Large-span super-heavy continuous box girder jacking device

Abstract

The application discloses a large-span super-heavy continuous box girder jacking device and belongs to the technical field of bridge construction. The device comprises a jacking plate, a plurality of elastic supporting blocks arranged in an array on the upper surface of the jacking plate, and a plurality of telescopic supporting assemblies arranged around the elastic supporting blocks. The upper end of an anti-skid block extends from the opening, the lower end of the anti-skid block is connected to a supporting plate inside the elastic supporting block, the bottom of the supporting plate is connected to the jacking plate through a first spring, the supporting plate and the first spring are in one-to-one correspondence, the upper side of each supporting plate is provided with at least one anti-skid block, the first spring abuts the supporting plate against the inner wall of the outer cover, the supporting plates are uniformly and spacedly arranged along the longitudinal direction of the box girder, the upper end of the outer side of the inner cylinder is provided with an annular outer edge, and an inner ring groove for limiting the annular outer edge is formed in the inner circumferential wall of the outer cover. The device can ensure the contact area of the continuous box girder and the jacking machine to a certain extent, and ensure that the construction can be smoothly carried out.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge construction, and particularly relates to a large-span super-heavy continuous box girder jacking device. BACKGROUND

[0002] The incremental launching method is quite different from the support launching method, hoisting method, swivel method and cantilever method in terms of construction environment, technical requirements and construction control, and the research on the construction process of the incremental launching method is also different from other construction methods due to the particularity of the construction principle of the incremental launching method. The setting of the temporary auxiliary structure increases the span of the bridge constructed by the incremental launching method and enables the unstressed alignment of the variable-curvature vertical curve continuous girder to be well controlled. Unlike the traditional small-scale box girder, the large-span super-heavy continuous box girder needs to use a large jacking device during the incremental launching process, and in order to ensure the smooth progress of the incremental launching, a large contact area needs to be ensured between the jacking machine and the continuous box girder to ensure sufficient static friction. However, due to the manufacturing precision of the box girder, the large-area range at the bottom of the box girder is often uneven, which causes the contact area between the continuous box girder and the jacking plate of the jacking machine to be unable to be ensured. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a large-span super-heavy continuous box girder jacking device which can ensure the contact area between the continuous box girder and the jacking machine to a certain extent and ensure the smooth progress of the construction.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] The large-span super-heavy continuous box girder jacking device disclosed by the present application comprises a jacking plate, a plurality of elastic support blocks are arranged in an array on the upper surface of the jacking plate, and a plurality of telescopic support assemblies are arranged around the four sides of the elastic support blocks; the elastic support block comprises an outer cover, an inner cylinder, a first spring, a second spring, a support plate and an anti-skid block, the lower end of the inner cylinder is fixedly connected to the jacking plate, the upper end of the inner cylinder is open and is slidably connected to the outer cover, a plurality of openings are uniformly formed in the upper surface of the outer cover along the longitudinal direction of the box girder, the anti-skid block is vertically slidably arranged in the opening, the upper end of the anti-skid block extends out of the opening, the lower end of the anti-skid block is connected to the support plate on the inner side of the elastic support block, the bottom of the support plate is connected to the jacking plate through the first spring, the support plate and the first spring are in one-to-one correspondence, at least one anti-skid block is installed on the upper side of each support plate, the first spring abuts the support plate against the inner wall of the outer cover, and the support plates are uniformly and spacedly arranged along the longitudinal direction of the box girder; an annular outer edge is arranged on the outer side of the upper end of the inner cylinder, and an inner annular groove for limiting the annular outer edge is formed in the inner circumferential wall of the outer cover.

[0006] Further, the telescopic support assembly comprises a top rod, an end plate, a screw rod, a sliding sleeve and a third spring, the inside of the jacking plate is formed with a cavity, the upper surface of the jacking plate is provided with a through hole, the upper end of the top rod extends out of the through hole, the lower end of the top rod is located in the cavity, the lower end of the top rod is provided with a threaded hole matched with the screw rod in rotation, and the screw rod is matched with the jacking plate in rotation.

[0007] Further, the outside of the screw rod is fixed with a first friction plate, the first friction plate is located in the cavity, the bottom of the sliding sleeve is fixed with a second friction plate, and the lower surface of the second friction plate is elastically abutted against the upper surface of the first friction plate under the action of the third spring.

[0008] Further, the first friction plate and the jacking plate are provided with balls, the lower surface of the first friction plate is formed with a first annular groove for limiting the balls, and the inside bottom surface of the jacking plate is formed with a second annular groove for limiting the balls.

[0009] Further, the outside of the sliding sleeve is slidably matched with a limiting sleeve, and the upper end of the limiting sleeve is fixedly connected with the inside top surface of the jacking plate.

[0010] Further, the inside of the jacking plate is fixed with an annular plate, the annular plate and the inside upper and lower surfaces of the jacking plate jointly form a hydraulic cavity, the hydraulic cavity is filled with hydraulic oil, and each group of elastic supporting blocks is correspondingly provided with one hydraulic cavity; the lower end of the top rod is slidably and sealingly arranged in the sliding sleeve, the lower outer wall of the sliding sleeve is provided with a hydraulic hole, and the sliding sleeve is in communication with the hydraulic cavity through the hydraulic hole.

[0011] Further, the lower end of the screw rod extends out of the jacking plate, the lower end of the screw rod is fixedly connected with a limiting plate, and the lower end of the screw rod is detachably connected with a sealing end cover.

[0012] Further, the jacking plate comprises an upper cover and a lower cover which is detachably connected with the upper cover, and the upper cover and the lower cover are connected to form the cavity.

[0013] Further, the jacking device further comprises a vertical jack, an L-shaped base and a horizontal jack, the upper end of the vertical jack is connected to the bottom of the L-shaped base, the side surface of the L-shaped base is fixedly connected with the horizontal jack, and the output end of the horizontal jack is fixedly connected to the jacking plate.

[0014] Further, the bottom of the box girder is fixed with a rack, the lower side of the rack is engaged with a gear, the gear is rotatably connected to the jacking plate through a rotating shaft, a ratchet is coaxially connected to the rotating shaft, one end of the ratchet is clamped with a pawl, the other end of the pawl is rotatably connected with a mounting plate through a pin shaft, the pawl and the mounting plate are provided with an elastic reset device, and the mounting plate is fixedly connected to the jacking plate.

[0015] The beneficial effects of the present application are that:

[0016] If the bottom of the box girder is uneven, the box girder and the jacking plate will only be in contact at the most protruding position of the box girder and the upper surface of the jacking plate, which will seriously waste the area of the jacking plate, and insufficient friction will lead to insufficient thrust. The jacking device for the large-span super-heavy continuous box girder disclosed in the present application supports the bottom of the box girder through the upper surface of the jacking plate by means of a plurality of elastic supporting blocks. Although the area of the jacking plate is dispersed, each elastic supporting block can adapt to the uneven shape of the bottom of the box girder. Through the elastic expansion and contraction, part of the elastic supporting blocks can be in contact with the protruding position, and the other part can be in contact with the recessed position, so that the upper surface of each elastic supporting block is in contact with the lower surface of the box girder, thereby achieving the purpose of increasing the overall contact area.

[0017] In the elastic supporting block disclosed in the present application, a plurality of anti-skid blocks are arranged, each anti-skid block can also adapt to the shape of the bottom of the box girder, and the anti-skid effect is achieved. Since the anti-skid blocks are supported by the first springs, each anti-skid block can be in contact with the bottom of the box girder, thereby achieving a better anti-skid effect. The outer cover and the inner cylinder can be supported by the second springs at the same time, and the anti-skid blocks are arranged in the longitudinal direction, which can also improve the anti-skid effect.

[0018] Other advantages, objects, and features of the present application will be apparent from the following specification and are pointed out in greater detail herein. The advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to make the purposes, technical solutions and beneficial effects of the present application clearer, the present application provides the following drawings for illustration:

[0020] Figure 1 It is a structural schematic view of the jacking device;

[0021] Figure 2 It is a structural schematic view of the jacking plate;

[0022] Figure 3 It is a sectional view of the jacking plate;

[0023] Figure 4 As Figure 3 Enlarged view at A;

[0024] Figure 5 As Figure 3 Enlarged view at B;

[0025] Figure 6 As Figure 3 Enlarged view at C;

[0026] Figure 7 As the schematic diagram of the ratchet and pawl cooperation;

[0027] Figure 8 As the working principle diagram of the elastic supporting block.

[0028] In the drawings, the following marks are as follows: jacking plate 1, elastic supporting block 2, telescopic supporting assembly 3, outer cover 4, inner cylinder 5, first spring 6, second spring 7, supporting plate 8, anti-skid block 9, opening 10, annular outer edge 11, inner ring groove 12, jacking rod 13, end plate 14, screw rod 15, sliding sleeve 16, third spring 17, cavity 18, through hole 19, threaded hole 20, first friction plate 21, second friction plate 22, ball 23, limiting sleeve 24, annular plate 25, hydraulic cavity 26, hydraulic hole 27, limiting plate 28, sealing end cover 29, upper cover 30, lower cover 31, vertical jack 32, L-shaped base 33, horizontal jack 34, rack 35, gear 36, rotating shaft 37, ratchet 38, pawl 39, pin shaft 40, mounting plate 41, elastic reset device 42. DETAILED DESCRIPTION

[0029] As Figures 1-8 shown, the jacking device for long-span and heavy continuous box girder disclosed by the application comprises a jacking plate 1, and the jacking plate 1 is in the shape of a rectangle as a whole. Under normal circumstances, the upper surface of the jacking plate 1 is parallel to the lower surface of the box girder. The upper surface of the jacking plate 1 is arrayed with nine groups of elastic supporting blocks 2. The size and quantity of the elastic supporting blocks 2 can be adjusted according to different scales, so that the elastic supporting blocks 2 can cover the surface of the jacking plate 1.

[0030] In the application, the elastic support block 2 is also rectangular structure, 10 groups of telescopic support assemblies 3 are arranged around the four sides of the elastic support block 2; the elastic support block 2 comprises an outer cover 4, an inner cylinder 5, a first spring 6, a second spring 7, a support plate 8 and an anti-skid block 9, the shapes of the inner cylinder 5 and the outer cylinder are also adaptive rectangular, the upper and lower ends of the inner cylinder 5 are not closed, the lower end of the inner cylinder 5 is fixedly connected with the upper surface of the jacking plate 1, the upper end of the inner cylinder 5 is open and is slidably connected with the outer cover 4, and the elastic support effect is realized through the connection of the second spring 7. In the technical scheme disclosed in the application, the upper surface of the jacking plate 1 is replaced by a plurality of elastic support blocks 2 to support the bottom of the box girder, which seems to disperse the area of the jacking plate 1, but in fact each elastic support block 2 can adapt to the uneven shape of the bottom of the box girder, and through the elastic telescopic effect, part of the elastic support blocks 2 can contact the protruding position, and the other part can contact the recessed position, so that the upper surfaces of the elastic support blocks 2 can contact the lower surface of the box girder to increase the overall contact area, thereby increasing the static friction force of the box girder during jacking.

[0031] Specifically, in the application, a plurality of openings 10 are uniformly formed on the upper surface of the outer cover 4 along the longitudinal direction of the box girder, the openings 10 are rectangular, the length of the opening extends along the transverse direction of the box girder, the anti-skid blocks 9 are vertically slidably arranged in the openings 10, the cross-sectional shape of the anti-skid blocks 9 is adapted to the shape of the openings 10, the upper end of the anti-skid blocks 9 extends out of the openings 10, the lower end of the anti-skid blocks 9 is connected to the support plates 8 on the inner side of the elastic support blocks 2, the bottom of the support plates 8 is connected to the jacking plate 1 through the first springs 6, the support plates 8 and the first springs 6 correspond to each other, at least one anti-skid block 9 is installed on the upper side of each support plate 8, the first spring 6 abuts the support plate 8 against the inner wall of the outer cover 4, the support plates 8 are uniformly and spacedly arranged along the longitudinal direction of the box girder, the outer side of the upper end of the inner cylinder 5 is provided with an annular outer edge 11, and an inner annular groove 12 for limiting the annular outer edge 11 is formed on the inner circumferential wall of the outer cover 4. By arranging a plurality of anti-skid blocks 9, each anti-skid block 9 can also adapt to the shape of the bottom of the box girder to achieve the anti-skid effect.

[0032] In the embodiment, the telescopic support assembly 3 comprises a top rod 13, an end plate 14, a screw rod 15, a sliding sleeve 16 and a third spring 17, the inner side of the jacking plate 1 is formed with a cavity 18, the cavity 18 is mainly used for accommodating the telescopic support assembly 3, the upper surface of the jacking plate 1 is provided with a through hole 19, the shape of the through hole 19 corresponds to the top rod 13, the top rod 13 is in the shape of a round rod, the upper end of the top rod 13 extends out of the through hole 19, and the upper end of the top rod 13 is higher than the upper surface of the elastic support block 2, so that the top rod 13 can better contact the recessed part. The lower end of the top rod 13 is located in the cavity 18, the lower end of the top rod 13 is provided with a threaded hole 20 which is rotationally connected with the screw rod 15, and the screw rod 15 is rotationally connected with the jacking plate 1; the top rod 13 is fixedly connected with the end plate 14 inside the cavity 18, the outer side of the top rod 13 is slidingly connected with the sliding sleeve 16, and the sliding sleeve 16 is connected with the end plate 14 through the third spring 17. By arranging the telescopic support assembly 3, the upper end of the top rod 13 can be deeply inserted into some small pits, so that when the jacking plate 1 drives the box girder to displace, the top rod 13 can change the friction force into a longitudinal thrust force acting on the pits of the box girder, thereby better force transmission effect can be achieved, and the problem of jacking failure caused by the sliding of the box girder relative to the jacking plate 1 can be prevented.

[0033] In the embodiment, the outer side of the screw rod 15 is fixedly connected with a first friction plate 21, the plane where the first friction plate 21 is located is perpendicular to the screw rod 15, the first friction plate 21 is located in the cavity 18, the bottom of the sliding sleeve 16 is fixedly connected with a second friction plate 22, and under the action of the third spring 17, the lower surface of the second friction plate 22 and the upper surface of the first friction plate 21 are elastically abutted together. When the bottom of the box girder has a protrusion, the protrusion can compress the top rod 13 to displace downward, and when the top rod 13 moves relative to the screw rod 15, the screw rod 15 can be driven to rotate, the rotation of the screw rod 15 can enable the first friction plate 21 and the second friction plate 22 to relatively rotate to generate damping, thereby the buffering effect can be achieved, and the damage of the telescopic support assembly 3 or the elastic support block 2 caused by the direct action of the protrusion of the box girder on the two components can be avoided. Even when the jacking plate 1 and the box girder relatively slide, the upper surface of the jacking plate 1 can be protected, and the effect of increasing the service life of the device can be achieved. By arranging the sliding sleeve 16, the inner wall of the sliding sleeve 16 can also be used for limiting the lower end of the screw rod 15, so as to prevent the device from loosening caused by the large deflection of the screw rod 15.

[0034] In the embodiment, the first friction plate 21 and the jacking plate 1 are provided with a ball 23, the lower surface of the first friction plate 21 is formed with a first annular groove for limiting the ball 23, and the inner bottom surface of the jacking plate 1 is formed with a second annular groove for limiting the ball 23. By arranging the ball 23, the friction effect between the first friction plate 21 and the inner wall of the jacking plate 1 can be reduced, and the main friction damping is still realized through the friction between the first friction plate 21 and the second friction plate 22.

[0035] In the embodiment, the outer side of the sliding sleeve 16 is slidingly fitted with a limiting sleeve 24, and the upper end of the limiting sleeve 24 is fixedly connected to the inner top surface of the jacking plate 1. By arranging the limiting sleeve 24, the upper end of the sliding sleeve 16 can be limited and sealed.

[0036] In the embodiment, the inner side of the jacking plate 1 is fixedly connected with an annular plate 25, the annular plate 25 and the inner upper and lower surfaces of the jacking plate 1 jointly form a hydraulic cavity 26, the hydraulic cavity 26 is filled with hydraulic oil, and each group of elastic supporting blocks 2 is correspondingly provided with one hydraulic cavity 26; the lower end of the jack rod 13 is slidingly and sealingly arranged in the sliding sleeve 16, the lower outer wall of the sliding sleeve 16 is provided with a hydraulic hole 27, and the sliding sleeve 16 is in communication with the hydraulic cavity 26 through the hydraulic hole 27. The sliding sleeves 16 are in communication through the hydraulic holes 27, and when some jack rods 13 in the same group are pressed downward, the hydraulic oil in the inner space of the sliding sleeve 16 can be extruded, the hydraulic oil can enter the inner space of the remaining sliding sleeves 16, and the remaining jack rods 13 can be lifted to be deeply inserted into the box girder pit. Through the balancing effect of the hydraulic oil, the difficulty of the lowering of the jack rods 13 can be balanced, so that the jack rods 13 can correspond to the pits or protrusions at the bottom of the box girder as much as possible.

[0037] In the embodiment, the lower end of the screw rod 15 extends out of the jacking plate 1, the lower end of the screw rod 15 is fixedly connected with a limiting plate 28, and the outer side of the lower end of the screw rod 15 is detachably connected with a sealing end cover 29. By arranging the sealing end cover 29, the lower end of the screw rod 15 can be protected, and dust can be prevented from entering.

[0038] In the embodiment, the jacking plate 1 comprises an upper cover 30 and a lower cover 31 detachably connected with the upper cover 30, the upper cover 30 and the lower cover 31 are connected to form the cavity 18, and by arranging the jacking plate 1 as the detachable upper cover 30 and the lower cover 31, the internal structure of the jacking plate 1 can be conveniently disassembled and maintained.

[0039] In the embodiment, the jacking device further comprises a vertical jack 32, an L-shaped base 33 and a horizontal jack 34, the upper end of the vertical jack 32 is connected to the bottom of the L-shaped base 33, the side surface of the L-shaped base 33 is fixedly connected with the horizontal jack 34, and the output end of the horizontal jack 34 is fixedly connected to the jacking plate 1. One jacking cycle is as follows: first, the L-shaped base 33 is lifted by the vertical jack 32, the jacking plate 1 on the L-shaped base 33 of each jacking device is in contact with the bottom of the box girder and drives the box girder to rise, at this time, the jacking plate 1 is in close contact with the bottom of the box girder, the horizontal jack 34 is started to drive the jacking plate 1 to push the box girder in the longitudinal direction, after the pushing is completed, the vertical jack 32 is started to descend, and then the horizontal jack 34 is started to return to the original position.

[0040] In the embodiment, the bottom of the box girder is fixed with a rack 35, the lower side of the rack 35 is engaged with a gear 36, the gear 36 is rotatably connected to the jacking plate 1 through a rotating shaft 37, the rotating shaft 37 is coaxially connected with a ratchet wheel 38, the ratchet wheel 38 is clamped with one end of a pawl 39, the other end of the pawl 39 is rotatably connected with a mounting plate 41 through a pin shaft 40, the pawl 39 and the mounting plate 41 are provided with an elastic reset device 42 therebetween, and the mounting plate 41 is fixedly connected to the jacking plate 1. If the box girder slips relative to the jacking plate 1 when encountering a slope, the rack 35 at the bottom of the box girder has a tendency to move to the left, drives the gear 36 to rotate counterclockwise, and the gear 36 drives the coaxial ratchet wheel 38 to rotate counterclockwise. Since the ratchet wheel 38 is limited by the pawl 39, a thrust force is generated to hinder the counterclockwise rotation of the ratchet wheel 38. By using the above device, the box girder can be prevented from moving back, so as to improve the construction efficiency and safety.

[0041] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application.

Claims

1. A long-span super-heavy continuous box girder jacking device, comprising a jacking plate, characterized in that: The upper surface of the jacking plate is provided with a plurality of elastic supporting blocks arranged in an array, and a plurality of telescopic supporting assemblies are arranged around the elastic supporting blocks; the elastic supporting block comprises an outer cover, an inner cylinder, a first spring, a second spring, a supporting plate and an anti-skid block, the lower end of the inner cylinder is fixedly connected with the jacking plate, the upper end of the inner cylinder is open and is in sliding connection with the outer cover, a plurality of openings are uniformly formed in the upper surface of the outer cover along the longitudinal direction of the box girder, the anti-skid block is arranged in the opening in a vertical sliding manner, the upper end of the anti-skid block extends out of the opening, the lower end of the anti-skid block is connected to the supporting plate on the inner side of the elastic supporting block, the bottom of the supporting plate is connected to the jacking plate through the first spring, the supporting plate and the first spring are in one-to-one correspondence, at least one anti-skid block is installed on the upper side of each supporting plate, the first spring abuts the supporting plate against the inner wall of the outer cover, each supporting plate is arranged in uniform spacing along the longitudinal direction of the box girder, the outer side of the upper end of the inner cylinder is provided with an annular outer edge, an inner ring groove for limiting the annular outer edge is formed in the inner circumferential wall of the outer cover, and the second spring is connected between the outer cover and the inner cylinder.

2. The long-span super-heavy continuous box girder jacking device according to claim 1, characterized in that: The telescopic supporting assembly comprises a top rod, an end plate, a screw rod, a sliding sleeve and a third spring, the inner side of the jacking plate is formed with a cavity, the upper surface of the jacking plate is provided with a through hole, the upper end of the top rod extends out of the through hole, the lower end of the top rod is located in the cavity, the lower end of the top rod is provided with a threaded hole in rotation cooperation with the screw rod, and the screw rod is in rotation cooperation with the jacking plate; the end plate is fixedly connected to the inner side of the top rod, the sliding sleeve is in sliding cooperation with the outer side of the top rod, and the third spring is connected between the sliding sleeve and the end plate.

3. The long-span super-heavy continuous box girder jacking device according to claim 2, characterized in that: The outer side of the screw rod is fixedly provided with a first friction plate, the first friction plate is located in the cavity, the bottom of the sliding sleeve is fixedly provided with a second friction plate, and the lower surface of the second friction plate is in elastic abutment with the upper surface of the first friction plate under the action of the third spring.

4. The long-span super-heavy continuous box girder jacking device according to claim 3, characterized in that: The first friction plate and the jacking plate are provided with a plurality of rolling balls, the lower surface of the first friction plate is formed with a first ring groove for limiting the rolling balls, and the inner bottom surface of the jacking plate is formed with a second ring groove for limiting the rolling balls.

5. The long-span super-heavy continuous box girder jacking device according to claim 2, characterized in that: The outer side of the sliding sleeve is in sliding cooperation with a limiting sleeve, and the upper end of the limiting sleeve is fixedly connected with the inner top surface of the jacking plate.

6. The long-span super-heavy continuous box girder jacking device according to claim 2, characterized in that: The inner side of the jacking plate is fixedly provided with an annular plate, the annular plate and the inner top and bottom surfaces of the jacking plate jointly form a hydraulic chamber, the hydraulic chamber is filled with hydraulic oil, and each group of elastic supporting blocks is correspondingly provided with one hydraulic chamber; the lower end of the top rod is arranged in the sliding sleeve in a sliding sealing mode, the lower outer wall of the sliding sleeve is provided with a hydraulic hole, and the sliding sleeve is in communication with the hydraulic chamber through the hydraulic hole.

7. The long-span super-heavy continuous box girder jacking device according to claim 2, characterized in that: The lower end of the screw rod extends out of the jacking plate, the lower end of the screw rod is fixedly connected with a limiting plate, and the lower end of the screw rod is detachably connected with a sealing end cover.

8. The long-span super-heavy continuous box girder jacking device according to claim 2, characterized in that: The jacking plate comprises an upper cover and a lower cover which is detachably connected with the upper cover, and the upper cover and the lower cover jointly form the cavity.

9. The long-span super-heavy continuous box girder jacking device according to claim 1, characterized in that: The jacking device further comprises a vertical jack, an L-shaped base and a horizontal jack, the upper end of the vertical jack is connected to the bottom of the L-shaped base, the side surface of the L-shaped base is fixedly connected with the horizontal jack, and the output end of the horizontal jack is fixedly connected to the jacking plate.

10. The long-span super-heavy continuous box girder jacking device according to claim 1, characterized in that: The bottom of the box girder is fixed with a rack, the lower side of the rack is engaged with a gear, the gear is rotationally connected to the jacking plate through a rotating shaft, a ratchet wheel is coaxially connected to the rotating shaft, the ratchet wheel is clamped with one end of a ratchet pawl, the other end of the ratchet pawl is rotationally connected with a mounting plate through a pin shaft, an elastic reset device is arranged between the ratchet pawl and the mounting plate, and the mounting plate is fixedly connected to the jacking plate.

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