Pole device and tower crane

Abstract

The application relates to the field of building hoisting machinery, and discloses a spud rod device and a tower crane. The spud rod device comprises a spud rod stand, a movable mounting assembly and an amplitude-changing assembly. The top end of the spud rod stand horizontally extends a spud rod jib. The bottom end of the spud rod stand is mounted on the chassis of the balance arm of the tower crane through the movable mounting assembly. The movable mounting assembly is used for driving the spud rod stand to walk and rotate on the chassis. The amplitude-changing assembly comprises a moving trolley and an amplitude-changing drum used for driving the moving trolley to move along the spud rod jib. The rotation and walking functions of the spud rod device are realized through the movable mounting assembly. The spud rod device can cover a larger working area around the balance arm of the tower crane, and the equipment does not need to be frequently disassembled and assembled. The amplitude-changing assembly flexibly adjusts the hoisting radius through the moving trolley, and further accurately controls the hoisting point.

Description

Technical Field

[0001] This application belongs to the field of construction lifting machinery, specifically relating to a derrick device and a tower crane. Background Technology

[0002] Tower cranes are one of the most widely used and important pieces of equipment in modern construction and hoisting operations. To address the difficulty of maintaining tower cranes at high altitudes, a derrick is added to the counterweight boom of the tower crane. This derrick is a lightweight lifting device primarily used for tower crane maintenance. When a component of the tower crane malfunctions, the derrick can lift the new component or part to the counterweight boom, reducing the workload of personnel. In existing technology, common derricks are usually fixedly installed on the boom, and the boom rotates around a fixed slewing axis. The working area of ​​such derricks is typically a circular area with the slewing axis as the center and the distance from the lifting hook to the center of rotation as the radius.

[0003] However, on tower cranes, in order to avoid interference from obstacles, the boom can only rotate within a limited range, and the actual working area that can be covered is small, resulting in a small working area that the boom can lift. Utility Model Content

[0004] In view of at least one of the above-mentioned defects or deficiencies in the prior art, this application provides a derrick device and a tower crane, which can effectively expand the working area of ​​the derrick.

[0005] To achieve the above objectives, this application provides a lifting pole device, which includes: A derrick column, with a derrick boom extending horizontally from its top; The bottom end of the boom column is mounted on the base frame of the counterweight boom of the tower crane via the movable mounting assembly. The movable mounting assembly is used to drive the boom column to move and rotate on the base frame. The luffing assembly includes a moving trolley and a luffing drum that drives the moving trolley to move along the boom.

[0006] In some implementations, the active installation component includes: The sliding slide block slides in conjunction with the sliding rail on the base frame; A slewing bearing is disposed on top of the traveling slide and connected to the bottom end of the boom column.

[0007] In some embodiments, the walking slide includes: The rail-holding slider is a U-shaped plate with its opening facing downwards; The traveling rollers are located inside the side plates on both sides of the rail-holding slider.

[0008] In some embodiments, the walking slide further includes: A parking screw is used to pass through the side plate of the rail-holding slider to abut against the base frame.

[0009] In some embodiments, the side plate of the rail-holding slider has a threaded hole through which the parking screw passes, and the parking screw is connected to the threaded hole.

[0010] In some embodiments, both the slewing bearing and the traveling slide are provided with limit holes at their tops, and the movable mounting assembly further includes a limit pin for passing through the limit holes of the slewing bearing and the traveling slide.

[0011] In some embodiments, the luffing assembly further includes luffing fixed pulleys, which are installed at both ends of the boom, and the luffing drum is fixedly installed on the boom column. The luffing wire rope of the luffing drum passes through the luffing fixed pulleys and is connected to the moving trolley.

[0012] In some embodiments, the derrick device further includes: The lifting assembly includes a lifting wire rope, a lifting drum, and multiple lifting pulleys. The lifting drum is connected to the boom column, and the lifting pulleys are connected to the top of the boom and the movable end of the boom. The lifting wire rope connects the lifting drum, the multiple lifting pulleys, and the moving trolley.

[0013] In some embodiments, the derrick device further includes: The tie rod is connected at one end to the boom of the derrick and at the other end to the top of the derrick column.

[0014] A second aspect of this application provides a tower crane including a counterweight boom and a derrick device according to any one of the preceding claims, the derrick device being connected to the base frame of the counterweight boom.

[0015] Through the above technical solution, the rotating and traveling functions of the boom device are realized through the movable mounting components. The boom device can cover a larger working area around the counterweight boom of the tower crane without frequent disassembly and assembly of the equipment. The luffing component flexibly adjusts the lifting radius through the moving trolley, further precisely controlling the lifting point. The combination of the three not only expands the physical working range of the boom, but also enhances its flexibility in adapting to complex construction scenarios, reduces the frequency of crane body movement, and improves lifting efficiency and safety. It is especially suitable for working conditions with limited space or requiring high-frequency adjustment of the lifting position.

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

[0017] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of the structure of the derrick device in this utility model; Figure 2 This is a schematic diagram showing the working range of the lever device in this utility model; Figure 3 for Figure 1 Enlarged view of section A; Figure 4 This is a schematic diagram of the walking slide of the lever device in this utility model; Figure 5 This is a schematic diagram of the amplitude-changing component of the boom device in this utility model; Figure 6 This is a schematic diagram of the lifting assembly of the boom device in this utility model; Figure 7 This is a schematic diagram of the structure of the derrick device of this utility model in a tower crane.

[0018] Explanation of reference numerals in the attached figures Detailed Implementation

[0019] The specific embodiments of this application 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 this application.

[0020] The present application will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0021] like Figure 1As shown, the first aspect of this application provides a boom derrick device 1, which includes a boom column 11, a movable mounting assembly 13, and a luffing assembly 14. The top end of the boom column 11 extends horizontally to form a boom 12. The bottom end of the boom column 11 is mounted on the base frame 2 of the counterweight boom of a tower crane via the movable mounting assembly 13. The movable mounting assembly 13 is used to drive the boom column 11 to travel and rotate on the base frame 2. The luffing assembly 14 includes a moving trolley 141 and a luffing drum 142 that drives the moving trolley 141 to move along the boom 12. The boom 12, which extends horizontally from the top of the boom column 11, serves as the main load-bearing structure. The bottom end of the boom column 11 is connected to the base frame 2 of the tower crane's counterweight arm via a movable mounting assembly 13. The movable mounting assembly 13 allows the boom column 11 to move along the base frame 2 and rotate around its own axis. The luffing assembly 14, through the luffing drum 142, winds up and unwinds the luffing wire rope 144, driving the moving trolley 141 to reciprocate laterally on the boom 12, thereby adjusting the horizontal position of the lifting point.

[0022] The lifting pole device 1 provided by this utility model realizes the rotation and movement functions of the lifting pole device 1 through the movable mounting component 13, such as... Figure 2 As shown, the boom derrick device 1 can cover a larger working area around the counterweight boom of the tower crane without frequent disassembly and assembly of the equipment; the luffing assembly 14 can flexibly adjust the lifting radius through the moving trolley 141, further precisely controlling the lifting point; the combination of the three not only expands the physical working range of the boom, but also enhances its flexibility in adapting to complex construction scenarios, reduces the frequency of crane body movement, and improves lifting efficiency and safety, especially suitable for working conditions where space is limited or high-frequency adjustment of the lifting position is required.

[0023] In some implementations, such as Figure 3 As shown, the movable mounting assembly 13 includes a traveling slide 131 and a slewing bearing 132. The traveling slide 131 is slidably engaged with the traveling slide rail on the base frame 2. The slewing bearing 132 is located on the top of the traveling slide 131 and connected to the bottom end of the boom column 11. The bottom of the traveling slide 131 is slidably engaged with the traveling slide rail on the base frame 2 and moves along the slide rail via a roller mechanism. The slewing bearing 132 is bolted to the boom column and the traveling base respectively. The top of the traveling base is provided with a connecting seat 1313, and the slewing bearing 132 is bolted to the connecting seat 1313 of the traveling base. The outer ring of the slewing bearing 132 is fixed to the connecting seat 1313 on the top of the traveling slide 131, and the inner ring is rigidly connected to the bottom end of the boom column 11. A small gear driven by an independent rotary motor meshes with the gear ring of the slewing bearing 132 to achieve horizontal rotation.

[0024] The traveling slide 131, in conjunction with the slide rail, allows the entire derrick device 1 to move along the length of the base frame 2, overcoming the area limitations of fixed installation points; the 360° rotation function of the slewing bearing 132 allows the derrick boom 12 to cover the circumferential working area. The combined operation of these two components not only greatly expands the lifting coverage area but also achieves rapid and precise positioning through a composite motion mode of traveling and rotating, reducing the number of times the crane body rotates. This improves lifting efficiency and reduces energy consumption and structural damage caused by frequent machine movement.

[0025] In some implementations, such as Figure 4 As shown, the traveling slide 131 includes a rail-clamping slider 1311 and traveling rollers 1312. The rail-clamping slider 1311 is a U-shaped plate with an opening facing downwards; the traveling rollers 1312 are disposed inside the side plates on both sides of the rail-clamping slider 1311. The rail-clamping slider 1311 adopts a U-shaped plate structure with an opening facing downwards. Its two vertical side plates clamp the traveling slide rail on both sides of the base frame 2 from above like jaws, forming an enclosed constraint. The traveling rollers 1312 are respectively installed on the inner side of these two side plates. The outer edge of the roller directly contacts and rolls with the side or top surface of the traveling slide rail, so that the slide rail is wrapped in the U-shaped space. The rollers bear the main load and realize rolling friction. Specifically, the traveling rollers 1312 are arranged in two rows on the side plates on both sides, clamping on the I-shaped rail of the base frame 2 and sliding on the I-shaped rail.

[0026] The U-shaped rail-holding slider 1311 prevents the traveling slide 131 from falling off the rail, enhancing the safety of the equipment during high-altitude operations. The traveling roller 1312 converts sliding friction into rolling friction, significantly reducing movement resistance and making the movement of the boom column 11 more effortless and stable. At the same time, it reduces the demand for drive power and the wear on the track surface. This ensures that the boom device 1 can easily and accurately adjust its position along the balance arm, providing a stable moving base for subsequent rotation and luffing operations, thereby improving the overall efficiency and reliability of hoisting operations.

[0027] In some implementations, such as Figure 4As shown, the traveling slide 131 also includes a parking screw 133, which passes through the side plate of the rail-holding slider 1311 to abut against the base frame 2. Specifically, the parking screw 133 is a long screw with a plug 1332 or a wrench interface. One end of the parking screw 133 passes through the side plate of the rail-holding slider 1311, so that its end directly abuts or presses against the side of the base frame 2. A rubber plug 1331 can also be provided at the end of the parking screw 133 inside the rail-holding slider 1311. The rubber plug 1331 abuts against the base frame 2, and the direct contact with the base frame 2 generates friction, which can effectively lock the relative movement between the traveling slide 131 and the base frame 2. When the boom 12 is used for lifting operations or encounters strong winds, the operator can quickly lock the base frame 2 with the parking screw 133, thereby preventing the traveling slide 131 from sliding unexpectedly. This provides important protection against falls and deviations for the entire boom device 1. It not only makes up for the lack of self-locking force that may exist in pure rolling mechanisms, but its mechanical locking method also does not require continuous power input, making it safe, reliable, simple in structure, and low in cost. It ensures that the equipment can be stably parked in the designated position during lifting operations, thus ensuring operational safety.

[0028] In some embodiments, the side plate of the rail-holding slider 1311 has a threaded hole through which the parking screw 133 passes, and the parking screw 133 is connected to the threaded hole. Specifically, internal threaded holes are machined on the vertical side plates on both sides of the rail-holding slider 1311, and the parking screw 133 is machined with external threads that precisely match them. During operation, by rotating the parking screw 133, its threaded part is screwed into the threaded hole of the side plate. Using the propulsion principle of the screw pair, the screw moves in the axial direction until it is firmly pressed against the side of the slide rail of the base frame 2. A rod 1332 can be installed at one end of the parking screw 133 located outside the rail-holding slider 1311. The rod 1332 passes through the parking screw 133. Through the lever principle, the parking screw 133 can be easily rotated by rotating the rod 1332, which is convenient for manual operation. The parking screw 133 can generate a huge axial clamping force during the locking process. Through the self-locking characteristic of the thread, this force will not loosen on its own once it is applied, thereby fixing the traveling slide 131 to the base frame 2 and enhancing the safety of anti-slipping and anti-overturning. The mechanical thread drive does not require additional power, has a simple structure, is easy to operate, and the locking status is clear at a glance. It provides an extremely reliable and cost-effective parking guarantee for high-altitude heavy-load operations and effectively prevents the risk of accidental movement of equipment under hoisting or windy conditions.

[0029] In some implementations, such as Figure 3As shown, both the slewing bearing 132 and the traveling slide 131 have limit holes at their tops. The movable mounting assembly 13 also includes a limit pin 134, which is used to connect the limit holes of the slewing bearing 132 and the traveling slide 131. Specifically, multiple limit holes are machined at corresponding positions on the top platform of the traveling slide 131 and the outer ring of the slewing bearing 132. When it is necessary to lock the boom column 11, a cylindrical limit pin 134 is inserted from top to bottom into the limit holes of the slewing bearing 132 and the traveling slide 131, thereby physically preventing the rotational movement of the slewing bearing 132 relative to the traveling slide 131 and locking the boom column 11. When the boom 12 does not need to rotate or is required for heavy lifting, the insertion of the limit pin 134 can lock the slewing bearing 132 and the traveling slide 131, effectively preventing the slewing bearing 132 from being accidentally started or slowly rotating and shaking due to external impact, providing a stable foundation for lifting operations; at the same time, the limit pin 134 locking mechanism also serves as a redundant safety measure to ensure operational safety, and is simple in structure, intuitive in operation, highly reliable, and requires no maintenance, significantly reducing the risk of the boom device 1 during operation.

[0030] In some implementations, such as Figure 5As shown, the luffing assembly 14 also includes luffing fixed pulleys 143, which are installed at both ends of the boom 12. The luffing drum 142 is fixedly installed on the boom column 11. The luffing wire rope 144 of the luffing drum 142 passes through the luffing fixed pulleys 143 and is connected to the moving trolley 141. Specifically, the luffing fixed pulleys 143 are respectively installed at the connecting end and the free end of the boom 12 to form a wire rope loop; the luffing drum 142 is fixedly installed at the lower middle part of the boom column 11. The luffing wire rope 144 wound on it is led out from the drum and passes through the fixed pulleys at the connecting end and the free end of the boom 12 in sequence, and finally connects to the moving trolley 141, thus forming a closed traction system. Specifically, the luffing wire rope 144 includes a first luffing wire rope 144a and a second luffing wire rope 144b. One end of the first luffing wire rope 144a and the second luffing wire rope 144b are connected to each other and wound around the luffing drum 142. The other ends of the first luffing wire rope 144a and the second luffing wire rope 144b pass through different luffing fixed pulleys 143 and are connected to both ends of the moving trolley 141. When the luffing drum 142 rotates forward or reverse to wind up or unwind the luffing wire rope 144, the moving trolley 141 can be reliably reciprocated along the track of the boom 12 by the first luffing wire rope 144a and the second luffing wire rope 144b, thereby realizing the luffing of the moving trolley 141. In addition, a handwheel can be installed on the luffing drum 142 to facilitate manual rotation of the luffing drum 142. The mobile trolley 141 is also equipped with a sliding roller 1412, which is used to slide in cooperation with the boom 12. When the luffing wire rope 144 pulls the mobile trolley 141, the mobile trolley 141 slides on the boom 12 via the sliding roller 1412.

[0031] The luffing drum 142 is fixed to the column, making the system run more smoothly. By rotating the drum in different directions, it is converted into different wire rope winding and unwinding movements, which in turn drive the bidirectional linear movement of the trolley. The force flow is clear and the mechanical efficiency is high. It can accurately and smoothly control the position and speed of the moving trolley 141, thereby realizing stepless adjustment of the lifting radius, which greatly expands the working range and operational flexibility of the boom. At the same time, the system has a compact structure, high reliability, and convenient maintenance.

[0032] In some implementations, such as Figure 6As shown, the boom derrick device 1 also includes a lifting assembly 15, which includes a lifting wire rope 151, a lifting drum 152, and multiple lifting pulleys 153. The lifting drum 152 is connected to the boom column 11, and the lifting pulleys 153 are connected to the top of the boom 12 and the movable end of the boom 12. The lifting wire rope 151 connects the lifting drum 152, the multiple lifting pulleys 153, and the moving trolley 141. The lifting drum 152 is installed on the boom column 11 and is located above the luffing drum 142. The lifting wire rope 151 is wound around the lifting drum 152 and leads out from the lifting drum 152, passing sequentially around one or more lifting pulleys 153 installed on the top of the boom 12, the lifting pulleys 153 at the movable end of the boom, then winding around the hook 1411 pulley on the moving trolley 141, and finally connecting to the boom. This winding method forms a multiplier pulley system, which allows the rotation of the hoisting drum 152 to directly control the vertical lifting and lowering movement of the hook 1411 through the winding and unwinding of the hoisting wire rope 151; moreover, when the trolley is luffing, the hoisting wire rope 151 can move freely around the moving trolley 141 and the hook 1411 pulley on the moving trolley 141, ensuring that the luffing and lifting actions do not conflict.

[0033] The hook 1411 pulley not only converts the rotational motion of the hoisting drum 152 into the vertical displacement of the load, but also effectively reduces the torque and tension required by the drum through a multiplier design, making the entire system more labor-saving and stable, and adaptable to heavy-duty lifting requirements. The independent hoisting function, combined with the luffing, traveling, and rotating functions, allows the operator to precisely control the position of the load in three-dimensional space, greatly expanding the working range and flexibility of the boom, forming a fully functional, highly efficient, and safe miniaturized lifting system.

[0034] In some embodiments, the derrick device 1 further includes a tie rod 16, one end of which is connected to the derrick boom 12, and the other end is connected to the top of the derrick column 11. The tie rod 16 is typically an adjustable-length rigid member, with one end connected to the middle and rear part of the derrick boom 12 and the other end also connected to the top of the derrick column 11. The tie rod 16, the derrick boom 12, and the derrick column 11 together form a stable triangular structure, significantly changing the force model of the boom and improving the stress condition of the derrick boom 12. The axial tension of the tie rod 16 effectively counteracts the huge bending moment generated by the lifting load, thereby greatly reducing the stress and deflection deformation at the root of the derrick boom 12. This makes the derrick boom 12 more stable and less deformed when under load, significantly improving the rigidity and stability of the entire derrick device 1. It also allows the derrick boom 12 to be designed to be longer or have a stronger load-bearing capacity, effectively expanding the working range of the derrick device 1 and improving the flexibility of lifting performance while ensuring operational safety.

[0035] The second aspect of this application provides a tower crane, such as Figure 7 As shown, the tower crane includes a counterweight boom and a derrick device 1 according to any one of the above-mentioned components. The derrick device 1 is connected to the base frame 2 of the counterweight boom. The derrick device 1 is mechanically connected to the base frame 2 of the tower crane's counterweight boom via a movable mounting assembly 13 at its bottom, making the derrick device 1 no longer a fixed accessory, but an independent working unit that can move on the counterweight boom and rotate around its own axis. The original counterweight boom of the tower crane provides it with a solid installation foundation and a high-altitude working platform, while the lifting, luffing, traveling, and rotating functions of the derrick device 1 complement the main structure of the tower crane, expanding the tower crane's own lifting functionality and operating range. Through its own rotation, traveling, and luffing movements, the derrick device 1 can cover blind spots that are difficult for the main boom of the tower crane to reach, and can flexibly adjust its position to accurately lift small parts or maintenance equipment. This not only significantly improves the adaptability and flexibility of the tower crane in complex construction sites, but also improves overall work efficiency, reduces energy consumption, and greatly facilitates the self-disassembly and assembly of the equipment.

[0036] In the description of this application, 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly 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 components; 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 expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. 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.

[0039] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A pole-lifting device, characterized in that, The lifting device (1) includes: A derrick column (11) has a derrick boom (12) extending horizontally from its top. The bottom end of the boom column (11) is mounted on the base frame (2) of the counterweight boom of the tower crane via the movable mounting assembly (13). The movable mounting assembly (13) is used to drive the boom column (11) to walk and rotate on the base frame (2). The luffing assembly (14) includes a trolley (141) and a luffing drum (142) that drives the trolley (141) to move along the boom (12).

2. The derrick device according to claim 1, characterized in that, The active installation component (13) includes: The traveling slide (131) slides in cooperation with the traveling slide rail on the base frame (2); A slewing bearing (132) is disposed on top of the traveling slide (131) and connected to the bottom end of the derrick column (11).

3. The pole-lifting device according to claim 2, characterized in that, The walking slide (131) includes: The rail-holding slider (1311) is a U-shaped plate with its opening facing downwards; The traveling rollers (1312) are located inside the side plates on both sides of the rail-holding slider (1311).

4. The pole-lifting device according to claim 3, characterized in that, The walking slide (131) also includes: A parking screw (133) is used to pass through the side plate of the rail-holding slider (1311) to abut against the base frame (2).

5. The pole-lifting device according to claim 4, characterized in that, The side plate of the rail-holding slider (1311) has a threaded hole through which the parking screw (133) passes, and the parking screw (133) is connected to the threaded hole.

6. The pole-lifting device according to claim 2, characterized in that, The top of both the slewing bearing (132) and the traveling slide (131) are provided with limit holes. The movable mounting assembly (13) also includes a limit pin (134), which is used to pass through the limit holes of the slewing bearing (132) and the traveling slide (131).

7. The derrick device according to any one of claims 1 to 6, characterized in that, The luffing assembly (14) also includes a luffing fixed pulley (143), which is installed at both ends of the boom (12). The luffing drum (142) is fixedly installed on the boom column (11). The luffing wire rope (144) of the luffing drum (142) passes through the luffing fixed pulley (143) and is connected to the moving trolley (141).

8. The derrick device according to any one of claims 1 to 6, characterized in that, The lifting device (1) further includes: The lifting assembly (15) includes a lifting wire rope (151), a lifting drum (152), and a plurality of lifting pulleys (153). The lifting drum (152) is connected to the boom column (11), and the lifting pulleys (153) are connected to the top of the boom (12) and the movable end of the boom (12). The lifting wire rope (151) connects the lifting drum (152), the plurality of lifting pulleys (153), and the moving trolley (141).

9. The derrick device according to any one of claims 1 to 6, characterized in that, The lifting device (1) further includes: The pull rod (16) is connected at one end to the boom (12) of the derrick and at the other end to the top of the derrick column (11).

10. A tower crane, characterized in that, It includes a counterweight arm and a lever device (1) according to any one of claims 1 to 9, the lever device (1) being connected to the base frame (2) of the counterweight arm.

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