Patent Publication Number: US-2022219952-A1

Title: Telescopic jib with swing-out mast

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the priority benefits of International Patent Application No. PCT/EP2020/072451, filed Aug. 11, 2020, and claims benefit of German patent application DE 10 2019 122 071.8, filed Aug. 16, 2019. 
    
    
     BACKGROUND AND FIELD OF THE INVENTION 
     The invention relates to a telescoping jib with a basic box, at least one inner box and at least one mast which can be folded out. 
     From the German utility model DE 202 19 126 U1 a guying arrangement for a telescoping jib of a crane with a guying mast on one of the telescoping sections is known. 
     A comparable guying arrangement is also known from German utility model DE 20 2014 006 460 U1. 
     Furthermore, from German laid-open document DE 2 258 807 A a mobile crane with a telescoping jib is already known, which, in a conventional manner, comprises a basic box and at least one inner box which can be pushed in and out. In addition, in the innermost inner box, a further inner box is arranged which can be pushed in and out and is referred to as a tip jib. The extended tip jib can be guyed with respect to the telescoping jib via two mast supports which can be folded out into a guying position. For this purpose, the two mast supports are pivotably mounted on a roller head of the innermost inner box and can be placed in an inoperative position on top of the basic box when the tip jib is retracted. 
     According to both disclosures, the guying masts are each arranged on the head of a telescoping section and so they can be mounted or dismounted. In relation to telescoping jibs without a guying mast such telescoping jibs have the disadvantage that they are harder to handle, especially when the guying mast is not required for lifting a load. Outlay for transporting and mounting the telescoping jib is also higher. 
     SUMMARY OF THE INVENTION 
     The present invention provides a telescoping jib on which an increase in load-bearing capacity with lower handling, transport and mounting outlay is rendered possible. 
     In accordance with the invention, in the case of a telescoping jib with a basic box, at least one inner box and at least one mast which can be folded out, a simplified increase in load-bearing capacity is achieved in that the mast is arranged on the inner box in such a way that the inner box can be pushed into the basic box together with the mast in the folded-in position. 
     In other words, the inner box and the folded-in mast are formed in such a way that the common clearance profile thereof is smaller than a receiving cross-section of the basic box. In this way, any cross-sectional shape for the fold-out mast, the inner box and the basic box is possible in principle. Therefore, the mast can remain on the inner box in the transport position or inoperative position, when said inner box is pushed into the basic box in a telescoping manner and therefore does not have to be laboriously attached or detached. In its inoperative position, preferably in every position, the mast preferably does not protrude beyond the overall length of the basic box and inner box, i.e. not even when the inner box is pushed into the basic box. 
     An increase in load-bearing capacity can easily be achieved in that the mast is folded out when required and guyed, e.g. in relation to the telescoping jib head. It is also possible for a jib extension to be attached to the telescoping jib head and for the mast then to be guyed in relation to the jib extension. In this way, a lever arm is produced between the telescoping jib or the jib extension and the mast, in particular the longitudinal position on the mast—e.g. the mast end on which the guying arrangement is articulated. The mast and the associated guying arrangement are thus used as aids for the application of a retaining force on the telescoping jib, preferably on the telescoping jib head thereof. Therefore, the raising or lowering of greater loads than in normal operation (without a mast) is possible. In terms of the invention, guying also includes pretensioning. 
     With the telescoping jib in accordance with the invention, the outlay in terms of costs and time for transportation and mounting can be reduced. In addition, a compact construction for the telescoping jib in the retracted position is achieved since the mast does not protrude beyond the cross-section of the basic box. Handling is facilitated especially during use without an increase in load-bearing capacity compared with prior art telescoping jibs with guying brackets since no limitation arises with the telescoping jib in accordance with the invention compared with a telescoping jib without an apparatus for increasing the load-bearing capacity. 
     In a particularly advantageous manner, provision is made for a plurality of inner boxes, which are also referred to a telescoping sections, to be arranged one inside another and together in the basic box, the mast being arranged on the innermost inner box and the innermost inner box together with the mast being able to be pushed into the second-innermost inner box in the folded-in position. In this embodiment, the innermost inner box and the folded-in mast are formed in such a way that the common clearance profile thereof is smaller than a receiving cross-section of the second-innermost, i.e. next outermost, inner box. The mast which can be folded out can remain on the innermost inner box when this box is pushed into the second-innermost inner box. In its inoperative position, preferably in every position, the mast does not protrude beyond the overall length of the basic box and all inner boxes, i.e. not even when all inner boxes are pushed into the basic box. 
     In an alternative embodiment, parts of the last inner box together with parts of the mast, in particular the head part with cable pulleys, protrude out of the second-innermost inner box. This has the advantage that even larger pulleys and larger cable diameters can be used for the guying arrangement. 
     In one embodiment, provision is made for the mast to be C-shaped and to partially surround the inner box. In this way it is ensured that the mast is resistant to twisting and yet the clearance profile of the inner box is not expanded. In terms of the invention, C-shaped means that the mast comprises a base, which extends in the longitudinal direction of the inner box and is preferably planar, and limbs which spread therefrom in the peripheral direction and are preferably linear. The mast can be e.g. in the form of a half-shell and partially surround the inner box. However, other surrounding angles for the limbs are also possible. Alternatively, the mast can also be formed wholly or partially as a hollow body. 
     In a further embodiment, provision is made for the inner mast to comprise a further mast. Both masts which can be folded out are preferably arranged on the periphery of the inner box and/or in relation to the longitudinal direction thereof on a middle axis in a mirrored arrangement. 
     In a constructionally simple manner, provision is made for the angle of spread formed between the masts in the folded-out position to be adjustable. The adjustment is preferably carried out by a corresponding arrangement of the fold-out joint on the periphery of the inner box. 
     In a particularly preferred manner, a connecting means, preferably a cable or a strut, is arranged between the masts in the folded-out position and is fastened in each case to the mast, preferably to the free end thereof. By this connecting means it is preferably ensured that the adjusted angle of spread does not change during raising and/or lowering of the load. In addition, transverse bending of the masts is reduced by the connecting means. When a cable is used, this cable is arranged in such a way that, with the mast folded in and the telescoping jib retracted, it can be jointly transported having been mounted thereon. 
     In an advantageous manner, one or each mast comprises a deflection means, preferably a pulley, which is preferably arranged at the free end thereof. This is arranged in such a way that, with the mast folded in and the telescoping jib retracted, it can be jointly transported having been mounted thereon. The deflection means serves to deflect a connecting means, in particular a cable, which is used for the guying of the mast. Alternatively, the deflection means can be arranged on the telescoping jib head or in the region of the telescoping jib foot. 
     In a particularly advantageous manner, provision is made for one or each mast to be able to be guyed in the folded-out position in relation to a telescoping jib head by a connecting means. The connecting means can be arranged in such a way that, with the mast folded in and the telescoping jib retracted, it can be jointly transported having been mounted thereon. 
     In a constructionally simple manner, provision is made for the connecting means to be a rod or cable and so the mast tip is arranged at a preset distance in the direction towards the telescoping jib head, and/or for the connecting means to be a cable and so the mast is able to be guyed in such a way that the angle between the mast and the telescoping jib head is variably adjustable in a range between 10 degrees and 170 degrees, preferably between 30 degrees and 110 degrees. The distance of the mast, in particular of the mast tip, from the inner box, the position of the fastening of the mast to the inner box and by reason of the type of articulation of the mast on the inner box therefore also the angle between the mast and inner box can thus be selected in a fundamentally individual manner. In this way, the desired lever arm, or the lever arm required for raising and lowering the load, between the mast and telescoping jib can be adjusted. When a rod is used for the guying arrangement the distance or the angle is to be selected prior to mounting of the rod. When a cable is used the distance or angle can be modified even during operation. In order to adjust the distance or angle the cable length is modified, in particular by means of a winch on the inner box. For this purpose, the deflection means can also be used on the mast. 
     It is also of particular advantage for one or each mast to be able to be erected by means of an auxiliary apparatus which preferably comprises a telescopable cylinder and/or a cable pull. For this purpose, the auxiliary apparatus is arranged and fastened at one of its ends on the inner box and arranged and fastened at its other end on the mast. The fastenings are preferably mounted in a rotationally articulated manner and so the change in the angle between the auxiliary apparatus and mast taking place during erection of the mast is rendered possible. In the case of corresponding guying of the mast, the auxiliary apparatus is load-free during raising and/or lowering of a load. When the mast is folded in, the auxiliary apparatus extends substantially parallel to the mast. It is also possible for a plurality of masts to be able to be erected by means of only one auxiliary apparatus. 
     Alternatively, the at least one mast can be used to erect the mast by a telescoping movement of a telescoping cylinder of the appropriate inner box and possibly correspondingly allocated cable pulls. In other words, the mast can be erected without further activity by extending the corresponding inner box. For this purpose, the mast which can be folded out is preferably connected at its free end by a connecting means to the telescoping jib in such a way that outwards telescoping of the inner box leads to pretensioning of the connecting means and so the mast is guyed in the desired way when the inner box is completely extended. A combination with other devices and/or apparatuses, such as e.g. the auxiliary apparatus, is possible. 
     Provision can also advantageously be made for the further flexible increase in load-bearing capacity of the telescoping jib in that a mast is arranged on a further inner box, is preferably C-shaped and partially surrounds the further inner box. In terms of the invention, a further inner box is to be understood to be any inner box apart from the innermost inner box. Thus, if a further increase in load-bearing capacity is necessary, this can be achieved by means of the mast or masts which can be folded out on the further inner box. As described above, a C-shaped form for the mast ensures that the mast is rigid in compression and yet does not significantly expand the clearance profile of the inner box. Provision is made for this mast also to be able to remain on the inner box when said box is pushed into the next-outermost inner box or into the basic box. 
     This mast is advantageously applicable to the erection of the mast on the innermost inner box. For this purpose, the mast on a further inner box is preferably erected first and then the mast on the innermost inner box. 
     In one advantageous embodiment, a foot of the, or of each, mast is arranged adjacent to a region of an overlap of the basic box or of one of the inner boxes with respect to the next-innermost inner box to which the mast is attached. The location of the arrangement point or articulation is preferably located at about 10 to 35% of the overall length of the inner box beginning from the start or from a rear bearing. In other words, the foot of the mast is preferably arranged in the region adjoining the overlap region with respect to the basic box or the next-outermost inner box, and is preferably articulated at that location. In this way, the greatest possible mast length can be ensured and/or a best possible result—in terms of static relief of loading of the telescoping jib—can be achieved. In principle, an arrangement of the foot of a mast in the direction of the telescoping jib head or of the overlap region with respect to half of the inner box orientated towards the next-innermost inner box is possible. In the case of such a variant, guying does not then necessarily take place at the head of the telescoping jib but preferably at an additionally mounted jib extension. 
     Provision is made in a particularly advantageous manner that, by means of a tensioning frame and of a connecting means, which preferably comprises a cable, one or each mast can be erected and guyed. The tensioning frame comprises a winch frame which is arranged e.g. on the basic box. However, it is also possible for the winch frame to be arranged independently of the telescoping jib. One or a plurality of guying cylinders, which pretension the connecting means in the region of the telescoping jib head or telescoping jib foot with a predetermined force, could be used in conjunction with, or without, a winch frame. Alternatively it is also possible for guying to be carried out only by a connecting means without a tensioning frame, e.g. via a cable or rod. Combinations of the above-mentioned variants are also possible. 
     In a constructionally simple manner, the tensioning frame comprises a luffing cable cross-member, preferably for multiple cable reeving. By means of the luffing cable cross-member it is possible to ensure guidance of the cable without a very large amount of diagonal pull. In addition, the connecting means can advantageously be deflected via a deflection means between the mast which can be folded and the tensioning frame in the region of a pivot axis of the telescoping jib. 
     In one embodiment provision is made for one or each mast to be able to be guyed with respect to a foot bearing of the telescoping jib by a connecting means which preferably comprises a cable. The telescoping jib is luffably mounted by means of the foot bearing. Alternatively, one or each mast can be guyed with respect to the basic box of the telescoping jib. However, guying with respect to any other position on the telescoping jib is also possible. 
     Provision can be advantageously made for an additional mast to be arranged on the telescoping jib, preferably on the basic box, for a further mast to be able to be mounted and for one or each mast which can be folded out to be guyed and/or tensioned by a connecting means via the additional mast. “To be able to be mounted” in terms of the invention means that this additional mast cannot be inserted with one of the inner boxes into the basic box or into one of the next-outermost inner boxes. The additional mast which can be mounted is attached at the operating location of the telescoping jib. 
     The invention also relates to a vehicle crane which comprises a telescoping jib in accordance with the invention. A telescoping jib of this type ensures an increase in load-bearing capacity for lower outlay in terms of handling, transport and mounting and ensures a higher level of safety for the vehicle crane, in particular when the crane is travelling with the telescoping jib retracted. In the present case, a vehicle crane is understood to be a mobile crane or crawler crane which can travel on the road or rails. 
     In one advantageous embodiment provision is made for one or each mast to be able to be guyed with respect to a superstructure of the vehicle crane by a connecting means. The telescoping jib is luffably mounted by means of the foot bearing which is preferably arranged on the superstructure. The telescoping jib can be luffed and can therefore be erected by means of a luffing cylinder. The vehicle crane comprises a lifting mechanism for raising and/or lowering a load and preferably a tensioning frame with which—as described above—the mast can be guyed. The vehicle crane also comprises a lower carriage on which the superstructure is arranged to be able to rotate about a vertical axis of rotation via a rotational connection. The vehicle crane also has driver&#39;s cabin and/or a further cabin on the superstructure. However, it is also possible for the crane to be remotely controlled and therefore only one or no (driver&#39;s) cabin is required. 
     Other applications of the telescoping jib in accordance with the invention are also possible, e.g. fixedly installed on a ship or on a rail-bound or rail-guided crane. 
     Exemplified embodiments of the invention will be explained in greater detail with reference to the figures and the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic side view of a telescoping jib with a folded-in mast and inner boxes partially pushed into the basic box; 
         FIG. 2  shows a schematic side view of the telescoping jib according to  FIG. 1  with a mast folded out by 90 degrees; 
         FIG. 3  shows a schematic side view of the telescoping jib according to  FIG. 1  with a mast folded out in an inclined manner; 
         FIG. 4  shows a schematic side view of a telescoping jib with a plurality of inner boxes and a folded-out mast; 
         FIG. 5  shows a schematic perspective view of an inner box with a C-shaped mast in the transport position or inoperative position; 
         FIG. 6  shows a schematic cross-sectional view (I-I) of the inner box according to  FIG. 5 ; 
         FIG. 7  shows a schematic cross-sectional view (II-II) of the inner box according to  FIG. 5 ; 
         FIG. 8  shows a schematic side view of a telescoping jib with a plurality of inner boxes and two folded-out masts on the innermost inner box; 
         FIG. 9  shows a schematic perspective view of an inner box with two masts in the transport position or inoperative position; 
         FIG. 10  shows a schematic cross-sectional view (III-III) of the inner box according to  FIG. 9 ; 
         FIG. 11  shows a schematic side view of a telescoping jib with a plurality of inner boxes, a folded-out mast on the innermost and a folded-out mast on the third-innermost inner box; 
         FIG. 12  shows a schematic side view of a telescoping jib with a plurality of inner boxes and two mounted additional masts; 
         FIG. 13  shows a schematic side view of a telescoping jib according to  FIG. 4  with a foot bearing and tensioning frame; and 
         FIG. 14  shows a schematic side view of a vehicle crane which can travel on the road, with a telescoping jib in accordance with the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a schematic side view of a telescoping jib  10 . This comprises a basic box  11 , an inner box  12  arranged in the basic box  11 , and a telescoping jib head  13 . The inner box  12  is shown pushed partially into the basic box  11 . A mast  20  which can be folded out and which is shown in the folded-in inoperative position is arranged on the inner box  12 . The mast  20  is thus in an inoperative position lying on the inner box  12 . In the inoperative position, the mast  20  extends with its longitudinal direction parallel to a longitudinal direction of the inner box  12 . It is very clear to see that the inner box  12  can be pushed into the basic box  11  together with the mast  20  in the folded-in inoperative position. The inner box  12  and the folded-in mast  20  are formed in such a way that the common clearance profile thereof is smaller than a receiving cross-section of the basic box  11 . The mast  20  can therefore remain on the inner box  12  when this box is pushed into the basic box  11  in a telescoping manner. In no position does the mast  20  protrude beyond the overall length of the basic box  11  and inner box  12 , i.e. not even when the inner box  12  is pushed into the basic box  11 . In the illustrated position of the telescoping jib  10 , this jib can be used to raise and/or lower a load, not shown, with the weight F without an increase in load-bearing capacity. For this purpose, a lifting cable, not shown, is deflected over the telescoping jib head  13 . 
     In an alternative embodiment, parts of the fold-out mast  20  of the last inner box  12 ,  12 ′, in particular a head part with cable pulleys of the fold-out mast  20 , protrude from the second-innermost inner box  12 ″. This produces the advantage that even larger cable pulleys and larger cable diameters can be used for the guying arrangement. 
       FIGS. 2 and 3  each show a schematic side view of the telescoping jib  10  according to  FIG. 1  with the folded-out mast  20 . By means of the mast  20  which can be folded out the load-bearing capacity of the telescoping jib  10  can be increased. The inner box  12  is fully extended out of the basic box  11  and the mast  20  folded out. It is also possible for the mast  20  to be formed in a telescopable manner. Connecting means  40 ,  50  engage at the free end of the mast  20 . The connecting means  40 ,  50  together with the mast  20  form a guying arrangement for the telescoping jib  10 . 
     The connecting means  40  is connected to the telescoping jib head  13 , in particular is fastened thereto. The function of the connecting means  40  is also to prevent the mast  20  flipping downwards. The connecting means  40  can be a rod, cylinder and/or a cable. When a rod is used, the mast  20  is arranged at a preset distance from the telescoping jib head  13 . The distance or angle b between the mast  20  and the telescoping jib  10  is to be selected prior to mounting of the rod. When a cable is used, the mast  20  can be guyed in such a way that the angle b can be variably adjusted in a range between 10 degrees and 170 degrees, preferably between 30 degrees and 110 degrees. When a cable is used, the distance or angle b can thus be modified even during operation. In order to adjust the distance or angle b the cable length is modified, in particular by means of a winch on the inner box  12 . For this purpose, a deflection means  60  can also be used on the mast  20  (see  FIG. 5 ). When a cable is used, the connecting means  40  is arranged in such a way that, with the mast  20  folded in and the telescoping jib  10  retracted, it can be jointly transported having been mounted thereon. 
     In  FIG. 2 , the mast  20  is folded out at a angle of b=90 degrees, i.e. at a right angle to the telescoping jib  10 , and protrudes downwards. In contrast to this, the mast  20  illustrated in  FIG. 3  is folded out at an angle of b&lt;90 degrees, for instance 60 degrees. 
     The connecting means  50  is connected to the basic box  11 , in particular is fastened thereto. It can also alternatively be connected to a tensioning frame  80  and/or a foot bearing  14  (see  FIG. 13 ). The connecting means  50  is preferably of modifiable length and is therefore a cable. The function of the connecting means  50  is also to prevent the mast  20  flipping upwards. 
     It is very clear to see that when the inner box  12  is in the fully extended position, the mast  20  is arranged with its foot in the region of the inner box  12  adjoining the overlap region with respect to the basic box  11 . In this way, a greatest possible mast length can be ensured and/or a best possible result—in terms of static relief of loading of the telescoping jib  10 —can be achieved. In principle, an arrangement of the foot of the mast  20  in a position pushed towards the telescoping jib head  13  is also possible. 
       FIG. 4  shows a schematic side view of a telescoping jib  10  with a plurality of inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″ and a folded-out mast  20 . All descriptions relating to the inner box  12  or inner boxes  12  apply equally to the inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″. The inner boxes  12  are each arranged one inside another and jointly in the basic box  11  and are fully extended. The mast  20  is arranged on the innermost inner box  12 ′. The innermost inner box  12 ′ can be pushed, together with the mast  20  in the folded-in position, into the second-innermost inner box  12 ″. In this embodiment, the innermost inner box  12 ′ and the folded-in mast  20  are formed in such a way that the common clearance profile thereof is smaller than a receiving cross-section of the second-innermost inner box  12 ″. The mast  20  can remain on the innermost inner box  12 ′ when this box is pushed into the second-innermost inner box  12 ″. In a preferred case, in no position does the mast  20  protrude beyond the overall length of the basic box  11  and all inner boxes  12 , i.e. not even when all inner boxes  12  are pushed into the basic box  11 . 
     It is very clear to see that when the innermost inner box  12 ′ is in the fully extended position, the mast  20  is arranged with its foot in the region of the innermost inner box  12 ′ adjoining the overlap region with respect to second-innermost inner box  12 ″. In this way, the greatest possible mast length can be ensured and/or a best possible result—in terms of static relief of loading of the telescoping jib  10 —can be achieved. In principle, an arrangement of the foot of the mast  20  in the half of the innermost inner box  12 ′ orientated towards the telescoping jib head  13  is also possible. 
     Otherwise, the statements relating to  FIGS. 1 to 3  also apply to the embodiment illustrated in  FIG. 4 . 
       FIG. 5  shows a schematic perspective view of an inner box  12 . The telescoping jib  10  with a plurality of inner boxes  12  is the innermost inner box  12 ′. The telescoping jib head  13  is arranged at one end of the inner box  12 . At the other end of the inner box  12  is the overlap region  12   a  with respect to the basic box  11  or with respect to the second-innermost inner box  12 ″. The inner box  12  consists of a main support  12   b  and the overlap region  12   a . The main support  12   b  is adjoined by the overlap region  12   a  and possibly in an opposing arrangement the telescoping jib head  13 . The main support  12   b  is a region of the inner box  12  with a smaller cross-section. The cross-sections of the overlap region  12   a  and of the main support  12   b  are shown in a simplified manner as a rectangle and hexagon in the illustration. However, both cross-sections preferably have a mutually tailored shape and are preferably rounded as shown in the cross-sectional view according to  FIG. 6 . 
     The mast  20  is arranged in the region of the main support  12   b . The mast  20  is C-shaped and partially surrounds the inner box  12  from above in the inoperative position shown at this point. In this way it is ensured that the mast  20  is rigid in compression but does not expand the clearance profile of the inner box  12  and so both can be pushed together into the basic box  11  or into the second-innermost inner box  12 ″. The mast  20 , referred to as C-shaped, comprises a planar base  20   b , which extends in the longitudinal direction of the inner box  12 , and limbs  20   c  which spread from the base in the peripheral direction and are preferably linear. Therefore, the mast  20  is substantially half-shell-shaped and partially surrounds the inner box  12  from above. Other surrounding angles for the limbs  20   c  are also possible. 
     The mast  20  is connected to the inner box  12  in an articulated manner via one or two fold-out joints  20   a , not illustrated. Two deflection means  60  (only the front one being shown) are rotatably mounted at the free end of the mast  20 . The deflection means  60  are arranged in such a way that, with the mast  20  folded in and the telescoping jib  10  retracted, they can be jointly transported having been mounted thereon. The deflection means  60  is in each case preferably a pulley and serves to deflect the connecting means  40 , preferably a cable, which is used for the guying of the mast  20  with respect to the telescoping jib head  13 . Alternatively, the deflection means  60  can in each case be arranged on the telescoping jib head  13 . 
     The mast  20  can be erected by means of an auxiliary apparatus  70 , not illustrated, which preferably comprises a telescopable cylinder and/or a cable pull. For this purpose, the auxiliary apparatus  70  is arranged and fastened at one of its ends on the inner box  12  and arranged and fastened at its other end on the mast  20 . The fastenings are preferably mounted in a rotationally articulated manner and so the change in the angle between the auxiliary apparatus  70  and mast  20  taking place during erection of the mast  20  is rendered possible. When the mast is guyed accordingly, the auxiliary apparatus  70  is load-free during raising and/or lowering of a load. When the mast  20  is folded in, the auxiliary apparatus  70  extends substantially parallel to the mast. 
       FIG. 6  shows a schematic cross-sectional view (I-I) of the inner box  12  according to  FIG. 5 . The C-shaped design of the mast  20  and the surrounding of the main support  12   b  of the inner box  12  are very clear to see. 
       FIG. 7  shows a schematic cross-sectional view (II-II) of the inner box  12  according to  FIG. 5 . The two fold-out joints  20   a  by means of which the mast  20  is connected in an articulated manner to a stiffening wall of the overlap region  12   a  of the inner box  12  are very clear to see. 
       FIG. 8  shows a schematic side view of a telescoping jib  10  with a plurality of inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″. All descriptions relating to the inner box  12  or inner boxes  12  apply equally to the inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″. In this embodiment, two masts  20 ,  20 ′, which can be folded out, are arranged on the innermost inner box  12 ′ and are shown folded out. The masts  20 ,  20 ′ are arranged on the periphery of the innermost inner box  12 ′ and as a mirror image with respect to the longitudinal direction thereof on a middle axis. In this way, the masts  20 ,  20 ′ are arranged in the folded-out position in a v-shape next to, and with respect to, each other. A spreading angle a is formed between the masts  20 ,  20 ′ in the folded-out position. The angle of spread a can be adjusted by a corresponding arrangement of the fold-out joint  20   a  on the periphery of the inner box  12 . The connecting means  40 ,  50  engage each mast  20 ,  20 ′ respectively at the free end thereof. The connecting means  40 ,  50  together with the masts  20 ,  20 ′ form a guying arrangement for the telescoping jib  10 . In addition, a connecting means  30 , preferably a cable or a strut, is arranged between the masts  20  in the folded-out position and is fastened in each case to the mast  20 ,  20 ′, preferably to the free end thereof. By this connecting means  30  it is ensured that the adjusted angle of spread a does not change during raising and/or lowering of a load. In addition, transverse bending of the masts  20 ,  20 ′ is reduced by the connecting means  30 . If a cable or a plurality of cables is/are used as connecting means  30 ,  40 ,  50 , each of the cables is arranged such that, with the mast  20 ,  20 ′ folded in and the telescoping jib  10  retracted, it can be jointly transported having been mounted thereon. 
       FIG. 9  shows a schematic perspective view of an inner box  12  with two masts  20 ,  20 ′ which can be folded out. A telescoping jib  10  with a plurality of inner boxes  12  is the innermost inner box  12 ′. The telescoping jib head  13  is arranged at one end of the inner box  12 . At the other end of the inner box  12  is the overlap region  12   a  with respect to the basic box  11  or with respect to the next-outermost inner box  12 ″. The inner box  12  consists of a main support  12   b  and the overlap region  12   a . The main support  12   b  is adjoined by the overlap region  12   a  and possibly in an opposing arrangement the telescoping jib head  13 . The main support  12   b  is a region of the inner box  12  with a smaller cross-section. The cross-sections of the overlap region  12   a  and of the main support  12   b  are shown in a simplified manner as a rectangle and hexagon in the illustration. However, both cross-sections preferably have a mutually tailored shape and are preferably rounded as shown in the cross-sectional view according to  FIG. 10 . 
     In the region of the main support  12   b , two masts  20 ,  20 ′ are arranged in the inoperative position illustrated in this case, each on one side of the main support  12   b . The masts  20 ,  20 ′ are connected in an articulated manner to the inner box  12  in each case via a fold-out joint  20   a . A deflection means  60  is rotatably mounted at the free end of each mast  20 ,  20 ′. The deflection means  60  are arranged in such a way that, with the masts  20 ,  20 ′ folded in and the telescoping jib  10  retracted, they can be jointly transported having been mounted thereon. The deflection means  60  is in each case preferably a pulley and serves to deflect the connecting means  40  which is used for the guying of the mast  20 ,  20 ′ with respect to the telescoping jib head  13 . Alternatively, the deflection means  60  can in each case be arranged on the telescoping jib head  13 . 
     Each mast  20 ,  20 ′ can be erected by means of an auxiliary apparatus  70  which preferably comprises a telescopable cylinder. For this purpose, the auxiliary apparatus  70  is arranged and fastened at one of its ends on the inner box  12  and arranged and fastened at its other end on the mast  20 ,  20 ′. The fastenings are preferably mounted in a rotationally articulated manner and so the change in the angle between the auxiliary apparatus  70  and mast  20 ,  20 ′ taking place during erection of the mast  20 ,  20 ′ is rendered possible. When the mast is guyed accordingly, the auxiliary apparatus  70  is load-free during raising and/or lowering of a load. When the mast  20 ,  20 ′ is folded in, the auxiliary apparatus  70  extends substantially parallel to the mast. 
     Alternatively, the masts  20 ,  20 ′ can be erected e.g. by means of a tensioning frame  80 , not illustrated. 
       FIG. 10  shows a schematic cross-sectional view (III-III) of the inner box  12  according to  FIG. 9 . The masts  20  arranged on both sides of the main support  12   b  of the inner box  12  are very clear to see. 
       FIG. 11  shows a schematic side view of a telescoping jib  10  with a plurality of inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″. All descriptions relating to the inner box  12  or inner boxes  12  apply equally to the inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″. In addition to the mast  20  arranged on the innermost inner box  12 ′, a further mast  21  is arranged on a further inner box  12 , the third-innermost inner box  12 ″′, in order to increase the load-bearing capacity of the telescoping jib  10  further in a flexible manner. This further mast  21  which can be folded out is preferably C-shaped. However, an embodiment with two independent masts  21 , as described above for the mast  20 ,  20 ′, is also possible. Thus, if a further increase in load-bearing capacity is necessary, this can be achieved by means of the further mast  21  or the masts  21 . Each mast  21  can be folded out and possibly telescoped. Provision is made for this mast  21  also to be able to remain on the third-innermost inner box  12 ″′ when said box is pushed into the next-outermost, the fourth-innermost, inner box  12 ″″. The mast  21  can be used to erect the mast  20 . For this purpose, the mast  21  can preferably be erected first and then the mast  20 . Both masts are preferably erected using the connecting means  50 . It is also possible for a further connecting means to be used between the masts  20 ,  21  and for the masts  20 ,  21  to be guyed with respect to each other thereby. The mast  21  would in this case be erected using the connecting means  50 , the mast  20  would be erected with the further connecting means. 
     It is very clear to see that when the third-innermost inner box  12 ″′ is in the fully extended position, the mast  21  is arranged with its foot in the region of the third-innermost inner box  12 ″′ adjoining the overlap region with respect to fourth-innermost inner box  12 ″″. In principle, an arrangement of the foot of the mast  20  in the half of the third-innermost inner box  12 ″′ orientated towards the overlap region  12   a  with respect to the second-innermost inner box  12 ″ is also possible. 
     Otherwise, the statements relating to  FIG. 4  also apply to the embodiment illustrated in  FIG. 11 . 
       FIG. 12  shows a schematic side view of a telescoping jib  10  with a plurality of inner boxes  12 ′,  12 ″,  12 ″′,  12 ″″, two masts  20 ,  20 ′ which can be folded out and two mounted additional masts  22 ,  22 ′. The connecting means  40 ,  50  engage each fold-out mast  20 ,  20 ′ respectively at the free end thereof. The masts  20 ,  20 ′ which can be folded out are each connected by the connecting means  50  to the mounted additional mast  22 ,  22 ′ and can be guyed with respect thereto. A tensioning frame  80  arranged on each of the two mounted additional masts  22 ,  22 ′ is used to pretension the connecting means  50 . The mounted additional masts  22 ,  22 ′ are connected to the telescoping jib  10  by a connecting means  51 . The connecting means  40 ,  50 ,  51  together with the masts  20 ,  20 ′ and the additional masts  22 ,  22 ′ form a guying arrangement for the telescoping jib  10 . 
     Otherwise, the statements relating to  FIG. 8  also apply to the embodiment illustrated in  FIG. 12 . 
       FIG. 13  shows a schematic side view of a telescoping jib  10  according to  FIG. 4  with a foot bearing  14  and tensioning frame  80 . The telescoping jib  10  is luffably mounted by means of the foot bearing  14 . The mast  20  can be erected and guyed by means of the tensioning frame  80  and the connecting means  50  which preferably comprises a cable. The tensioning frame  80  comprises a winch frame which is arranged on the foot bearing  14 . However, it is also possible for the winch frame to be arranged on the basic box  11 . Alternatively it is also possible for guying to be carried out only by a connecting means  50  without a tensioning frame  80 , e.g. via a cable or rod. The tensioning frame  80  comprises a luffing cable cross-member, preferably for multiple cable reeving. By means of the luffing cable cross-member it is possible to ensure guidance of the cable without a considerable amount of diagonal pull. One or a plurality of guying cylinders, which pretension the connecting means in the region of the telescoping jib head or telescoping jib foot with a predetermined force, could be used in conjunction with or without a winch frame. 
     Otherwise, the statements relating to  FIG. 4  also apply to the embodiment illustrated in  FIG. 12 . 
       FIG. 14  shows a schematic side view of a vehicle crane  100 , in particular a mobile crane, which can travel on the road, having a lower carriage  101  and a superstructure  102  arranged to be able to rotate on the lower carriage  101  via a rotational connection  107  about a vertical axis of rotation. The superstructure  102  and lower carriage  101  can alternatively also be rigidly mounted one on the other. A telescoping jib  10  in accordance with the invention is mounted on the superstructure  102  via a foot bearing  12  and can be luffed by a luffing cylinder  108 . The telescoping jib  10  is shown erect but can also be laid on the lower carriage  101  when the inner box  12  is fully retracted, in particular for the purpose of road travel. 
     The telescoping jib  10  is illustrated schematically in the form of the basic box  11  and has a plurality of inner boxes  12 , not shown for reasons of simplification, which are arranged one inside another and can be telescoped out. The illustrated telescoping jib head  13  is arranged on the innermost inner box  12 ′. For an increase in load-bearing capacity, the telescoping jib  10  can be provided with a mast  20  and/or a mast  21  and/or an additional mast  22 —as described above. The mast or masts  20 ,  20 ′,  21 ,  22 ,  22 ′ of the telescoping jib  10  is/are able to be guyed and/or deflected with respect to the superstructure  102  and/or with respect to the foot bearing  14  arranged thereon. Guying can be effected e.g. by the tensioning frame  80  which can be arranged on the superstructure  102 , the telescoping jib  10  and/or the additional masts  22 ,  22 ′. A load, not shown, can be lifted by a lifting mechanism which is also arranged on the superstructure  102 . 
     The lower carriage  101  additionally comprises nine vehicle axles  105  which are each provided with two rubber-tyred wheels  106  suitable for road travel. The lower carriage  101  can naturally comprise more or less than nine vehicle axles  105  or alternatively can comprise a crawler track. The vehicle crane  100  has a driver&#39;s cabin  104 . 
     It is self-evident that the principle of the present invention can also be applied to crawler cranes. In addition, other applications of the telescoping jib  10 , e.g. fixedly installed on a ship, are possible.