A work platform for the inner wall of a penstock

Abstract

The utility model discloses a pressure steel pipe inner wall workstation car, including lower platform, upper platform, first middle platform and second middle platform, the lower platform middle part is equipped with the direction support subassembly, the upper platform is slid and is established in the direction support subassembly, the first middle platform with lower platform between and second middle platform with lower platform between all articulate to have the lower cat ladder subassembly, the first middle platform with upper platform between and second middle platform with upper platform between all articulate to have the upper cat ladder subassembly, the lower platform bottom is equipped with the liftable walking wheel subassembly, the first middle platform and second middle platform are close to pressure steel pipe one end and all are equipped with side tight top subassembly, and side tight top subassembly can tight top pressure steel pipe inner wall or relax. The utility model has the advantages of adaptable different pipe diameter size, good stability.

Description

Technical Field

[0001] This utility model relates to the technical field of pressure steel pipe construction equipment, specifically to a pressure steel pipe inner wall work trolley. Background Technology

[0002] In the installation of pressure steel pipes in the water conservancy and hydropower industry, a series of tasks, including assembly, welding, non-destructive testing, and corrosion protection, must be carried out on the installation site for each pipe section's circumferential welds. Generally, a mobile welding trolley for pressure steel pipes, as disclosed in patent CN222857185U, is used. This welding trolley can adjust the welding angle by adjusting the movable plate. However, a set of water diversion steel pipes typically contains hundreds of circumferential welds, a large number, and the diameter of the pressure steel pipe varies along its entire length. This welding trolley cannot be applied to pressure steel pipes of different diameters, exhibiting poor adaptability. Furthermore, the overall platform of this welding trolley is large in size and weight, and it is prone to lateral slippage along the circumference during operation, posing a significant safety risk. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology and provide a pressure steel pipe inner wall working trolley that can adapt to different pipe diameters and has good stability.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A pressure steel pipe inner wall working trolley includes a lower platform, an upper platform, a first middle platform, and a second middle platform. A guide support assembly is provided on the lower platform, and the upper platform is slidably mounted on the guide support assembly. Lower ladder assemblies are hinged between the first middle platform and the lower platform, and between the second middle platform and the lower platform. Upper ladder assemblies are hinged between the first middle platform and the upper platform, and between the second middle platform and the upper platform. A liftable traveling wheel assembly is provided at the bottom of the lower platform. A side clamping assembly and a side wheel assembly are provided at the end of the first middle platform and the second middle platform near the pressure steel pipe. The side clamping assembly can clamp against or disengage from the inner wall of the pressure steel pipe.

[0005] As a further improvement to the above technical solution: The walking wheel assembly includes a walking wheel, a rotating lifting shaft, and a first rotating handwheel. One end of the rotating lifting shaft is threadedly connected to the lower platform, the walking wheel is installed on the other end of the rotating lifting shaft, and the first rotating handwheel is fixedly sleeved on the outside of the rotating lifting shaft.

[0006] The walking wheels are provided in multiple ways, and the multiple walking wheels are arranged at intervals along the length of the pressure steel pipe.

[0007] The side clamping assembly includes a clamping rod, a mounting shaft, and a second handwheel. The mounting shaft is located at the end of the corresponding middle platform. One end of the clamping rod is threadedly connected to the mounting shaft, and the second handwheel is fixedly sleeved on the outside of the clamping rod.

[0008] The side wheel assembly includes a first side wheel and a second side wheel, which are located on both sides of the clamping rod and are arranged at intervals along the length of the pressure steel pipe.

[0009] The guide support assembly includes a first guide support rod and a second guide support rod, which are arranged on the front and rear sides of the middle of the lower platform, and the upper platform is slidably mounted on the first guide support rod and the second guide support rod.

[0010] Both the first guide support rod and the second guide support rod are equipped with anti-detachment limiting components. The anti-detachment limiting components are located above the upper platform and are used to prevent the upper platform from detaching from the first guide support rod and the second guide support rod.

[0011] The anti-detachment limiting component includes a limiting ring and a locking member. The limiting ring is slidably mounted on a corresponding guide support rod, and the locking member is used to lock the limiting ring.

[0012] The upper ladder assembly includes two sets of first ladder frames and multiple first steps. Each set of first ladder frames includes a first support and a second support. The second supports are arranged parallel to each other above the first supports. Each of the two second supports is equipped with a first guardrail. One end of each of the first and second supports is hinged to the lower platform at hinge points A and B, respectively. The other end of each of the first and second supports is hinged to the corresponding middle platform at hinge points C and D, respectively. The ABCD structure forms a parallelogram. First ladder mounting rods are connected between the first supports of the two sets of first ladder frames at connection points E and F, respectively. Second ladder mounting rods are connected between the second supports of the two sets of first ladder frames at connection points G and H, respectively. EG and FH are parallel to AB and CD, respectively. The first steps are mounted on the corresponding first and second ladder mounting rods. The lower ladder assembly includes two sets of second ladder frames and multiple second steps. Each set of first ladder frames includes a third support and a fourth support. The fourth support is arranged parallel to the third support above it. Each of the two fourth supports is equipped with a second guardrail. One end of each third and fourth support is hinged to the corresponding middle platform, with hinge points a and b respectively. The other end of each third and fourth support is hinged to the upper platform, with hinge points c and d respectively. The abcd structure forms a parallelogram. A third ladder mounting rod is connected between the third supports of the two sets of second ladder frames, with connection points e and f respectively. A fourth ladder mounting rod is connected between the fourth supports of the two sets of second ladder frames, with connection points g and h respectively. eg and fh are parallel to ab and cd. The second steps are installed on the corresponding third and fourth ladder mounting rods.

[0013] The first step slides on the first and second ladder mounting rods, and the second step slides on the third and fourth ladder mounting rods.

[0014] Compared with the prior art, the advantages of this utility model are: This utility model discloses a pressure steel pipe inner wall working trolley. When constructing or inspecting the pressure steel pipe, the traveling wheel assembly rises, and the two ends of the lower platform contact and bear force with the inner wall of the pressure steel pipe. The weight of the trolley acts on the lower platform, and the traveling wheel assembly is no longer under force. Simultaneously, the side clamping assembly presses tightly against the side of the inner wall of the pressure steel pipe. Combined with the support of the guide support assembly, the trolley is fixed to prevent movement. Operators can perform construction or inspection of the pressure steel pipe through the lower and upper climbing ladder assemblies. When the construction or inspection is completed and the position needs to be moved, the traveling wheel assembly descends to contact the pressure steel pipe, and the lower platform disengages from the inner wall of the pressure steel pipe. At the same time, the side clamping assembly is released from its clamping position on the pressure steel pipe, leaving only the side wheel assembly in contact with the pressure steel pipe. At this point, the weight of the trolley acts on the traveling wheel assembly, and the side wheel assembly experiences a slight lateral force. The trolley can be moved using the traveling wheel assembly and the side wheel assembly. The system allows for the construction or inspection of pipe sections. Furthermore, the lower ladder assembly is hinged between the lower platform and the corresponding middle platform, while the upper ladder assembly is hinged between the upper platform and the corresponding middle platform. This adapts to pipe sections with different diameters. Specifically, when facing a smaller diameter pipe section, the first and second middle platforms retract closer together, and the hinge angle of the upper and lower ladder assemblies changes accordingly, causing the upper platform to move upwards along the guide support rod. Conversely, when facing a larger diameter pipe section, the first and second middle platforms extend further apart, and the hinge angle of the upper and lower ladder assemblies changes accordingly, causing the upper platform to move downwards along the guide support rod. This achieves the goal of completing the construction or inspection of the entire pressure steel pipe without replacing the trolley. In addition to its supporting function, the guide support assembly also guides the movement of the upper platform, preventing the upper platform, the first middle platform, and the second middle platform from tilting to one side, ensuring the stability and balance of the trolley. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the pressure steel pipe inner wall worktable trolley of this utility model.

[0016] Figure 2 This is a schematic diagram of the main structure of the pressure steel pipe inner wall worktable of this utility model.

[0017] Figure 3 This is a side view of the working trolley for the inner wall of the pressure steel pipe of this utility model.

[0018] Figure 4 This is a schematic diagram of the main structure of the traveling wheel assembly in the pressure steel pipe inner wall worktable of this utility model.

[0019] Figure 5 This is a semi-sectional structural schematic diagram of the clamping assembly in the pressure steel pipe inner wall worktable of this utility model.

[0020] Figure 6 yes Figure 2 Enlarged structural diagram at point K.

[0021] The labels in the diagram represent: 1. Lower platform; 2. Upper platform; 3. First intermediate platform; 4. Second intermediate platform; 5. Guide support assembly; 51. First guide support rod; 52. Second guide support rod; 53. Anti-detachment limiting assembly; 54. Limiting ring; 55. Locking component; 6. Lower ladder assembly; 61. Second step; 62. Third bracket; 63. Fourth bracket; 64. Third ladder mounting rod; 65. Fourth ladder mounting rod; 66. Second guardrail. 7. Upper ladder assembly; 71. First step; 72. First bracket; 73. Second bracket; 74. First ladder mounting rod; 75. Second ladder mounting rod; 76. First guardrail; 8. Walking wheel assembly; 81. Walking wheel; 82. Rotary lifting shaft; 83. First rotating handwheel; 9. Side tightening assembly; 91. Tightening rod; 92. Mounting shaft; 93. Second handwheel; 10. Side wheel assembly; 101. First side wheel; 102. Second side wheel. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] Figures 1 to 6 An embodiment of the pressure steel pipe inner wall work trolley of this utility model is shown, such as... Figure 1 and Figure 2 As shown, the pressure steel pipe inner wall work trolley of this embodiment includes a lower platform 1, an upper platform 2, a first middle platform 3, and a second middle platform 4. The lower platform 1 is provided with a guide support assembly 5, and the upper platform 2 is slidably mounted on the guide support assembly 5. The first middle platform 3 and the lower platform 1 are hinged together with the second middle platform 4 and the lower platform 1, and the first middle platform 3 and the upper platform 2 are hinged together with the second middle platform 4 and the upper platform 2. The bottom of the lower platform 1 is provided with a liftable walking wheel assembly 8. The first middle platform 3 and the second middle platform 4 are both provided with a side clamping assembly 9 and a side wheel assembly 10 at the end near the pressure steel pipe. The side clamping assembly 9 can clamp onto or disengage from the inner wall of the pressure steel pipe.

[0027] When the pressure steel pipe inner wall working trolley is used for construction or inspection of the pressure steel pipe, the traveling wheel assembly 8 rises, and the two ends of the lower platform 1 contact and bear force with the inner wall of the pressure steel pipe. The weight of the trolley acts on the lower platform 1, and the traveling wheel assembly 8 is no longer under force. At the same time, the side clamping assembly 9 is tightly pressed against the side of the inner wall of the pressure steel pipe. Combined with the support of the guide support assembly 5, the trolley is fixed to prevent movement. The operator can carry out construction or inspection of the pressure steel pipe through the lower ladder assembly 7 and the upper ladder assembly 6. When the construction or inspection is completed and the position needs to be moved, the traveling wheel assembly 8 descends to contact the pressure steel pipe, and the lower platform 1 is disengaged from the inner wall of the pressure steel pipe. At the same time, the side clamping assembly 9 is released from the pressure steel pipe, leaving only the side wheel assembly 10 in contact with the pressure steel pipe. At this time, the weight of the trolley acts on the traveling wheel assembly 8, and the side wheel assembly 10 is subjected to a slight lateral force. The trolley can be moved by the traveling wheel assembly 8 and the side wheel assembly 10 to perform other pipe sections of the pressure steel pipe. For construction or inspection, the lower ladder assembly 6 is hinged between the lower platform 1 and the corresponding middle platform, and the upper ladder assembly 7 is hinged between the upper platform 2 and the corresponding middle platform. This allows for adaptation to pipe sections with different diameters. When facing a smaller diameter pipe section, the first middle platform 3 and the second middle platform 4 retract inward and move closer together, changing the hinge angle between the upper ladder assembly 7 and the lower ladder assembly 6. The upper platform 2 then moves upward along the guide support rod 5. Conversely, when facing a larger diameter pipe section, the first middle platform 3 and the second middle platform 4 move outward and away from each other, changing the hinge angle between the upper ladder assembly 7 and the lower ladder assembly 6. The upper platform 2 then moves downward along the guide support rod 5. This achieves the goal of completing the construction or inspection of the entire pressure steel pipe without replacing the trolley. In addition to its supporting function, the guide support assembly 5 also guides the movement of the upper platform 2, preventing the upper platform 2, the first middle platform 3, and the second middle platform 4 from tilting to one side, thus ensuring the stability and balance of the trolley.

[0028] Furthermore, such as Figures 1 to 4As shown, in this embodiment, the walking wheel assembly 8 includes a walking wheel 81, a rotating lifting shaft 82, and a first rotating handwheel 83. One end of the rotating lifting shaft 82 is threadedly connected to the lower platform 1, and the walking wheel 81 is installed on the other end of the rotating lifting shaft 82. The first rotating handwheel 83 is fixedly sleeved on the outside of the rotating lifting shaft 82. By turning the first rotating handwheel 85, the rotating lifting shaft 84 can be driven to extend or retract the mounting plate 81, thereby realizing the lifting and lowering of the walking wheel 82. This allows for switching between contact between the walking wheel 82 and the inner wall of the pressure steel pipe, facilitating the fixing of the trolley during construction and saving effort during movement.

[0029] Furthermore, such as Figure 3 As shown, in this embodiment, multiple traveling wheels 81 are provided, and the multiple traveling wheels 81 are arranged at intervals along the length of the pressure steel pipe. This facilitates maintaining the balance of the moving trolley.

[0030] Furthermore, such as Figure 5 As shown, in this embodiment, the side-tightening assembly 9 includes a tightening rod 91, a mounting shaft 92, and a second handwheel 93. The mounting shaft 92 is located at the end of the corresponding middle platform. One end of the tightening rod 91 is threadedly connected to the mounting shaft 92, and the second handwheel 93 is fixedly sleeved on the outside of the tightening rod 91. By turning the second handwheel 93, the contact between the tightening rod 91 and the inner wall of the pressure steel pipe is switched. The tightening rod 91 is pressed tightly against the inner wall of the pressure steel pipe to fix the trolley. When the trolley needs to move, the tightening rod 91 retracts into the mounting shaft 92, the side wheel assembly 10 is supported on the inner wall of the pressure steel pipe, and the tightening rod 91 disengages from the inner wall of the pressure steel pipe to move the trolley.

[0031] Furthermore, such as Figure 3 As shown, in this embodiment, the side wheel assembly 10 includes a first side wheel 101 and a second side wheel 102. The first side wheel 101 and the second side wheel 102 are located on both sides of the clamping rod 91, and the three are arranged at intervals along the length of the pressure steel pipe. This facilitates the movement of the trolley and provides lateral support when the clamping rod 91 is disengaged from the pressure steel pipe.

[0032] Furthermore, such as Figure 1 As shown, in this embodiment, the guide support assembly 5 includes a first guide support rod 51 and a second guide support rod 52. The first guide support rod 51 and the second guide support rod 52 are arranged on the front and rear sides of the middle of the lower platform 1, and the upper platform 2 is slidably mounted on the first guide support rod 51 and the second guide support rod 52. This provides a more balanced support and guidance.

[0033] Furthermore, such as Figure 1 and Figure 6As shown in this embodiment, both the first guide support rod 51 and the second guide support rod 52 are equipped with anti-detachment limiting components 53. The anti-detachment limiting components 53 are located above the upper platform 2 and are used to prevent the upper platform 2 from detaching from the first guide support rod 51 and the second guide support rod 52. This prevents the upper platform 2 from detaching from the first guide support rod 51 and the second guide support rod 52 during the movement of the trolley with pipe sections of different diameters, thus ensuring the construction safety of the trolley.

[0034] Furthermore, such as Figure 6 As shown, in this embodiment, the anti-detachment limiting component 53 includes a limiting ring 54 and a locking member 55. The limiting ring 54 is slidably mounted on the corresponding guide support rod, and the locking member 55 is used to lock the limiting ring 54. The limiting height of the limiting ring 54 can be adjusted according to the actual construction and maintenance situation to further improve the applicability of the trolley.

[0035] Furthermore, such as Figure 1 and Figure 2As shown, in this embodiment, the upper ladder assembly 7 includes two sets of first ladder frames and multiple first step stools 71. Each set of first ladder frames includes a first support 72 and a second support 73. The second support 73 is arranged parallel above the first support 72. Each of the two second supports 73 is provided with a first guardrail 76. One end of the first support 72 and the second support 73 is hinged to the lower platform 1, with hinge points A and B respectively. The other end of the first support 72 and the second support 73 is hinged to the corresponding middle platform, with hinge points C and D respectively. ABCD forms a parallelogram structure. A first ladder mounting rod 74 is connected between the first supports 72 of the two sets of first ladder frames, with connection points E and F respectively. A second ladder mounting rod 75 is connected between the second supports 73 of the two sets of first ladder frames, with connection points G and H respectively. EG and FH are parallel to AB and CD. The first step stool 71 is installed on the corresponding first ladder mounting rod 74 and second ladder mounting rod 75. On the pole 75, the lower ladder assembly 6 includes two sets of second ladder frames and multiple second steps 61. Each set of first ladder frames includes a third support 62 and a fourth support 63. The fourth support 63 is arranged parallel above the third support 62. Each of the two fourth supports 63 is equipped with a second guardrail 66. One end of the third support 62 and the fourth support 63 is hinged to the corresponding middle platform, with hinge points a and b respectively. The other end of the third support 62 and the fourth support 63 is hinged to the upper platform 2, with hinge points c and d respectively. abcd forms a parallelogram structure. A third ladder mounting rod 64 is connected between the third supports 62 of the two sets of second ladder frames, with connection points e and f respectively. A fourth ladder mounting rod 65 is connected between the fourth supports 63 of the two sets of second ladder frames, with connection points g and h respectively. eg and fh are parallel to ab and cd. The second steps 61 are installed on the corresponding third ladder mounting rod 64 and fourth ladder mounting rod 65. In the upper ladder assembly 7, ABCD forms a parallelogram structure, and EG and FH are parallel to AB and CD. This ensures that when the hinge angle between the first support 72 and the second support 73 and the lower platform 1 and the corresponding middle platform changes, the first step 71 remains parallel to the lower platform 1, maintaining a horizontal state and improving stepping safety. The same applies to the lower ladder assembly 6, which will not be elaborated here.

[0036] Furthermore, such as Figure 1 As shown, in this embodiment, the first step 71 is slidably mounted on the first ladder mounting rod 74 and the second ladder mounting rod 75, and the second step 61 is slidably mounted on the third ladder mounting rod 64 and the fourth ladder mounting rod 65. If the first step 71 and the second step 61 obstruct construction, the first step 71 and the second step 61 can be moved to facilitate construction.

[0037] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, should fall within the protection scope of the present invention.

Claims

1. A pressure steel pipe inner wall working trolley, characterized in that: It includes a lower platform (1), an upper platform (2), a first middle platform (3) and a second middle platform (4). The lower platform (1) is provided with a guide support assembly (5). The upper platform (2) is slidably mounted on the guide support assembly (5). The first middle platform (3) and the lower platform (1) are hinged together with the second middle platform (4) and the lower platform (1). The first middle platform (3) and the upper platform (2) are hinged together with the second middle platform (4) and the upper platform (2). The bottom of the lower platform (1) is provided with a liftable walking wheel assembly (8). The first middle platform (3) and the second middle platform (4) are both provided with a side clamping assembly (9) and a side wheel assembly (10) at the end near the pressure steel pipe. The side clamping assembly (9) can clamp or detach from the inner wall of the pressure steel pipe.

2. The pressure steel pipe inner wall working trolley according to claim 1, characterized in that: The walking wheel assembly (8) includes a walking wheel (81), a rotating lifting shaft (82) and a first rotating handwheel (83). One end of the rotating lifting shaft (82) is threadedly connected to the lower platform (1), the walking wheel (81) is installed on the other end of the rotating lifting shaft (82), and the first rotating handwheel (83) is fixedly sleeved on the outside of the rotating lifting shaft (82).

3. The pressure steel pipe inner wall working trolley according to claim 2, characterized in that: The walking wheels (81) are provided in multiples, and the multiple walking wheels (81) are arranged at intervals along the length direction of the pressure steel pipe.

4. The pressure steel pipe inner wall working trolley according to any one of claims 1 to 3, characterized in that: The side clamping assembly (9) includes a clamping rod (91), a mounting shaft (92), and a second handwheel (93). The mounting shaft (92) is located at the end of the corresponding middle platform. One end of the clamping rod (91) is threadedly connected to the mounting shaft (92), and the second handwheel (93) is fixedly sleeved on the outside of the clamping rod (91).

5. The pressure steel pipe inner wall working trolley according to claim 4, characterized in that: The side wheel assembly (10) includes a first side wheel (101) and a second side wheel (102), which are located on both sides of the clamping rod (91) and are arranged at intervals along the length of the pressure steel pipe.

6. The pressure steel pipe inner wall working trolley according to any one of claims 1 to 3, characterized in that: The guide support assembly (5) includes a first guide support rod (51) and a second guide support rod (52). The first guide support rod (51) and the second guide support rod (52) are arranged on the front and rear sides of the middle of the lower platform (1), and the upper platform (2) is slidably mounted on the first guide support rod (51) and the second guide support rod (52).

7. The pressure steel pipe inner wall working trolley according to claim 6, characterized in that: The first guide support rod (51) and the second guide support rod (52) are each provided with an anti-detachment limiting component (53). The anti-detachment limiting component (53) is located above the upper platform (2) and is used to prevent the upper platform (2) from detaching from the first guide support rod (51) and the second guide support rod (52).

8. The pressure steel pipe inner wall working trolley according to claim 7, characterized in that: The anti-detachment limiting component (53) includes a limiting ring (54) and a locking member (55). The limiting ring (54) is slidably mounted on the corresponding guide support rod, and the locking member (55) is used to lock the limiting ring (54).

9. The pressure steel pipe inner wall working trolley according to any one of claims 1 to 3, characterized in that: The upper ladder assembly (7) includes two sets of first ladder frames and multiple first steps (71). Each set of first ladder frames includes a first support (72) and a second support (73). The second supports (73) are arranged parallel above the first supports (72). Each of the two second supports (73) is provided with a first guardrail (76). One end of each of the first supports (72) and the second supports (73) is hinged to the lower platform (1), with hinge points A and B respectively. The other end of each of the first supports (72) and the second supports (73) is... The corresponding middle platform is hinged, with hinge points C and D respectively. The ABCD forms a parallelogram structure. The first support (72) of the two sets of first ladder frames is connected by a first ladder mounting rod (74), with connection points E and F respectively. The second support (73) of the two sets of first ladder frames is connected by a second ladder mounting rod (75), with connection points G and H respectively. EG and FH are parallel to AB and CD. The first step (71) is installed on the corresponding first ladder mounting rod (74) and second ladder mounting rod (75). The lower ladder assembly (6) includes two sets of second ladder frames and multiple second steps (61). Each set of first ladder frames includes a third support (62) and a fourth support (63). The fourth support (63) is arranged parallel above the third support (62). Each of the two fourth supports (63) is provided with a second guardrail (66). One end of the third support (62) and the fourth support (63) is hinged to the corresponding middle platform, with hinge points a and b respectively. The other end of the third support (62) and the fourth support (63) is... The upper platform (2) is hinged, with hinge points c and d respectively. The abcd forms a parallelogram structure. The third ladder mounting rod (64) is connected between the third supports (62) of the two sets of second ladder frames, with connection points e and f respectively. The fourth ladder mounting rod (65) is connected between the fourth supports (63) of the two sets of second ladder frames, with connection points g and h respectively. The eg and fh are parallel to ab and cd. The second step (61) is installed on the corresponding third ladder mounting rod (64) and fourth ladder mounting rod (65).

10. The pressure steel pipe inner wall working trolley according to claim 9, characterized in that: The first step (71) is slidably mounted on the first ladder mounting rod (74) and the second ladder mounting rod (75), and the second step (61) is slidably mounted on the third ladder mounting rod (64) and the fourth ladder mounting rod (65).

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