Truck bottom opening and closing device and truck

Abstract

The present invention discloses a truck bottom opening and closing device and a truck. The truck bottom opening and closing device comprises a bottom plate frame structure and a bottom plate, one side of the bottom plate frame structure is provided with a front and rear telescopic device, and the telescopic section of the front and rear telescopic device is configured to drive the bottom plate to move forward and backward along the bottom plate frame structure; the bottom plate is provided with an automatic locking device, the automatic locking device comprises a lock core fixed to one side of the bottom plate and a lock tongue matched with the lock core, and the automatic locking device further comprises an elastic device for pressing the lock tongue down into the lock core. The truck bottom opening and closing device of the present invention can make the bottom of the truck open automatically.

Description

Technical Field

[0001] The invention relates to an opening and closing device for a truck bottom and the truck. Background Art

[0002] Railway transportation has always been an important way to transport bulk cargo, which mainly includes coal, ore, grain crops, etc. At present, most trucks, whether for railway transportation or road transportation, do not have the ability to load and unload goods independently. With the introduction of the concept of cost reduction, efficiency improvement, and lean saving, truck loading and unloading has gradually entered the automation stage, and the vehicle automatic loading technology depends on the vehicle's own configuration.

[0003] The unloading of bulk cargo is usually completed through the bottom door of the truck. At present, the bottom door of the truck usually directly welds the bottom door plate and other accessories to the opening reserved at the bottom of the truck through combination, which can only be operated manually and has no automatic opening and closing function and self-locking function.

[0004] Therefore, the development of a truck bottom opening and closing device with a high degree of automation will greatly help promote the automation of bulk cargo trucks. Summary of the invention

[0005] In view of this, an object of the present invention is to provide an opening and closing device for the bottom of a truck, which can be automatically opened and closed and automatically locked, which not only improves the automation level of loading and unloading goods on the truck, but also can automatically lock to prevent theft.

[0006] Another object of the present invention is to provide a truck equipped with the above-mentioned truck bottom opening and closing device.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0008] The present invention provides a truck bottom opening and closing device, comprising a bottom plate frame structure and a bottom plate, wherein the bottom plate frame structure is configured to be fixedly connected to the bottom opening of the truck;

[0009] A front-to-back telescopic device is provided on one side of the base frame structure, and the telescopic section of the front-to-back telescopic device is configured to be able to drive the base plate to move forward and backward along the base frame structure;

[0010] The bottom plate is provided with an automatic locking device, which includes a lock core fixed to one side of the bottom plate and a lock tongue matched with the lock core, and the automatic locking device also includes an elastic device for pressing the lock tongue down into the lock core;

[0011] One end of the lock tongue is hinged to one side of the base frame structure, and the other end of the lock tongue is connected to the elastic device; the elastic device is fixed to one side of the base frame structure; a downward protrusion is provided in the middle of the lock tongue, and an upward protrusion is provided in the middle of the telescopic section of the front and rear telescopic device, and a first roller is provided between the downward protrusion and the upward protrusion.

[0012] When the elastic device of the present invention presses the lock tongue into the lock core, the bottom plate covers the bottom opening of the truck, so that the opening is in a closed state; after the lock tongue pops out from the lock core, the bottom plate moves backward under the action of the front and rear telescopic devices, and the bottom plate gradually moves away and opens the bottom opening of the truck.

[0013] In the present invention, the bottom opening of the truck is sealed by the bottom plate frame structure and the bottom plate. The bottom plate frame structure is fixed at the opening, and the bottom plate moves forward and backward along the bottom plate frame structure under the drive of the front and rear telescopic devices, thereby realizing the automatic opening and closing of the truck bottom opening and closing device. When the telescopic sections of the front and rear telescopic devices are extended and retracted, the upward protrusion is driven to move forward and backward, but the downward protrusion set in the middle of the lock tongue cannot move forward and backward, but can only move up and down. Therefore, under the action of the upward protrusion and the first roller, the lock tongue moves up and down, thereby realizing the opening or locking of the lock tongue and the lock core. When it is necessary to open the truck bottom opening and closing device, the front and rear telescopic devices drive the telescopic sections to move the lock tongue upward to open the automatic locking device; when it is necessary to lock the truck bottom opening and closing device, the front and rear telescopic devices drive the telescopic sections to move the lock tongue downward to lock the automatic locking device, and the elastic device presses the lock tongue into the lock core. According to a specific embodiment of the present invention, the first roller is arranged at the lower middle part or the bottom of the downward protrusion.

[0014] According to the truck bottom opening and closing device of the present invention, preferably, the bottom plate frame structure is provided with a second roller, and the lower surface of the bottom plate is rollingly connected to the second roller. This can avoid damage caused by rigid friction of the bottom plate on the bottom plate frame, and extend the service life of the bottom opening and closing device. In addition, this can reduce the driving force during opening and closing, and provide convenience for manual operation.

[0015] According to the truck bottom opening and closing device of the present invention, preferably, a rotating shaft is provided under the bottom plate, and the end of the rotating shaft is fixed to the bottom plate frame structure through a bearing; a gear is provided on the rotating shaft, and a rack meshing with the gear is provided under the bottom plate. When the driving device drives the bottom plate to move forward and backward, the gear and the rack mesh, making the forward and backward movement of the bottom plate smoother and easier. According to a specific embodiment of the present invention, slide grooves are provided on the left and right sides of the bottom plate frame structure, and the left and right sides of the bottom plate are slidably connected in the slide grooves of the bottom plate frame structure. The slide groove limits the bottom plate to only move forward and backward along the slide groove, restricting its up and down movement and left and right movement, thereby improving the sealing and safety of the bottom opening and closing device. Preferably, the gear is provided at the end of the rotating shaft. More preferably, the number of the gears is two, which are respectively provided at the two ends of the rotating shaft.

[0016] According to the truck bottom opening and closing device of the present invention, preferably, the bottom plate frame structure is provided with a second roller, and the bottom surface of the bottom plate is rollingly connected to the second roller. This avoids damage caused by rigid friction of the bottom plate on the bottom plate frame, prolongs the service life of the bottom opening and closing device, reduces the driving force during opening and closing, and provides convenience for manual operation.

[0017] According to the truck bottom opening and closing device of the present invention, preferably, the automatic locking device also includes a lock box, which is fixed on the bottom plate frame structure; the elastic device includes a pull-up spring and a transmission rod; one end of the pull-up spring is connected to one side of the lock box, the other end of the pull-up spring is rotationally connected to one end of the transmission rod, the other end of the transmission rod is hinged to one end of the lock tongue, the middle part of the transmission rod is rotationally connected to one side of the lock box through a pin, and the end of the pin is provided with a first rotating wrench. The pull-up spring pulls up one end of the transmission rod, and because the middle part is rotationally connected to the lock box, the other end of the transmission rod will produce a downward pressure on the lock tongue, and the lock tongue is pressed into the lock core, thereby achieving locking, and the bottom plate and the bottom plate frame structure no longer move forward and backward. The end of the pin can be designed as a non-standard shape or a national standard shape as needed, and then equipped with a corresponding first rotating wrench. If the automatic locking device needs to be manually opened, it is only necessary to rotate the end of the pin through the first rotating wrench, thereby rotating the transmission rod, so that the end of the transmission rod hinged with the lock tongue is lifted upward, and the locking state can be released. After the automatic locking device is released, the truck bottom opening and closing device can be opened by manually moving the floor. Manual opening requires specific tools to improve the anti-theft performance.

[0018] According to the truck bottom opening and closing device of the present invention, preferably, a strip hole is provided at the end of the telescopic section of the front and rear telescopic device; the strip hole is arranged along the telescopic direction of the telescopic device; and a fixing column capable of passing through the strip hole is provided on one side of the bottom plate. When the telescopic section pushes the bottom plate backward, the lock core on the bottom plate will also move backward. In order to avoid the lock core and the lock tongue from getting stuck, the strip hole can make the lock tongue lift up in advance to avoid getting stuck. When the lock tongue is lifted and separated from the lock core, the telescopic section continues to move the bottom plate by pushing the fixing column.

[0019] According to the truck bottom opening and closing device of the present invention, preferably, a limit stop is provided on one side of the lock box to limit the downward pressure of the lock tongue. This structure can limit the downward pressure of the lock tongue. In the present invention, preferably, the limit stop is a cylindrical or strip-shaped protrusion.

[0020] According to the truck bottom opening and closing device of the present invention, preferably, it also includes an auxiliary frame arranged at the bottom opening of the truck and corresponding to the floor frame structure; the edge of the floor frame structure is an L-shaped steel structure, and the L-shaped steel structure has a horizontal edge and a vertical edge; a plurality of first threaded holes are arranged on the horizontal edge, and a plurality of second threaded holes corresponding to the first threaded holes are arranged on the auxiliary frame; the vertical edge is for the rotating shaft to pass through; a second rotating wrench is arranged at the end of the rotating shaft. According to one embodiment of the present invention, the four sides of the floor frame structure and the auxiliary frame are all composed of L-shaped steel structures, and corresponding threaded holes are arranged on the horizontal edges of the L-shaped steel structures of the floor frame structure and the auxiliary frame, and the floor frame structure is mounted on the auxiliary frame by bolts.

[0021] In the present invention, the auxiliary frame is connected to the bottom opening of the truck by threads or fixed welding, and the bottom plate frame structure is connected to the auxiliary frame by threads. Compared with traditional welding, the present invention avoids deformation caused by welding, thereby avoiding jamming and leakage caused by deformation. In manual operation, the second rotating wrench is used to rotate the rotating shaft to push the bottom plate to move forward and backward. The end of the rotating shaft can be set to a non-standard shape as needed, and the second wrench is equipped with a corresponding shape. Manual opening requires a specific tool to improve the anti-theft performance.

[0022] According to the truck bottom opening and closing device of the present invention, preferably, it also includes a fulcrum frame; the lock core is fixed to one side of the bottom plate through the fulcrum frame; the lock core is fixed to the top of the fulcrum frame; the fixing column is fixed to one side of the fulcrum frame. The setting of the fulcrum frame provides an operating space for the automatic locking device.

[0023] According to the truck bottom opening and closing device of the present invention, preferably, it also includes a crossbeam; the number of the bottom plates is two, they are horizontally spaced and connected by the crossbeam; the two ends of the crossbeam are fixed to the left and right sides of the bottom plate frame structure; the fulcrum frame is arranged at a position where the crossbeam is between the two bottom plates; the front and rear telescopic devices and the lock box are both arranged at a position where the bottom plate frame structure is between the two bottom plates.

[0024] The above structure is mainly applicable to the existing design of two adjacent funnel-shaped bottom openings at the bottom of a truck. The bottom plate frame structure is installed at the two bottom openings of the funnel, one bottom plate closes one opening, and the space between the two openings is used to install the telescopic device, the fulcrum frame and the lock box. The fulcrum frame is installed on the crossbeam connecting the two bottom plates, and the front and rear telescopic devices and the lock box are installed on the bottom plate frame structure or on a fixed external structure such as the bottom of the funnel.

[0025] The present invention also provides a truck, which is equipped with the truck bottom opening and closing device as described above. The bottom opening and closing device can realize automatic opening and closing, and improves its sealing performance and safety performance.

[0026] The truck bottom opening and closing device of the present invention can realize automatic opening and closing of the bottom door, and its sealing performance and safety performance are greatly improved, and is suitable for automatic loading and unloading trucks with high automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic structural diagram of a truck bottom opening and closing device matched with an auxiliary frame and a wear pad.

[0028] Figure 2 The present invention is a schematic structural diagram of a truck bottom opening and closing device.

[0029] Figure 3 The present invention is a schematic structural diagram of an automatic locking device and a front and rear telescopic device that cooperate with each other.

[0030] Figure 4 The present invention is a schematic structural diagram of a base frame structure and a base plate that cooperate with each other.

[0031] Figure 5 The present invention is a schematic diagram of the disassembled structure of a truck bottom opening and closing device.

[0032] Figure 6 It is a structural schematic diagram of an automatic locking device of the present invention.

[0033] Among them, 1-bottom plate frame structure, 2-bottom plate, 3-rotating shaft, 4-lock box, 7-front and rear telescopic device, 8-auxiliary frame, 9-fulcrum frame, 10-wear pad, 11-bearing, 13-upward protrusion, 14-first roller, 15-downward protrusion, 16-lock cylinder, 17-cross beam, 18-rack, 19-gear, 20-rotating shaft bracket, 21-support member, 22-support beam, 23-second roller, 24-lock tongue, 25-pull-up spring, 26-pin shaft, 27-limit gear, 28-bar hole, 29-fixing column, 30-transmission rod. DETAILED DESCRIPTION

[0034] The following is a more detailed description of the present invention with reference to specific embodiments, and further elaboration of the present invention, but these embodiments are by no means intended to limit the present invention.

[0035] Example 1

[0036] Figure 1 The present invention is a schematic structural diagram of a truck bottom opening and closing device matched with an auxiliary frame and a wear pad. Figure 2 It is a structural schematic diagram of a truck bottom opening and closing device of the present invention. The truck bottom opening and closing device of this embodiment includes a rectangular bottom plate frame structure 1, a rectangular bottom plate 2 and an auxiliary frame 8. The bottom plate frame structure 1 is fixedly connected to the bottom opening of the truck through the auxiliary frame 8. The bottom plate frame structure 1 is provided with slide grooves (not marked in the figure) on the left and right sides, and the bottom plate 2 is installed in the slide grooves on the left and right sides, and is connected to the bottom plate frame structure 1 by front and rear sliding. The four sides of the bottom plate frame structure 1 and the auxiliary frame 8 are composed of L-shaped steel structures, and the horizontal edges of the L-shaped steel structures of the bottom plate frame structure 1 and the auxiliary frame 8 are provided with corresponding threaded holes, and the bottom plate frame structure 1 is installed on the auxiliary frame 8 by bolts.

[0037] Figure 3 The figure is a schematic diagram of the structure of the automatic locking device and the front and rear telescopic device of the present invention. A rotating shaft 3 is provided below the bottom plate 2. Both ends of the rotating shaft 3 are fixed by bearings 11 and pass through the vertical edge of the L-shaped steel structure of the bottom plate frame structure 1. Figure 5 The figure is a schematic diagram of the disassembled structure of a truck bottom opening and closing device of the present invention. Figure 5 As shown, a gear 19 is provided on the rotating shaft 3. A rack 18 meshing with the gear 19 is provided below the bottom plate 2. Figure 4 FIG. 1 is a schematic diagram of a structure of a base frame structure and a base plate in cooperation with each other according to the present invention. Figure 4 As shown, a fulcrum frame 9 is fixed to one side of the base plate 2 , and a lock core 16 is provided on the top of the fulcrum frame 9 .

[0038] like Figure 1 As shown, the front and rear telescopic devices 7 and the lock box 4 are installed on the bottom plate frame structure 1. Figure 6 FIG. 1 is a schematic diagram of the structure of the automatic locking device of the present invention. Figure 6 As shown, the lock box 4 is provided with a pull-up spring 25, a transmission rod 30 and a lock tongue 24; one end of the pull-up spring 25 is connected to one side of the lock box 4, the other end of the pull-up spring 25 is rotatably connected to one end of the transmission rod 30, the other end of the transmission rod 30 is hinged to one end of the lock tongue 24, and the middle part of the transmission rod 30 is rotatably connected to one side of the lock box 4 through a pin 26. The lock tongue 24 is arranged above the lock core 16, one end of the lock tongue 24 is hinged to the transmission rod 30, and the other end of the lock tongue 24 is hinged to one side of the lock box 4.

[0039] A downward protrusion 15 is provided in the middle of the locking tongue 24. An upward protrusion 13 is provided in the middle of the telescopic section of the front and rear telescopic device 7. A first roller 14 is provided between the downward protrusion 15 and the upward protrusion 13. A strip hole 28 is provided at the end of the telescopic section of the front and rear telescopic device 7, and the strip hole 28 is arranged along the telescopic direction of the telescopic section of the front and rear telescopic device 7. A fixing column 29 is provided on one side of the fulcrum frame 9, and the fixing column 29 passes through the strip hole 28.

[0040] Example 2

[0041] Figure 1 The present invention is a schematic structural diagram of a truck bottom opening and closing device matched with an auxiliary frame and a wear pad. Figure 2 The schematic diagram of the structure of a truck bottom opening and closing device of the present invention. The truck bottom opening and closing device of this embodiment includes a floor frame structure 1, a rectangular floor 2, and an auxiliary frame 8. The floor frame structure 1 is fixedly connected to the bottom opening of the rectangular truck through the auxiliary frame 8. The floor frame structure 1 is provided with slide grooves (not marked in the figure) on the left and right sides. The floor 2 is installed in the slide grooves on the left and right sides and is connected to the floor frame structure 1 by front and rear sliding. Among them, the four sides of the floor frame structure 1 and the auxiliary frame 8 are composed of L-shaped steel structures. The horizontal edges of the L-shaped steel structures of the floor frame structure 1 and the auxiliary frame 8 are provided with corresponding threaded holes, and the floor frame structure 1 is installed on the auxiliary frame 8 by bolts.

[0042] Figure 3 The figure is a schematic diagram of the structure of the automatic locking device and the front and rear telescopic device of the present invention. A rotating shaft 3 is provided under the bottom plate 2. The two ends of the rotating shaft 3 are fixed by bearings 11 and pass through the vertical edge of the L-shaped steel structure of the bottom plate frame structure 1. Figure 5 This is a schematic diagram of the disassembled structure of a truck bottom opening and closing device of the present invention. Figure 5 As shown, a gear 19 is provided on the rotating shaft 3. A rack 18 meshing with the gear 19 is provided below the bottom plate 2. Figure 4 FIG. 1 is a schematic diagram of a structure of a base frame structure and a base plate in cooperation with each other according to the present invention. Figure 4As shown, a fulcrum frame 9 is fixed to one side of the base plate 2 , and a lock core 16 is provided on the top of the fulcrum frame 9 .

[0043] like Figure 1 As shown, a front and rear telescopic device 7 and a lock box 4 are fixedly installed on one side of the base frame structure 1. Figure 6 FIG. 1 is a schematic diagram of the structure of the automatic locking device of the present invention. Figure 6 As shown, the lock box 4 is provided with a pull-up spring 25, a transmission rod 30 and a lock tongue 24, one end of the pull-up spring 25 is connected to one side of the lock box 4, the other end of the pull-up spring 25 is rotatably connected to one end of the transmission rod 30, the other end of the transmission rod 30 is hinged to one end of the lock tongue 24, and the middle part of the transmission rod 30 is rotatably connected to one side of the lock box 4 through a pin 26. The lock tongue is arranged above the lock core 16, one end of the lock tongue 24 is hinged to the transmission rod 30, and the other end of the lock tongue 24 is hinged to one side of the lock box 4.

[0044] A downward protrusion 15 is provided in the middle of the locking tongue 24. An upward protrusion 13 is provided in the middle of the telescopic section of the front and rear telescopic device 7, and a first roller 14 is provided between the downward protrusion 15 and the upward protrusion 13. A strip hole 28 is provided at the end of the telescopic section of the front and rear telescopic device 7, and the strip hole 28 is arranged along the telescopic direction of the telescopic section. A fixing column 29 is provided on one side of the fulcrum frame 9, and the fixing column 29 passes through the strip hole 28.

[0045] The end of the pin shaft 26 is provided with a first rotating wrench (not shown), and the end of the rotating shaft 3 is provided with a second rotating wrench (not shown).

[0046] Example 3

[0047] like Figure 5 As shown, the bottom plate frame structure 1 of the truck bottom opening and closing device of this embodiment is provided with left and right support beams 22, one side of the support beam 22 is provided with front and rear support members 21, and the support member 21 is provided with a second roller 23, the second roller 23 rotates forward and backward, and the lower surface of the bottom plate 2 is rollingly connected to the second roller 23. The rest of the structure is the same as that of the second embodiment.

[0048] Example 4

[0049] In the truck bottom opening and closing device of this embodiment, a wear pad 10 is provided between the bottom frame structure 1 and the auxiliary frame 8. The rest of the structure is the same as that of the third embodiment.

[0050] Example 5

[0051] This embodiment provides a truck, which has two funnel-shaped truck bottom openings arranged at intervals at the bottom, an auxiliary frame 8 is fixed to each truck bottom opening, a bottom plate frame structure 1 is threadedly connected to the two auxiliary frames 8, and each bottom opening is also equipped with a bottom plate 2, the bottom plate 2 is movably connected to the bottom plate frame structure 1 in front and back directions, and is connected by a crossbeam 17, the two ends of the crossbeam 17 are fixed to the left and right sides of the bottom plate frame structure 1, the fulcrum frame 9 is arranged at the position between the crossbeam 17 and the two bottom plates 2, and the front and rear telescopic devices 7 and the lock box 4 are both arranged at the position between the two bottom plates 2 of the bottom plate frame structure 1. The two bottom plates 2 share a rotating shaft 3, and the rotating shaft 3 is provided with two gears 19. Through such an arrangement, the two openings of the truck can be opened and closed at the same time, and the front and rear telescopic devices 7 and the lock box 4 are both arranged on the outside of the truck for easy operation and maintenance. The remaining structures are the same as those of Example 4.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the contents of the present invention.

Claims

1. A truck bottom opening and closing device, characterized in that: It includes a floor frame structure and a floor, wherein the floor frame structure is configured to be fixedly connected to the bottom opening of the truck; A front-to-back telescopic device is provided on one side of the base frame structure, and the telescopic section of the front-to-back telescopic device is configured to be able to drive the base plate to move forward and backward along the base frame structure; slide grooves are provided on the left and right sides of the base frame structure, and the left and right sides of the base plate are slidably connected in the slide grooves of the base frame structure; The bottom plate is provided with an automatic locking device, which includes a lock core fixed to one side of the bottom plate, a lock tongue matched with the lock core, an elastic device for pressing the lock tongue down into the lock core, and a lock box; the lock box is fixed to the bottom plate frame structure; One end of the lock tongue is hinged to one side of the base frame structure, and the other end of the lock tongue is connected to the elastic device; the elastic device is fixed to one side of the base frame structure; the elastic device comprises a pull-up spring and a transmission rod; one end of the pull-up spring is connected to one side of the lock box, and the other end of the pull-up spring is rotatably connected to one end of the transmission rod, and the other end of the transmission rod is hinged to one end of the lock tongue, and the middle part of the transmission rod is rotatably connected to one side of the lock box through a pin shaft, and the end of the pin shaft is provided with a first rotating wrench; a downward protrusion is provided at the middle part of the lock tongue, and an upward protrusion is provided at the middle part of the telescopic section of the front and rear telescopic device, and a first roller is provided between the downward protrusion and the upward protrusion; a strip hole is provided at the end of the telescopic section of the front and rear telescopic device; the strip holes are arranged along the telescopic direction of the telescopic device; a fixing column that can pass through the strip hole is provided on one side of the base plate.

2. The truck bottom opening and closing device according to claim 1, characterized in that: The bottom plate frame structure is provided with a second roller, and the lower surface of the bottom plate is rollingly connected to the second roller.

3. The truck bottom opening and closing device according to claim 1, characterized in that: A rotating shaft is provided below the bottom plate, and the end of the rotating shaft is fixed to the bottom plate frame structure through a bearing; a gear is provided on the rotating shaft, and a rack meshing with the gear is provided below the bottom plate.

4. The truck bottom opening and closing device according to claim 3, characterized in that: A limit stop that can limit the downward pressure of the lock tongue is provided on one side of the lock box.

5. The truck bottom opening and closing device according to claim 3, characterized in that: It also includes an auxiliary frame disposed at the bottom opening of the truck and corresponding to the floor frame structure; The edge of the base frame structure is an L-shaped steel structure, and the L-shaped steel structure has a horizontal edge and a vertical edge; a plurality of first threaded holes are provided on the horizontal edge, and a plurality of second threaded holes corresponding to the first threaded holes are provided on the auxiliary frame; the vertical edge is for the rotating shaft to pass through; a second rotating wrench is provided at the end of the rotating shaft.

6. The truck bottom opening and closing device according to claim 1 or 4, characterized in that: It also includes a fulcrum frame; the lock core is fixed to one side of the base plate through the fulcrum frame; the lock core is fixed to the top of the fulcrum frame; and the fixing column is fixed to one side of the fulcrum frame.

7. The truck bottom opening and closing device according to claim 6, characterized in that: It also includes a crossbeam; the number of the bottom plates is two, which are arranged horizontally at intervals and connected by the crossbeam; the two ends of the crossbeam are fixed to the left and right sides of the bottom plate frame structure; The fulcrum frame is arranged at a position where the cross beam is between the two bottom plates; the front and rear telescopic devices and the lock box are both arranged at a position where the bottom plate frame structure is between the two bottom plates.

8. A truck, characterized in that: The truck bottom opening and closing device is installed therein as claimed in any one of claims 1 to 7.

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