Telescopic boom unit and lifting machinery

Abstract

This invention belongs to the field of engineering machinery technology and provides a telescopic boom unit and lifting machinery. The telescopic boom unit includes an outer boom section, an inner boom section, and a slider assembly. The outer boom section is a polygonal cylindrical boom, and the inner boom section is located inside the outer boom section and is also a polygonal cylindrical boom. The number of sides of the inner boom section is less than the number of sides of the outer boom section. The slider assembly is located between the outer and inner boom sections. By setting the number of sides of the inner boom section to be less than that of the outer boom section, while ensuring that both the inner and outer boom sections meet the lifting performance requirements of the telescopic boom, reducing the number of sides of the inner boom section can lower the manufacturing difficulty of the inner boom section, thereby reducing the overall manufacturing cost of the telescopic boom.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, specifically relating to a telescopic boom unit and lifting machinery. Background Technology

[0002] Currently, the multi-section telescopic booms of existing folding boom truck-mounted cranes, both domestically and internationally, are mostly of a uniform cross-section. That is, the telescopic boom of a truck-mounted crane has a cross-section of hexagon, octagon, decagon, or other similar shapes. Using the same cross-section telescopic boom for the same truck-mounted crane not only results in higher manufacturing costs, but also leads to a waste of performance due to some telescopic boom units having excessive performance margins. Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies, the present invention provides a telescopic boom unit and lifting machinery, which aims to reduce the manufacturing cost of telescopic booms.

[0004] To achieve the above objectives, the present invention provides a telescopic arm unit, which includes an outer arm section, an inner arm section, and a slider assembly. The outer arm section is a polygonal cylindrical arm, and the inner arm section is disposed inside the outer arm section and is also a polygonal cylindrical arm. The number of sides of the inner arm section is less than the number of sides of the outer arm section. The slider assembly is disposed between the outer arm section and the inner arm section.

[0005] In embodiments of the present invention, the outer arm section is a decagonal cylindrical arm, and the inner arm section is an octagonal cylindrical arm or a hexagonal cylindrical arm; or the outer arm section is an octagonal cylindrical arm, and the inner arm section is a hexagonal cylindrical arm.

[0006] In an embodiment of the present invention, the slider assembly includes a shoulder slider disposed between the shoulder of the outer arm segment and the shoulder of the inner arm segment. The shoulder slider is mounted on one of the outer arm segment and the inner arm segment and slides in contact with the other. The shoulder slider is respectively attached to the shoulder wall of the outer arm segment and the shoulder wall of the inner arm segment.

[0007] In an embodiment of the present invention, the shoulder of the outer arm segment is provided with an inclined and adjacent first outer shoulder wall and a second outer shoulder wall, and the shoulder slider is provided with a first contact surface and a second contact surface for respectively contacting the first outer shoulder wall and the second outer shoulder wall, the first contact surface and the second contact surface being aligned and parallel to the first outer shoulder wall and the second outer shoulder wall, respectively.

[0008] In an embodiment of the present invention, an arc transition edge is provided between the first outer shoulder wall and the second outer shoulder wall, and the shoulder slider further includes an arc fitting surface located between the first fitting surface and the second fitting surface.

[0009] In an embodiment of the present invention, the shoulder of the inner arm segment is provided with an inclined first inner shoulder wall, the first inner shoulder wall being radially aligned with the first outer shoulder wall and the second outer shoulder wall respectively, and the shoulder slider is provided with a third contact surface for fitting with the first inner shoulder wall, the third contact surface being arranged parallel to the first inner shoulder wall.

[0010] In an embodiment of the present invention, a limiting installation component is provided on the outer side of the first inner shoulder wall, and the shoulder slider is limited and installed on the limiting installation component.

[0011] In an embodiment of the present invention, the limiting installation assembly includes a limiting plug-in post disposed on the first inner shoulder wall, and the shoulder slider is plugged into the limiting plug-in post and connected to the first inner shoulder wall through a connector.

[0012] In an embodiment of the invention, the slider assembly includes a bottom slider disposed between the bottom inner side of the outer arm segment and the bottom outer side of the inner arm segment.

[0013] To achieve the above objectives, the present invention also provides a lifting machine, wherein the lifting machine includes a telescopic boom unit as described above.

[0014] Through the above technical solution, the telescopic arm unit provided in the embodiments of the present invention has the following beneficial effects:

[0015] In this embodiment of the invention, both the outer and inner boom sections are formed by bending a single high-strength steel plate using a specific process. Each section has only one weld seam. For the same mass and size, this structure provides stronger bending resistance, but correspondingly, the processing cost is higher than existing welded boom sections. Furthermore, the more sides a boom section has, the higher the processing difficulty and cost. Considering that the inner boom section is closer to the head during operation, it requires less structural strength than the outer boom section for the same lifting weight. Therefore, this invention takes a different approach: by setting the number of sides of the inner boom section to be less than that of the outer boom section, while ensuring both the inner and outer boom sections meet the lifting performance requirements of the telescopic boom, reducing the number of sides of the inner boom section lowers its manufacturing difficulty, thereby reducing the overall manufacturing cost of the telescopic boom.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a structural schematic diagram of the telescopic arm unit according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the shoulder slider according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the inner arm segment according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the cross-sectional shape of the outer arm section according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the cross-sectional shape of the inner arm section according to an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures

[0024] 1. Outer arm section; 11. First outer shoulder wall; 12. Second outer shoulder wall; 13. Arc transition edge; 2. Inner arm section; 21. First inner shoulder wall; 3. Slider assembly; 31. Shoulder slider; 311. First mating surface; 312. Second mating surface; 313. Arc mating surface; 314. Third mating surface; 315. Limiting insertion hole; 316. Threaded connection hole; 4. Limiting mounting assembly; 41. Limiting insertion post. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0026] The telescopic arm unit of the present invention will now be described with reference to the accompanying drawings.

[0027] The cross-sectional design of a telescopic boom is closely related to the lifting performance of a crane. Higher lifting performance requires greater resistance to bending and torsion. Conversely, given the weight and size limitations of the telescopic boom, a greater number of sides results in stronger bending resistance. Therefore, increasing the number of sides is the most common way to improve lifting performance.

[0028] On the market, all the boom sections of a telescopic boom on a folding boom crane have the same cross-sectional shape. For example, if the number of sides of the basic boom section in some telescopic booms is generally hexagonal, octagonal, decagonal, etc., then the number of sides of the head boom section and the middle boom sections in the telescopic boom are the same as those of the basic boom section.

[0029] For articulated boom cranes, during lifting operations, the load on the boom section near the head is much less than that on the boom section near the root. Setting the number of sides of the head boom section, middle boom section, and root boom section to be the same will not only waste the boom section performance, but also increase the manufacturing difficulty and lead to higher production costs.

[0030] Based on the above considerations, such as Figure 1 , Figure 4 and Figure 5 As shown, the present invention provides a telescopic arm unit, the telescopic arm unit comprising:

[0031] Outer arm section 1 is a polygonal cylindrical arm;

[0032] Inner arm section 2 is set inside outer arm section 1 and is also a polygonal cylindrical arm. The number of sides of inner arm section 2 is less than the number of sides of outer arm section 1.

[0033] The slider assembly 3 is disposed between the outer arm section 1 and the inner arm section 2.

[0034] Among them, outer arm segment 1 refers to the arm segment closer to the root in the telescopic arm, and inner arm segment 2 refers to the arm segment closer to the head in the telescopic arm. Both outer arm segment 1 and inner arm segment 2 are hollow cylindrical arm segments. Inner arm segment 2 is fitted inside outer arm segment 1 and can telescopically move relative to outer arm segment 1.

[0035] A polygonal barrel arm means that the cross-sections of the outer arm section 1 and the inner arm section 2 are polygonal.

[0036] like Figure 4 and Figure 5 As shown, in this embodiment of the invention, both the outer boom section 1 and the inner boom section 2 are formed by bending a single high-strength steel plate using a specific process. The cross-sections of the outer boom section 1 and the inner boom section 2 each have only one weld seam. This type of boom section offers stronger bending resistance for the same mass and size, but correspondingly, the processing cost is higher than that of existing welded boom sections. Furthermore, the more sides a boom section of this type has, the higher the processing difficulty and cost will be.

[0037] Given the already mature technology, it is difficult to reduce the production cost of the boom section by optimizing the process. Considering that the inner boom section 2 is closer to the head during operation, the structural strength required for the inner boom section 2 is less than that for the outer boom section 1 under typical lifting conditions. Therefore, this invention takes a different approach: by setting the number of sides of the inner boom section 2 to be less than that of the outer boom section 1, while ensuring that both the inner and outer boom sections 2 and 1 meet the lifting performance requirements of the telescopic boom, reducing the number of sides of the inner boom section 2 can lower its manufacturing difficulty, thereby reducing the overall production cost of the telescopic boom unit.

[0038] like Figure 1 , Figure 4 and Figure 5 As shown in the embodiments of the present invention, the outer arm section 1 and the inner arm section 2 can be configured in many ways. For example, the outer arm section 1 can be a decagonal cylindrical arm, and the inner arm section 2 can be an octagonal cylindrical arm or a hexagonal cylindrical arm. Alternatively, the outer arm section 1 can be an octagonal cylindrical arm, and the inner arm section 2 can be a hexagonal cylindrical arm. Of course, the number of sides of the inner arm section 2 and the outer arm section 1 can also be odd, such as the outer arm section 1 being a heptagonal cylindrical arm, and the inner arm section 2 being a hexagonal cylindrical arm, a pentagonal cylindrical arm, a quadrilateral cylindrical arm, etc.

[0039] The slider assembly 3 generally includes a shoulder slider 31 disposed between the shoulder of the outer arm segment 1 and the shoulder of the inner arm segment 2. The shoulder slider 31 is mounted on one of the outer arm segment 1 and the inner arm segment 2 and slides in contact with the other. The shoulder slider 31 can separate the outer arm segment 1 and the inner arm segment 2, ensuring normal sliding between the inner arm segment 2 and the outer arm segment 1.

[0040] After the outer arm section 1 and inner arm section 2 with different numbers of sides are assembled, due to the different cross-sectional shapes, if the shoulder slider 31 uses the existing general-purpose slider without the use of special materials, the slider is easily deformed or broken due to uneven force. Therefore, the structure of the slider needs to be specially designed.

[0041] To address the issue of the shoulder slider 31 being prone to deformation or breakage, in embodiments of the present invention, the shape of the shoulder slider 31 needs to be optimized so that it is smoothly positioned between the outer arm segment 1 and the inner arm segment 2. This optimization can be achieved by configuring the shoulder slider 31 to fit against the shoulder wall of the outer arm segment 1 and the shoulder wall of the inner arm segment 2, respectively. This fit ensures that the stress of the outer arm segment 1 is evenly distributed across the shoulder slider 31.

[0042] Specifically, such as Figure 1 and Figure 2 As shown, taking the outer arm segment 1 as an example of a decagonal cylindrical arm, when the number of sides of the arm segment exceeds that of a pentagon, a sloping wall will form at the shoulder of the arm segment, and the more sides the arm segment has, the more sloping walls there will be at the shoulder.

[0043] like Figure 2 , Figure 4 and Figure 5 As shown, for the decagonal boom, the shoulder of the outer boom section 1 is provided with an inclined first outer shoulder wall 11 and a second outer shoulder wall 12. The first outer shoulder wall 11 and the second outer shoulder wall 12 are two adjacent walls with a certain included angle. In order to achieve the fit between the shoulder slider 31 and the outer boom section 1, a first contact surface 311 and a second contact surface 312 for fitting with the first outer shoulder wall 11 and the second outer shoulder wall 12 can be provided on the side of the shoulder slider 31 facing the outer boom section 1, and the first contact surface 311 and the second contact surface 312 are respectively aligned and parallel to the corresponding first outer shoulder wall 11 and second outer shoulder wall 12. By providing the first contact surface 311 and the second contact surface 312, the contact area between the shoulder slider 31 and the outer boom section 1 can be increased, and the fit between the shoulder slider 31 and the outer boom section 1 can be better ensured, thereby ensuring that the stress of the outer boom section 1 can be evenly distributed on the shoulder slider 31 through the first contact surface 311 and the second contact surface 312.

[0044] like Figure 2 , Figure 4 and Figure 5As shown in the embodiment of the present invention, since the outer arm section 1 is formed by bending a single piece of steel plate through a special process, an arc transition edge 13 will inevitably be formed between the first outer shoulder wall 11 and the second outer shoulder wall 12. In order to further increase the fit between the shoulder slider 31 and the outer arm section 1, an arc fitting surface 313 for fitting with the arc transition edge 13 can be provided between the first fitting surface 311 and the second fitting surface 312 of the shoulder slider 31.

[0045] In embodiments of the present invention, when the outer arm section 1 is a decagonal cylindrical arm, the inner arm section 2 can be a nonagonal cylindrical arm, an octagonal cylindrical arm, a heptagonal cylindrical arm, a hexagonal cylindrical arm, etc. To further highlight the characteristics of the shoulder slider 31, the structure of the shoulder slider 31 will be described below using the example of the inner arm section 2 being a hexagonal cylindrical arm.

[0046] like Figure 2 , Figure 4 and Figure 5 As shown, the cross-sectional shape of the hexagonal cylindrical arm differs significantly from that of the decagonal cylindrical arm. The decagonal cylindrical arm has a first outer shoulder wall 11 and a second outer shoulder wall 12 at its shoulder, while the hexagonal cylindrical arm only includes a first inner shoulder wall 21 at its shoulder. The first inner shoulder wall 21 is radially aligned with both the first outer shoulder wall 11 and the second outer shoulder wall 12. A third contact surface 314 is provided on the side of the shoulder slider 31 opposite to the first contact surface 311 and the second contact surface 312 for contacting the first inner shoulder wall 21. The third contact surface 314 is parallel to the first inner shoulder wall 21. By providing the third contact surface 314, it is ensured that the other side of the shoulder slider 31 can be well contacted with the inner arm section 2, thereby ensuring that the stress borne by the shoulder slider 31 can be evenly transmitted to the first inner shoulder wall 21.

[0047] like Figure 4 and Figure 5 As shown, in an embodiment of the present invention, the waist of the inner arm section 2 and the outer arm section 1 may also be provided with vertically extending vertical guide edges. The vertical guide edges can better limit the extension and retraction of the arm sections and ensure the alignment of the inner arm section 2 and the outer arm section 1.

[0048] Understandably, when the number of sides of the inner arm segment 2 changes to other quantities, the shape of the third mating surface 314 can be adapted to make the first mating surface 311 conform to the shoulder of the inner arm segment 2. Or, when the number of sides of the outer arm segment 1 changes to other quantities, the shapes of the first mating surface 311 and the second mating surface 312 can be adapted to make the shoulder slider 31 conform to the shoulder of the outer arm segment 1.

[0049] In summary, the telescopic arm unit of the present invention uses a non-circular slider between the inner arm section 2 and the outer arm section 1 for transition, so that when arm sections with different cross-sectional shapes are fitted together, it can also ensure uniform force and normal telescopic movement between the arm sections.

[0050] like Figure 1 , Figure 2 and Figure 3 As shown, in an embodiment of the present invention, the shoulder slider 31 can be installed on the inner side of the outer arm segment 1 and configured to slide in contact with the outer surface of the inner arm segment 2, or the shoulder slider 31 can be installed on the outer side of the inner arm segment 2 and configured to slide in contact with the inner surface of the outer arm segment 1. For ease of installation, it is preferable to install the shoulder slider 31 on the outer side of the inner arm segment 2, as this installation method can prevent the shoulder slider 31 from falling off during installation.

[0051] Specifically, such as Figure 1 , Figure 2 and Figure 3 As shown, in an embodiment of the present invention, a limiting installation component 4 may be provided on the outer surface of the first inner shoulder wall 21 of the inner arm joint 2, and the shoulder slider 31 is preferably detachably mounted on the first inner shoulder wall 21 through the limiting installation component 4.

[0052] like Figure 1 , Figure 2 and Figure 3 As shown, the limiting installation assembly 4 may include a limiting insertion post 41 disposed on the first inner shoulder wall 21. The limiting insertion post 41 can be installed on the first inner shoulder wall 21 by welding or other means. In order to cooperate with the limiting insertion post 41, the side of the shoulder slider 31 facing the first inner shoulder wall 21 (the third mating surface 314) needs to be provided with a limiting insertion hole 315 for interlocking with the limiting insertion post 41. By interlocking the shoulder slider 31 with the limiting insertion post 41, the X-axis and Y-axis limiting of the shoulder slider can be realized. In order to realize the installation and fixation of the shoulder slider 31 and the Z-axis limiting, a connector can be used to connect the shoulder slider 31 and the first inner shoulder wall 21. Alternatively, glue can be used to bond the shoulder slider 31 to the first inner shoulder wall 21.

[0053] like Figure 1 and Figure 3 As shown, in the embodiment of the present invention, both sides of the inner arm section 2 are provided with a first inner shoulder wall 21, and each first inner shoulder wall 21 can be provided with a plurality of limiting plug-in posts 41. Through the plugging and matching of the plurality of limiting plug-in posts 41, the stability and firmness of the shoulder slider 31 installation can be increased.

[0054] In embodiments of the present invention, the limiting insertion post 41 can be circular, square, elliptical, etc.

[0055] In an embodiment of the present invention, the limiting insertion hole 315 can be provided through the shoulder slider 31 to facilitate installation.

[0056] In embodiments of the present invention, the limiting insertion hole 315 can be a round hole, a square hole, an elliptical hole, etc.

[0057] like Figure 1 , Figure 2 and Figure 3 As shown, in the embodiments of the present invention, the connector can be a threaded connector such as a bolt or screw. The shoulder slider 31 and the first inner shoulder wall 21 can also be provided with threaded connection holes 316 for alignment. Preferably, the threaded connection hole 316 on the shoulder slider 31 can be a countersunk hole. After the connector is aligned with the threaded connection hole 316 of the shoulder slider 31 and the first inner shoulder wall 21, the head of the connector can be located inside the countersunk hole, thereby preventing the head of the connector from protruding from the surface of the shoulder slider 31 and affecting the sliding of the arm section.

[0058] like Figure 1 As shown, in an embodiment of the present invention, shoulder sliders 31 are provided on both lateral shoulders of the inner arm segment 2, that is, the number of shoulder sliders 31 can be two.

[0059] In embodiments of the present invention, the arrangement of the limiting installation component 4 can be varied, such as welding a limiting block onto the first inner shoulder wall 21, or directly fixing the shoulder slider 31 onto the first inner shoulder wall 21 with several screws.

[0060] It is particularly important to emphasize that the shoulder slider 31 is a consumable part and needs to be replaced regularly. It is installed using the limit plug 41, which facilitates quick disassembly and replacement of the shoulder slider 31 in the future.

[0061] In an embodiment of the present invention, the slider assembly 3 includes a bottom slider (not shown in the figure) disposed between the bottom inner side of the outer arm segment 1 and the bottom outer side of the inner arm segment 2. The bottom slider is generally disposed at the head end of the outer arm segment 1, and the shoulder slider 31 is generally disposed at the root end of the inner arm segment 2. Through the cooperation of the bottom slider and the shoulder slider 31, the smooth extension and retraction of the inner arm segment 2 can be ensured.

[0062] To achieve the above objectives, the present invention also provides a lifting machine, wherein the lifting machine includes at least one set of telescopic boom units as described above. That is, the lifting machine has at least two boom sections, and any adjacent boom sections constitute a telescopic boom unit. Since the lifting machine adopts all the technical solutions of the above embodiments, it has at least the beneficial effects brought by the above embodiments, and will not be repeated here.

[0063] In summary, this invention breaks the current situation of uniform telescopic boom cross-section on the same articulated boom crane by assembling two boom sections with different numbers of sides together, thereby reducing the cost of the telescopic boom unit. At the same time, the slider adopts a transition design, which can achieve the matching of boom sections with different cross-sections without the use of special materials, thus improving the durability and reliability of the slider.

[0064] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A telescopic arm unit, characterized in that, The telescopic arm unit comprises: an outer arm section (1) which is a polygonal cylindrical arm; an inner arm section (2) which is arranged in the outer arm section (1) and is a polygonal cylindrical arm, the number of sides of the inner arm section (2) being less than that of the outer arm section (1); and a slider assembly (3) which is arranged between the outer arm section (1) and the inner arm section (2). The slider assembly (3) comprises a shoulder slider (31) which is arranged between the shoulder of the outer arm section (1) and the shoulder of the inner arm section (2). The shoulder of the outer arm section (1) is provided with an inclined and adjacent first outer shoulder wall (11) and a second outer shoulder wall (12), and the shoulder slider (31) is provided with a first abutting surface (311) and a second abutting surface (312) for abutting with the first outer shoulder wall (11) and the second outer shoulder wall (12) respectively, the first abutting surface (311) and the second abutting surface (312) being arranged in parallel with the first outer shoulder wall (11) and the second outer shoulder wall (12) respectively. The shoulder of the inner arm section (2) is provided with an inclined first inner shoulder wall (21) which is arranged in radial alignment with the first outer shoulder wall (11) and the second outer shoulder wall (12) respectively, and the shoulder slider (31) is provided with a third abutting surface (314) for abutting with the first inner shoulder wall (21), the third abutting surface (314) being arranged in parallel with the first inner shoulder wall (21).

2. The boom unit according to claim 1, characterized by The outer arm section (1) is a decagonal cylindrical arm, and the inner arm section (2) is an octagonal cylindrical arm or a hexagonal cylindrical arm; or the outer arm section (1) is an octagonal cylindrical arm, and the inner arm section (2) is a hexagonal cylindrical arm.

3. The boom unit of claim 1, wherein The shoulder slider (31) is mounted on one of the outer arm section (1) and the inner arm section (2) and is in sliding contact with the other, and the shoulder slider (31) abuts with the shoulder wall of the outer arm section (1) and the shoulder wall of the inner arm section (2) respectively.

4. The boom unit of claim 1, wherein An arc transition edge (13) is arranged between the first outer shoulder wall (11) and the second outer shoulder wall (12), and the shoulder slider (31) further comprises an arc abutting surface (313) which is located between the first abutting surface (311) and the second abutting surface (312).

5. The boom unit of claim 1, wherein The outer side of the first inner shoulder wall (21) is provided with a limiting mounting assembly (4), and the shoulder slider (31) is limitingly mounted on the limiting mounting assembly (4).

6. A boom unit according to claim 5, characterized in that The limiting mounting assembly (4) comprises a limiting plug-in column (41) which is arranged on the first inner shoulder wall (21), and the shoulder slider (31) is plug-in matched with the limiting plug-in column (41) and connected with the first inner shoulder wall (21) through a connecting piece.

7. The boom unit according to any one of claims 1 to 6, characterized in that, The slider assembly (3) comprises a bottom slider which is arranged between the inner side of the bottom of the outer arm section (1) and the outer side of the bottom of the inner arm section (2).

8. A hoisting machine characterized by The telescopic arm unit according to any one of claims 1 to 7.

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