Device for measuring depth of pile hole

Abstract

The invention relates to the technical field of compaction pile construction, and discloses a pile hole depth measuring device, which comprises a frame body placed on the ground on the outer side of a pile hole; the upper part of the vertical rod is hinged with the frame body through a hinged support; the balancing weight is arranged at the lower end of the vertical rod; the range finder is mounted on the lower side of the balancing weight and faces the bottom of the pile hole; the copper plate is connected to the upper end of the vertical rod; the magnet is mounted on the frame body and positioned on the upper side of the copper plate; a gap is formed between the magnet and the copper plate; the distance measuring instrument supported by the vertical rod is used for measuring the depth of the pile hole, the structure is simple, operation is convenient, a measuring rope does not need to be wound and unwound, the distance measuring instrument can be fast and stable through electromagnetic damping, meanwhile, it can be guaranteed that the measuring direction of the distance measuring instrument is vertically downward all the time, and the measuring accuracy and efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of compaction pile construction, and in particular to a device for measuring the depth of a pile hole. Background Art

[0002] Compaction piles are a common foundation treatment method. The main functions of compaction piles include increasing the bearing capacity of the foundation, reducing the compressibility of the foundation, eliminating the collapse of the foundation, and improving the stability of the foundation.

[0003] The traditional method for measuring the depth of pile bottom sediment at the construction site is to measure the distance by tying a plumb bob under a measuring rope. During measurement, the construction workers need to hold the measuring rope. On the one hand, it cannot remain stable throughout the measurement process. The measuring rope will shake slightly for a long time during the measurement process, causing the distance display value to jump. On the other hand, when measuring after the plumb bob touches the bottom, it cannot be guaranteed that the measuring direction of the measuring rope is always vertically downward, and there may be errors in the measurement. Summary of the invention

[0004] The object of the present invention is to provide a device for measuring the depth of a pile hole in order to solve the above-mentioned problems in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A device for measuring the depth of a pile hole, comprising: The frame is placed on the ground outside the pile hole; A vertical rod, the upper part of which is hinged to the frame through a hinge seat; A counterweight block is arranged at the lower end of the vertical rod; a distance meter, mounted on the underside of the counterweight and facing the bottom of the pile hole; Copper plate, connected to the upper end of the vertical rod; The magnet is installed on the frame and located on the upper side of the copper plate; there is a gap between the magnet and the copper plate.

[0006] Furthermore, the hinge seat includes a square frame connected to the frame body, a rotating shaft is rotatably connected inside the square frame, a rectangular frame is provided in the middle of the vertical rod, and the middle of the rotating shaft passes through the inner side of the middle of the rectangular frame; a secondary shaft is vertically connected to the rotating shaft, and the secondary shaft is rotatably connected to the rectangular frame.

[0007] Furthermore, a first conical cover is connected to the upper part of the frame, and a plurality of magnets are evenly arranged on the lower side of the first conical cover; a second conical cover is connected to the upper end of the vertical rod, and a plurality of copper plates are evenly arranged on the upper side of the second conical cover.

[0008] Furthermore, a plurality of iron plates are evenly arranged on the upper side of the second conical cover, and the iron plates and the copper plates are alternately arranged in a circle; and the first conical cover is horizontally rotatably connected to the frame.

[0009] Furthermore, the hinge seat is connected to the transverse plate, a vertical guide rod is arranged on the frame, and the guide rod passes through the transverse plate and is slidably connected to the transverse plate.

[0010] Furthermore, a door-shaped sub-frame is connected to the upper middle part of the frame body, a height-adjustable lifting plate is provided on the inner side of the sub-frame, a vertical axis is connected to the upper side of the first conical cover, the vertical axis passes through the lifting plate and is rotatably connected to the lifting plate; a turntable is connected to the upper end of the vertical axis, a plurality of radial grooves are provided on the upper side of the turntable; and a movable handle is also included, which cooperates with the radial grooves to limit the rotation of the turntable.

[0011] Furthermore, a vertical rack is provided in the sub-frame, the end of the lifting plate slides vertically along the sub-frame, a sliding seat and a sliding body that slides horizontally through the sliding seat are provided on the upper side of the lifting plate, teeth that cooperate with the rack are provided on the side of the sliding body facing the rack, a protrusion is provided on the outer side of one end of the sliding body near its teeth, a spring is connected between the sliding seat and the protrusion, and the spring causes the sliding body to move toward the rack.

[0012] Furthermore, the slide seat and the sliding body are provided in two groups and are symmetrically arranged at the two ends of the upper side of the lifting plate, and the two sides of the movable handle are connected to the sliding bodies at the two ends of the lifting plate by ropes.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a distance meter supported by a vertical rod to measure the depth of a pile hole, which has a simple structure and is easy to operate. It is unnecessary to retract or release a measuring rope. The distance meter can be quickly stabilized through electromagnetic damping, and the measuring direction of the distance meter can be ensured to always be vertically downward, thereby improving the measurement accuracy and efficiency. The present invention forms stable electromagnetic damping by using multiple groups of copper plates and magnets evenly distributed around the circumference, and makes the vertical rod and the rangefinder quickly stabilize and maintain stability through electromagnetic damping in multiple directions, effectively suppressing slight swing of the vertical rod, which is beneficial to improving the measurement accuracy; The rangefinder of the present invention is located at the center of the upper end of the pile hole when in use. The magnet can cooperate with the iron plate through rotation and lifting to absorb and lift the vertical rod and the rangefinder, so that the height of the rangefinder is increased, which is convenient for storage of the device. The present invention can adjust the height of the magnet and thus adjust the damping effect through the cooperation of the sliding body, the movable handle and the turntable, and can also limit the rotation of the turntable and the magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0015] Figure 2 This is a schematic diagram of the structure of the third embodiment of the present invention.

[0016] Figure 3 It is a schematic diagram of the three-dimensional structure of embodiment 3 of the present invention.

[0017] Figure 4It is a schematic diagram of the hinge seat structure of the present invention.

[0018] Figure 5 This is a schematic diagram of the sub-frame structure of embodiment 3 of the present invention.

[0019] Figure 6 This is a schematic diagram of a lifting plate and its connection structure according to Embodiment 3 of the present invention.

[0020] Figure 7 Schematic diagram of magnet distribution in embodiments 2 and 3 of the present invention.

[0021] Figure 8 It is a schematic diagram of the upper structure of the second cone cover in embodiments 2 and 3 of the present invention.

[0022] In the figure: 1, frame; 2, vertical rod; 3, hinge seat; 4, counterweight; 5, rangefinder; 6, copper plate; 7, magnet; 8, guide rod; 9, first cone cover; 10, second cone cover; 11, iron plate; 12, sub-frame; 13, lifting plate; 14, vertical axis; 15, turntable; 16, radial groove; 17, movable handle; 18, slide seat; 19, sliding body; 20, rope; 21, spring; 22, rack; 201. rectangular frame; 31. square frame; 32. rotating shaft; 33. secondary shaft; 34. horizontal plate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "provided with" that may appear should be understood in a broad sense. For example, the object "provided with" may be a part of the body, or may be arranged separately from the body and connected to the body, and the connection may be a detachable connection or an inseparable connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Specific embodiment 1 of the device for measuring the depth of a pile hole provided by the present invention: See also Figure 1 and Figure 4 A device for measuring the depth of a pile hole comprises a frame 1, a vertical rod 2, a counterweight 4, a rangefinder 5, a copper plate 6 and a magnet 7.

[0026] The frame 1 is door-shaped and is placed on the ground outside the pile hole; both ends of the frame 1 are supported on the ground, and the middle part of the frame 1 is located above the hole opening of the compacted pile hole.

[0027] The upper part of the vertical rod 2 is hinged to the frame 1 through a hinge seat 3; the hinge seat 3 includes a horizontal square frame 31 connected to the frame 1, and the middle part of the inner side of the square frame 31 is rotatably connected to a rotating shaft 32. A rectangular frame 201 is provided in the middle of the vertical rod 2, and the middle part of the rotating shaft 32 passes through the middle part of the inner side of the rectangular frame 201; the rotating shaft 32 is vertically connected to a horizontal secondary shaft 33, and the two ends of the secondary shaft 33 are rotatably connected to the two side walls of the rectangular frame 201.

[0028] The hinge seat 3 enables the vertical rod 2 to swing in two horizontal directions respectively, so that the vertical rod 2 can swing freely to a vertical state under the action of gravity.

[0029] The counterweight block 4 is arranged at the lower end of the vertical rod 2. The counterweight block 4 applies a downward force to overcome the friction force at the hinge seat 3, so that the vertical rod 2 can be in a vertical state.

[0030] The rangefinder 5 is installed at the lower side of the counterweight 4 and faces the bottom of the pile hole. The rangefinder 5 can be an ultrasonic rangefinder 5 or a laser rangefinder 5. The height of the probe end of the rangefinder 5 is the same as the height of the lower end of the frame 1, that is, the probe end of the rangefinder 5 is at the same height as the ground.

[0031] The vertical rod 2 in the vertical state enables the rangefinder 5 to vertically downwardly detect the depth of the pile hole to ensure the accuracy of the depth measurement. The vertical rod 2 is used to replace the traditional measuring rope, and the measuring rope does not need to be retracted and released for a long time, which helps to improve the measurement efficiency.

[0032] After the frame 1 is placed, in the process of making the vertical rod 2 vertical simply by relying on the gravity of the counterweight 4, the vertical rod 2 swings slightly for a long time, resulting in low measurement efficiency; In this embodiment, an electromagnetic damping structure is provided, which includes a copper plate 6 and a magnet 7. The copper plate 6 is connected to the upper end of the vertical rod 2; the magnet 7 is mounted on the frame 1 and located on the upper side of the copper plate 6; and there is a gap between the magnet 7 and the copper plate 6.

[0033] When the vertical rod 2 swings, the vertical rod 2 drives the copper plate 6 to move under the magnet 7; according to Faraday's law of electromagnetic induction, when the relative angle between the copper plate 6 and the magnet 7 changes, the copper plate 6 will cut the magnetic flux lines, causing the magnetic flux passing through the copper plate 6 to change, and an induced electromotive force will be generated in the copper plate 6. The copper plate 6 is a conductor, and an induced current will be generated under the action of the induced electromotive force. According to Lenz's law, the magnetic field generated by the induced current will hinder the change of the magnetic flux that causes the induced current, that is, hinder the relative movement between the copper plate 6 and the magnet 7, which is manifested as the damping of the copper plate 6 on a macroscopic scale. When the angle of the copper plate 6 relative to the magnet 7 changes, in addition to electromagnetic induction, eddy currents will also be generated inside the copper plate 6. Eddy currents will also generate magnetic fields, interact with the external magnetic field, and hinder the movement of the copper plate 6.

[0034] The electromagnetic damping effect can make the vertical rod 2 stop swinging quickly and stop in a vertical state, which is conducive to ensuring the stability of the vertical rod 2 in the vertical state. Then the value measured by the rangefinder 5 is the pile hole depth. This greatly improves the efficiency and accuracy of the rangefinder 5 in measuring distance.

[0035] Specific embodiment 2 of the device for measuring the depth of pile holes provided by the present invention: See also Figure 7 and Figure 8 The difference between this embodiment and the first embodiment is that: a first conical cover 9 is connected to the upper part of the frame 1, and a plurality of magnets 7 are evenly arranged on the circumference of the lower side of the first conical cover 9; a second conical cover 10 is connected to the upper end of the vertical rod 2, and a plurality of copper plates 6 are evenly arranged on the circumference of the upper side of the second conical cover 10.

[0036] A plurality of iron plates 11 are evenly arranged on the upper side of the second conical cover 10 , and the iron plates 11 and the copper plates 6 are alternately arranged circumferentially; the first conical cover 9 is horizontally rotatably connected to the frame 1 .

[0037] In this embodiment, the number of the magnet 7 , the number of the copper plate 6 and the number of the iron plate 11 are all four.

[0038] Since the probe end at the lower end of the rangefinder 5 is supported by the frame 1 and at the same height as the ground, when the rangefinder 5 corresponds to the pile hole, the rangefinder 5 is not disturbed by the ground. When the entire device is placed on a flat ground, the rangefinder 5 will contact the ground or even be hit by the ground, causing the rangefinder 5 to be damaged.

[0039] In this embodiment, the hinge seat 3 is connected to the horizontal plate 34, that is, the horizontal plates 34 are connected to both sides of the square frame 31, and two vertical guide rods 8 are arranged at the lower side of the middle part of the frame body 1. The two guide rods 8 pass through the ends of the two horizontal plates 34 respectively and are slidably connected with the horizontal plates 34; the lower end of the guide rod 8 is provided with a limit block to realize the lower limit of the horizontal plate 34, the hinge seat 3 and the vertical rod 2. When the hinge seat 3 and the vertical rod 2 are located at the lower limit position, that is, the horizontal plate 34 is located at the lower end of the guide rod 8, the lower end probe of the rangefinder 5 is at the same height as the ground.

[0040] When the device is not in use, the first conical cover 9 is rotated so that the four magnets 7 are located on the upper sides of the four iron plates 11 on the upper sides of the four second conical covers 10. The magnets 7 will attract the iron plates 11 and make the iron plates 11 rise to a certain height. The iron plates 11 drive the second conical cover 10, the vertical rod 2, the hinge seat 3, the counterweight 4 and the rangefinder 5 to rise slightly by a certain distance, and the horizontal plate 34 rises by a certain distance along the guide rod 8. At this time, the height of the rangefinder 5 rises slightly by a certain distance, and the lower end of the rangefinder 5 is higher than the lower end of the frame 1. When the device is placed, the rangefinder 5 will not hit the ground, reducing the damage to the rangefinder 5.

[0041] During use, when the device is placed on the upper side of the pile hole for depth measurement, the gaps between the four magnets 7 correspond to the upper side of the four copper plates 6, and the multiple groups of copper plates 6 and magnets 7 evenly distributed around the circumference form a four-way stable electromagnetic damping. The electromagnetic damping in four directions makes the vertical rod 2 and the rangefinder 5 quickly stabilized and remain stable during use, which is conducive to improving the measurement accuracy. When the copper plate 6 swings, the copper plate 6 is a horizontal distance away from the vertical rod 2 relative to the first embodiment. With the same slight swing, the position and angle of the copper plate 6 change more obviously, the electromagnetic damping effect is stronger, and there are multiple multi-directional electromagnetic damping, which can more effectively suppress the slight swing of the vertical rod 2. Therefore, the distribution form of the copper plates 6 and the magnets 7 of this embodiment has a better damping effect on the slight swing of the vertical rod 2; before use, the vertical rod 2 can be manually stabilized to avoid the violent swing of the vertical rod 2. This embodiment can quickly stop the slight swing of the vertical rod 2.

[0042] Specific embodiment 3 of the device for measuring the depth of pile holes provided by the present invention: See also Figure 2-8 In the second embodiment, the vertical rod 2 and the rangefinder 5 can rise to a relatively small height. On some uneven ground, it cannot be guaranteed that the rangefinder 5 will not collide with the ground when the device is placed. In addition, during use, the vertical gap between the copper plate 6 and the magnet 7 cannot be adjusted, so that the damping effect cannot adjust the intensity. And the adsorption connection between the magnet 7 and the iron plate 11 sometimes requires manual assistance.

[0043] Therefore, in this embodiment, a door-shaped sub-frame 12 is connected to the upper middle side of the frame body 1, and a through hole is provided in the middle of the frame body 1 for the first conical cover 9 and the second conical cover 10 to pass through. A height-adjustable lifting plate 13 is provided inside the sub-frame 12, and a vertical shaft 14 is connected to the upper side of the first conical cover 9, and the vertical shaft 14 passes through the lifting plate 13 and is rotatably connected to the lifting plate 13; a limit ring is provided on the outer side of the vertical shaft 14 on the lower side of the lifting plate 13, so that the vertical shaft 14 can only rotate relative to the lifting plate 13 but cannot move vertically relative to the lifting plate 13. A turntable 15 is connected to the upper end of the vertical shaft 14, and a plurality of radial grooves 16 are provided on the upper side of the turntable 15 along the diameter direction of the turntable 15, and the number of radial grooves 16 is four; in this embodiment, a frame-shaped movable handle 17 is provided, and the movable handle 17 cooperates with the radial groove 16 to limit the rotation of the turntable 15, and the movable handle 17 leaves the radial groove 16, and the turntable 15 can rotate.

[0044] Two vertical grooves are symmetrically provided on the inner side of the sub-frame 12, and both grooves are located in the vertical part of the sub-frame 12. Vertical racks 22 are provided in the grooves. The ends of the lifting plate 13 slide vertically along the sub-frame 12. Both ends of the lifting plate 13 are horizontally U-shaped, and both ends of the U-shaped lifting plate 13 are respectively attached to the two vertical parts of the sub-frame 12 to slide vertically.

[0045] A slide seat 18 and a sliding body 19 that slides horizontally through the slide seat 18 are provided on the upper side of the lifting plate 13. The sliding body 19 is provided with teeth that cooperate with the rack 22 on the side facing the rack 22. A protrusion is provided on the outer side of the sliding body 19 near one end of the teeth. A plurality of springs 21 are connected between the slide seat 18 and the protrusion, and the springs 21 enable the sliding body 19 to move toward the rack 22.

[0046] Two groups of slide seats 18 and sliding bodies 19 are provided, and the two groups are symmetrically arranged at the two ends of the upper side of the lifting plate 13 . Both sides of the movable handle 17 and the sliding bodies 19 at the two ends of the lifting plate 13 are connected by ropes 20 .

[0047] The rope 20 is made of non-elastic material. When the spring 21 moves the sliding body 19 outward until the teeth of the sliding body 19 extend into the teeth of the rack 22 to form a vertical limit, the sliding body 19 tightens the rope 20, the lower wall of the movable handle 17 extends into the radial groove 16, and the lifting plate 13 cannot move vertically; at this time, the movable handle 17 can limit the rotation of the turntable 15, the vertical shaft 14 and the first conical cover 9. When the movable handle 17 is manually moved up to disengage from the radial groove 16, the turntable 15, the vertical shaft 14 and the first conical cover 9 can rotate freely. During the upward movement of the movable handle 17, the sliding body 19 is moved toward the center of the lifting plate 13 through the rope 20, and the spring 21 is compressed, the teeth of the sliding body 19 are separated from the rack 22, and the lifting plate 13 can also move freely vertically.

[0048] The lifting and lowering of the lifting plate 13 and the rotation of the first conical cover 9, combined with the position and function of the magnet 7: through the height adjustment of the lifting plate 13, the height of the first conical cover 9 and the magnet 7 can be adjusted, and then the vertical spacing between the magnet 7 and the copper plate 6 and the iron plate 11 can be adjusted, which is specifically manifested in that the damping strength between the magnet 7 and the copper plate 6 can be changed respectively, and the magnet 7 can directly fit with the iron plate 11 to form a magnetic connection with the iron plate 11. After the movable handle 17 is separated from the turntable 15, not only the height of the lifting plate 13 and the first conical cover 9 can be adjusted, but also the turntable 15 and the first conical cover 9 can be rotated. The rotation of the first conical cover 9 adjusts the position of the magnet 7. When measuring the depth, the magnet 7 corresponds to the copper plate 6 vertically, and when the device is stored, the magnet 7 corresponds to the iron plate 11.

[0049] The lifting plate 13 can drive the first conical cover 9 to move up a long distance along the sub-frame 12. After the magnet 7 adsorbs the iron plate 11, the lifting plate 13 drives the first conical cover 9, the second conical cover 10, the vertical rod 2, the counterweight 4 and the rangefinder 5 to rise together for a long distance. The magnetic attraction of multiple magnets 7 and the iron plate 11 can stably adsorb the second conical cover 10, the vertical rod 2, the counterweight 4 and the rangefinder 5. Compared with the second embodiment, the rangefinder 5 of this embodiment rises to a higher height and is far away from the ground. On uneven ground, the device can be safely placed to prevent the rangefinder 5 from colliding with the ground.

[0050] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for measuring the depth of a pile hole, characterized in that: include: The frame (1) is placed on the ground outside the pile hole; A vertical rod (2), the upper portion of which is hingedly connected to the frame (1) via a hinge seat (3); A counterweight (4) is arranged at the lower end of the vertical rod (2); A distance meter (5) is mounted on the lower side of the counterweight (4) and faces the bottom of the pile hole; A copper plate (6) connected to the upper end of the vertical rod (2); The magnet (7) is mounted on the frame (1) and is located on the upper side of the copper plate (6); a gap is provided between the magnet (7) and the copper plate (6).

2. The device for measuring the depth of a pile hole according to claim 1, characterized in that: The hinge seat (3) comprises a square frame (31) connected to the frame body (1); a rotating shaft (32) is rotatably connected inside the square frame (31); a rectangular frame (201) is provided in the middle of the vertical rod (2); the middle of the rotating shaft (32) passes through the inner side of the middle of the rectangular frame (201); the rotating shaft (32) is vertically connected to a secondary shaft (33); the secondary shaft (33) is rotatably connected to the rectangular frame (201).

3. The device for measuring the depth of a pile hole according to claim 1, characterized in that: The upper part of the frame (1) is connected to a first conical cover (9), and a plurality of magnets (7) are evenly arranged on the lower side of the first conical cover (9); the upper end of the vertical rod (2) is connected to a second conical cover (10), and a plurality of copper plates (6) are evenly arranged on the upper side of the second conical cover (10).

4. The device for measuring the depth of a pile hole according to claim 3, characterized in that: A plurality of iron plates (11) are evenly arranged on the upper side of the second conical cover (10), and the iron plates (11) and the copper plates (6) are alternately arranged in a circle; and the first conical cover (9) is horizontally rotatably connected to the frame (1).

5. The device for measuring the depth of a pile hole according to claim 4, characterized in that: The hinge seat (3) is connected to the transverse plate (34), and a vertical guide rod (8) is arranged on the frame body (1). The guide rod (8) passes through the transverse plate (34) and is slidably connected to the transverse plate (34).

6. The device for measuring the depth of a pile hole according to claim 5, characterized in that: The frame body (1) is connected to a door-shaped sub-frame (12) on the upper side of the middle part, and a height-adjustable lifting plate (13) is provided on the inner side of the sub-frame (12). A vertical shaft (14) is connected to the upper side of the first conical cover (9), and the vertical shaft (14) passes through the lifting plate (13) and is rotatably connected to the lifting plate (13). A turntable (15) is connected to the upper end of the vertical shaft (14), and a plurality of radial grooves (16) are provided on the upper side of the turntable (15). The frame body (1) also includes a movable handle (17), and the movable handle (17) cooperates with the radial grooves (16) to limit the rotation of the turntable (15).

7. The device for measuring the depth of a pile hole according to claim 6, characterized in that: A vertical rack (22) is provided in the sub-frame (12), the end of the lifting plate (13) slides vertically along the sub-frame (12), a slide seat (18) and a sliding body (19) passing through the slide seat (18) and sliding horizontally are provided on the upper side of the lifting plate (13), a tooth matching with the rack (22) is provided on the side of the sliding body (19) facing the rack (22), a protrusion is provided on the outer side of one end of the sliding body (19) close to the tooth, a spring (21) is connected between the sliding seat (18) and the protrusion, and the spring (21) enables the sliding body (19) to move toward the rack (22).

8. The device for measuring the depth of a pile hole according to claim 7, characterized in that: The sliding seat (18) and the sliding body (19) are provided in two groups and are symmetrically arranged at the two ends of the upper side of the lifting plate (13); the two sides of the movable handle (17) and the sliding bodies (19) at the two ends of the lifting plate (13) are connected by ropes (20).

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