Limiting structure for stepping ladder of container of self-discharging trailer
By installing brackets and hinged door limiting structures at the bottom of the cargo box chassis, the problem of the step ladder slipping off due to shaking and bumps during driving is solved, thus achieving stable placement and safe use of the step ladder.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANDONG ZHONGLI AUTOMOBILE TECHNOLOGY CO LTD
- Filing Date
- 2025-07-29
- Publication Date
- 2026-05-19
AI Technical Summary
In the existing technology, the steps of the cargo box of a self-unloading trailer may slip off due to shaking and bumping during driving, posing a safety hazard.
A bracket is installed at the bottom of the cargo box chassis, and a step ladder is placed inside the bracket. The movement of the step ladder is restricted by the cooperation of the hinge door and the limit hook to prevent it from slipping off during the journey.
This effectively prevents the step ladder from slipping due to shaking and bumps during vehicle operation, ensuring the safety of the operator, preventing the step ladder from injuring pedestrians, and improving the safety and stability of use.
Smart Images
Figure CN224256556U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of auxiliary equipment for self-unloading trailers, specifically relating to a limiting structure for the step ladder of a self-unloading trailer cargo box. Background Technology
[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.
[0003] The cargo box of a dump truck is usually connected to the tow hook of the vehicle in front via a tow bar and a handlebar for transporting goods. The operator needs to enter the cargo box to perform operations such as sorting the goods and covering them with tarpaulins.
[0004] Because of the height of the cargo box, without the aid of a ladder, the operator would have to climb up by stepping on the tires and holding onto the side rails, which is very dangerous. Therefore, the existing technology usually involves hanging a ladder on the side rails of the cargo box. When in use, the operator removes the ladder from the side rails of the cargo box, climbs onto the cargo box to perform operations such as sorting goods and covering with tarpaulins, and then hangs the ladder back on the side rails of the cargo box.
[0005] While existing ladders hanging on the side rails of cargo boxes can be removed for easy access, they can slip off during vehicle operation due to the shaking and swaying of the cargo box, posing a safety hazard. Utility Model Content
[0006] In view of this, the purpose of this utility model is to provide a limiting structure for the step ladder of a self-unloading trailer cargo box, which stores the step ladder at the bottom of the cargo box chassis. This solves the problem in the prior art where the step ladder hanging on the side rail of the cargo box will slip off during driving due to the shaking and up-and-down bumps of the cargo box, causing safety hazards.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A limit structure for the step ladder of a self-unloading trailer cargo box is provided, including a bracket fixed to the rear end of the bottom of the cargo box chassis, a step ladder placed inside the bracket, and a hinge door provided at the corresponding position of the rear bumper of the cargo box chassis on the bracket.
[0009] The bracket includes opposing slotted plates, and a plug is provided at the end of the bracket away from the rear bumper. Multiple sets of fixing ear assemblies are evenly fixed to the side of the slotted plates.
[0010] The fixed ear assembly includes a long ear plate and a short ear plate. Both the long ear plate and the short ear plate include a vertical plate and a horizontal plate. The vertical plate of the long ear plate is longer than that of the short ear plate. The two vertical plates are stacked and fixed to the side of the trough plate. The horizontal plate of the short ear plate faces the trough plate, while the horizontal plate of the long ear plate faces away from the trough plate and is fixed to the chassis of the cargo box.
[0011] Limit blocks are installed on opposite sides of the end of the staircase, and corresponding limit hooks are installed on the inside of the hinge door; the limit blocks face upwards, and when the hinge door is closed, the opening of the limit hook faces downwards and engages with the limit block.
[0012] Preferably, the top of the limiting block is set to an arc shape, and the opening of the limiting hook is also set to an arc shape.
[0013] Preferably, the step ladder includes a crossbar, and multiple treads are evenly arranged between two crossbars, with a hook fixedly installed at one end of the step ladder.
[0014] Preferably, the crossbar is made of channel steel, and the grooved surface of the channel steel faces outward.
[0015] Preferably, the treads are also made of angle iron, and when the staircase is placed horizontally, both sides of the treads are inclined relative to the horizontal plane.
[0016] Preferably, the side of the foot bar facing the hook has anti-slip texture.
[0017] Preferably, locking ear plates are provided on opposite sides of both hinge doors, and locking ear plates are also provided at corresponding positions on the rear bumper. Through holes are provided on the locking ear plates, and after the locking ear plates are aligned, bolts or pins are passed through the through holes for fixation.
[0018] Preferably, the bottom of the cargo box chassis is provided with multiple connecting bars, which are fixedly connected to the cross plate of the long ear plate.
[0019] Preferably, a base plate is fixed at the bottom of the rear bumper, the base plate is fixed to the bottom of the bracket, and the hinge door is hinged to the base plate.
[0020] Preferably, the hinge door has a fixed handle on the outside.
[0021] Compared with the prior art, the advantages and positive effects of this utility model are:
[0022] This invention features a bracket fixed to the bottom of the cargo box chassis and a hinged door on the rear bumper, housing the staircase within the bracket. This solves the technical problem in existing technologies where the staircase might fall from the side rail of the cargo box and injure pedestrians. Furthermore, this invention includes a limiting block on the opposite side of the staircase's tail end and a limiting hook inside the hinged door, allowing the limiting block and hook to engage. In the axial direction, this works with a plug to prevent the staircase from shifting; in the height direction, it prevents the tail end of the staircase from bouncing up and down; and in the lateral direction of the cargo box, the limiting hook is located on the opposite side of the staircase's tail end, preventing the tail end of the staircase from swaying laterally. This ensures the stable placement of the staircase during vehicle operation. Attached Figure Description
[0023] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.
[0024] Figure 1 This is a schematic diagram of the installation position of the limiting structure according to an embodiment of the present utility model;
[0025] Figure 2 This is a schematic diagram of the step ladder within the bracket according to an embodiment of the present invention;
[0026] Figure 3 This is a schematic diagram of the bracket structure according to an embodiment of the present utility model;
[0027] Figure 4 This is a schematic diagram of the limiting block and limiting hook in the engaged state according to an embodiment of this utility model;
[0028] Figure 5 This is a schematic diagram of the limiting block and limiting hook in the open state according to an embodiment of the present utility model;
[0029] Figure 6 This is a schematic diagram of the step ladder extending from the bracket according to an embodiment of the present utility model;
[0030] Figures 7 to 10 This is a schematic diagram of the process by which the limiting block and limiting hook gradually open from their self-locking state in an embodiment of this utility model.
[0031] In the picture:
[0032] 1. Cargo box chassis; 11. Rear bumper; 12. Hinged door; 13. Handle; 14. Floor plate; 15. Limit hook; 16. Locking ear plate; 17. Connecting bar; 2. Bracket; 21. Channel plate; 22. Fixing ear assembly; 23. Long ear plate; 24. Short ear plate; 25. End cap; 3. Step ladder; 31. Crossbar; 32. Step bar; 33. Hook; 34. Limit block. Detailed Implementation
[0033] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0034] The present invention will now be described in detail with reference to the accompanying drawings.
[0035] This embodiment discloses a limiting structure for the step ladder of a self-unloading trailer cargo box, such as... Figure 1 , Figure 2As shown, the system includes two brackets 2 symmetrically fixed to the rear end of the bottom of the cargo box chassis 1 along its axis. A step ladder 3 slides within the brackets 2. A hinged door 12 is installed on the rear bumper 11 of the cargo box chassis 1 at the corresponding position on the brackets 2. When the step ladder 3 is needed, the hinged door 12 is opened to pull it out. After use, the step ladder 3 is pushed back into the brackets 2, and then the hinged door 12 is closed. Compared to the traditional method of hanging the step ladder 3 on the side rail of the cargo box, hiding the step ladder 3 at the bottom of the cargo box is safer. If the step ladder 3 falls from the side rail, it may injure a passerby. The brackets 2 supporting the step ladder 3 at the bottom of the cargo box prevent this from happening.
[0036] Specifically, such as Figures 3 to 5 As shown, the bracket 2 includes two opposing slotted plates 21. The slotted plates 21 are made of angle iron, and multiple sets of fixing ear assemblies 22 are evenly fixed to the sides of the slotted plates 21. According to the width of the step ladder 3, the two slotted plates 21 are fixed to the bottom of the cargo box chassis 1 through the fixing ear assemblies 22. The two slotted plates 21 are opposite to each other, so that the bottom edge of the slotted plates 21 of the bracket 2 can support the step ladder 3.
[0037] It should be noted that the length of the groove plate 21 is a certain distance longer than the length of the step ladder 3. This is to prevent the hinge door 12 from failing to close properly when the length of the groove plate 21 is equal to the length of the step ladder 3. The distance between the two groove plates 21 in the same bracket 2 is greater than the width of the step ladder 3. This is to prevent the groove plate 21 and the step ladder 3 from having a squeezing friction when the distance between the two groove plates 21 is equal to the width of the step ladder 3, which would prevent the step ladder 3 from being pulled out or pushed into the bracket 2 properly.
[0038] In this embodiment, the length of the groove plate 21 is one to two centimeters longer than the length of the step ladder 3, and the distance between the two groove plates 21 in the same bracket 2 is one centimeter larger than the inner dimension and two centimeters larger than the outer dimension of the step ladder 3.
[0039] like Figure 1 , Figure 2 As shown, the fixed ear assembly 22 includes a long ear plate 23 and a short ear plate 24 fixedly connected. Both the long ear plate 23 and the short ear plate 24 are inverted L-shaped plates, including a vertical plate and a horizontal plate. The length of the vertical plate of the long ear plate 23 is greater than the length of the short ear plate 24. The vertical plates of the long ear plate 23 and the short ear plate 24 are stacked and fixedly connected together, so that the vertical plate of the short ear plate 24 is fixedly connected to the side of the groove plate 21. The horizontal plate of the short ear plate 24 is set facing the groove plate 21, while the horizontal plate of the long ear plate 23 is set away from the groove plate 21.
[0040] In this embodiment, the horizontal plate of the long ear plate 23 is positioned with its back to the groove plate 21, so that it is fixedly connected to the bottom of the cargo box chassis 1. The horizontal plate of the short ear plate 24 is positioned facing the groove plate 21 so that the horizontal plate of the short ear plate 24 and the groove plate 21 can cooperate to form a groove, into which the step ladder 3 is pushed. When bumps occur during vehicle travel, the step ladder 3 may jump upwards, and the horizontal plate of the short ear plate 24 can block the step ladder 3 from above, thus limiting its movement.
[0041] In this embodiment, the distance between the bottom edge of the groove plate 21 and the horizontal plate of the short ear plate 24 is greater than the height of the step ladder 3. This is to avoid the groove plate 21 and the step ladder 3 having a squeezing friction force, which would prevent the step ladder 3 from being properly pulled out or pushed into the bracket 2. In this embodiment, the distance between the bottom edge of the groove plate 21 and the horizontal plate of the short ear plate 24 is half a centimeter greater than the height of the step ladder 3.
[0042] like Figure 3 As shown, a plug 25 is provided at the end of the bracket 2 away from the rear bumper 11. The function of the plug 25 is to prevent the step ladder 3 from sliding out of the bracket 2 from the front end of the bracket 2.
[0043] like Figures 4 to 5 As shown, limit blocks 34 are provided on opposite sides of the tail end of the step ladder 3, and corresponding limit hooks 15 are provided on the inner side of the hinge door 12. That is, the distance between the limit hooks 15 is equal to the distance between the limit blocks 34. The limit blocks 34 face upwards, and when the hinge door 12 is closed, the openings of the limit hooks 15 face downwards. Push the step ladder 3 into the bracket 2 so that the front end of the step ladder 3 rests on the end cap 25, and then close the hinge door 12. The limit hooks 15 can be engaged with the limit blocks 34. At this time, the opposite inner sides of the step ladder 3 are all in contact with the limit hooks 15, thereby preventing the tail end of the step ladder 3 from jumping up and down relative to the height of the cargo box, and also preventing the tail end of the step ladder 3 from moving left and right relative to the cargo box, and preventing the step ladder 3 from swaying axially relative to the cargo box.
[0044] It should be noted that in order to prevent the step ladder 3 from being unable to be pushed into the bracket 2 due to the squeezing friction, the overall size of the bracket 2 is larger than that of the step ladder 3. However, this also causes the step ladder 3 to shake and move inside the bracket 2 due to bumps and swaying when the dump trailer cargo box is moving with the vehicle.
[0045] Therefore, in this embodiment, a limiting block 34 is provided on the opposite side of the tail end of the step ladder 3, and a limiting hook 15 is provided on the inner side of the hinge door 12, so that the limiting block 34 and the limiting hook 15 are engaged. In the axial direction, it cooperates with the plug 25 to prevent the step ladder 3 from moving. In the height direction, it prevents the tail end of the step ladder 3 from jumping up and down. In the lateral direction of the cargo box, the limiting hook 15 is located on the opposite side of the tail end of the step ladder 3, which can prevent the tail end of the step ladder 3 from swaying left and right in the lateral direction. This ensures the stable placement of the step ladder 3 during vehicle operation.
[0046] like Figures 7 to 10 As shown, in this embodiment, the top of the limiting block 34 is arc-shaped, and the opening of the limiting hook 15 is also arc-shaped. The limiting block 34 and the limiting hook 15 are fastened together, and the distance between the limiting block 34 and the limiting hook 15 after fastening is 2.5mm-5.5mm; ensuring that the limiting block 34 and the limiting hook 15 can be properly fastened or separated when the hinge door 12 is opened or closed. In this embodiment, both the limiting hook 15 and the limiting block are made of steel to ensure that they can play a limiting role under impact.
[0047] It should be noted that, compared to the traditional method of hanging the step ladder 3 on the side rail of the cargo box, this embodiment hides the step ladder 3 at the bottom of the cargo box, which is not only safer; in this embodiment, a limiting block 34 is set on the opposite side of the tail end of the step ladder 3, which cooperates with the limiting hook 15 on the hinge door 12 to restrict the movement of the tail end of the step ladder 3, so that the step ladder 3 is placed stably in the bracket 2, preventing the step ladder 3 from loosening, moving around or even being thrown out of the bracket 2 due to bumps during vehicle travel.
[0048] like Figure 4 , Figure 5 As shown, the step ladder 3 includes a crossbar 31, with multiple steps 32 evenly arranged between two crossbars 31. A hook 33 is fixedly installed at one end of the step ladder 3, meaning that the two crossbars 31 are fixedly connected to the hook 33 on the same section. The operator can pull the step ladder 3 out of the bracket 2, place it with one end of the hook 33 facing upwards or hang it on the cargo box, and then step onto the cargo box.
[0049] like Figure 6 As shown, the crossbar 31 of the staircase 3 is made of channel steel, with the grooved surface of the channel steel facing outwards, i.e., the wing plate of the channel steel faces outwards; the two ends of the treads 32 are welded and fixed to the web plate of the channel steel. Using channel steel ensures strength while reducing weight and saving costs compared to using square tubing. In this embodiment, the hooks 33 are made of steel and are fixedly connected to the crossbar 31 by welding.
[0050] like Figures 4 to 6 As shown, the pedal 32 is also made of angle iron, and the pedal 32 is fixed to the crossbar 31 by welding; as Figure 4 As shown, when the step ladder 3 is placed horizontally, both sides of the treads 32 are inclined relative to the horizontal plane. This is because, except for straight ladders, the step ladder 3 is usually placed at an angle.
[0051] In this embodiment, the optimal tilt angle range of the step ladder 3 can be determined based on the height of the cargo box and the length of the step ladder 3, and the angle between the side of the step bar 32 facing the hook 33 and the horizontal plane of the crossbar 31 can be designed (in this embodiment, the angle can be 45°). When the operator tilts the step ladder 3, the side of the step bar 32 facing the hook 33 can be as close to horizontal as possible, making it easier for the operator to step on the ladder.
[0052] In this embodiment, the side of the step bar 32 facing the hook 33 is provided with anti-slip texture, which can provide a good anti-slip effect when the operator steps on the ladder, ensuring operational safety.
[0053] like Figure 2 As shown, locking ear plates 16 are provided on opposite sides of the two hinge doors 12, and locking ear plates 16 are also provided at corresponding positions on the rear bumper 11. The locking ear plates 16 are provided with through holes. When the locking ear plates 16 of the hinge doors 12 are aligned with the locking ear plates 16 of the rear bumper 11, bolts or pins are passed through the through holes to fix them, thereby closing the hinge doors 12; this prevents the hinge doors 12 from opening due to bumps during driving, which could cause the step ladder 3 to slip.
[0054] like Figure 1 , Figure 2 As shown, the bottom of the cargo box chassis 1 is provided with multiple connecting bars 17. The connecting bars 17 are used to weld and fix the cross plate of the long ear plate 23 or to fix it by bolts, thereby fixing the bracket 2 to the bottom of the cargo box chassis 1.
[0055] like Figure 1 , Figure 2 , Figure 6 As shown, a base plate 14 is welded and fixed to the bottom of the rear bumper 11. The base plate 14 is welded and fixed to the bottom of the bracket 2. The hinge door 12 is hinged to the base plate 14, so that the hinge door 12 can rotate relative to the rear bumper 11. A handle 13 is fixed to the outside of the hinge door 12 to facilitate the operator to open or close the hinge door 12.
[0056] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.
Claims
1. A limiting structure for the step ladder of a self-unloading trailer cargo box, characterized in that, Includes a bracket fixed to the rear end of the bottom of the cargo box chassis, with a step ladder placed inside the bracket, and a hinged door installed on the rear bumper of the cargo box chassis at the corresponding position of the bracket; The bracket includes opposing groove plates, and a plug is provided at the end of the bracket away from the rear bumper. Multiple sets of fixing ear assemblies are evenly fixed to the side of the groove plates. The fixed ear assembly includes a long ear plate and a short ear plate, both of which include a vertical plate and a horizontal plate. The vertical plate of the long ear plate is longer than that of the short ear plate. The two vertical plates are stacked and fixed to the side of the trough plate. The horizontal plate of the short ear plate faces the trough plate, while the horizontal plate of the long ear plate faces away from the trough plate and is fixed to the chassis of the cargo box. Each side of the staircase's tail end is equipped with an upward-facing limit block, and the inner side of the hinge door is equipped with a corresponding limit hook; when the hinge door is closed, the opening of the limit hook faces downward and engages with the limit block.
2. The self-unloading trailer cargo box step ladder limiting structure as described in claim 1, characterized in that, The top of the limiting block is arc-shaped, and the opening of the limiting hook is also arc-shaped.
3. The self-unloading trailer cargo box step ladder limiting structure as described in claim 1, characterized in that, The staircase includes a crossbar, and multiple treads are evenly arranged between two crossbars. A hook is fixedly installed at one end of the staircase.
4. The self-unloading trailer cargo box step ladder limiting structure as described in claim 3, characterized in that, The crossbar is made of channel steel, and the grooved surface of the channel steel faces outward.
5. The self-unloading trailer cargo box step ladder limiting structure as described in claim 3, characterized in that, The step bar is also made of angle iron. When the step ladder is placed horizontally, both sides of the step bar are inclined relative to the horizontal plane.
6. The self-unloading trailer cargo box step limiting structure as described in claim 5, characterized in that, The side of the foot bar facing the hook has anti-slip texture.
7. The self-unloading trailer cargo box step ladder limiting structure as described in claim 1, characterized in that, Locking ear plates are provided on opposite sides of both hinge doors, and locking ear plates are also provided at corresponding positions on the rear bumper. The locking ear plates are provided with through holes. After the locking ear plates are aligned, bolts or pins are passed through the through holes for fixation.
8. The self-unloading trailer cargo box step ladder limiting structure as described in claim 1, characterized in that, The bottom of the cargo box chassis is provided with multiple connecting bars, which are fixedly connected to the cross plate of the long ear plate.
9. The self-unloading trailer cargo box step ladder limiting structure as described in claim 1, characterized in that, A base plate is fixed at the bottom of the rear bumper, and the base plate is fixed to the bottom of the bracket. The hinge door is hinged to the base plate.
10. The self-unloading trailer cargo box step limiting structure as described in claim 1, characterized in that, The hinge door has a fixed handle on the outside.