Secondary locking mechanism of bottom door of railway hopper car

Abstract

The invention discloses a secondary locking mechanism for a bottom door of a railway hopper car, which relates to the technical field of railway hopper cars and comprises a handle component, a first pull rod component, a lever fulcrum component, a second pull rod component, a rotating shaft component, a tension spring seat, a tension spring, a third pull rod component and a locking lever component. The handle assemblies are fixed to the two sides of a bottom frame, the lever fulcrum assembly is fixed to the lower portion of a vehicle, the two ends of the first pull rod assembly are movably connected with the handle assemblies and the lever fulcrum assembly through pin shafts respectively, and the second pull rod assembly is movably connected with the rotating shaft assembly through a pin shaft. The tension spring seat is fixed in the middle of the bottom frame, one end of the tension spring is sleeved with the tension spring seat, the other end of the tension spring is connected with the rotating shaft assembly, and the third pull rod assembly is movably connected with the rotating shaft assembly and the locking lever assembly through pin shafts. The two-stage locking mechanism is manually opened and closed, ground facilities do not need to be independently arranged, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of railway hopper cars, and more specifically to the technical field of a secondary locking mechanism of a bottom door of a railway hopper car. Background Art

[0002] The existing patent discloses the following bottom door locking device for railway hopper car:

[0003] The patent with publication number CN104139783A and patent name “A self-locking device for bottom door of hopper car and bottom door of hopper car” discloses the following contents: The self-locking device for bottom door of hopper car includes an anti-rotation mechanism. When the main shaft rotates to the position where the bottom door is in a closed position, the anti-rotation mechanism is used to prevent the main shaft of the bottom door of the hopper car from rotating. The anti-rotation mechanism can prevent the bottom door from opening accidentally and keep the bottom door in a stable closed state. At the same time, when the bottom door needs to be opened, the anti-rotation mechanism will not hinder the free rotation of the main shaft of the bottom door of the hopper car, and the bottom door can be opened as needed. The bottom door of the hopper car provided by the present invention also has the above-mentioned technical effects because it has the self-locking device, so it is safer and more reliable to use.

[0004] The patent with the publication number of CN103552566A and the patent name of "Secondary Locking Device for Bottom Door of Hopper Car and Hopper Car" discloses the following contents: the railway hopper car includes a bottom door and a primary locking device; the secondary locking device includes: a hook component, the hook component is mounted on the car body outside the bottom door through a pivot and can pivot along the car body, the first side of the hook component includes a guide part and a locking part, the locking part is suitable for forming a locking match with the bottom door of the hopper car to apply an upward lifting force to the bottom door, and the guide component is suitable for guiding the hook component and the bottom of the hopper car from a disengaged state to a locked state; one end of the spring unit is connected to the second side of the hook component, the second side and the first side are respectively located on both sides of the pivot, and the other end of the spring unit is connected to other parts of the car body outside the bottom door, for applying force to the hook component. The secondary locking is achieved by the above method, which improves the safety of the hopper car.

[0005] There are two ways of locking the bottom door of the above-mentioned patent and the current railway hopper cars in my country. One is a single-stage locking method, which mainly uses hydraulic, pneumatic, and electronic control equipment to directly act on the bottom door, or indirectly act on the bottom door with the help of ground facilities to achieve the effect of locking the bottom door; the other is a two-stage locking method, which mainly adds a second-stage locking while using a single-stage locking method. This method mostly uses ground facilities and adopts a roller touch-type automatic locking of the bottom door, or manually adjusts the locking device at the bottom of the hopper to achieve the effect of preventing the bottom door from opening.

[0006] The first method is highly dependent on external equipment. If there are problems with hydraulic, pneumatic and other equipment, the bottom door cannot be closed. Although the second method can reduce dependence on external equipment, it is necessary to set up bottom door facilities for the secondary locking mechanism, which increases additional costs. When manual adjustment is used, it is limited by the operating space, which increases labor costs.

[0007] Therefore, it is necessary to study a new type of secondary locking mechanism which does not rely on external additional facilities, is simple to operate, and has a reliable locking function. Summary of the invention

[0008] The purpose of the present invention is to solve the technical problem that the secondary locking mechanism of the existing bottom door needs to rely on external force and has a complex structure. The present invention provides a secondary locking mechanism for the bottom door of a railway hopper car.

[0009] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0010] The present invention provides a secondary locking mechanism for a railway hopper car bottom door, comprising a handle assembly, a first pull rod assembly, a lever fulcrum assembly, a second pull rod assembly, a rotating shaft assembly, a tension spring seat, a tension spring, a third pull rod assembly and a locking lever assembly;

[0011] The handle assembly is fixed on both sides of the base frame, the lever fulcrum assembly is fixed under the vehicle, the two ends of the first pull rod assembly are movably connected to the handle assembly and the lever fulcrum assembly through a pin shaft, the second pull rod assembly is movably connected to the rotating shaft assembly through a pin shaft, the tension spring seat is fixed to the middle of the base frame, one end of the tension spring is sleeved in the tension spring seat, and the other end is connected to the rotating shaft assembly, and the third pull rod assembly is movably connected to the rotating shaft assembly and the locking lever assembly through a pin shaft.

[0012] Specifically, when the bottom door is opened, the handle is rotated to a certain angle, and the handle drives the first and second pull rod assemblies to move, thereby driving the rotating shaft assembly to rotate, and then driving the third pull rod assembly to move, and finally driving the locking lever assembly to rotate and disengage from the main shaft locking block. At this time, the secondary locking mechanism is unlocked, and after the bottom door is successfully opened, the handle is returned to its original position to lock the secondary locking mechanism.

[0013] When the bottom door is closed, the secondary locking mechanism must be unlocked first, that is, the handle is rotated to a certain angle, and the handle drives the first and second pull rod assemblies to move, thereby driving the rotating shaft assembly to rotate, and then driving the third pull rod assembly to move, and finally driving the locking lever assembly to rotate and disengage from the main shaft locking block. At this time, the secondary locking mechanism is unlocked, and after the bottom door is successfully closed, the handle is returned to its original position to lock the secondary locking mechanism.

[0014] In addition, the spring will generate a certain pre-tension in the normal door closing state to ensure that the locking mechanism is in a stressed state.

[0015] In one embodiment, the handle assembly includes two symmetrically arranged handle units and a handle shaft connecting the two handle units.

[0016] In one embodiment, each of the handle units comprises a handle, a seat plate, a rib plate, a handle shaft, a mounting plate and a stopper;

[0017] The seat plate is fixedly connected to the rib plate, and both the seat plate and the rib plate are vertically fixed on both sides along the longitudinal direction of the vehicle body to expand the operating space and facilitate personnel to operate the mechanism outside the vehicle. The mounting plate is movably connected to the seat plate by bolts to facilitate subsequent disassembly and maintenance. The two ends of the handle shaft respectively pass through the mounting plates of the two handle units, and the two ends of the handle shaft are respectively fixedly connected to the corresponding handles to facilitate personnel to operate on either side of the vehicle. The block is fixed on the mounting plate to limit the handle.

[0018] In one embodiment, the axis of the handle shaft is orthogonal to the axis of the first tie rod assembly.

[0019] In one embodiment, the first tie rod assembly includes a tie rod and tie rod heads disposed at both ends of the tie rod;

[0020] The pull rod head near one side of the mounting plate is movably connected to the mounting plate, a threaded hole connected to the pull rod is provided in the middle of the pull rod head, threaded sections that cooperate with the corresponding threaded holes and can adjust the length are provided at both ends of the pull rod, and the length of the threaded section can be adjusted according to actual manufacturing conditions during installation, and two concentric through holes are provided on the pull rod head for convenient movable connection with the two side parts.

[0021] In one embodiment, the rotating shaft assembly includes a plurality of rotating shaft levers, two mounting plates, a rotating shaft, and two tension spring levers;

[0022] A plurality of the rotating shaft levers are evenly arranged on the rotating shaft, two tension spring levers are arranged in the middle of the rotating shaft, and two mounting plates are respectively fixed to the two ends of the rotating shaft and connected to the shaft seat by bolts;

[0023] A pull rod connected to the tension spring is arranged between the ends of the two tension spring levers;

[0024] One of the rotating shaft levers at the end is connected to the second pull rod assembly via a pin;

[0025] The other two rotating shaft levers are connected to the corresponding third pull rod assemblies via pins.

[0026] In one embodiment, the mounting plate is provided with oblong holes for reducing mounting difficulties caused by manufacturing errors.

[0027] In one embodiment, the locking lever assembly includes a locking lever, a locking shaft, and a lever; the locking lever is fixed to one end of the locking shaft, and the lever is connected to the other end of the locking lever via a fastener.

[0028] In one embodiment, the locking lever contacts the surface of the locking block of the main shaft to block the rotation of the main shaft, and the lever is movably connected to the corresponding third pull rod assembly via a pin.

[0029] In one embodiment, the spindle mounting plate is fixed below the base frame, and when the bottom door is closed, a certain gap is reserved between the locking lever and the locking block.

[0030] The beneficial effects of the present invention are as follows:

[0031] 1. The handle is set on the outside of the vehicle body, which is convenient for personnel to operate on the outside and increases the operating space. Operating handles are set on both sides of the vehicle body, and personnel can operate on either side of the vehicle, reducing the influence of the vehicle's traveling direction.

[0032] 2. The manual opening and closing secondary locking mechanism is adopted, which eliminates the need to set up separate ground facilities and reduces manufacturing costs.

[0033] 3. The components are connected flexibly, and the installation and maintenance of the mechanism are flexible, which reduces the difficulty of maintenance and labor costs.

[0034] 4. The handle is set on the outside of the vehicle body, which is convenient for personnel to operate on the outside and increases the operating space. Operating handles are set on both sides of the vehicle body, and personnel can operate on either side of the vehicle, reducing the influence of the vehicle's travel direction.

[0035] 5. The manual opening and closing two-stage locking mechanism is adopted, and there is no need to set up separate ground facilities, which reduces the manufacturing cost. The components are connected flexibly, and the mechanism is flexible to install and maintain, which reduces the difficulty of maintenance and labor costs.

[0036] 6. A set of two-stage locking mechanism can lock two sets of bottom doors at the same time, with a compact space layout, which greatly saves the use space at the bottom of the hopper car. The two-stage locking mechanism can prevent the bottom door from accidentally opening due to vehicle vibration, bottom door control system failure, etc. during the operation of the vehicle, and has higher safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 It is a schematic diagram of the structure of the present invention;

[0039] Figure 2 yes Figure 1 The enlarged view of point A in the middle;

[0040] Figure 3 is a schematic diagram of the structure of the handle assembly;

[0041] Figure 4 is a schematic diagram of the structure of the rotating shaft assembly;

[0042] Figure 5 is a schematic diagram of the structure of a locking lever assembly;

[0043] Figure numerals: 1-handle assembly, 2-first pull rod assembly, 3-lever fulcrum assembly, 4-second pull rod assembly, 5-rotation axis assembly, 6-tension spring seat, 7-tension spring, 8-third pull rod assembly, 9-locking lever assembly, 10-locking block, 11-spindle;

[0044] 1.1-handle, 1.2-seat plate, 1.3-rib plate, 1.4-handle shaft, 1.5-mounting plate, 1.6-stopper;

[0045] 5.1-rotating shaft lever, 5.2-mounting plate, 5.3-rotating shaft, 5.4-tension spring lever;

[0046] 9.1 - locking lever, 9.2 - locking shaft, 9.3 - lever. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0050] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation.

[0051] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances, and therefore cannot be understood as limiting the present invention.

[0052] Example 1

[0053] like Figures 1 to 5 As shown, this embodiment provides a two-stage locking mechanism for a railway hopper car bottom door, including a handle assembly 1, a first pull rod assembly 2, a lever fulcrum assembly 3, a second pull rod assembly 4, a rotating shaft assembly 5, a tension spring seat 6, a tension spring 7, a third pull rod assembly 8 and a locking lever assembly 9;

[0054] The handle assembly 1 is fixed on both sides of the chassis, the lever fulcrum assembly 3 is fixed under the vehicle, the two ends of the first pull rod assembly 2 are movably connected to the handle assembly 1 and the lever fulcrum assembly 3 through a pin shaft, the second pull rod assembly 4 is movably connected to the rotating shaft assembly 5 through a pin shaft, the tension spring seat 6 is fixed to the middle of the chassis, one end of the tension spring 7 is sleeved in the tension spring seat 6, and the other end is connected to the rotating shaft assembly 5, and the third pull rod assembly 8 is movably connected to the rotating shaft assembly 5 and the locking lever assembly 9 through a pin shaft.

[0055] Specifically, when the bottom door is opened, the handle is rotated to a certain angle, and the handle drives the first and second pull rod assemblies to move, thereby driving the rotating shaft assembly to rotate, and then driving the third pull rod assembly to move, and finally driving the locking lever assembly to rotate and disengage from the main shaft locking block. At this time, the secondary locking mechanism is unlocked, and after the bottom door is successfully opened, the handle is returned to its original position to lock the secondary locking mechanism.

[0056] When the bottom door is closed, the secondary locking mechanism must be unlocked first, that is, the handle is rotated to a certain angle, and the handle drives the first and second pull rod assemblies to move, thereby driving the rotating shaft assembly to rotate, and then driving the third pull rod assembly to move, and finally driving the locking lever assembly to rotate and disengage from the main shaft locking block. At this time, the secondary locking mechanism is unlocked, and after the bottom door is successfully closed, the handle is returned to its original position to lock the secondary locking mechanism.

[0057] In addition, the spring will generate a certain pre-tension in the normal door closing state to ensure that the locking mechanism is in a stressed state.

[0058] Example 2

[0059] like Figures 1 to 5 As shown, this embodiment provides a two-stage locking mechanism for a railway hopper car bottom door, including a handle assembly 1, a first pull rod assembly 2, a lever fulcrum assembly 3, a second pull rod assembly 4, a rotating shaft assembly 5, a tension spring seat 6, a tension spring 7, a third pull rod assembly 8 and a locking lever assembly 9;

[0060] The handle assembly 1 is fixed on both sides of the chassis, the lever fulcrum assembly 3 is fixed under the vehicle, the two ends of the first pull rod assembly 2 are movably connected to the handle assembly 1 and the lever fulcrum assembly 3 through a pin shaft, the second pull rod assembly 4 is movably connected to the rotating shaft assembly 5 through a pin shaft, the tension spring seat 6 is fixed to the middle of the chassis, one end of the tension spring 7 is sleeved in the tension spring seat 6, and the other end is connected to the rotating shaft assembly 5, and the third pull rod assembly 8 is movably connected to the rotating shaft assembly 5 and the locking lever assembly 9 through a pin shaft.

[0061] The handle assembly 1 includes two symmetrically arranged handle units and a handle shaft 1.4 connecting the two handle units.

[0062] Each of the handle units comprises a handle 1.1, a seat plate 1.2, a rib plate 1.3, a handle shaft 1.4, a mounting plate 1.5 and a stopper 1.6;

[0063] The seat plate 1.2 is fixedly connected to the rib plate 1.3, and both the seat plate 1.2 and the rib plate 1.3 are vertically fixed on both sides along the longitudinal direction of the vehicle body to expand the operating space and facilitate personnel to operate the mechanism outside the vehicle. The mounting plate 1.5 is movably connected to the seat plate 1.2 by bolts to facilitate subsequent disassembly and maintenance. The two ends of the handle shaft 1.4 respectively pass through the mounting plates 1.5 of the two handle units, and the two ends of the handle shaft 1.4 are respectively fixedly connected to the corresponding handles 1.1, which is convenient for personnel to operate on either side of the vehicle. The stop block 1.6 is fixed on the mounting plate 1.5 to limit the handle 1.1.

[0064] The axis of the handle shaft 1.4 is orthogonal to the axis of the first pull rod assembly 2.

[0065] Example 3

[0066] This embodiment is further optimized on the basis of embodiment 2, specifically:

[0067] The first pull rod assembly 2 includes a pull rod and a pull rod head arranged at both ends of the pull rod; the pull rod head close to the side of the mounting plate 1.5 is movably connected to the mounting plate 1.5, and a threaded hole connected to the pull rod is arranged in the middle of the pull rod head, and threaded sections that cooperate with the corresponding threaded holes and can be adjusted in length are arranged at both ends of the pull rod. During installation, the length of the threaded section can be adjusted according to actual manufacturing conditions, and two concentric through holes are arranged on the pull rod head for convenient movable connection with the two side components.

[0068] Example 4

[0069] This embodiment is further optimized on the basis of embodiment 2, specifically:

[0070] The rotating shaft assembly 5 comprises a plurality of rotating shaft levers 5.1, two mounting plates 5.2, a rotating shaft 5.3 and two tension spring levers 5.4;

[0071] A plurality of the rotating shaft levers 5.1 are evenly arranged on the rotating shaft 5.3, two tension spring levers 5.4 are arranged in the middle of the rotating shaft 5.3, and two mounting plates 5.2 are respectively fixed to the two ends of the rotating shaft 5.3 and connected to the shaft seat by bolts;

[0072] A pull rod connected to the tension spring 7 is arranged between the ends of the two tension spring levers 5.4;

[0073] One of the rotating shaft levers 5.1 located at the end is connected to the second pull rod assembly 4 via a pin shaft;

[0074] The other two rotating shaft levers 5.1 are connected to the corresponding third pull rod assemblies 8 via pins.

[0075] The mounting plate 5.2 is provided with an oblong hole for reducing the difficulty of mounting due to manufacturing errors.

[0076] Example 5

[0077] This embodiment is further optimized on the basis of embodiment 2, specifically:

[0078] The locking lever assembly 9 comprises a locking lever 9.1, a locking shaft 9.2 and a lever 9.3; the locking lever 9.1 is fixed to one end of the locking shaft 9.2, and the lever 9.3 is connected to the other end of the locking lever 9.1 via a fastener.

[0079] The locking lever 9.1 contacts the surface of the locking block 10 of the main shaft 11 to block the rotation of the main shaft 11, and the lever 9.3 is movably connected to the corresponding third pull rod assembly 8 through a pin shaft.

[0080] The spindle mounting plate is fixed below the base frame. When the bottom door is closed, a certain gap is reserved between the locking lever 9.1 and the locking block 10.

Claims

1. A secondary locking mechanism for a railway hopper car bottom door, characterized in that: It comprises a handle assembly (1), a first pull rod assembly (2), a lever fulcrum assembly (3), a second pull rod assembly (4), a rotating shaft assembly (5), a tension spring seat (6), a tension spring (7), a third pull rod assembly (8) and a locking lever assembly (9); The handle assembly (1) is fixed on both sides of the chassis, the lever fulcrum assembly (3) is fixed under the vehicle, the two ends of the first pull rod assembly (2) are movably connected to the handle assembly (1) and the lever fulcrum assembly (3) respectively through a pin shaft, the second pull rod assembly (4) is movably connected to the rotating shaft assembly (5) through a pin shaft, the tension spring seat (6) is fixed to the middle of the chassis, one end of the tension spring (7) is sleeved in the tension spring seat (6), and the other end is connected to the rotating shaft assembly (5), and the third pull rod assembly (8) is movably connected to the rotating shaft assembly (5) and the locking lever assembly (9) respectively through a pin shaft.

2. The secondary locking mechanism of the railway hopper car bottom door according to claim 1, characterized in that: The handle assembly (1) comprises two symmetrically arranged handle units and a handle shaft (1.4) connecting the two handle units.

3. The secondary locking mechanism of the railway hopper car bottom door according to claim 2, characterized in that: Each of the handle units comprises a handle (1.1), a seat plate (1.2), a rib plate (1.3), a handle shaft (1.4), a mounting plate (1.5) and a stopper (1.6); The seat plate (1.2) is fixedly connected to the rib plate (1.3), and both the seat plate (1.2) and the rib plate (1.3) are vertically fixed on both sides along the longitudinal direction of the vehicle body; the mounting plate (1.5) is movably connected to the seat plate (1.2) by bolts; the two ends of the handle shaft (1.4) respectively pass through the mounting plates (1.5) of the two handle units, and the two ends of the handle shaft (1.4) are respectively fixedly connected to the corresponding handles (1.1); the stopper (1.6) is fixed on the mounting plate (1.5) to limit the handle (1.1).

4. The secondary locking mechanism of the railway hopper car bottom door according to claim 3, characterized in that: The axis of the handle shaft (1.4) is orthogonal to the axis of the first pull rod assembly (2).

5. The secondary locking mechanism of the railway hopper car bottom door according to claim 2, characterized in that: The first tie rod assembly (2) comprises a tie rod and tie rod heads arranged at both ends of the tie rod; The pull rod head on one side close to the mounting plate (1.5) is movably connected to the mounting plate (1.5), a threaded hole connected to the pull rod is provided in the middle of the pull rod head, and threaded sections that cooperate with the corresponding threaded holes and can adjust the length are provided at both ends of the pull rod.

6. The secondary locking mechanism of the railway hopper car bottom door according to claim 1, characterized in that: The rotating shaft assembly (5) comprises a plurality of rotating shaft levers (5.1), two mounting plates (5.2), a rotating shaft (5.3) and two tension spring levers (5.4); A plurality of rotating shaft levers (5.1) are evenly arranged on the rotating shaft (5.3), two tension spring levers (5.4) are arranged in the middle of the rotating shaft (5.3), and two mounting plates (5.2) are respectively fixed to two ends of the rotating shaft (5.3) and connected to the shaft seat via bolts; A pull rod connected to the tension spring (7) is arranged between the ends of the two tension spring levers (5.4); A rotating shaft lever (5.1) located at the end is connected to the second pull rod assembly (4) via a pin shaft; The other two rotating shaft levers (5.1) are connected to the corresponding third pull rod assemblies (8) via pins.

7. A secondary locking mechanism for a railway hopper car bottom door according to claim 6, characterized in that: The mounting plate (5.2) is provided with an oblong hole for reducing mounting difficulties caused by manufacturing errors.

8. The secondary locking mechanism of the railway hopper car bottom door according to claim 7, characterized in that: The locking lever assembly (9) comprises a locking lever (9.1), a locking shaft (9.2) and a lever (9.3); the locking lever (9.1) is fixed to one end of the locking shaft (9.2), and the lever (9.3) is connected to the other end of the locking lever (9.1) via a fastener.

9. A secondary locking mechanism for a railway hopper car bottom door according to claim 8, characterized in that: The locking lever (9.1) contacts the surface of the locking block (10) of the main shaft (11) to block the rotation of the main shaft (11), and the lever (9.3) is movably connected to the corresponding third pull rod assembly (8) via a pin shaft.

10. A secondary locking mechanism for a railway hopper car bottom door according to claim 9, characterized in that: The main shaft mounting plate is fixed below the base frame, and when the bottom door is closed, a gap is reserved between the locking lever (9.1) and the locking block (10).

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