Tail folding type climbing ladder for semi-trailer

Abstract

The application discloses a tail folding type climbing ladder for a semitrailer and relates to the technical field of semitrailers.The tail folding type climbing ladder comprises a mounting frame assembly, adjusting assemblies are arranged on the two sides of the mounting frame assembly, folding ladder assemblies are arranged between the mounting frame assemblies, and the mounting frame assembly changes the use mode of the folding ladder assembly through the adjusting assemblies.The mounting frame assembly comprises two mounting plates, a first mounting rod and a second mounting rod, the first mounting rod is fixedly connected to one side between the two mounting plates, and the second mounting rod is fixedly connected to the other side between the two mounting plates.The tail folding type climbing ladder is provided with a through groove linear guide and an arc groove rotary displacement composite guide structure, and is matched with the automatically lockable adjusting assemblies, so that the tail folding type climbing ladder can realize quick tool-free switching between two use modes of sliding folding and folding folding, the switching can be achieved by only pulling a control plate to release the limiting, and the folding ladder assembly can be automatically reset and locked by the first spring after the folding ladder assembly is moved and hands are released, so that the operation process is simple, no additional auxiliary tools are needed, and the switching efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of semi-trailer technology, and in particular to a rear-mounted folding step ladder for semi-trailers. Background Technology

[0002] The semi-trailer rear folding step ladder consists of a fixed base, multi-section hinged ladder body, anti-slip steps, locking and limiting mechanism, and reset component. The base is rigidly fixed to the rear frame / tail crossbeam of the semi-trailer, and each ladder section is hinged by pins to form a foldable rotating joint. When the vehicle is in motion, the ladder body folds inward and upward and is fixed to the rear of the vehicle by the locking mechanism, without exceeding the legal outline of the vehicle. When personnel are working, the lock is unlocked, and the ladder body unfolds downward and outward by its own weight / springs. Each ladder section unfolds in sequence to form a continuous step ladder, allowing personnel to move between the ground and the trailer loading platform. It is a rear personnel boarding accessory assembly that also has the functions of folding and storage, anti-slip load-bearing, and anti-reverse collision protection.

[0003] Existing folding ladders for semi-trailers typically have only one type of rear ladder with a single storage method, which can be divided into two categories: chassis-mounted sliding type and fence-mounted folding type. The two types have independent structures and are not interchangeable. Vehicle manufacturers need to design and stock two sets of ladder parts separately, resulting in high production costs and inventory pressure. In addition, the single guide structure only supports one movement, sliding or rotating, which makes it difficult to adapt to different chassis heights, rear installation spaces and fence models, resulting in a narrow range of applications.

[0004] Therefore, it is necessary to propose a rear-folding step ladder for semi-trailers to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a rear-mounted folding ladder for semi-trailers, which solves the problem that rear ladders only have a single storage form, divided into two types: chassis-mounted sliding type and fence-mounted folding type. The two types have independent structures and cannot be used interchangeably. Vehicle manufacturers need to design and stock two sets of ladder body parts separately, resulting in high production costs and inventory pressure. In addition, the single guide structure only supports one movement, sliding or rotation, which makes it difficult to adapt to different chassis heights, rear installation spaces and fence models, resulting in a narrow range of applications.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a rear folding step ladder for a semi-trailer, comprising a mounting frame assembly, adjusting components on both sides of the mounting frame assembly, and a folding ladder assembly disposed between the mounting frame assemblies, wherein the mounting frame assembly changes the usage mode of the folding ladder assembly through the adjusting components; The mounting bracket assembly includes two mounting plates, a first mounting rod, and a second mounting rod. The first mounting rod is fixedly connected to one side between the two mounting plates, and the second mounting rod is fixedly connected to the other side between the two mounting plates. A through groove is formed in the middle of each of the two mounting plates, and an arc-shaped groove is formed on one side of the through groove. The adjustment assembly includes an adjustment block, a connecting column, and two first cylindrical grooves. The adjustment block is slidably disposed in the arc-shaped groove, and circular grooves are provided on both sides of the adjustment block. The folding ladder assembly includes a step frame, a first rotating rod, and two second rotating rods. The first rotating rod is fixedly connected to one side of the step frame. When the first rotating rod is located in the through groove, it is in a first usage mode. When the first rotating rod is located in the arc groove, it is in a second usage mode. The mounting bracket assembly has snap-fit ​​components on both sides away from the adjustment assembly, and the snap-fit ​​components are used to snap-fit ​​and position the folding ladder assembly.

[0007] Preferably, the connecting column is fixedly connected to the side wall of the adjusting block, two first cylindrical grooves are formed on one side of the mounting plate, a first sliding rod is slidably connected in the first cylindrical groove, a control plate is fixedly connected to one end of the connecting column, and the side wall of the control plate is fixedly connected to the ends of the two first sliding rods.

[0008] Preferably, a circular plate is slidably disposed inside the first cylindrical groove, the side wall of the circular plate is fixedly connected to the end of the first sliding rod, a first spring is fixedly connected to the side wall of the circular plate, one end of the first spring is fixedly connected to the side wall of the first cylindrical groove, and the first spring is movably sleeved on the outer periphery of the first sliding rod.

[0009] Preferably, both second rotating rods are rotatably mounted on the inner wall of the pedal frame, and the two second rotating rods are staggered. The outer periphery of the two second rotating rods is fixedly connected to two second ladder frame main beams and two first ladder frame main beams, respectively. The two second ladder frame main beams are rotatably connected to multiple third rotating rods. The outer periphery of each of the multiple third rotating rods is fixedly connected to a flip-up pedal. A fourth rotating rod is fixedly connected to one side of the flip-up pedal. The fourth rotating rod is rotatably connected between the two first ladder frame main beams. The outer periphery of each third rotating rod is rotatably connected to two folding hinges. The grooves of the two folding hinges are slidably connected to the corresponding fourth rotating rods. The side walls of the two first ladder frame main beams are provided with insertion holes.

[0010] Preferably, the snap-fit ​​assembly includes a second sliding rod, a snap-fit ​​plate, and a second cylindrical groove. The second sliding rod is slidably connected to one side of the mounting plate. When the folding ladder assembly is in the first usage mode, the second sliding rod passes through the corresponding mounting plate and is inserted into the corresponding socket. The second cylindrical groove is opened inside one side of the mounting plate. An annular piece is slidably disposed inside the second cylindrical groove. A second spring is movably connected to the side wall of the annular piece. The end of the second spring is movably connected to the side wall of the second cylindrical groove. The annular piece is fixedly sleeved on the outer periphery of the second sliding rod, and the second spring is movably sleeved on the outer periphery of the second sliding rod.

[0011] Preferably, the snap-fit ​​plate is fixedly sleeved on the outer periphery of the second sliding rod. The snap-fit ​​plate is located on one side of the mounting plate. When the folding ladder assembly is in the first state, limit plates are installed at the bottom of the two mounting plates. The limit plates have slots on both sides, and the snap-fit ​​plate snaps into the corresponding slots.

[0012] Preferably, when the folding ladder assembly is in the first state, two connecting brackets are installed on the top of the two mounting plates, and when the folding ladder assembly is in the second state, hanging brackets are installed on the side walls of the two mounting plates.

[0013] The technical effects and advantages of this invention are as follows: This invention features a composite guide structure combining a through-groove linear guide and an arc-shaped groove rotational displacement, along with an automatically locking adjustment component. This allows for quick, tool-free switching between two usage modes: sliding and folding. Switching is as simple as pulling the control panel to release the limit. After moving the folding ladder component, releasing the control panel allows for automatic reset and locking by the first spring. The operation is simple, requires no additional auxiliary tools, and offers high switching efficiency. This invention features dual working modes to adapt to diverse installation conditions of semi-trailers. The sliding retractable mode relies on the top connecting frame to be suspended below the trailer chassis, suitable for low chassis and narrow rear installation spaces. The folding retractable mode involves removing the matching connecting parts and replacing the mounting bracket, which is then suspended from the top of the trailer railing, suitable for high chassis and railing-type body structures. It is compatible with various semi-trailers with different chassis heights, rear spaces, and railing structures, covering the vast majority of vehicle installation scenarios. It has extremely strong versatility, and one device can meet the needs of multiple vehicles, reducing the development and inventory costs of supporting parts for automakers. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the first usage method of the present invention.

[0015] Figure 2 This is a first-view structural schematic diagram of the second usage method of the present invention.

[0016] Figure 3 This is a schematic diagram of the second usage method of the present invention from a second perspective.

[0017] Figure 4 This is a schematic cross-sectional view of the structure of the first usage method of the present invention.

[0018] Figure 5 For the present invention Figure 4 Enlarged diagram of point A in the middle.

[0019] Figure 6 For the present invention Figure 4 Enlarged diagram of point B in the middle.

[0020] In the diagram: 1. Mounting bracket assembly; 11. Mounting plate; 12. First mounting rod; 13. Second mounting rod; 14. Through groove; 15. Arc groove; 16. Hanger; 17. Connecting bracket; 2. Folding ladder assembly; 21. Step frame; 22. First rotating rod; 23. Second rotating rod; 24. First ladder frame main beam; 25. Second ladder frame main beam; 26. Third rotating rod; 27. Fourth rotating rod; 28. Folding hinge; 29. ​​Flip-up step; 210. Insertion hole 3. Adjustment component; 31. Adjustment block; 32. Connecting column; 33. First cylindrical groove; 34. First sliding rod; 35. Circular piece; 36. First spring; 37. Control panel; 4. Snap-fit ​​assembly; 41. Second sliding rod; 42. Snap-fit ​​plate; 43. Second cylindrical groove; 44. Annular piece; 45. Second spring; 5. Limiting plate; 51. Card slot. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] This invention provides, for example Figures 1-6 The diagram shows a rear-mounted folding ladder for a semi-trailer, comprising a mounting frame assembly 1, adjustment components 3 on both sides of the mounting frame assembly 1, and a folding ladder assembly 2 between the mounting frame assembly 1. The mounting frame assembly 1 can change the usage mode of the folding ladder assembly 2 through the adjustment components 3. The folding ladder assembly 2 has two usage modes: folding and sliding. It can adapt to different chassis heights, rear installation spaces, and guardrail structures of semi-trailers, and is compatible with various vehicle models and installation scenarios. It is highly versatile and adaptable to different usage needs. When it is necessary to change the usage mode, the adjustment components 3 are pulled, and then the position of the folding ladder assembly 2 is adjusted to achieve the adjustment of the usage mode.

[0023] It should be noted that the mounting frame assembly 1 includes two mounting plates 11, a first mounting rod 12, and a second mounting rod 13. The first mounting rod 12 is fixedly connected to one side between the two mounting plates 11, and the second mounting rod 13 is fixedly connected to the other side between the two mounting plates 11. Both mounting plates 11 have through slots 14 in the middle, and an arc-shaped groove 15 is formed on one side of the through slots 14. The through slots 14 are straight structures to meet the horizontal sliding and unfolding guidance requirements of the folding ladder assembly 2. The arc-shaped groove 15 is a rounded transition structure to adapt to the rotation and displacement of the folding ladder assembly 2, realizing the structural basis for switching between the two working modes. The first mounting rod 12 and the second mounting rod 13 help connect the two mounting plates 11 to form a complete frame. When the folding ladder assembly 2 is in the second usage mode, the second mounting rod 13 can provide close-fitting limiting support for the folding ladder assembly 2, effectively distributing the stepping load, preventing the ladder body from shifting or shaking under force, and ensuring the stable and normal use of the folding ladder assembly 2.

[0024] Furthermore, the adjustment component 3 includes an adjustment block 31, a connecting column 32, and two first cylindrical grooves 33. The adjustment block 31 is slidably disposed in the arc groove 15, and circular grooves are provided on both sides of the adjustment block 31. It can precisely fit with the end of the first rotating rod 22 to achieve all-round limit locking and prevent the folding ladder component 2 from deviating during operation. When it is necessary to change the usage mode, slide the adjustment component 3. After the adjustment component 3 moves out of the arc groove 15, move the folding ladder component 2 to the top of the arc groove 15 or into the through groove 14. The two working states can be changed quickly. The switching process is simple and does not require auxiliary tools.

[0025] It should be noted that the connecting column 32 is fixedly connected to the side wall of the adjusting block 31, and two first cylindrical grooves 33 are opened on one side of the mounting plate 11. A first sliding rod 34 is slidably connected in the first cylindrical groove 33. A control plate 37 is fixedly connected to one end of the connecting column 32, and the side wall of the control plate 37 is fixedly connected to the ends of the two first sliding rods 34. When the user uses the adjusting component 3 to change the state of the folding ladder component 2, the user pulls the control plate 37 outward. The control plate 37 drives the connecting column 32 and the first sliding rod 34 to move outward. The movement of the connecting column 32 drives the adjusting block 31 to move in the arc groove 15. When the adjusting block 31 moves away from the arc groove 15, the folding ladder component 2 can change its state.

[0026] It should also be noted that a circular piece 35 is slidably disposed inside the first cylindrical groove 33. The side wall of the circular piece 35 is fixedly connected to the end of the first sliding rod 34. A first spring 36 is fixedly connected to the side wall of the circular piece 35. One end of the first spring 36 is fixedly connected to the side wall of the first cylindrical groove 33. The first spring 36 is movably sleeved on the outer periphery of the first sliding rod 34. By utilizing the spring elastic reset structure, the adjustment component 3 is automatically locked without manual reset, eliminating the safety hazard caused by human forgetting to lock. When the first sliding rod 34 is moved, the first sliding rod 34 moves and drives the circular piece 35 to move within the first cylindrical groove 33. The cooperation between the circular piece 35 and the first cylindrical groove 33 compresses the first spring 36. After adjustment, the first sliding rod 34 is released, and the first spring 36 uses its elasticity to restore the circular piece 35 to its original position. The circular piece 35 drives the first sliding rod 34 and the adjustment block 31 to return to the initial locking state synchronously, automatically completing the limiting and fixing of the folding ladder component 2. The state adjustment has a high degree of automation.

[0027] In this invention, the folding ladder assembly 2 includes a footrest frame 21, a first rotating rod 22, and two second rotating rods 23. The first rotating rod 22 is fixedly connected to one side of the footrest frame 21. When the first rotating rod 22 is in the through groove 14, it is in the first usage mode; when the first rotating rod 22 is in the arc groove 15, it is in the second usage mode. The first rotating rod 22, in conjunction with the guide structure of the through groove 14 and the arc groove 15, realizes the dual movement modes of sliding and rotation of the folding ladder assembly 2, adapting to different storage and unfolding conditions. When the first usage mode is needed, the folding ladder assembly 2 is pulled out from the mounting frame assembly 1, and the first rotating rod 22 slides in the through groove 14. The end of the first rotating rod 22 is equipped with a bearing structure to facilitate rotation. After the folding ladder assembly 2 is fully pulled out, it is pressed down to open the folding ladder assembly 2. When the device is in the second usage mode, the folding ladder assembly 2 is rotated, and the folding ladder assembly 2 rotates from between the mounting frame assemblies 1 to be perpendicular to the mounting frame assemblies 1. Then, the folding ladder assembly 2 is pressed down to fully open the folding ladder assembly 2.

[0028] It should be noted that both second rotating rods 23 are rotatably mounted on the inner wall of the pedal frame 21, and the two second rotating rods 23 are staggered. Two second ladder main beams 25 and two first ladder main beams 24 are respectively fixedly connected to the outer periphery of the two second rotating rods 23. Multiple third rotating rods 26 are rotatably connected to the two second ladder main beams 25. A flip-up pedal 29 is fixedly connected to the outer periphery of each of the multiple third rotating rods 26. A fourth rotating rod 27 is fixedly connected to one side of the flip-up pedal 29. The fourth rotating rod 27 is rotatably connected between the two first ladder main beams 24. Two folding hinges 28 are rotatably connected to the outer periphery of each third rotating rod 26. The grooves of the two folding hinges 28... Both are slidably connected to the corresponding fourth rotating rod 27. The side walls of the two first ladder main beams 24 are provided with insertion holes 210. When the first ladder main beam 24 and the second ladder main beam 25 are rotated, the first ladder main beam 24 and the second ladder main beam 25 rotate, causing the corresponding second rotating rod 23 to rotate in the pedal frame 21. The first ladder main beam 24 and the second ladder main beam 25 rotate downwards to open. The first ladder main beam 24 and the second ladder main beam 25 complete the opening of the flip pedal 29 through the third rotating rod 26 and the fourth rotating rod 27. The folding hinge 28 limits the flip pedal 29 to ensure that the flip pedal 29 rotates to a state parallel to the ground, ensuring the safety and comfort of stepping.

[0029] This invention features a composite guide structure consisting of a through groove 14 for linear guidance and an arc groove 15 for rotational displacement. Combined with an automatically locking adjustment component 3, it enables quick, tool-free switching between two usage modes: sliding and folding. Switching is achieved simply by pulling the control plate 37 to release the limit. After moving the folding ladder component 2, releasing the control plate allows it to automatically reset and lock itself using the first spring 36. The operation is simple, requires no additional tools, and offers high switching efficiency.

[0030] In this invention, the mounting bracket assembly 1 is provided with locking components 4 on both sides away from the adjustment component 3. The locking components 4 are used to lock and position the folding ladder assembly 2. The locking components 4 can adapt to both sliding and folding working modes, realize precise locking in both states, and fully cover the storage conditions of the folding ladder assembly 2. This effectively prevents the ladder from loosening, shaking, making abnormal noises, or even falling off during vehicle operation. The locking components 4 can lock and position the folding ladder assembly 2 in different states, which facilitates the storage and fixation of the folding ladder assembly 2 and improves the overall stability of the device.

[0031] Furthermore, the snap-fit ​​assembly 4 includes a second sliding rod 41, a snap-fit ​​plate 42, and a second cylindrical groove 43. The second sliding rod 41 is slidably connected to one side of the mounting plate 11. When the folding ladder assembly 2 is in the first usage mode, the second sliding rod 41 passes through the corresponding mounting plate 11 and is inserted into the corresponding insertion hole 210. The second cylindrical groove 43 is opened inside one side of the mounting plate 11. An annular piece 44 is slidably disposed inside the second cylindrical groove 43. A second spring 45 is movably connected to the side wall of the annular piece 44. The end of the second spring 45 is movably connected to the side wall of the second cylindrical groove 43. The annular piece 44 is fixedly sleeved on the outer periphery of the second sliding rod 41, and the second spring 42 is movably sleeved on the second sliding rod 43. The outer periphery of the second sliding rod 41; when in the first usage mode, when the folding ladder assembly 2 needs to be pulled out, the second sliding rod 41 is pulled, and the second sliding rod 41 moves outward away from the insertion hole 210. The movement of the second sliding rod 41 drives the annular piece 44 to move. The cooperation between the annular piece 44 and the second cylindrical groove 43 compresses the second spring 45. After the second sliding rod 41 moves away from the folding ladder assembly 2, the folding ladder assembly 2 can move normally. When the folding ladder assembly 2 needs to be stored, the second sliding rod 41 is released, and the second spring 45 uses its elasticity to restore the second sliding rod 41 to its original position. The second sliding rod 41 is inserted into the insertion hole 210 to complete the locking and limiting of the folding ladder assembly 2.

[0032] It should also be noted that the snap-fit ​​plate 42 is fixedly sleeved on the outer periphery of the second sliding rod 41. The snap-fit ​​plate 42 is located on one side of the mounting plate 11. When the folding ladder assembly 2 is in the first state, the bottom of the two mounting plates 11 is equipped with limit plates 5. The limit plates 5 have slots 51 on both sides. The snap-fit ​​plate 42 snaps into the corresponding slots 51. When the second sliding rod 41 is pulled out, the second sliding rod 41 is rotated. The rotation of the second sliding rod 41 drives the snap-fit ​​plate 42 to rotate. After the snap-fit ​​plate 42 rotates to the position of the slot 51, the second sliding rod 41 is released. The cooperation of the components makes the snap-fit ​​plate 42 snap into the slot 51, so as to avoid the second sliding rod 41 from obstructing the movement of the folding ladder assembly 2.

[0033] Furthermore, when the folding ladder assembly 2 is in the second state, after the folding ladder assembly 2 is stored between the mounting plates 11, the second sliding rod 41 is located on one side of the first ladder frame main beam 24 and contacts the side wall of the first ladder frame main beam 24, locking the first ladder frame main beam 24 between the mounting plates 11. When it needs to be opened, the second sliding rod 41 is pulled away from the side wall of the first ladder frame main beam 24.

[0034] In this invention, when the folding ladder assembly 2 is in the first state, two connecting brackets 17 are installed on the top of the two mounting plates 11. When the folding ladder assembly 2 is in the second state, hanging brackets 16 are installed on the side walls of the two mounting plates 11. When the device is in the first usage mode, when the device is horizontally installed at the bottom of the semi-trailer, the connecting brackets 17 are installed on the top of the mounting plates 11, and the device is installed under the semi-trailer through the connecting brackets 17. When the device is in the second usage mode, the connecting brackets 17 and the limiting plate 5 on the device are removed, the hanging brackets 16 are installed on the side walls of the mounting plates 11, and the hanging brackets 16 are hung on the top of the semi-trailer fence, so that the device is in the second usage mode.

[0035] This invention features dual working modes to adapt to different installation conditions of semi-trailers. In the sliding retractable mode, the top connecting frame 17 is suspended below the trailer chassis, which is suitable for low chassis and narrow rear installation spaces. In the folding retractable mode, the matching connecting parts are removed and the mounting bracket 16 is installed, which is suspended from the top of the trailer railing. This mode is suitable for high chassis and railing-type body structures. It can be compatible with various semi-trailers with different chassis heights, rear spaces, and railing structures, covering the installation scenarios of most vehicle models. It has strong versatility, and one set of devices can meet the needs of multiple vehicles, reducing the development and inventory costs of supporting parts for vehicle manufacturers.

Claims

1. A rear-mounted folding step ladder for a semi-trailer, comprising a mounting frame assembly (1), characterized in that: The mounting frame assembly (1) is provided with adjustment components (3) on both sides, and a folding ladder assembly (2) is provided between the mounting frame assemblies (1). The mounting frame assembly (1) changes the usage mode of the folding ladder assembly (2) through the adjustment components (3). The mounting bracket assembly (1) includes two mounting plates (11), a first mounting rod (12) and a second mounting rod (13). The first mounting rod (12) is fixedly connected to one side between the two mounting plates (11), and the second mounting rod (13) is fixedly connected to the other side between the two mounting plates (11). A through groove (14) is provided in the middle of each of the two mounting plates (11), and an arc groove (15) is provided on one side of the through groove (14). The adjustment component (3) includes an adjustment block (31), a connecting column (32) and two first cylindrical grooves (33). The adjustment block (31) is slidably disposed in the arc groove (15), and circular grooves are provided on both sides of the adjustment block (31). The folding ladder assembly (2) includes a step frame (21), a first rotating rod (22) and two second rotating rods (23). The first rotating rod (22) is fixedly connected to one side of the step frame (21). When the first rotating rod (22) is in the through groove (14), it is in the first usage mode. When the first rotating rod (22) is in the arc groove (15), it is in the second usage mode. The mounting bracket assembly (1) is provided with snap-fit ​​components (4) on both sides away from the adjustment assembly (3), and the snap-fit ​​components (4) are used to snap-fit ​​and position the folding ladder assembly (2).

2. The rear folding step ladder for a semi-trailer according to claim 1, characterized in that: The connecting column (32) is fixedly connected to the side wall of the adjusting block (31). Two first cylindrical grooves (33) are opened on one side of the mounting plate (11). A first sliding rod (34) is slidably connected in the first cylindrical groove (33). A control plate (37) is fixedly connected to one end of the connecting column (32). The side wall of the control plate (37) is fixedly connected to the ends of the two first sliding rods (34).

3. A folding rear-end step ladder for a semi-trailer according to claim 2, characterized in that: A circular piece (35) is slidably disposed inside the first cylindrical groove (33). The side wall of the circular piece (35) is fixedly connected to the end of the first sliding rod (34). A first spring (36) is fixedly connected to the side wall of the circular piece (35). One end of the first spring (36) is fixedly connected to the side wall of the first cylindrical groove (33). The first spring (36) is movably sleeved on the outer periphery of the first sliding rod (34).

4. A folding rear-end step ladder for a semi-trailer according to claim 1, characterized in that: Two second rotating rods (23) are rotatably mounted on the inner wall of the pedal frame (21). The two second rotating rods (23) are staggered. Two second ladder main beams (25) and two first ladder main beams (24) are fixedly connected to the outer periphery of the two second rotating rods (23). Multiple third rotating rods (26) are rotatably connected to the two second ladder main beams (25). A flip pedal (29) is fixedly connected to the outer periphery of the multiple third rotating rods (26). A fourth rotating rod (27) is fixedly connected to one side of the flip pedal (29). The fourth rotating rod (27) is rotatably connected between the two first ladder main beams (24). Two folding hinges (28) are rotatably connected to the outer periphery of each third rotating rod (26). The grooves of the two folding hinges (28) are slidably connected to the corresponding fourth rotating rods (27). Insertion holes (210) are opened on the side walls of the two first ladder main beams (24).

5. A folding rear-end step ladder for a semi-trailer according to claim 4, characterized in that: The snap-fit ​​assembly (4) includes a second sliding rod (41), a snap-fit ​​plate (42), and a second cylindrical groove (43). The second sliding rod (41) is slidably connected to one side of the mounting plate (11). When the folding ladder assembly (2) is in the first usage mode, the second sliding rod (41) passes through the corresponding mounting plate (11) and is inserted into the corresponding insertion hole (210). The second cylindrical groove (43) is opened inside one side of the mounting plate (11). An annular piece (44) is slidably arranged inside the second cylindrical groove (43). A second spring (45) is movably connected to the side wall of the annular piece (44). The end of the second spring (45) is movably connected to the side wall of the second cylindrical groove (43). The annular piece (44) is fixedly sleeved on the outer periphery of the second sliding rod (41), and the second spring (45) is movably sleeved on the outer periphery of the second sliding rod (41).

6. A folding rear-end step ladder for a semi-trailer according to claim 5, characterized in that: The snap-fit ​​plate (42) is fixedly sleeved on the outer periphery of the second sliding rod (41). The snap-fit ​​plate (42) is located on one side of the mounting plate (11). When the folding ladder assembly (2) is in the first state, the bottom of the two mounting plates (11) is equipped with limit plates (5). The limit plates (5) have slots (51) on both sides. The snap-fit ​​plate (42) snaps into the corresponding slots (51).

7. A folding rear-end step ladder for a semi-trailer according to claim 1, characterized in that: When the folding ladder assembly (2) is in the first state, two connecting brackets (17) are installed on the top of the two mounting plates (11). When the folding ladder assembly (2) is in the second state, hanging brackets (16) are installed on the side walls of the two mounting plates (11).

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