4 face towards one another.

(22) The upper boom 3 of each crane girder 2 is connected to the associated lower boom 4 by means of a plurality of braces 5 designed having a flat shape and by means of a plurality of posts 6 which, in a second embodiment, are also designed having a flat shape and are vertically oriented. The basic structure of the flat-shaped posts 6 that are formed in this second embodiment correspondswith correspondingly adapted dimensionssubstantially to the structure of the flat-shaped braces 5. However, instead of two bar-shaped posts 6 only one flat-shaped post 6 is arranged between two adjacent braces 5. In this case, each post 6 that is formed in the flat-shaped second embodiment extends with a main surface 6a transversely with respect to the longitudinal direction LR of the crane girder 2 and with auxiliary surfaces 6b that are folded at a right angle thereto in this longitudinal direction LR. The flat-shaped posts 6 can also be arranged or oriented in such a manner that the auxiliary surfaces 6b point towards, or away from, one of the ends of the crane girder 2.

(23) However, it is fundamentally also possible to provide the crane girders 2 of the first crane 1a, which is designed as a single-girder crane, with the flat-shaped posts 6 formed in the second embodiment.

(24) The braces 5 are identical for the two crane girders 2 of the second crane 1b, i.e., they are formed as in the case of the first crane 1a in accordance with FIG. 1a in a mirror-symmetrical manner in relation to their longitudinal axis LA.

(25) Moreover, it is indicated in FIG. 2b that the crane trolley 9 for the cable winch, not illustrated, is not suspended from the lower booms 4 of the crane girders 2 but rather from lower booms 3 thereof. For this purpose, a running rail having a corresponding running surface 3c is provided, preferably centrally, on each of the two upper booms 3, so that the crane trolley 9 is arranged between the crane girders 2 and accordingly, as illustrated in FIG. 1b, is movable in the longitudinal direction LR between the travelling mechanisms 7, 8 of the second crane 1b.

(26) Braces 5 are arranged in the manner of pitched roof (FIG. 2b) in substantially the same way as in the case of the crane girder 2 illustrated in FIG. 2a. However, in this case two adjacent braces 5 are allocated only one post 6 designed having a flat shape, such that the braces 5 and the post 6 meet one another at a common lower node point UK on the lower booms 4. Therefore, each brace 5 forms, together with the associated flat-shaped post 6 in the region of the corresponding lower node point UK on the lower booms 4, a second setting angle 2 of the same size which, just like the first setting angle 1, is preferably in a range from about 35 to 55, and in a particularly preferred manner is about 45. Therefore, by reason of the even number of braces 5 arranged accordingly in pairs the last brace 5 descends towards the lower boom 4 at both ends of the crane girder 2. However, in contrast to the crane girder 2 illustrated in FIG. 2a, a flat-shaped post 6 is also arranged at each end of the crane girder 2 after the last brace 5.

(27) FIG. 3 illustrates a cross-sectional view of the crane girder 2 in accordance with FIG. 2a. Referring now to FIG. 3, the basic structure of the braces 5 corresponds substantially to the fundamental structure of the posts 6 which, in the second embodiment, are likewise designed having a flat shape, but can differ therefrom in terms of dimensions. Accordingly, the statements made in relation to FIG. 3 also apply to the crane girders 2 illustrated in FIG. 2b and to the posts 6 used in this case in the flat-shaped second embodiment. For the sake of simplicity, with respect to the description of FIG. 3 reference is made only to the braces 5; the reference numerals 5a to 5h mentioned in this case similarly designate the corresponding elements of the flat-shaped posts 6, which are indicated at the same points as reference numerals 6a to 6h.

(28) The brace 5 designed having a flat shape and illustrated in FIG. 3 includes an elongated shape with a substantially rectangular main surface 5a. The main surface 5a extends along the longitudinal axis LA of the brace 5 and in each case in a central region over at least half the width B of the crane girder 2 transversely with respect to the longitudinal direction LR of the crane girder 2, in particular over at least half the spaced interval between the inner sides of the limbs 3a or the limbs 4a. The braces 5 are produced from a steel sheet preferably by means of laser-cutting. Moreover, the braces 5 comprise a lower first and a lower second brace end 5g, 5h. In particular, two brace feet 5f are formed on the lower first brace end 5g in the region of the lower corners of the brace 5, in that an aperture 5e is provided centrally on the lower first brace end 5g in the main surface 5a. The aperture 5e includes a cross-section which, in relation to the longitudinal axis LA, is mirror-symmetrical and is approximately trapezoidal. The braces 5 are inserted with their lower first brace ends 5g between the upwardly pointing limbs 4a of the lower boom 4. In this case, the brace feet 5f lie with their longitudinal sides of the main surface 5a, which extend between the lower recesses 5c and the lower first brace end 5g, against the inner sides of the limbs 4a of the lower boom 4 and are welded to the limbs 4a. However, the brace feet 5f do not lie on the flat profile 4b of the lower boom 4. It can also be seen in FIG. 3 that the two upper boom profiles 3d, 3e lie with their vertical limbs 3a against the corresponding longitudinal sides of the main surface 5a that extend between the upper recesses 5d and the upper second brace end 5h, and that a welded connection is established at this location.

(29) It is likewise feasible for the limbs 3a, 4a not to be spaced equally apart from one another. Accordingly, the outer longitudinal sides of the brace ends 5g, 5h, in particular also the brace feet 5f, are then also spaced at different distances apart from one another, in order to be able to lie against the limbs 3a, 4a, which are arranged vertically in a non-flush manner, and to be able to be welded thereto.

(30) In the region of its opposite, lower first and upper second brace ends 5g, 5h, two lower recesses 5c and two upper recesses 5d are provided on both longitudinal sides of the brace 5. The lower and upper recesses 5c, 5d adjoin the limbs 3a, 4a of the upper and lower booms 3, 4 in each case, in order to relieve the weld seam S or the associated weld seam run-out. The recesses 5c, 5d are round, preferably circular arc-shaped in formation.

(31) Between the lower and upper recesses 5c, 5d, an auxiliary surface 5b that is folded at right angles and extends in parallel with the longitudinal axis LA adjoins the main surface 5a at each longitudinal side of the brace 5. The auxiliary surfaces 5b are formed substantially in a trapezoidal manner. By folding both the auxiliary surfaces 5b in this same direction, the brace 5 illustrated in FIG. 3 includes, at least in the region of the auxiliary surfaces 5b, a U-shaped cross-section as seen in the direction of the longitudinal axis LA of the brace 5. It is likewise feasible for the auxiliary surfaces 5b to be folded in opposite directions, so that as seen in the direction of the longitudinal axis LA, a Z-shaped cross-section would be produced at least in part. By omitting an auxiliary surface 5b or by providing merely one single auxiliary surface 5b, the brace 5 can also comprise in a corresponding manner an at least partially L-shaped cross-section as seen in the direction of the longitudinal axis LA. The buckling strength of the braces 5 is increased by means of the auxiliary surfaces 5b. The auxiliary surfaces 5b are located outside the limbs 3a, 4a, so that only the regions of the longitudinal sides of the main surfaces 5a, which are not folded back, are welded to the limbs 3a, 4a.

(32) In one possible embodiment, the total length of a brace is 890 mm. In this case, the longitudinal sides of the lower first and the upper second brace ends 5g, 5h have been inserted in each case at an insertion length of 80 mm between the limbs 3a, 4a of the upper and lower booms 3a, 4a or are welded to the limbs 3a, 4a over the length. The spaced interval between the inserted regions of the longitudinal sides and the auxiliary surfaces 5b, i.e., the length of the membrane joints formed in this region, is then 100 mm in each case. Accordingly, in relation to the longitudinal axis LA the auxiliary surfaces 5b have an auxiliary surface length of 530 mm, i.e., auxiliary surfaces 5b extend in their longitudinal direction over the auxiliary surface length of 530 mm.

(33) The auxiliary surface lengths may be in a range of about 40% to 70% of the total length of the brace 5 and the insertion lengths may be in a range of about 5% to 15% of the total length of the brace 5.

(34) Respective adapters 12 (FIG. 4a) are arranged at the opposite ends of a crane girder 2 for the first crane 1a. The crane girder 2 is designed as a truss having two upper boom profiles 3d, 3e. A brace 5 is also shown, which is adjusted at the first setting angle 1 with respect to a bar-shaped post 6.

(35) An auxiliary surface 5b of the brace 5 has a trapezoidal formation, which auxiliary surface is folded from the main surface 5a, such as shown in FIG. 4a. The auxiliary surface 5b is arranged outside the limbs 3a, 4a of the upper and lower booms 3, 4 and extends in a vertical plane that includes the longitudinal direction LR of the crane girder 2.

(36) In order to adjust the desired length L of the crane girders 2, the adapter 12 is placed against the upper boom 3 and the lower boom 4, is oriented in the longitudinal direction LR and is welded thereto. For each adapter, length dimensions of +/5 millimeters in the longitudinal direction LR can be achieved. Accordingly, the crane girder 2 already has almost the desired length L prior to attaching the adapters 12. In this case, the construction of the adapter 12 is selected such that for the purpose of fine-adjustment of the length L it is displaceable relative to the upper boom profiles 3d, 3e and the lower boom prior to welding.

(37) The end of the crane girder 2 illustrated in FIG. 4a shows the termination of the truss construction, wherein the two upper boom profiles 3d, 3e of the upper boom 3 are connected to the lower boom 4 to form a frame. For this purpose, the adapter 12 includes two identically formed rib-like adapter walls 12e that extend in the longitudinal direction LR and are connected at their upper and lower ends to the limbs 3a, 4a. In this case, the adapter walls 12e are spaced apart from one another and are arranged in parallel with one another and in parallel with the limbs 3a, 4a and point with their surfaces correspondingly transversely with respect to the longitudinal direction LR of the crane girder 2.

(38) Each adapter wall 12e includes a head part 12f that is designed substantially as a rectangular and planar plate and has four corners E1 to E4. At the upper sides of the adapter walls 12e that connect the upper first corner E1 and the upper second corner E2, a horizontally oriented head plate 12b is placed onto the adapter walls 12e and is welded thereto. The head plate 12b is formed in a planar and rectangular manner. The vertically oriented connection plate 12a is fastened to the connection side of the adapter walls 12e that connects the first corner E1 to the third corner E3 arranged vertically therebelow. The connection plate 12a is also formed in a planar and rectangular manner, wherein as seen in the longitudinal direction LR, the connection plate 12a protrudes laterally beyond the adapter walls 12e. The connection plate 12a and the head plate 12b are thus arranged substantially at right angles with respect to one another and meet one another in the region of the first corner E1. In the region of a fourth corner E4 located diagonally opposite the first corner E1, the head part 12f of the adapter walls 12e transitions into a connection limb 12g. In this case, the connection limbs 12g adjoin the head part 12f of the respective adapter wall 12e in such a manner as to extend diagonally or obliquely downwards directed away from the connection side of the adapter walls 12e. The connection limbs 12g are formed in a flat and elongate manner and therefore their basic structure resembles substantially the structure of the limbs 3a, 4a of the upper boom 3a or the lower boom 4a.

(39) In the case of an adapter 12, which is placed onto the corresponding end of the crane girder 2, the diagonal progression of the connection limbs 12g permits the connection to the lower boom 4, which is designed to be shorter than the upper boom 3. In this case, the dimensions of the adapter walls 12e, in particular with regard to their head parts 12f and their connection limbs 12g, are selected in dependence upon the spaced interval between the upper boom 3 and the lower boom 4 such that the connection limbs 12g reach the lower boom 4 and in this case lie outside the limbs 4a against their outer sides such that they can still be connected or welded laterally to one another. In contrast to the upper and lower booms 3, 4 in FIG. 3, the limbs 3a of the upper boom 3 in FIG. 4a are thus not aligned in each case in a vertically flush manner with the limbs 4a of the lower boom 4, but rather the limbs 3a are spaced further apart from one another in the horizontal direction than the limbs 4a. Therefore, the connection brace 12g (which arrives at the lower boom 4) and the last brace 5 also intersect inside or outside the respective limb 4a.

(40) However, it is also possible that the limbs 3a, 4a are arranged with respect to one another as shown in FIG. 3 and the lower ends of the connection limbs 12g are inserted to a corresponding extent between the limbs 4a thereof, in order to be able to be connected thereto. Accordingly, the adapter walls 12e are arranged to be spaced so far apart from one another that in the region of the head parts 12f they lie with their outer sides flat against the inner sides of the limbs 3a, 3b of the upper boom profiles 3d, 3e of the upper boom 3 or the lower boom 4 in the same way as they lie against the lower free ends of the connection limbs 12g.

(41) It is likewise feasible that when the limbs 3a, 4a are spaced unequally apart from one another the adapter plates 12 lie with their head parts 12f between the limbs 3a of the upper boom 3, but lie with their connection limbs 12g outside the limbs 4a of the lower boom 4 against the outer sides thereof.

(42) In order to ensure that the adapter 12 or its correspondingly mutually spaced-apart adapter walls 12e, in particular the connection limbs 12g thereof, acquire sufficient rigidity and stability, an end plate 12h is provided on the lower sides of the adapter walls 12e. The end plate 12h extends starting from the third corner E3 of the head part 12e in the direction of the fourth corner E4, initially in a horizontal manner and then follows diagonally downwards the progression of the connection limbs 12e until it terminates at the lower boom 4. The end plate 12h that is bent in this manner is welded to the undersides of the adapter walls 12e. Moreover, a substantially rectangular recess 12i is provided at one end of the connection plate, which faces away from the head parts 12f.

(43) Adaptation to the desired length L of a crane girder 2 can also be effected if in contrast to the illustration in FIG. 4aas for example in the case of the second crane 1beach crane girder 2 includes an upper boom 3 with a flat profile 3b. In the case of an upper boom 3 that is designed in one piece as a flat profile 3b, the adapter walls 12e are set back below the head plate 12b to such an extent that the adapter 12 lies only with its head plate 12b on the upper boom 3. The adapter walls 12e then no longer lie laterally against the limbs 3a, 4a.

(44) In order to complete the length of the crane girder 2, the adapter 12 is slid onto one end of the crane girder 2, wherein its head plate 12b lies flat on the upper sides of the upper boom 3 or the two upper boom profiles 3d, 3e. The length L that is to be adjusted is defined by connection surfaces 12c of the connection plates 12a arranged at both ends of the crane girder 2, wherein the connection surfaces 12c point in opposite directions away from the upper booms 3. Finally, the length L is adjusted in a dimensionally accurate manner, in that the adapter 12 that lies with the head plate 12b on the upper boom 3 is displaced correspondingly in the longitudinal direction LR. In order to fix the length L that is adjusted in this manner, the adapters 12 are then welded to the upper boom 3 and the lower boom 4.

(45) However, it is also possible initially to slide an adapter 12 without a connection plate 12a onto the end of the crane girder and to adjust the length L. The connection plate 12a is then finally welded thereto, in order to orient the two opposite connection plates 12a with one another, as the connection plates 12a are already provided with bores 12d, by means of which the travelling mechanisms 7, 8 are fastened to the adapters 12 and thus to the corresponding crane girder 2.

(46) The adapter 12, as seen in the longitudinal direction LR of the crane girder 2 (FIG. 4b), is slid onto an end of the crane girder 2. It is apparent that the horizontally oriented head plate 12b of the adapter 12 lies on the upper boom 3 or its upper boom profiles 3d, 3e. This is adjoined by the vertically oriented connection plate 12a having the bores 12d for fastening one of the travelling mechanisms 7, 8. Arranged below the connection plate 12a is the end plate 12h, on whose end facing towards the lower boom 4 the recess 12i is provided. Through the recess 12i, it is possible to see a brace 5 that is inserted with its brace feet 5f between the limbs 4a of the flat profile 4b of the lower boom 4. Indicated on the outer longitudinal sides of the brace feet 5f is in each case one of the weld seams S, by means of which the brace 5 is fastened to the lower boom 4.

(47) Changes and modifications to the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law including the doctrine of equivalents.