A method for lengthening a tire type beam lifter at a construction site

Abstract

The application discloses a lengthening reconstruction method of a tire type beam lifting machine on a construction site, which comprises the following steps: controlling the tire type beam lifting machine to lift and transport a plurality of box girders and stack the box girders on a high pedestal; controlling the beam lifting machine to move along the longitudinal direction of the box girders, arranging a first supporting pad below a detachable connecting end of a front half of a main girder to support the main girder on the box girders; arranging a temporary supporting leg which can move longitudinally below a rear half of the main girder close to a detachable connecting end of the rear half and fixing the temporary supporting leg; disconnecting the front half of the main girder from the rear half; pulling the supporting leg of the rear half of the main girder to move the rear half of the main girder to a predetermined position; hoisting a main girder splicing segment above the box girders and connecting the main girder splicing segment after aligning with the detachable connecting end of the front half of the main girder; and pushing the rear half of the main girder to connect the rear half of the main girder with the main girder splicing segment after aligning, thereby completing the lengthening reconstruction of the main girder. The application has the advantages that the reconstruction is carried out in a beam field, equipment returning to a factory is avoided, the existing equipment in the beam field is fully utilized, the reconstruction mode is simple, the reconstruction period is short, and investment is saved.

Description

Technical Field

[0001] This invention belongs to the technical field of beam lifting machine equipment, specifically relating to a method for extending and modifying a tire-type beam lifting machine on a construction site. Background Technology

[0002] A beam lifting machine is a type of gantry crane used to lift and transport precast box girders. Conventional beam lifting machines lift and transport precast box girders through the main beam and its hoisting mechanism, but the span of the main beam is fixed and cannot be adjusted.

[0003] If a precast box girder yard has two or more box girder lengths and the construction period allows for phased precasting, the beam lifting machine may have a span that is too small to lift the longer box girder.

[0004] To address these technical issues, those skilled in the art need to make temporary modifications to the tire-mounted beam lifting machines in the beam yard to adapt to the lifting and transport of box girders of different sizes and models. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing a method for extending and modifying a tire-mounted beam lifting machine on a construction site. This method involves splitting the main beam of the tire-mounted beam lifting machine into a front half and a rear half. The detachable connecting end of the front half is supported on a box girder, while the rear half is longitudinally disengaged by temporary outriggers. With the support of the box girder, the splicing segment of the main beam is bolted to the front half of the main beam. Finally, guided by the temporary outriggers and the box girder, the splicing segment of the main beam is aligned and bolted to the splicing segment, thus completing the extension and modification.

[0006] The objective of this invention is achieved through the following technical solutions:

[0007] A method for extending and modifying a tire-mounted beam lifting machine on a construction site, characterized by the following steps:

[0008] S1: Arrange several elevated platforms at preset positions; control the tire-type beam lifting machine to lift several box girders and stack them on the elevated platforms from bottom to top;

[0009] S2: Control the tire-type beam lifting machine to move longitudinally along the box girder, so that the front half of the main beam of the tire-type beam lifting machine moves longitudinally out of the area of ​​the box girder and the rear half is located directly above the box girder. The front half and the rear half of the main beam are connected in a detachable manner through the main beam bolt joint. A first pad is set below the detachable connection end of the front half of the main beam so that the front half of the main beam is supported on the box girder.

[0010] S3: A longitudinally movable temporary support leg is installed below the rear half of the main beam near its detachable connection end. The top surface of the temporary support leg supports the lower surface of the rear half of the main beam and is fixed to each other.

[0011] S4: Release the bolt joint between the front and rear halves of the main beam; pull the support leg of the rear half of the main beam through an external push-pull mechanism to move the rear half of the main beam longitudinally to a predetermined position;

[0012] S5: Several second pads are set on the upper surface of the box girder. The main beam splicing segment is lifted to the top of the box girder by a truck crane and then unloaded and supported on the second pads after being aligned with the detachable connection end of the front half of the main beam. The main beam splicing segment is then bolted to the front half of the main beam.

[0013] S6: The rear half of the main beam is pushed by the external push-pull mechanism, so that the rear half of the main beam is aligned with the splicing segment of the main beam and then bolted together, thus completing the extension and modification of the main beam.

[0014] The external push-pull mechanism is an excavator; when pulling the outriggers of the rear half of the main beam, a cable is connected between the excavator arm of the external push-pull mechanism and the outriggers, and the outriggers are pulled by controlling the retraction of the excavator arm of the external push-pull mechanism; when pushing the outriggers of the rear half of the main beam, the bucket of the external push-pull mechanism is directly controlled to abut against the outriggers and push them.

[0015] There are two temporary support legs, which are located on both sides of the box girder. A truss is arranged horizontally between the tops of the temporary support legs on both sides to connect them into a whole, and the top surface of the truss supports the rear half of the main girder.

[0016] The main body of the temporary support leg is an isosceles trapezoidal frame structure, and the bottom of the temporary support leg is equipped with a running wheel mechanism.

[0017] A guide portion is fixedly installed on the inner side of the temporary support leg. The installation height of the guide portion corresponds to the height of the top plate of the lowest box girder, and an internal support for the box girder is provided in the cavity below the top plate of the box girder. When installing the temporary support leg, the guide portions of the temporary support legs on each side are set against the flanges on both sides of the box girder so that the temporary support leg moves longitudinally along the box girder when supporting the rear half of the main girder. The guide portion includes a horizontal plate and a vertical plate. The lower surface of the horizontal plate is provided with a vertical guide wheel and travels against the upper surface of the flange of the box girder. The inner side of the vertical plate is provided with a horizontal guide wheel and travels against the side wall of the flange of the box girder.

[0018] After the main beam is extended, the tire-mounted beam lifting machine is locally reinforced and inspected for defects, and the modification is completed and accepted.

[0019] The temporary support leg is located directly below the main beam. The top surface of the temporary support leg supports the lower rear half of the main beam and is fixed to each other. The bottom surface of the temporary support leg is mounted on a temporary guide rail on the upper surface of the box girder. The temporary guide rail is arranged longitudinally along the box girder.

[0020] The advantages of this invention are:

[0021] (1) Modify within the beam yard to avoid equipment returning to the factory; make full use of the existing equipment in the beam yard, the modification method is simple, the modification period is short, and the temporary investment is small;

[0022] (2) Using the existing box girder in the beam yard as the longitudinal guide rail for the rear half of the tire-type beam lifting machine, the guide part set on the temporary support leg can make the rear half of the tire-type beam lifting machine move longitudinally along the flange of the box girder, preventing it from deviating during the longitudinal movement, which would result in a lot of adjustment time required for subsequent alignment and bolting with the main beam assembly segment. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the tire-type beam lifting machine for transporting box girders in this invention;

[0024] Figure 2 For the present invention Figure 1 AA view in the middle;

[0025] Figure 3 This is a schematic diagram of the tire-type beam lifting machine in this invention lifting the box girder onto the high platform;

[0026] Figure 4 For the present invention Figure 3 Cross-sectional view showing the vertical positional relationship between the main beam and the box girder;

[0027] Figure 5 This is a schematic diagram of the tire-type beam lifting machine moving longitudinally along the box girder in this invention;

[0028] Figure 6 This is a schematic diagram of Embodiment 1 of the present invention, in which pads are provided under the front half of the main beam and temporary support legs are provided under the rear half of the main beam.

[0029] Figure 7 This is Embodiment 1 of the present invention. Figure 6 BB diagram in the middle;

[0030] Figure 8 This is Embodiment 1 of the present invention. Figure 6 CC diagram in the image;

[0031] Figure 9 This is Embodiment 1 of the present invention. Figure 8 A magnified view of part D in the diagram;

[0032] Figure 10This is a schematic diagram of how the rear half of the main beam is moved backward by an excavator in Embodiment 1 of the present invention;

[0033] Figure 11 This is a schematic diagram of the main beam splicing segment being connected to the detachable connecting end of the main beam in Embodiment 1 of the present invention;

[0034] Figure 12 This is a schematic diagram of how the rear half of the main beam is pushed forward by an excavator and connected to the splicing segment of the main beam in Embodiment 1 of the present invention;

[0035] Figure 13 This is a schematic diagram of the tire-type beam lifting machine completing the extension modification in this invention;

[0036] Figure 14 This is a schematic diagram of Embodiment 2 of the present invention, in which pads are provided under the front half of the main beam and temporary support legs are provided under the rear half of the main beam;

[0037] Figure 15 This is Example 2 of the present invention. Figure 14 EE diagram in the image;

[0038] Figure 16 This is a schematic diagram of how the rear half of the main beam is moved backward by an external push-pull mechanism in Embodiment 2 of the present invention;

[0039] Figure 17 This is a schematic diagram of the main beam splicing segment being connected to the detachable connecting end of the main beam in Embodiment 2 of the present invention;

[0040] Figure 18 This is a schematic diagram of how the rear half of the main beam is pushed forward by an excavator and connected to the splicing segment of the main beam in Embodiment 2 of the present invention. Detailed Implementation

[0041] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art:

[0042] like Figure 1-18 The markings in the figure are as follows: Main beam 1, front half 1a, rear half 1b, box girder 2, outrigger 3, main beam bolt joint 4, lifting system 5, high platform 6, first lifting pad 7, temporary outrigger 8, box girder internal support 9, guide section 10, horizontal plate 10a, vertical plate 10b, vertical guide wheel 10c, horizontal guide wheel 10d, truss 11, cable 12, external push-pull mechanism 13, second lifting pad 14, main beam splicing segment 15, temporary outrigger 16, temporary guide rail 17.

[0043] Example 1: As Figure 1-13As shown, this embodiment specifically relates to a method for extending and modifying a tire-mounted girder lifting machine on a construction site. The precast box girder yard requires a tire-mounted girder lifting machine capable of simultaneously lifting 24m and 30m long box girders. Therefore, the existing tire-mounted girder lifting machine, which can only lift 24m box girders, is extended and modified to enable it to simultaneously lift 30m long box girders. The specific steps include:

[0044] (S1) As Figure 1-4 As shown, several elevated platforms 6 are arranged at the pre-set location where the extension modification is to be carried out. During the arrangement, it should be ensured that there is at least one set of elevated platforms 6 at both ends. The tire-mounted beam lifting machine is controlled to lift two sets of 24m long box girders 2 and stack them sequentially from bottom to top on the pre-set elevated platforms 6. The existing tire-mounted beam lifting machine has a main beam 1 with a length slightly greater than 24m and can only lift 24m long box girders 2. The main beam 1 is specifically composed of a front half 1a and a rear half 1b, which are bolted together by a main beam bolt joint 4. The main beam 1 has a lifting system 5 for lifting the box girders 2, and the front and rear ends of the main beam 1 are supported and driven by outriggers 3.

[0045] (S2) For example Figure 5 As shown, after the stacking of box girder 2 is completed, the tire-mounted lifting machine is controlled to move longitudinally along box girder 2, with the longitudinal direction of box girder 2 as the moving direction. This causes the front half 1a of the main beam 1 of the tire-mounted lifting machine to move longitudinally out of the area of ​​box girder 2, while the rear half of the main beam 1 is located directly above box girder 2. More precisely, the front half 1a of the main beam 1 moves longitudinally out of the area above box girder 2, but the detachable connection end of the front half 1a used to set the main beam bolt joint 4 remains above box girder 2. Figure 6 , 7 As shown, a first support pad 7 is provided below the detachable connection end of the front half 1a of the main beam 1. The bottom surface of the first support pad 7 supports the upper surface of the box beam 2, and the top surface supports the lower surface of the front half 1a of the main beam 1, thus providing support for the front half 1a of the main beam 1 and keeping its position fixed. It should be noted that in order to ensure that the box beam 2 can have sufficient support performance, an internal support 9 is built into its cavity.

[0046] (S3) such as Figure 6 , 8As shown, two longitudinally movable temporary supports 8 are erected below the rear half 1b of the main beam 1 near its detachable connecting end. Specifically, two temporary supports 8 are erected on both sides of the box girder 2, and the two temporary supports 8 are connected to each other by a truss 11 to form a whole. The upper surface of the truss 11 supports and fixes the rear half 1b of the main beam 1, that is, when the temporary supports 8 move longitudinally, they can drive the rear half 1b of the main beam 1 to move synchronously. In this embodiment, the main body of the temporary support 8 is an isosceles trapezoidal frame structure, and the bottom of the temporary support 8 is provided with a traveling wheel mechanism to support its longitudinal movement. To ensure that the temporary support leg 8 maintains linear movement and avoids deviation when driving the rear half 1b of the main beam 1 longitudinally, a guide part 10 is provided on the inner side of the temporary support leg 8. The installation height of the guide part 10 corresponds to the top plate height of the lower box girder 2. When installing the temporary support leg 8, it should be ensured that the guide part 10 can fit against the flange of the box girder 2; Figure 9 As shown, the guide section 10 includes a horizontal plate 10a and a vertical plate 10b, which are welded or integrally cast to form an L-shape. The horizontal plate 10a is located above the flange of the box girder 2, and a vertical guide wheel 10c is provided on the lower surface of the horizontal plate 10a and travels against the upper surface of the flange of the box girder 2. The vertical plate 10b is located on one side of the flange of the box girder 2, and a horizontal guide wheel 10d is provided on the inner side of the vertical plate 10b and travels against the side wall of the flange of the box girder 2. When the rear half 1b of the main beam 1 is longitudinally moved by the support of the leg 8 and the truss 11 between them, the vertical guide wheel 10c on the guide part 10 can closely fit on the flange of the box beam 2 under the vertical downward force of the rear half 1b of the main beam 1. The horizontal guide wheel 10d can effectively regulate the longitudinal movement trajectory of the rear half of the main beam 1 by closely fitting on the side wall of the flange of the box beam 2. After moving backward, it can move forward again to return to its original position, which can also ensure accurate alignment in the future.

[0047] (S4) such as Figure 10 As shown, the main beam bolt joint 4 between the front half 1a and the rear half 1b of the main beam 1 is released, and at the same time, the electrical system and the lifting system 5 on it are released. Then, the outrigger 3 of the rear half 1b of the main beam 1 is pulled by the external push-pull mechanism 13 to move it backward longitudinally. After the displacement is greater than the length of the subsequent main beam splice segment 15, the pulling of the outrigger 3 of the rear half 1b of the main beam 1 is stopped. In this embodiment, the external push-pull mechanism 13 is specifically an excavator. When pulling the outrigger 3 of the rear half 1b of the main beam 1, a cable 12 is connected between the excavator's digging arm and the outrigger 3. The backward pulling of the outrigger 3 is achieved by controlling the retraction of the excavator's digging arm.

[0048] (S5) For example Figure 11As shown, several second pads 14 are set on the upper surface of the box girder 2. The second pads 14 are arranged in the installation area of ​​the main beam splicing segment 15. The number of second pads 14 is preferably sufficient to support the main beam splicing segment 15. The main beam splicing segment 15 is lifted to the top of the box girder 2 using a truck crane and then unloaded and supported on the second pads 14 after being aligned with the detachable connection end of the front half 1a of the main beam 1. Then, the main beam splicing segment 15 is bolted to the front half 1a of the main beam 1 using the main beam bolt joint 4.

[0049] (S6) For example Figure 12 , 13 As shown, the rear half 1b of the main beam 1 is slowly pushed by the external push-pull mechanism 13, so that the rear half 1b of the main beam 1 is aligned with the splicing segment 15 of the main beam, and then bolted together by the main beam bolt joint 4, thus completing the extension and modification of the main beam 1. Figure 12 As shown, simultaneously, the electrical system and lifting system 5 were reinstalled, and the tire-mounted beam lifting machine underwent local reinforcement and flaw detection. After the modification and acceptance were completed, it could lift box girders 2 with lengths of 24m and 30m. Among them, when the external push-pull mechanism 13 pushes the outrigger 3 of the rear half 1b of the main beam 1, it directly controls the excavator's bucket to abut against the outrigger 3 for pushing. During the pushing, the guide part 10 can ensure that the temporary outrigger 8 drives the rear half 1b of the main beam 1 to move longitudinally along the box beam 2.

[0050] The beneficial effects of this embodiment are:

[0051] (1) Modify within the beam yard to avoid equipment returning to the factory; make full use of the existing equipment in the beam yard, the modification method is simple, the modification period is short, and the temporary investment is small;

[0052] (2) Using the existing box girder in the beam yard as the longitudinal guide rail for the rear half of the tire-type beam lifting machine, the guide part set on the temporary support leg can make the rear half of the tire-type beam lifting machine move longitudinally along the flange of the box girder, preventing it from deviating during the longitudinal movement, which would result in a lot of adjustment time required for subsequent alignment and bolting with the main beam assembly segment.

[0053] Example 2: As Figure 1-5 As shown in Figures 13-18, this embodiment specifically relates to a method for extending and modifying a tire-mounted beam lifting machine on a construction site. The precast box girder yard requires a tire-mounted beam lifting machine capable of simultaneously lifting 24m and 30m long box girders. Therefore, the existing tire-mounted beam lifting machine, which can only lift 24m box girders, is extended and modified to enable it to simultaneously lift 30m long box girders. The main difference between this embodiment and Embodiment 1 lies in the structural form and arrangement of the temporary support leg 16. The specific steps include:

[0054] (S1) As Figure 1-4As shown, several elevated platforms 6 are arranged at the pre-set location where the extension modification is to be carried out. During the arrangement, it should be ensured that there is at least one set of elevated platforms 6 at both ends. The tire-mounted beam lifting machine is controlled to lift two sets of 24m long box girders 2 and stack them sequentially from bottom to top on the pre-set elevated platforms 6. The existing tire-mounted beam lifting machine has a main beam 1 with a length slightly greater than 24m and can only lift 24m long box girders 2. The main beam 1 is specifically composed of a front half 1a and a rear half 1b, which are bolted together by a main beam bolt joint 4. The main beam 1 has a lifting system 5 for lifting the box girders 2, and the front and rear ends of the main beam 1 are supported and driven by outriggers 3.

[0055] (S2) For example Figure 5 As shown, after the stacking of box girder 2 is completed, the tire-mounted lifting machine is controlled to move longitudinally along box girder 2, with the longitudinal direction of box girder 2 as the moving direction. This causes the front half 1a of the main beam 1 of the tire-mounted lifting machine to move longitudinally out of the area of ​​box girder 2, while the rear half of the main beam 1 is located directly above box girder 2. More precisely, the front half 1a of the main beam 1 moves longitudinally out of the area above box girder 2, but the detachable connection end of the front half 1a used to set the main beam bolt joint 4 remains above box girder 2. Figure 14 , 15 As shown, a first support pad 7 is provided below the detachable connection end of the front half 1a of the main beam 1. The bottom surface of the first support pad 7 supports the upper surface of the box beam 2, and the top surface supports the lower surface of the front half 1a of the main beam 1, thus providing support for the front half 1a of the main beam 1 and keeping its position fixed. It should be noted that in order to ensure that the box beam 2 can have sufficient support performance, an internal support 9 is built into its cavity.

[0056] (S3) such as Figure 14 , 15 As shown, a longitudinally movable temporary support leg 16 is installed below the rear half 1b of the main beam 1 near its detachable connection end, and a temporary guide rail 17 is arranged longitudinally on the upper surface of the box girder 2. The length of the temporary guide rail 17 should ensure that it covers the longitudinal movement area of ​​the temporary support leg 16. The upper part of the temporary support leg 16 supports the rear half 1b of the main beam 1, and the lower part is assembled on the temporary guide rail 17. The temporary support leg 16 can move longitudinally back and forth under the guidance of the temporary guide rail 17.

[0057] (S4) such as Figure 16As shown, the main beam bolt joint 4 between the front half 1a and the rear half 1b of the main beam 1 is released, and at the same time, the electrical system and the lifting system 5 on it are released. Then, the outrigger 3 of the rear half 1b of the main beam 1 is pulled by the external push-pull mechanism 13 to move it backward longitudinally. After the displacement is greater than the length of the subsequent main beam splice segment 15, the pulling of the outrigger 3 of the rear half 1b of the main beam 1 is stopped. In this embodiment, the external push-pull mechanism 13 is specifically an excavator. When pulling the outrigger 3 of the rear half 1b of the main beam 1, a cable is connected between the excavator's digging arm and the outrigger 3. The backward pulling of the outrigger 3 is achieved by controlling the retraction of the excavator's digging arm.

[0058] (S5) For example Figure 17 As shown, several second pads 14 are set on the upper surface of the box girder 2. The second pads 14 are arranged in the installation area of ​​the main beam splicing segment 15. The number of second pads 14 is preferably sufficient to support the main beam splicing segment 15. The main beam splicing segment 15 is lifted to the top of the box girder 2 using a truck crane and then unloaded and supported on the second pads 14 after being aligned with the detachable connection end of the front half 1a of the main beam 1. Then, the main beam splicing segment 15 is bolted to the front half 1a of the main beam 1 using the main beam bolt joint 4.

[0059] (S6) For example Figure 18 , 13 As shown, the rear half 1b of the main beam 1 is slowly pushed by the external push-pull mechanism 13, so that the rear half 1b of the main beam 1 is aligned with the splicing segment 15 of the main beam, and then bolted together by the main beam bolt joint 4, thus completing the extension and modification of the main beam 1. Figure 18 As shown, simultaneously, the electrical system and lifting system 5 were reinstalled, and the tire-mounted beam lifting machine underwent local reinforcement and flaw detection. After the modification and acceptance were completed, it could lift box girders 2 with lengths of 24m and 30m. Among them, when the external push-pull mechanism 13 pushes the outrigger 3 of the rear half 1b of the main beam 1, it directly controls the excavator's bucket to abut against the outrigger 3 for pushing. During the pushing, the temporary guide rail 17 can ensure that the temporary outrigger 16 drives the rear half 1b of the main beam 1 to move longitudinally along the box girder 2.

Claims

1. A method for extending and modifying a tire-mounted beam lifting machine on a construction site, characterized in that... The extension and modification method includes the following steps: S1: Arrange several elevated platforms at preset positions; control the tire-type beam lifting machine to lift several box girders and stack them on the elevated platforms from bottom to top; S2: Control the tire-mounted beam lifting machine to move longitudinally along the box girder, so that the front half of the main beam of the tire-mounted beam lifting machine moves longitudinally out of the area of ​​the box girder and the rear half is located directly above the box girder. The front half and the rear half of the main beam are connected in a detachable manner through the main beam bolt joint. The front half of the main beam is used to set the detachable connection end of the main beam bolt joint and keep it above the box girder. A first pad is set below the detachable connection end of the front half of the main beam so that the front half of the main beam is supported on the box girder. S3: A longitudinally movable temporary support leg is installed below the rear half of the main beam near its detachable connection end. The top surface of the temporary support leg supports the lower surface of the rear half of the main beam and is fixed to each other. S4: Release the bolt joint between the front and rear halves of the main beam; pull the support leg of the rear half of the main beam through an external push-pull mechanism to move the rear half of the main beam longitudinally to a predetermined position; S5: Several second pads are set on the upper surface of the box girder. The main beam splicing segment is lifted to the top of the box girder by a truck crane and then unloaded and supported on the second pads after being aligned with the detachable connection end of the front half of the main beam. The main beam splicing segment is then bolted to the front half of the main beam. S6: The rear half of the main beam is pushed by the external push-pull mechanism, so that the rear half of the main beam is aligned with the splicing segment of the main beam and then bolted together, thus completing the extension and modification of the main beam.

2. The method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 1, characterized in that... The external push-pull mechanism is an excavator; when pulling the outriggers of the rear half of the main beam, a cable is connected between the excavator arm of the external push-pull mechanism and the outriggers, and the outriggers are pulled by controlling the retraction of the excavator arm of the external push-pull mechanism; when pushing the outriggers of the rear half of the main beam, the bucket of the external push-pull mechanism is directly controlled to abut against the outriggers and push them.

3. The method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 1, characterized in that... There are two temporary support legs, which are located on both sides of the box girder. A truss is arranged horizontally between the tops of the temporary support legs on both sides to connect them into a whole, and the top surface of the truss supports the rear half of the main girder.

4. The method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 3, characterized in that... The main body of the temporary support leg is an isosceles trapezoidal frame structure, and the bottom of the temporary support leg is equipped with a running wheel mechanism.

5. The method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 4, characterized in that... A guide portion is fixedly installed on the inner side of the temporary support leg. The installation height of the guide portion corresponds to the height of the top plate of the lowest box girder, and an internal support for the box girder is provided in the cavity below the top plate of the box girder. When installing the temporary support leg, the guide portions of the temporary support legs on each side are set against the flanges on both sides of the box girder so that the temporary support leg moves longitudinally along the box girder when supporting the rear half of the main girder. The guide portion includes a horizontal plate and a vertical plate. The lower surface of the horizontal plate is provided with a vertical guide wheel and travels against the upper surface of the flange of the box girder. The inner side of the vertical plate is provided with a horizontal guide wheel and travels against the side wall of the flange of the box girder.

6. The method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 1, characterized in that... After the main beam is extended, the tire-mounted beam lifting machine is locally reinforced and inspected for defects, and the modification is completed and accepted.

7. A method for extending and modifying a tire-mounted beam lifting machine on a construction site according to claim 1, characterized in that... The temporary support leg is located directly below the main beam. The top surface of the temporary support leg supports the lower rear half of the main beam and is fixed to each other. The bottom surface of the temporary support leg is mounted on a temporary guide rail on the upper surface of the box girder. The temporary guide rail is arranged longitudinally along the box girder.

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