CN220351646U - Anti-falling device of straight-top type hydraulic lifting platform - Google Patents

Abstract

The utility model relates to the technical field of hydraulic lifting platforms, in particular to a falling prevention device of a straight-top hydraulic lifting platform, which has a simple structure, is sensitive in triggering of falling prevention actions, and has more reliable falling prevention effect through two groups of falling prevention mechanisms; the hydraulic cylinder pushes the platform to lift; the anti-falling mechanism comprises a plurality of vertical columns, a plurality of protruding blocks, a plurality of square frames, a plurality of linkage mechanisms and an auxiliary anti-falling mechanism, wherein the protruding blocks are uniformly arranged on the outer side walls of the vertical columns, one ends of the square frames are rotatably arranged on the platform, the square frames are respectively sleeved on the vertical columns, the square frames are obliquely arranged, the linkage mechanisms are arranged on the platform, the linkage mechanisms are linked with the vertical columns and drive the other ends of the square frames to be hung on the protruding blocks and in tight contact with the side walls of the vertical columns when the platform falls, the auxiliary anti-falling mechanism is arranged on the platform, and the auxiliary anti-falling mechanism locks the platform on the vertical columns.

Description

Anti-falling device of straight-top type hydraulic lifting platform

Technical Field

The utility model relates to the technical field of hydraulic lifting platforms, in particular to a falling prevention device of a straight-top hydraulic lifting platform.

Background

The straight-top hydraulic lifting platform is driven by hydraulic pressure, and when in work, the platform is lifted to a high position through hydraulic driving. The application is very wide. In order to improve the safety of the straight-top type hydraulic lifting platform, various anti-falling devices are proposed in the prior art, for example, the anti-falling device of the hydraulic lifting platform is provided in the Chinese utility model patent with the patent number of ZL202220061107.7, the device pushes the second control rod to move through the first control rod, so that the control block is separated from the second gear, the spring is further enabled to push the U-shaped frame to move, the engagement of the U-shaped frame and the tooth column is realized, the lifting platform is further fixed through the locking fixing box, and the problem that the existing hydraulic system is caused, and the falling accident is caused because goods and the platform are rapidly lowered is solved.

However, the device is complex, the falling speed difference between the lifting platform and the fixed box is relied on for the falling speed difference of the triggering device, once the falling speed difference between the lifting platform and the fixed box is reduced to the point that the falling speed difference cannot trigger the falling speed difference due to the blockage of oil sludge, the abrasion of equipment and the like, the falling failure is easily caused, and the reliability is poor.

Disclosure of Invention

In order to solve the technical problems, the utility model provides the straight-top type hydraulic lifting platform anti-falling device which is simple in structure, sensitive in triggering of anti-falling actions and more reliable in anti-falling effect through two groups of anti-falling mechanisms.

The utility model relates to a falling prevention device of a straight-top type hydraulic lifting platform, which comprises a plurality of upright posts, a platform and a hydraulic cylinder, wherein the upright posts are vertically arranged, the platform is slidably arranged on the upright posts, and the hydraulic cylinder pushes the platform to lift; the auxiliary falling prevention mechanism is arranged on the platform, and the auxiliary falling prevention mechanism locks the platform on the plurality of upright posts; during operation, the hydraulic cylinder stretches to push the platform to rise along the plurality of stand columns, the plurality of linkage mechanisms level the plurality of square frames under the driving of the plurality of stand columns in the process of rising the platform, one end of the plurality of square frames is separated from the side walls of the plurality of stand columns and the plurality of convex blocks, the platform is convenient to stably rise, after the platform rises to a designated height, the auxiliary anti-falling mechanism is operated to lock the platform on the plurality of stand columns, when unexpected falling occurs, the plurality of square frames are inclined under the driving of the plurality of stand columns, the other end of the plurality of square frames is hung on the convex blocks and closely contacted with the side walls of the plurality of stand columns, so that the platform is pulled to complete anti-falling, the anti-falling device is simple in structure, sensitive in triggering of anti-falling actions, and more reliable in anti-falling effect through the two groups of anti-falling mechanisms.

Preferably, the linkage mechanism comprises a plurality of round bars, a wheel frame, gears and push rods, wherein the plurality of round bars are uniformly arranged on the plurality of upright posts, the wheel frame is arranged on the platform, a vertical chute is arranged on the wheel frame, an intermediate shaft of the gears is slidably arranged in the sliding of the wheel frame, the gears are meshed with column rows formed by the plurality of round bars, one end of each push rod is rotationally connected with the intermediate shaft of the corresponding gear, and the lower end of each push rod is rotationally connected with the middle part of the corresponding square frame; when the platform rises, the gear rotates under the meshing action of a plurality of round bars, the gear descends along the sliding grooves of the wheel frames under the resistance of the plurality of round bars, the gear pushes the square frames to be flat through the push rods, so that the square frames are separated from the convex blocks and the upright posts.

Preferably, the device further comprises a plurality of first springs, wherein the upper ends of the first springs are respectively connected with transverse plates on intermediate shafts of the plurality of gears, the lower ends of the first springs are respectively connected with supporting plates on the lower parts of the plurality of wheel frames, and when the platform stops, the elastic force of the first springs pushes the plurality of gears to rise, so that the plurality of gears are pulled by the push rod to incline and lift the square frame; through the spring I that sets up for when the platform reached appointed height, the elasticity of a plurality of springs I promoted a plurality of gears and risen along the spout of a plurality of wheel carriers, thereby makes a plurality of gears through a plurality of push rods pulling square frame slope raise, makes the other end of a plurality of square frames hang respectively on a plurality of lugs and close on the lateral wall of a plurality of stands, makes a plurality of square frames and a plurality of lug articulates more reliably stable.

Preferably, the device further comprises a plurality of pull rods and a plurality of clamping blocks, wherein the upper ends of the pull rods are respectively and rotatably arranged on a transverse plate on a middle shaft of the gears, the clamping blocks are arranged in the middle of the pull rods, through holes matched with the pull rods are formed in supporting plates at the lower parts of the wheel frames, gaps for avoiding the clamping blocks are formed in the edges of the through holes, and the lower parts of the pull rods are slidably inserted into the through holes; the platform is lifted, the pull rods are downwards pulled and rotated before the platform is lifted, the clamping blocks are clamped at the bottom of the supporting plate, so that the springs are compressed, the gears are lowered along the sliding grooves, the square frames are placed flat through the push rods, the square frames are prevented from colliding with the convex blocks when the platform is lifted, and the lifting smoothness of the platform is improved.

Preferably, the auxiliary anti-falling mechanism comprises a plurality of sliding sleeves, a plurality of inserting rods and a plurality of springs II, wherein the sliding sleeves are arranged at the bottom of the platform, the inserting rods are respectively and slidably inserted into the sliding sleeves, the outer ends of the inserting rods are obliquely arranged downwards, one ends of the springs II are respectively connected with the sliding sleeves, the other ends of the springs II are respectively connected with the inner ends of the inserting rods, and the outer ends of the inserting rods are respectively inserted between the round rods of the upright posts by the elasticity of the springs II; when the platform rises, a plurality of inserted bars that the slope set up can be promoted the direction by a plurality of round bars, and after the platform reached appointed height, the elasticity of a plurality of springs two was inserted a plurality of inserted bars's outer ends respectively between a plurality of round bars, accomplished the supplementary anti-falling locking to the platform, improved the stability of platform.

Preferably, the rotary table further comprises a plurality of rotary plates, a plurality of hand wheels and a plurality of connecting rods, wherein the middle parts of the rotary plates are rotatably arranged on the platform through rotating shafts, the hand wheels are arranged at the middle parts of the round rods, the two ends of the rotary plates are respectively and rotatably connected with the inner ends of the connecting rods, and the outer ends of the connecting rods are respectively and rotatably connected with the inner ends of the inserting rods; when the platform descends, the rotating plates are rotated through the plurality of hand wheels, the plurality of inserting rods are pulled through the plurality of connecting rods at the two ends of the plurality of rotating plates respectively, the outer ends of the plurality of inserting rods are separated from the plurality of round rods, a plurality of inserting rods and a plurality of round rods are unlocked, and the practicality is good.

Compared with the prior art, the utility model has the beneficial effects that: during operation, the hydraulic cylinder stretches to push the platform to rise along the plurality of stand columns, the plurality of linkage mechanisms level the plurality of square frames under the driving of the plurality of stand columns in the process of rising the platform, one end of the plurality of square frames is separated from the side walls of the plurality of stand columns and the plurality of convex blocks, the platform is convenient to stably rise, after the platform rises to a designated height, the auxiliary anti-falling mechanism is operated to lock the platform on the plurality of stand columns, when unexpected falling occurs, the plurality of square frames are inclined under the driving of the plurality of stand columns, the other end of the plurality of square frames is hung on the convex blocks and closely contacted with the side walls of the plurality of stand columns, so that the platform is pulled to complete anti-falling, the anti-falling device is simple in structure, sensitive in triggering of anti-falling actions, and more reliable in anti-falling effect through the two groups of anti-falling mechanisms.

Drawings

FIG. 1 is a schematic diagram of the structure of the present utility model;

FIG. 2 is a schematic diagram of the front view of the present utility model;

FIG. 3 is a schematic view of a partial enlarged structure at A in FIG. 1;

FIG. 4 is a schematic diagram of the structure of the block and linkage mechanism;

fig. 5 is a schematic diagram of the structure of the linkage mechanism and the like in an exploded state;

FIG. 6 is a schematic structural view of the auxiliary fall protection mechanism and the like;

the reference numerals in the drawings: 1. a column; 2. a platform; 3. a hydraulic cylinder; 4. a bump; 5. a block; 6. a round bar; 7. a wheel carrier; 8. a gear; 9. a push rod; 10. a first spring; 11. a pull rod; 12. a clamping block; 13. a sliding sleeve; 14. a rod; 15. a second spring; 16. a rotating plate; 17. a hand wheel; 18. and (5) connecting a rod.

Detailed Description

In order that the utility model may be readily understood, a more complete description of the utility model will be rendered by reference to the appended drawings. This utility model may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Examples

The anti-falling device of the straight-top type hydraulic lifting platform comprises a plurality of upright posts 1, a platform 2 and a hydraulic cylinder 3, wherein the upright posts 1 are vertically arranged, the platform 2 is slidably arranged on the upright posts 1, and the hydraulic cylinder 3 pushes the platform 2 to lift; the anti-falling mechanism is characterized by further comprising a plurality of protruding blocks 4, a plurality of square frames 5, a plurality of linkage mechanisms and an auxiliary anti-falling mechanism, wherein the protruding blocks 4 are uniformly arranged on the outer side walls of the plurality of upright posts 1, one ends of the plurality of square frames 5 are rotatably arranged on the platform 2, the plurality of square frames 5 are respectively sleeved on the plurality of upright posts 1, the plurality of square frames 5 are obliquely arranged, the linkage mechanisms are arranged on the platform 2, the plurality of linkage mechanisms are linked with the plurality of upright posts 1 and drive the other ends of the plurality of square frames 5 to hang on the protruding blocks 4 and tightly contact with the side walls of the plurality of upright posts 1 when the platform 2 falls, the auxiliary anti-falling mechanism is arranged on the platform 2, and the auxiliary anti-falling mechanism locks the platform 2 on the plurality of upright posts 1.

During operation, the hydraulic cylinder 3 stretches to push the platform 2 to rise along the plurality of upright posts 1, in the process of rising of the platform 2, the plurality of square frames 5 are placed flat under the driving of the plurality of upright posts 1 by the plurality of linkage mechanisms, one ends of the plurality of square frames 5 are separated from the side walls of the plurality of upright posts 1 and the plurality of convex blocks 4, the platform 2 is convenient to stably rise, after the platform 2 rises to a designated height, the platform 2 is locked on the plurality of upright posts 1 by the auxiliary anti-falling mechanism, when accidental falling occurs, the plurality of square frames 5 are inclined under the driving of the plurality of upright posts 1 by the plurality of linkage mechanisms, the other ends of the plurality of square frames 5 are hung on the convex blocks 4 and are tightly contacted with the side walls of the plurality of upright posts 1, so that the platform 2 is pulled to complete anti-falling, the anti-falling device is simple in structure, the triggering of anti-falling action is sensitive, and the anti-falling effect is more reliable through the two groups of anti-falling mechanisms.

As shown in fig. 3, 4 and 5, the linkage mechanism comprises a plurality of round bars 6, a wheel frame 7, a gear 8 and a push rod 9, wherein the plurality of round bars 6 are uniformly arranged on the plurality of upright posts 1, the wheel frame 7 is arranged on the platform 2, a vertical chute is arranged on the wheel frame 7, the middle shaft of the gear 8 is slidably arranged in the sliding of the wheel frame 7, the gear 8 is meshed with a column row formed by the plurality of round bars 6, one end of the push rod 9 is rotatably connected with the middle shaft of the gear 8, and the lower end of the push rod 9 is rotatably connected with the middle part of the square frame 5; the device further comprises a plurality of first springs 10, wherein the upper ends of the first springs 10 are respectively connected with transverse plates on intermediate shafts of the plurality of gears 8, the lower ends of the first springs 10 are respectively connected with supporting plates on the lower parts of the plurality of wheel frames 7, and when the platform 2 stops, the elasticity of the first springs 10 pushes the plurality of gears 8 to rise, so that the plurality of gears 8 pull the square frame 5 to tilt and lift through the push rod 9; still include a plurality of pull rods 11 and a plurality of fixture block 12, the upper end of a plurality of pull rods 11 rotates respectively and installs on the diaphragm on the jackshaft of a plurality of gears 8, and the middle part of a plurality of pull rods 11 all sets up fixture block 12, and the layer board of the lower part of a plurality of wheel carriers 7 is provided with the through-hole that matches with pull rod 11, and the through-hole edge sets up the breach of dodging fixture block 12, and the lower part slip cartridge of a plurality of pull rods 11 is in a plurality of through-holes.

When the platform 2 rises, the gear 8 rotates under the meshing action of the round rods 6, the gear 8 descends along the sliding grooves of the wheel frames 7 under the resistance of the round rods 6, the gear 8 pushes the square frames 5 to be flat through the push rods 9, so that the square frames 5 are separated from the convex blocks 4 and the upright posts 1, when the platform 2 falls, the gear 8 rotates under the meshing action of the round rods 6, the gear 8 ascends along the sliding grooves of the wheel frames 7 under the resistance of the round rods 6, the gear 8 pulls the square frames 5 to incline and lift through the push rods 9, the other ends of the square frames 5 are hung on the convex blocks 4 and closely contact with the side walls of the upright posts 1, the platform 2 is pulled to finish anti-falling, the reaction is sensitive, the driving is reliable, when the platform 2 reaches a designated height through the first spring 10, the elastic force of the first spring pushes the square frames 8 to rise along the sliding grooves of the wheel frames 7, so that the square frames 8 are pulled by the push rods 9 to incline and lift, the other ends of the square frames 5 are respectively hung on the convex blocks 4 and abutted to the upright posts 4, the side walls of the square frames 5 are pulled by the push rods 9, the square frames 2 can be smoothly pressed down along the side walls of the convex frames 4, and the side walls of the square frames 2 are compressed by the side walls of the flat frames 2, and the flat frames 2 can be prevented from being pushed down by the side frames 2, and the side frames 2 are further compressed by the side frames 2 to be more than the side frames 11 to be more normal, and the side frames are compressed to the side frames 2 to be more normal, and the side frames are lifted to be lifted down.

As shown in fig. 6, the auxiliary anti-falling mechanism comprises a plurality of sliding sleeves 13, a plurality of inserting rods 14 and a plurality of second springs 15, wherein the sliding sleeves 13 are arranged at the bottom of the platform 2, the inserting rods 14 are respectively and slidably inserted into the sliding sleeves 13, the outer ends of the inserting rods 14 are obliquely downward arranged, one ends of the second springs 15 are respectively connected with the sliding sleeves 13, the other ends of the second springs 15 are respectively connected with the inner ends of the inserting rods 14, and the outer ends of the inserting rods 14 are respectively inserted between the round rods 6 of the upright posts 1 by the elastic force of the second springs 15; the rotary table further comprises a plurality of rotary plates 16, a plurality of hand wheels 17 and a plurality of connecting rods 18, wherein the middle parts of the rotary plates 16 are rotatably arranged on the platform 2 through rotating shafts, the hand wheels 17 are arranged at the middle parts of the round rods 6, the two ends of the rotary plates 16 are respectively and rotatably connected with the inner ends of the connecting rods 18, and the outer ends of the connecting rods 18 are respectively and rotatably connected with the inner ends of the inserting rods 14.

When the platform 2 rises, a plurality of inserted bars 14 that the slope set up can be promoted the direction by a plurality of round bars 6, after the platform 2 reached appointed height, the elasticity of a plurality of springs two 15 inserts respectively between a plurality of round bars 6 with the outer end of a plurality of inserted bars 14, accomplish the supplementary anti-falling locking to the platform 2, improve the stability of platform 2, when the platform 2 descends, rotate the swivel plate 16 through a plurality of hand wheels 17, the both ends of a plurality of swivel plate 16 are respectively through a plurality of connecting rods 18 pulling a plurality of inserted bars 14 for the outer end of a plurality of inserted bars 14 breaks away from between a plurality of round bars 6, realize a plurality of inserted bars 14 and a plurality of round bars 6 unblock, the practicality is good.

As shown in fig. 1 to 6, in the anti-falling device for a straight-top type hydraulic lifting platform, when the anti-falling device works, firstly, a hydraulic cylinder 3 stretches to push a platform 2 to lift along a plurality of upright posts 1, during the lifting process of the platform 2, a gear 8 rotates under the meshing action of a plurality of round rods 6, the gear 8 descends along the sliding grooves of wheel frames 7 under the resistance of the plurality of round rods 6, the gear 8 pushes a square frame 5 to be flat through a push rod 9, one end of the square frame 5 is separated from the side walls of the plurality of upright posts 1 and a plurality of convex blocks 4, the platform 2 is convenient to lift stably, then after the platform 2 is lifted to a designated height, the elastic force of a plurality of springs 10 pushes the plurality of gears 8 to lift along the sliding grooves of the plurality of wheel frames 7, so that the plurality of gears 8 pull the square frame 5 to lift obliquely through the plurality of push rods 9, the other ends of the square frame 5 are respectively hung on the plurality of convex blocks 4 and abutted against the side walls of the plurality of upright posts 1, the outer ends of the inserting rods 14 are respectively inserted between the round rods 6 by the elastic force of the springs II 15, the platform 2 is locked on the upright posts 1, then when accidental falling occurs, the gear 8 rotates under the meshing action of the round rods 6, the gear 8 rises along the sliding grooves of the wheel frame 7 under the resistance of the round rods 6, the gear 8 pulls the square frame 5 to be obliquely lifted through the push rod 9, the other ends of the square frame 5 are hung on the convex blocks 4 and closely contacted with the side walls of the upright posts 1, the platform 2 is pulled to complete anti-falling, finally, when the platform 2 descends, the rotating plate 16 is rotated through the hand wheels 17, the two ends of the rotating plate 16 pull the inserting rods 14 through the connecting rods 18 respectively, the outer ends of the inserting rods 14 are separated from the round rods 6, the plurality of pull rods 11 are pulled downwards and rotated to enable the plurality of clamping blocks 12 to be clamped at the bottom of the supporting plate, so that the plurality of first springs 10 are compressed, the plurality of gears 8 are lowered along the sliding grooves, the plurality of square frames 5 are placed flat through the plurality of push rods 9, and the operating platform 2 can be smoothly lowered.

The main functions realized by the utility model are as follows:

1. the triggering of the anti-falling action is sensitive;

2. through two sets of anti-falling mechanisms, the anti-falling effect is more reliable.

The anti-falling device of the straight-top type hydraulic lifting platform has the advantages that the installation mode, the connection mode or the setting mode of the anti-falling device is a common mechanical mode, and the anti-falling device can be implemented as long as the beneficial effects of the anti-falling device can be achieved; the hydraulic cylinder 3, the second spring 15 and the first spring 10 of the anti-falling device of the straight-top hydraulic lifting platform are purchased in the market, and a person skilled in the art only needs to install and operate according to the attached instruction of the person, and the person skilled in the art does not need to carry out creative labor.

All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present utility model, and these modifications and variations should also be regarded as the scope of the utility model.

Claims (6)

1. The anti-falling device of the straight-top type hydraulic lifting platform comprises a plurality of upright posts (1), a platform (2) and a hydraulic cylinder (3), wherein the upright posts (1) are vertically arranged, the platform (2) is slidably arranged on the upright posts (1), and the hydraulic cylinder (3) pushes the platform (2) to lift; the anti-falling mechanism is characterized by further comprising a plurality of protruding blocks (4), a plurality of square frames (5), a plurality of linkage mechanisms and an auxiliary anti-falling mechanism, wherein the protruding blocks (4) are uniformly arranged on the outer side walls of the plurality of upright posts (1), one ends of the plurality of square frames (5) are rotatably arranged on the platform (2), the plurality of square frames (5) are respectively sleeved on the plurality of upright posts (1), the plurality of square frames (5) are obliquely arranged, the linkage mechanisms are arranged on the platform (2), the linkage mechanisms are linked with the plurality of upright posts (1) and drive the other ends of the plurality of square frames (5) to be hung on the protruding blocks (4) and in tight contact with the side walls of the plurality of upright posts (1) when the platform (2) falls, the auxiliary anti-falling mechanism is arranged on the platform (2), and the auxiliary anti-falling mechanism locks the platform (2) on the plurality of upright posts (1).

2. The anti-falling device for the straight-top type hydraulic lifting platform according to claim 1, wherein the linkage mechanism comprises a plurality of round rods (6), a wheel frame (7), gears (8) and push rods (9), the plurality of round rods (6) are uniformly arranged on the plurality of upright posts (1), the wheel frame (7) is arranged on the platform (2), a vertical chute is arranged on the wheel frame (7), an intermediate shaft of the gears (8) is slidably arranged in the sliding of the wheel frame (7), the gears (8) are meshed with column rows formed by the plurality of round rods (6), one ends of the push rods (9) are rotatably connected with the intermediate shaft of the gears (8), and the lower ends of the push rods (9) are rotatably connected with the middle part of the square frame (5).

3. The anti-falling device of the straight-top type hydraulic lifting platform according to claim 2, further comprising a plurality of first springs (10), wherein the upper ends of the first springs (10) are respectively connected with a transverse plate on an intermediate shaft of the plurality of gears (8), the lower ends of the first springs (10) are respectively connected with a supporting plate on the lower part of the plurality of wheel frames (7), and when the platform (2) is stopped, the elastic force of the first springs (10) pushes the plurality of gears (8) to rise, so that the plurality of gears (8) pull the square frame (5) to incline through the push rod (9).

4. The anti-falling device of the straight-top type hydraulic lifting platform according to claim 2 or 3, further comprising a plurality of pull rods (11) and a plurality of clamping blocks (12), wherein the upper ends of the pull rods (11) are respectively rotatably installed on a transverse plate on a middle shaft of the plurality of gears (8), the clamping blocks (12) are arranged in the middle of the plurality of pull rods (11), through holes matched with the pull rods (11) are formed in supporting plates at the lower parts of the plurality of wheel frames (7), gaps for avoiding the clamping blocks (12) are formed in edges of the through holes, and the lower parts of the plurality of pull rods (11) are slidably inserted into the through holes.

5. The anti-falling device of the straight-top type hydraulic lifting platform according to claim 2, wherein the auxiliary anti-falling mechanism comprises a plurality of sliding sleeves (13), a plurality of inserting rods (14) and a plurality of second springs (15), the sliding sleeves (13) are arranged at the bottom of the platform (2), the inserting rods (14) are respectively and slidably inserted into the sliding sleeves (13), the outer ends of the inserting rods (14) are obliquely arranged downwards, one ends of the second springs (15) are respectively connected with the sliding sleeves (13), the other ends of the second springs (15) are respectively connected with the inner ends of the inserting rods (14), and the outer ends of the inserting rods (14) are respectively inserted between the round rods (6) of the upright posts (1) by the elastic force of the second springs (15).

6. The straight-top type hydraulic lifting platform anti-falling device according to claim 5, further comprising a plurality of rotating plates (16), a plurality of hand wheels (17) and a plurality of connecting rods (18), wherein the middle parts of the rotating plates (16) are rotatably arranged on the platform (2) through rotating shafts, the hand wheels (17) are arranged at the middle parts of the round rods (6), two ends of the rotating plates (16) are respectively and rotatably connected with the inner ends of the connecting rods (18), and the outer ends of the connecting rods (18) are respectively and rotatably connected with the inner ends of the inserting rods (14).