A swing limiting device for a boom of a bridge crane

Abstract

The present application belongs to the technical field of bridge cranes, in particular to a hook group rotary limiting device of a bridge crane, which comprises a fixed box, a rotating disc, a hook, an electric push rod and a motor, the rotating disc is rotationally connected to the bottom of the fixed box, the hook is fixedly connected to the bottom of the rotating disc, the electric push rod is fixedly connected to the inner wall of the fixed box, a control box is fixedly connected to the right side of the fixed box, the motor is fixedly connected to the inner wall of the control box, the top of the rotating disc extends to the inner wall of the fixed box, the present application realizes the function of conveniently adjusting the rotation angle of the hook according to the use requirements through the cooperation of the motor, the electric push rod, the fixing assembly and the limiting assembly, and the operation is simple and convenient, and the hook can be fixed, so that the hook remains stable during use, prevents the effect of rotation caused by strong airflow or external force error touch and collision, avoids unnecessary safety hazards, and has strong practicality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge cranes, in particular to a limited-position rotating device for a lifting arm of a bridge crane. BACKGROUND

[0002] A bridge crane is a hoisting device for hoisting and transporting materials above a workshop, warehouse or material yard. Since its two ends are seated on high cement columns or metal supports, it looks like a bridge. The bridge of the bridge crane runs longitudinally along the tracks laid on the high supports on both sides, can fully utilize the space below the bridge for hoisting and transporting materials, and is not hindered by ground equipment. It is the most widely used and largest number of hoisting machinery.

[0003] In the prior art, the rotating angle of the lifting arm of the bridge crane is generally fixed and limited in actual use. When the rotating angle needs to be adjusted, it needs to be adjusted additionally, which affects the work efficiency, and lacks the function of limiting position. When encountering strong airflow or external force, it is easy to cause the lifting arm to rotate, which exists certain safety hidden trouble, causing inconvenience to use. Therefore, the present application provides a limited-position rotating device for a lifting arm of a bridge crane to solve the above technical problems. SUMMARY

[0004] Based on the technical problems in the background that the rotating angle of the lifting arm is generally fixed and limited in actual use, when the rotating angle needs to be adjusted, it needs to be adjusted additionally, which affects the work efficiency, and lacks the function of limiting position. When encountering strong airflow or external force, it is easy to cause the lifting arm to rotate, which exists certain safety hidden trouble, causing inconvenience to use, the present application provides a limited-position rotating device for a lifting arm of a bridge crane.

[0005] The limited-position rotating device for a lifting arm of a bridge crane provided by the present application comprises a fixed box, a rotating disc, a lifting hook, an electric push rod and a motor, the rotating disc is rotationally connected to the bottom of the fixed box, the lifting hook is fixedly connected to the bottom of the rotating disc, the electric push rod is fixedly connected to the inner wall of the fixed box, a control box is fixedly connected to the right side of the fixed box, and the motor is fixedly connected to the inner wall of the control box.

[0006] The top of the rotating disc extends to the inner wall of the fixed box, the top of the rotating disc is fixedly connected with a positioning wheel, the positioning wheel is a hollow structure, a plurality of insertion holes are equidistantly arranged on the inner wall of the positioning wheel, the insertion holes are arranged in a ring shape, the top of the rotating disc is fixedly connected with an internal gear, an adjusting gear is rotationally connected to the bottom of the control box, the adjusting gear is engaged with the internal gear, the inner wall of the fixed box is provided with a fixing assembly, and the inner wall of the control box is provided with a limiting assembly.

[0007] By the above mechanism: the fixed assembly can be driven by the electric push rod, the fixed assembly can conveniently limit the positioning wheel, the rotating disc and the hook are fixed, the hook is prevented from rotating when hoisting articles due to strong air flow or external force, collision and other influences, safety hazards are avoided, the limiting assembly can be driven by the motor, the rotating disc and the hook are conveniently driven to rotate by the limiting assembly, and the rotating angle of the hook is adjusted, and the hook is convenient to use.

[0008] Preferably, the fixed assembly comprises a sliding plate, a push rod, two driving rods and two insertion plates.

[0009] The sliding plate is slidably connected to the inner wall of the fixed box, the left side of the sliding plate is fixedly connected to the right side of the electric push rod, the push rod is rotatably connected to the front side of the sliding plate, the two driving rods are rotatably connected to the inner wall of the fixed box, the rear side of the two driving rods is rotatably connected to the front side of the corresponding sliding rod, the two insertion plates are slidably connected to the inner wall of the fixed box, and the front side of the two insertion plates is rotatably connected to the rear side of the corresponding driving rod, the driving rod is of a telescopic structure, and the two insertion plates are matched with the corresponding insertion holes.

[0010] Further, the push rod can be moved by moving the sliding plate, the sliding rod can be moved downward when the push rod moves, and the driving rod can be pushed when the sliding rod moves downward, the insertion plate can be moved by rotating the driving rod, and the positioning wheel is limited.

[0011] Preferably, the limiting assembly comprises a transmission gear, a rack, a movable rod, a connecting plate, two positioning rods, two positioning plates and a positioning gear.

[0012] The bottom of the motor output shaft is fixedly connected with a telescopic rod, the transmission gear is fixedly connected to the outer wall of the telescopic rod, the rack is slidably connected to the inner wall of the control box, and the transmission gear is engaged with the rack, the rack is of a hollow structure, the movable rod is slidably connected to the inner wall of the rack, and the movable rod penetrates through the rack, the connecting plate is slidably connected to the inner wall of the control box, the two positioning rods are rotatably connected to the bottom of the connecting plate, the top of the adjusting gear extends to the inner wall of the control box, the top of the adjusting gear is fixedly connected with a limiting wheel, the positioning gear is fixedly connected to the outer wall of the limiting wheel, the two positioning plates are slidably connected to the inner wall of the control box, the two positioning plates are matched with the positioning gear, the rear side of the two positioning rods is rotatably connected to the front side of the corresponding positioning plate, the bottom of the telescopic rod is fixedly connected with a connecting block, the top of the limiting wheel is provided with a connecting groove, the connecting block is matched with the connecting groove, the connecting plate is of a hollow structure, and the inner wall of the connecting plate is fixedly connected with the outer wall of the telescopic rod.

[0013] Further, the rotation of the transmission gear can drive the meshing rack to move, the rack movement can push the movable rod to move horizontally, when the movable rod moves horizontally, the movable rod can drive the rotating wheel to move horizontally, at this time, the rotating wheel slides along with the direction of the guide plate, when the connecting plate moves downward, the connecting plate can push the positioning rod, when the positioning rod moves, the positioning rod can push the two positioning plates to move away from each other, at this time, the positioning plate is out of contact with the positioning gear, so that the limiting wheel is unlocked.

[0014] Preferably, the inner wall of the fixed box is symmetrically and fixedly connected with limiting frames, and the number of the limiting frames is two, and the side close to each other of the two inserting plates is slidably connected with the inner wall of the side away from each other of the two limiting frames.

[0015] Further, the limiting frame facilitates limiting the inserting plate, so that the inserting plate moves vertically stably.

[0016] Preferably, the inner wall of the two limiting frames is fixedly connected with a spring, and the top of the two inserting plates is fixedly connected with the bottom of the corresponding spring.

[0017] Further, the spring facilitates pushing the inserting plate to reset and engage with the jack.

[0018] Preferably, the inner wall of the control box is fixedly connected with a spring, and the right side of the rack is fixedly connected with the left side of the spring.

[0019] Further, the spring facilitates pushing the rack to reset and drive the movable rod to reset.

[0020] Preferably, the front side of the movable rod is rotatably connected with a rotating wheel, the inner wall of the control box is fixedly connected with a guide plate, and the outer wall of the rotating wheel is movably in contact with the top of the guide plate.

[0021] Further, the movable rod facilitates driving the rotating wheel to move, and the guide plate and the rotating wheel facilitate guiding the movable rod to move obliquely.

[0022] Preferably, the inner wall of the control box is symmetrically and fixedly connected with a limiting rod and a spring, and the number of the limiting rod and the spring is two, and the two limiting rods penetrate through the connecting plate, and the bottom of the connecting plate is fixedly connected with the top of the two springs.

[0023] Further, the limiting rod can limit the connecting plate to move vertically stably, and the spring facilitates driving the connecting plate to reset.

[0024] The beneficial effects of the present application are as follows:

[0025] The electric push rod can drive the fixing assembly, the fixing assembly can conveniently limit the positioning wheel, the rotating disc and the lifting hook are fixed, the lifting hook is prevented from rotating when hoisting articles due to strong air flow or external force error touch and collision, safety hidden danger is avoided, the motor can drive the limiting assembly, the limiting assembly can conveniently drive the rotating disc and the lifting hook to rotate, the rotating angle of the lifting hook is adjusted, and use is facilitated.

[0026] The sliding plate moves to drive the push rod to move, the push rod moves to push the sliding rod to move downward, the sliding rod moves to push the driving rod, the driving rod rotates to conveniently drive the insertion plate to move, and the positioning wheel is limited.

[0027] The transmission gear rotates to drive the meshing rack to move, the rack moves to push the movable rod to move transversely, the movable rod moves transversely to drive the rotating wheel to move transversely, the rotating wheel slides along with the direction of the guide plate at this time, the connecting plate moves downward to push the positioning rod, the positioning rod moves to push the two positioning plates to move away from each other, the positioning plates are separated from the positioning gear at this time, and the limiting wheel is unlocked.

[0028] The motor, the electric push rod, the fixing assembly and the limiting assembly are combined, the rotating angle of the lifting hook is adjusted conveniently according to use requirements, the operation is simple and convenient, the lifting hook can be fixed, the lifting hook remains stable during use, the effect that the lifting hook is prevented from rotating due to strong air flow or external force error touch and collision is achieved, unnecessary safety hidden danger is avoided, and the device has strong practicability. ACCURACY OF DRAWINGS

[0029] Figure 1 It is a front view of the structure schematic diagram of the bridge crane's lifting arm limitable rotary device;

[0030] Figure 2 It is a front view of the structure schematic diagram of the bridge crane's lifting arm limitable rotary device's fixing box;

[0031] Figure 3 It is a front view of the structure schematic diagram of the bridge crane's lifting arm limitable rotary device's control box;

[0032] Figure 4 It is a structure schematic diagram of the bridge crane's lifting arm limitable rotary device's positioning gear and positioning plate;

[0033] Figure 5 It is a three-dimensional view of the bridge crane's lifting arm limitable rotary device's connecting plate and movable rod.

[0034] In the figure: 1, fixed box; 2, rotating disc; 3, inner gear; 4, lifting hook; 5, positioning wheel; 6, electric push rod; 7, sliding plate; 8, push rod; 9, sliding rod; 10, driving rod; 11, insertion plate; 12, No. 1 spring; 13, control box; 14, motor; 15, transmission gear; 16, rack; 17, movable rod; 18, guide plate; 19, No. 2 spring; 20, connecting plate; 21, limiting rod; 22, No. 3 spring; 23, positioning rod; 24, positioning plate; 25, positioning gear; 26, adjusting gear. DETAILED DESCRIPTION

[0035] The application is further explained below in connection with specific embodiments.

[0036] REFERENCE Figures 1-5The embodiment proposes a bridge crane's lifting arm position-limiting rotating device, which comprises a fixed box 1, a rotating disc 2, a lifting hook 4, an electric push rod 6, and a motor 14. The rotating disc 2 is rotationally connected to the bottom of the fixed box 1, and the lifting hook 4 is fixedly connected to the bottom of the rotating disc 2. The electric push rod 6 is fixedly connected to the inner wall of the fixed box 1. The right side of the fixed box 1 is fixedly connected with a control box 13, and the motor 14 is fixedly connected to the inner wall of the control box 13. The top of the rotating disc 2 extends to the inner wall of the fixed box 1. The top of the rotating disc 2 is fixedly connected with a positioning wheel 5, and the positioning wheel 5 is a hollow structure. A plurality of insertion holes are equidistantly arranged on the inner wall of the positioning wheel 5 and arranged in a ring shape. The top of the rotating disc 2 is fixedly connected with an internal gear 3. The bottom of the control box 13 is rotationally connected with an adjusting gear 26, and the adjusting gear 26 is engaged with the internal gear 3. The inner wall of the fixed box 1 is provided with a fixed assembly, and the inner wall of the control box 13 is provided with a limiting assembly. The fixed assembly comprises a sliding plate 7, a push rod 8, two driving rods 10, and two insertion plates 11. The sliding plate 7 is slidingly connected to the inner wall of the fixed box 1, and the left side of the sliding plate 7 is fixedly connected with the right side of the electric push rod 6. The push rod 8 is rotationally connected to the front side of the sliding plate 7. The two driving rods 10 are symmetrically rotationally connected to the inner wall of the fixed box 1. The rear side of the two driving rods 10 is rotationally connected with the front side of the corresponding sliding rod 9. The two insertion plates 11 are symmetrically slidingly connected to the inner wall of the fixed box 1, and the front side of the two insertion plates 11 is rotationally connected with the rear side of the corresponding driving rod 10. The driving rod 10 is a telescopic structure. The two insertion plates 11 are matched with the corresponding insertion holes. The limiting assembly comprises a transmission gear 15, a rack 16, a movable rod 17, a connecting plate 20, two positioning rods 23, two positioning plates 24, and a positioning gear 25. The bottom of the output shaft of the motor 14 is fixedly connected with a telescopic rod. The transmission gear 15 is fixedly connected to the outer wall of the telescopic rod. The rack 16 is slidingly connected to the inner wall of the control box 13, and the transmission gear 15 is engaged with the rack 16. The rack 16 is a hollow structure. The movable rod 17 is slidingly connected to the inner wall of the rack 16, and the movable rod 17 penetrates through the rack 16. The connecting plate 20 is slidingly connected to the inner wall of the control box 13. The two positioning rods 23 are symmetrically rotationally connected to the bottom of the connecting plate 20. The top of the adjusting gear 26 extends to the inner wall of the control box 13. The top of the adjusting gear 26 is fixedly connected with a limiting wheel. The positioning gear 25 is fixedly connected to the outer wall of the limiting wheel. The two positioning plates 24 are symmetrically slidingly connected to the inner wall of the control box 13. The two positioning plates 24 are matched with the positioning gear 25. The rear side of the two positioning rods 23 is rotationally connected with the front side of the corresponding positioning plate 24. The bottom of the telescopic rod is fixedly connected with a connecting block. The top of the limiting wheel is provided with a connecting groove, and the connecting block is matched with the connecting groove. The connecting plate 20 is a hollow structure, and the inner wall of the connecting plate 20 is fixedly connected with the outer wall of the telescopic rod.

[0037] Through the above mechanism: through the electric push rod 6 can drive the slide plate 7 to move so that the push rod 8 moves, when the push rod 8 moves, it will push the slide rod 9 to move down, when the slide rod 9 moves down, it will push the driving rod 10, the driving rod 10 rotates to facilitate the movement of the plug plate 11, thereby limiting the positioning wheel 5, through the motor 14 can drive the transmission gear 15 to rotate so that the meshing rack 16 moves, the rack 16 moves to push the movable rod 17 to move horizontally, when the movable rod 17 moves horizontally, it will drive the rotating wheel to move horizontally, at this time the rotating wheel slides with the direction of the guide plate 18, when the connecting plate 20 moves down, it will push the positioning rod 23, when the positioning rod 23 moves, it will push the two positioning plates 24 to move away from each other, at this time the positioning plate 24 and the positioning gear 25 are out of contact to unlock the limiting wheel to limit the positioning wheel 5, so that the rotating disc 2 and the hook 4 are fixed, prevent the hook 4 from rotating when lifting the goods, affected by strong airflow or external force, accidental touch, collision, avoid safety hazards, through the motor 14 can drive the limiting assembly, through the limiting assembly to facilitate the rotation of the rotating disc 2 and the hook 4, thereby adjusting the rotation angle of the hook 4, convenient to use, through the cooperation of the motor 14, the electric push rod 6, the fixing assembly and the limiting assembly, the function of adjusting the rotation angle of the hook 4 according to the use requirement is realized, and the operation is simple and convenient, and the hook 4 can be fixed, so that the hook 4 remains stable during use, prevents the hook 4 from rotating when encountering strong airflow or external force, accidental touch, collision, avoids unnecessary safety hazards, and has strong practicality.

[0038] In the embodiment, the inner walls of the fixed box 1 are symmetrically and fixedly connected with limiting frames, and the number of the limiting frames is two. The two plug plates 11 are slidably connected with the inner walls of the two limiting frames away from each other on the side close to each other. The limiting frames facilitate limiting the plug plates 11, so that the plug plates 11 stably and vertically move.

[0039] In the embodiment, the inner walls of the two limiting frames are fixedly connected with a first spring 12, and the top of the two plug plates 11 is fixedly connected with the bottom of the corresponding first spring 12. Through the elastic force of the first spring 12, the plug plates 11 are conveniently pushed to reset and engage with the plug hole.

[0040] In the embodiment, the inner wall of the control box 13 is fixedly connected with a second spring 19, and the right side of the rack 16 is fixedly connected with the left side of the second spring 19. Through the elastic force of the second spring 19, the rack 16 is conveniently pushed to reset and drive the movable rod 17 to reset.

[0041] In the embodiment, the front side of the movable rod 17 is rotatably connected with a rotating wheel, the inner wall of the control box 13 is fixedly connected with a guide plate 18, and the outer wall of the rotating wheel is movably in contact with the top of the guide plate 18. Through the movable rod 17, the rotating wheel is conveniently moved. Through the cooperation of the guide plate 18 and the rotating wheel, the movable rod 17 is conveniently guided to move obliquely.

[0042] In the embodiment, the inner wall of the control box 13 is symmetrically and fixedly connected with the limiting rods 21 and the third springs 22, and the number of the limiting rods 21 and the third springs 22 is two. The two limiting rods 21 are all penetrated through the connecting plate 20, the bottom of the connecting plate 20 is fixedly connected with the top of the two third springs 22, the limiting rods 21 can limit the connecting plate 20, the connecting plate 20 can stably and vertically move, and the third springs 22 are convenient for driving the connecting plate 20 to reset.

[0043] Working principle: in actual use, when the hook 4 is needed, the rope of the bridge crane is connected with the top of the fixed box 1 to drive the fixed box 1 to move, the electric push rod 6 is started to extend, the electric push rod 6 extends to push the sliding plate 7 to move, the sliding plate 7 moves to push the push rod 8, the push rod 8 moves to push the sliding rod 9 to move down, the sliding rod 9 moves down to push the driving rod 10 to rotate, the driving rod 10 rotates to retract and drive the plug plate 11 to move up, the limiting frame limits the plug plate 11, the plug plate 11 moves to compress the first spring 12, the first spring 12 is compressed to store energy, and the plug plate 11 moves to be out of contact with the jack to unlock the positioning wheel 5, the rotating disc 2 and the hook 4 are unlocked, the motor 14 is started, the output shaft of the motor 14 rotates to drive the telescopic rod to rotate, the telescopic rod drives the transmission gear 15 to rotate, the transmission gear 15 rotates to drive the meshing rack 16 to move, the rack 16 moves to compress the second spring 19, the rack 16 is limited by the teeth, the second spring 19 cooperates with the rack 16 to make the rack 16 and the transmission gear 15 keep meshing, the motor 14 is started to drive the transmission gear 15 to rotate, the rack 16 keeps on one side, and the rack 16 moves to push the movable rod 17 to move horizontally, the movable rod 17 moves horizontally to drive the rotating wheel to move horizontally, the third spring 22 is unlocked to pull the connecting plate 20 to move down, the rotating wheel slides along with the direction of the guide plate 18, the connecting plate 20 moves down to push the positioning rod 23, the limiting rod 21 limits the connecting plate 20 to move up and down, the positioning rod 23 moves to push the two positioning plates 24 to move away from each other, the positioning plates 24 are out of contact with the positioning gear 25 to unlock the limiting wheel, and the connecting plate 20 moves to drive the telescopic rod to extend, the telescopic rod extends to drive the connecting block to move down and be clamped in the connecting groove to make the limiting wheel rotate, the limiting wheel rotates to drive the adjusting gear 26 to rotate, the adjusting gear 26 rotates to drive the meshing internal gear 3 to rotate, the internal gear 3 rotates to drive the rotating disc 2 and the hook 4 to rotate, the rotating speed and the number of rotations of the motor 14 are controlled to control the rotation degree of the hook 4, the hook 4 is controlled to rotate, the motor 14 is stopped, the second spring 19 pushes the rack 16 to reset and drives the movable rod 17 to reset, the movable rod 17 drives the connecting plate 20 to move up to make the telescopic rod retract and drive the connecting block to move away from the connecting groove, the connecting plate 20 drives the positioning rod 23 to move to make the positioning plate 24 and the positioning gear 25 clamped to fix the adjusting gear 26, the electric push rod 6 is controlled to reset, the sliding plate 7 moves left to drive the push rod 8 to move to make the sliding rod 9 move up, the sliding rod 9 rotates to reset, the first spring 12 drives the plug plate 11 to move to make the plug plate 11 and the jack clamped to fix the positioning wheel 5, the rotating disc 2 and the hook 4 are fixed,The hook 4 is kept stable in use, and is prevented from rotating due to external force impact, so as to limit the hook 4.

[0044] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A position-limited slewing device for a bridge crane, comprising a fixed box (1), a rotating disc (2), a hook (4), an electric push rod (6) and an electric motor (14), characterized in that, The rotating disc (2) is rotationally connected at the bottom of the fixed box (1), the hook (4) is fixedly connected at the bottom of the rotating disc (2), the electric push rod (6) is fixedly connected at the inner wall of the fixed box (1), the right side of the fixed box (1) is fixedly connected with the control box (13), and the motor (14) is fixedly connected at the inner wall of the control box (13); The top of the rotating disc (2) extends to the inner wall of the fixed box (1), the top of the rotating disc (2) is fixedly connected with the positioning wheel (5), the positioning wheel (5) is a hollow structure, a plurality of insertion holes are equidistantly arranged at the inner wall of the positioning wheel (5) and arranged in a ring shape, the top of the rotating disc (2) is fixedly connected with the internal gear (3), the bottom of the control box (13) is rotationally connected with the adjusting gear (26), the adjusting gear (26) is engaged with the internal gear (3), the inner wall of the fixed box (1) is provided with a fixing assembly, and the inner wall of the control box (13) is provided with a limiting assembly; The fixing assembly comprises a sliding plate (7), a push rod (8), two driving rods (10) and two insertion plates (11); The sliding plate (7) is slidingly connected at the inner wall of the fixed box (1), the left side of the sliding plate (7) is fixedly connected with the right side of the electric push rod (6), the push rod (8) is rotationally connected at the front side of the sliding plate (7), the two driving rods (10) are symmetrically rotationally connected at the inner wall of the fixed box (1), the rear side of each driving rod (10) is rotationally connected with the front side of the corresponding sliding rod (9), the two insertion plates (11) are symmetrically slidingly connected at the inner wall of the fixed box (1), the front side of each insertion plate (11) is rotationally connected with the rear side of the corresponding driving rod (10), the driving rod (10) is of an extendable structure, and the two insertion plates (11) are matched with the corresponding insertion holes; The limiting assembly comprises a transmission gear (15), a rack (16), a movable rod (17), a connecting plate (20), two positioning rods (23), two positioning plates (24) and a positioning gear (25). The bottom of the motor (14) output shaft is fixedly connected with a telescopic rod, a transmission gear (15) is fixedly connected to the outer wall of the telescopic rod, a rack (16) is slidingly connected to the inner wall of the control box (13), and the transmission gear (15) is engaged with the rack (16), the rack (16) is a hollow structure, a movable rod (17) is slidingly connected to the inner wall of the rack (16), and the movable rod (17) penetrates the rack (16), a connecting plate (20) is slidingly connected to the inner wall of the control box (13), two positioning rods (23) are symmetrically and rotatably connected to the bottom of the connecting plate (20), the top of an adjusting gear (26) extends to the inner wall of the control box (13), the top of the adjusting gear (26) is fixedly connected with a limiting wheel, a positioning gear (25) is fixedly connected to the outer wall of the limiting wheel, two positioning plates (24) are symmetrically and slidingly connected to the inner wall of the control box (13), the two positioning plates (24) are adapted to the positioning gear (25), the rear side of the two positioning rods (23) is rotatably connected to the front side of the corresponding positioning plate (24), the bottom of the telescopic rod is fixedly connected with a connecting block, the top of the limiting wheel is provided with a connecting groove, the connecting block is adapted to the connecting groove, the connecting plate (20) is a hollow structure, the inner wall of the connecting plate (20) is fixedly connected with the outer wall of the telescopic rod, the connecting plate (20) is a hollow structure, and the inner wall of the connecting plate (20) is fixedly connected with the outer wall of the telescopic rod.

2. A bridge crane jib positionable slewing device according to claim 1, characterised in that, The inner wall of the fixed box (1) is fixedly connected with limiting frames, and the number of the limiting frames is two.

3. A bridge crane jib slew limiter according to claim 2, characterised in that, The inner wall of the two limiting frames is fixedly connected with a spring (12), and the top of the two plugboards (11) is fixedly connected with the bottom of the corresponding spring (12).

4. A bridge crane jib positionable slewing device according to claim 1 wherein, The inner wall of the control box (13) is fixedly connected with a spring (19), and the right side of the rack (16) is fixedly connected with the left side of the spring (19).

5. A bridge crane jib swing limiter according to claim 1, characterised in that The front side of the movable rod (17) is rotatably connected with a rotating wheel, the inner wall of the control box (13) is fixedly connected with a guide plate (18), and the outer wall of the rotating wheel is in movable contact with the top of the guide plate (18).

6. A bridge crane jib slew limiter according to claim 1, characterised in that, The inner wall of the control box (13) is fixedly connected with a limiting rod (21) and a spring (22), and the number of the limiting rod (21) and the spring (22) is two.

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