Telescopic jib of a mobile crane

Abstract

To provide a telescopic jib capable of being unlocked easily in an emergency.SOLUTION: The present invention relates to a telescopic jib (1) of a mobile crane having a basic box (10) and a plurality of inner boxes (20, 30, 40). The plurality of inner boxes (20, 30, 40) can be extended from retraction positions (A) to extension positions (B, C, D), respectively, and can be locked and unlocked together at the respective retraction positions (A) or the extension positions (B, C, D) by bolting holes (12, 22, 32) arranged in the basic and inner boxes (10, 20, 30, 40), and related lock bolts (21, 31, 41). It is proposed that the bolting holes (12, 22, 32) for the extension positions (B, C, D) are aligned with each other at the retraction positions (A) of the basic and inner boxes (10, 20, 30, 40), in order to provide the telescopic jib (1) of the mobile crane capable of being unlocked easily in an emergency.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a telescopic boom of a mobile crane having a basic box and a plurality of inner boxes, wherein the plurality of inner boxes can each extend from a retracted position to an extended position, and are locked and unlocked together at their respective retracted or extended positions via bolt holes arranged in the basic box and the inner boxes, and associated lock bolts.

Background Art

[0002] German Published Document DE19811813A1 already describes a telescopic boom of a mobile crane, in particular a locking system for this telescopic boom. The telescopic boom usually consists of a number of telescopic boxes, one of which is inserted into the other and can be individually and continuously retracted and extended by a telescopic device to change the length of the telescopic boom. Each adjacent telescopic box is fixed against extension or retraction at its retracted position and each pre-specified extended position via one or more lock bolts. These lock bolts are each arranged inside, except for the lower end of the telescopic box and the outermost telescopic box, and in their locking positions, in each case project into the bolt holes of the next outermost telescopic box. Accordingly, the corresponding bolt holes for each of the retracted position and the pre-specified extended position are arranged along the longitudinal direction of each telescopic box. Since the individual telescopic boxes usually have the same extension length over the pre-specified arrangement of the bolt holes, the bolt holes are in each case covered by the outermost telescopic boxes adjacent to each other on the outside.

[0003] To move the telescopic box, the locking and fixing unit of the telescopic device moves into the area of ​​the lock bolts of the moving telescopic box. In this position, the drive bolts located in the locking and fixing unit are then coupled to the corresponding drive openings on the moving telescopic box. The locking and fixing unit then moves the lock bolts of the moving telescopic box to their unlocked positions. At this point, the moving telescopic box is pushed out by the locking and fixing unit through the telescopic device from its retracted position to the desired extended position, and can then be locked again in this extended position via the lock bolts. The drive bolts are then released, and the telescopic device with the locking and fixing unit is retracted.

[0004] In the event that normal extension and retraction is interrupted, it may be necessary to unlock the lock bolt in an emergency. For this purpose, a threaded screw is provided that can be screwed in via a lever to unlock the spring-loaded lock bolt. For this purpose, the hole is usually provided within the area of ​​bolt holes in the extension box adjacent to all exteriors, so that the threaded screw can be screwed in from the outside of the extension box.

[0005] Furthermore, the telescopic jib of a mobile crane is already known from German Patent Specification DE3146311C2, and it consists of a base section, two intermediate sections, and an end section. The intermediate sections can be extended and retracted via a screw drive. A pair of stop bolts are provided on the innermost end section so that the end section can also be extended, and the end can be connected to a screw drive as needed. For this purpose, the stop bolts can be manually adjusted from the outside via a further screw drive using a hand crank. Since the further screw drive is located on the innermost end section, the hand crank should in any case be inserted from the outside through the base section, the two intermediate sections, and the end section to the further screw drive. This is done via an access opening for the hand crank that is aligned for this purpose on the base section, the two intermediate sections, and the end section. [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, the objective of the present invention is to provide a telescopic jib that can be easily unlocked in an emergency.

[0007] This objective is achieved by a telescopic jib having the features of claim 1. Advantageous embodiments of the present invention are described in dependent claims 2 to 4. [Means for solving the problem]

[0008] According to the present invention, in the case of a telescopic jib of a mobile crane comprising a base box and multiple inner boxes, each of the multiple inner boxes can extend from a retracted position to an extended position, and can be locked and unlocked together at their respective retracted or extended positions via bolt holes located in the base box and inner boxes, as well as associated lock bolts, and a simple option for emergency unlocking is realized thanks to the fact that the bolt holes for the extended positions are aligned with each other at the retracted positions of the base box and inner boxes. Thus, the lock bolts are easily accessible from the outside for emergency unlocking without the large manufacturing cost of additional holes for emergency unlocking, and without weakening the inner and outer boxes by the additional holes. Furthermore, corresponding static designs for the inner and outer boxes with additional holes are not required. According to the present invention, the vertical arrangement of the bolt holes is achieved by matching the lengths of the stepped extensions of the inner boxes with each other so that all bolt holes are located vertically and therefore all lock bolts can be reached from the outside without the need for additional holes.

[0009] In the extended position, a particular advantage is that the lock bolt can be unlocked from the outside through the bolt hole in an emergency.

[0010] In the context of the present invention, an emergency unlocking event is understood to be a condition in which, for example, the lock bolt fails to fasten, the inner box fails to be secured by the telescopic cylinder, or the telescopic system completely fails. The present invention simplifies the accessibility of the lock bolt from the outside, and in an emergency unlocking event, the lock bolt can be released in a first step, thereby allowing for further action to be taken.

[0011] From a structural standpoint, it is advantageous that, at the extended position, the front end of the lock bolt is accessible from the outside through the bolt hole of the adjacent inner box.

[0012] Therefore, it avoids the need for additional holes that would otherwise have to be statically designed, which would increase manufacturing costs.

[0013] In the advantageous configuration, it is specified that an externally accessible unlocking element is located at the front end of the lock bolt.

[0014] The present invention will be described in more detail below with the help of exemplary embodiments shown in the drawings. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic plan cross-sectional view of the telescopic jib of the present invention. [Figure 2] This is an enlarged view of the cross-section of Figure 1 from the foot end region of the telescopic jib. [Figure 3] This is an enlarged view of the cross-section of Figure 1 from the area of ​​the bolt holes. [Figure 4] Figure 3 shows an extended inner box and a locking bolt in a locked state. [Modes for carrying out the invention]

[0016] Figure 1 shows a schematic plan cross-sectional view of the telescopic jib 1 of the present invention. The telescopic jib 1 extends in its longitudinal direction L from its foot end 2 to its head end 3 and is substantially composed of an outermost base box 10 in which a first inner box 20, a second inner box 30, and a third inner box 40 are retractably inserted into each other. In a horizontally oriented telescopic jib 1, the plane of the cross-section is located approximately in the middle of the telescopic jib 1 and extends towards the center through its left and right side walls 4, 5. In the corresponding configuration, the cross-section is also typically located on the side walls 4, 5 and in either case extends along the base box 10 and the inner boxes 20, 30 through bolt holes 12, 22, 32 located at the retracted position A, the first extended position B, the second extended position C, and the third extended position D. Since the innermost third inner box 40 is bolted in the bolt holes 32 of the adjacent second inner box 30, no bolt holes are provided in the innermost third inner box 40. In principle, it is conceivable that additional bolt holes could be provided in the third inner box 40 to accommodate further inner boxes not shown.

[0017] The telescopic jib 1 is a component of a mobile crane (not shown) that can move on public roads and typically consists of a lower carriage with rubber-tired wheels and a superstructure that can pivot on it around a vertical axis. The telescopic jib 1 is then articulated to the superstructure and opposed to a counterweight so that it can rumble around a horizontal axis. This articulation is made via a leg joint 15 on the base box 10 shown in Figure 1.

[0018] Typically, to change the length of the telescopic jib 1, the inner boxes 20, 30, and 40 are individually and continuously retracted and extended linearly from the base box 10 or the subsequent outer inner boxes 20 and 30 by telescopic devices, which are not shown for clarity. The telescopic device substantially consists of a hydraulic telescopic cylinder located in the center of the telescopic jib 1, supported within the area of ​​the foot connection 15 of the base box 10, extending in the longitudinal direction L, and carrying a so-called fixing and locking unit, not shown, at its extendable portion, particularly at its lower end of the cylinder tube. On the one hand, via a fixing and locking unit, the telescopic cylinders can be coupled via drive bolts for retraction and extension of their respective inner boxes 20, 30, and 40, with recesses located in the area of ​​each foot end 2 at these positions; on the other hand, the inner boxes 20, 30, and 40 to be retracted or extended in either case can be unlocked by moving the respective lock bolts 21, 31, and 41 from the locked position to the unlocked position in either case before the retraction or extension movement, and can be locked after the retraction or extension movement by moving the respective lock bolts 21, 31, and 41 from their unlocked position to their locked position.

[0019] For clarity, the telescopic device, telescopic cylinder, fixing and locking unit, drive bolt, and recess for the drive bolt are not shown in Figure 1.

[0020] In relation to the retraction and extension of each of the inner boxes 20, 30, and 40, the first lock bolt 21, the second lock bolt 31, and the third lock bolt 41 are also shown in Figures 1 and 2, where Figure 2 shows an enlarged view of the cross section of Figure 1 from the area of ​​the foot end 2 of the telescopic jib 1.

[0021] In the telescopic jib according to the prior art, the retracted position A, as well as the extended positions B, C, and D, should in each case be associated with the lengths of specific equal extensions of the inner box, for example, values of 0%, 45%, 90%, and 100% of the extension length. At the foot end of the inner box, since the locking bolts protrude inward, the next inner box cannot be fully inserted in any case. The corresponding situation also exists in the telescopic jib 1 according to the present invention (see FIGS. 1 and 2). Each of the inner boxes according to the prior art has the same extension length with values such as 0%, 45%, 90%, and 100%, so when the telescopic jib is in the fully inserted state as in the retracted position A, the bolt holes are also offset from each other at the respective extended positions B, C, and D in the longitudinal direction of the telescopic jib. However, in this way, the desired equal extension length is achieved regardless of which inner box is extended. As an example, the achievable extension lengths according to the retracted or extended positions of the inner box for the telescopic jib according to the prior art are listed in the following table.

Table 1

[0022] Normally, the 100% extension length is determined so that the individual inner boxes have a sufficient clamping length from the perspective of being fixed, so they are already offset from each other in the prior art. However, no attention is paid to ensuring that the bolt holes are positioned vertically. Instead, attention is paid to making the inner box be utilized as effectively as possible.

[0023] In contrast, when the telescopic jib 1 according to the present invention is in a state where the telescopic jib 1 is completely inserted, each of the bolt holes 12, 22, 32 (see FIGS. 3 and 4) is in the longitudinal direction L of the telescopic jib 1 and the respective heights of the side walls 4, 5 of each of the basic box 10 or the inner boxes 20, 30, 40, It is realized that they are aligned with each other within the regions of the first extended position B, the second extended position C, and the third extended position D. The bolt holes 12, 22, 32 are described only as an example in the first extended position B, and of course, they can also be seen at all other extended positions C, D, and the retracted position A. In particular, the round bolt holes 12, 22, 32 each have the same opening, particularly the same diameter, so that the inner space 6 of the telescopic jib 1 or the third inner box 40 is accessible from the outside of the telescopic jib 1. In any case, the bolt holes 12, 22, 32 overlap such that a pin-shaped tool having a diameter in the range of at least 5 mm to 20 mm can pass through them from the outside.

[0024] The aligned arrangement of the bolt holes 12, 22, 32 of the present invention results in different extension lengths for each of the inner boxes 20, 30, 40 with respect to the extended positions B, C, D. In other words, the extension lengths of the inner boxes 20, 30, 40 are selected such that the bolt holes 12, 22, 32 at the extended positions B, C, D are aligned with each other. The lengths of these extensions are listed in the following table. Here, the extension lengths are still described as 0%, 45%, 90%, and 100% as before for better comparison with the above table, but here they vary around these percentage values.

Table 2

[0025] Furthermore, in Figures 1 and 2, it can be seen that the first lock bolt 21 is located inside the foot end 2 of the first inner box 20, the second lock bolt 31 is located inside the foot end 2 of the second inner box 30, and the third lock bolt 41 is located inside the foot end 2 of the third inner box 40. The base box 10 and the inner boxes 20, 30, and 40 are designed as tubular bodies having substantially rectangular cross-sections, and the lock bolts 21, 31, and 41 are located laterally to the top or bottom surface of the base box 10 or the inner boxes 20, 30, and 40, respectively, and inside one of the two side walls 4, 5 of the base box 10 or the inner boxes 20, 30, and 40. In addition, the lock bolts 21, 31, and 41 are each movable laterally with respect to the longitudinal direction L of the telescopic jib 1, and are movable horizontally with respect to the telescopic jib 1 oriented horizontally in the longitudinal direction L from the unlocked position to the locked position by fixing and locking units (not shown). In the locked position, each lock bolt 21, 31, and 41 connects the inner boxes 20, 30, and 40 in which they are located to the next outer inner boxes 20, 30, and base box 10, respectively, in such a way that they move into the corresponding bolt holes 12, 22, and 32. Thus, the retraction and extension movement of each base box or inner box 10, 20, 30, and 40 in the longitudinal direction L is prevented by each lock bolt 21, 31, and 41 in the locked position. In the unlocked position, the lock bolts 21, 31, and 41 release the bolt holes 12, 22, and 32 of the next outer inner boxes 20, 30, or base box 10.

[0026] Figure 3 shows an enlarged view of the cross section of Figure 1 from the region of the first extension position B and the associated bolt holes 12, 22, 32 in the left wall 4. As described above, the arrangement of the bolt holes 12, 22, 32 in the base box 10 or inner boxes 20, 30, 40 is such that, in the case of the telescopic jib 1 with the inner boxes 20, 30, 40 inserted into the retracted position A, all bolt holes 12, 22, 32 are aligned with each other on their central axes or are positioned vertically relative to each other when viewed from the inside.

[0027] Figure 4 shows a diagram according to Figure 3, where the innermost third inner box 40 extends to the first extension position B. In the corresponding configuration, the third lock bolt 41 associated with the third inner box 40 is then positioned in the locked state within the third bolt hole 32 of the adjacent second inner box 30, with its front or outer end protruding into the third bolt hole 32. Figure 4 also clearly shows that the third lock bolt 41, particularly its front end 43, is easily accessible from the outside of the telescopic jib 1 through the first bolt hole 12 and the second bolt hole 22, and can therefore be easily unlocked in an emergency if necessary. For this purpose, the lock bolt 41 may then have a corresponding emergency unlocking opening or device. The extent to which the lock bolt can be manually unlocked is not the subject of the present invention; the present invention relates only to the accessibility of the front end 43 of the lock bolt from the outside.

[0028] The lock bolt 41 has an internal locking mechanism (not shown) that holds the lock bolts 21, 31, and 41 in a locked position, also called the bolted position. This locking mechanism can be manually unlocked from the outside by pressing a release element 44 located at the front end 43 of the lock bolt 41, which can be designed as a screw. For this purpose, the release element 44 is manually pressed inward. The lock bolt 41 can then be manually pushed inward to the unlocked position, also called the bolted-out position. The same applies to the other lock bolts 21 and 31.

[0029] The above description also applies to the bolt holes at the second extension position C and the third extension position D, as well as to the associated lock bolts not specified by reference number.

[0030] The exemplary embodiments described above relate to a telescopic jib 1 having one base box 10 and three inner boxes 20, 30, and 40. It is also apparent that a telescopic jib 1 having more than three inner boxes 20, 30, and 40 can be designed. [Explanation of Symbols]

[0031] 1. Telescopic jib 2 Foot end 3 Head end 4 Left side wall 5 Right side wall 6. Interior space 10 Basic Boxes 12 First bolt hole 15 Foot connection part 20 First inner box 21 First rock bolt 22 Second bolt hole 30 Second inner box 31. Second rock bolt 32 Third bolt hole 40 Third inner box 41 Third rock bolt 43 Front end 44 Unlocking elements A Retraction position B First extension position C Second extension position D Third extension position L Longitudinal direction

Claims

1. A telescopic jib (1) of a mobile crane having a base box (10) and a plurality of inner boxes (20, 30, 40), The plurality of inner boxes (20, 30, 40) can each be extended from a retracted position (A) to an extended position (B, C, D), and can be locked and unlocked together at each of the retracted position (A) or extended position (B, C, D) by bolt holes (12, 22, 32) and associated lock bolts (21, 31, 41) located in the base and inner boxes (10, 20, 30, 40), wherein the bolt holes (12, 22, 32) for the extended positions (B, C, D) are aligned with each other at the retracted position (A) of the base and inner boxes (10, 20, 30, 40), and the front end (43) of the lock bolt (41) is accessible from the outside through the bolt holes (12, 22) of the outwardly adjacent inner boxes (10, 20). Telescopic jib (1).

2. In an emergency, the lock bolts (21, 31, 41) can be unlocked from the outside through the bolt holes (12, 22, 32) at the extension positions (B, C, D). The telescopic jib (1) according to claim 1.

3. The unlocking element (44) is characterized by being located at the front end (43) of the lock bolt (41), The telescopic jib (1) according to claim 1.

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