Arrangement and matching method of fully mechanized caving working face in steeply inclined thick coal seam

Abstract

The present invention discloses a method for matching a fully mechanized caving working face with a high-inclination thick coal seam: ① A four-quadrant high-inclination coal mining machine and a scraper conveyor with anti-skid measures are selected. The scraper conveyor adopts a simple tail and a single motor drive for the head. The tail has no driving part, that is, the driving part is on the lower side of the working face, and there is no driving part on the upper side. ② A method for opening a cutting eye on a high-inclination working face: a semi-coal-rock tunnel is excavated in the lower chute, and coal skin is reserved in the lower section of the working face so that the angle between the bottom plate of the lower working face and the bottom plate of the tunnel is less than 25 degrees. The coal retention length of the bottom plate of the lower working face is 10-15m, which provides favorable conditions for the subsequent arrangement of hydraulic supports for mining. ③ An end support is arranged in the lower chute, and three transition frames are arranged adjacent to the end support on the lower working face. Middle supports are arranged in the rest of the places. No transition support is arranged on the upper working face. When the inclination angle of the working face changes, the length of the working face also changes, so it is convenient to increase or decrease the middle support.

Description

Technical Field

[0001] The invention relates to a matching method for arranging a fully mechanized caving working face in a thick coal seam with a large inclination angle. Background Art

[0002] my country has abundant and widely distributed coal reserves. With the reduction of thick and extra-thick coal seams with excellent storage conditions in the central and eastern mining areas, how to improve the mining efficiency of thick coal seams with high dip angles in the northwest has become an increasingly urgent issue. Coal seams with dip angles below 25° are gently inclined coal seams, and those with dip angles greater than 25° are collectively referred to as steeply inclined coal seams. The use of fully mechanized caving in steeply inclined thick coal seams is due to the large dip angle of the working face, complex geological conditions, large changes in the length of the working face during mining, and difficulty in controlling the stability of the fully mechanized caving support. At present, the fully mechanized caving in steeply inclined thick coal seams has developed more slowly than that in gently inclined coal seams. The main reason is that the storage conditions of steeply inclined coal seams are complex, the requirements for fully mechanized mining equipment, especially hydraulic supports, are extremely high, and safety assurance measures are extremely difficult. One-time mining of full-height and high-angle working faces is widely used in southwest my country, and high-angle fully-mechanized top-caving is also partially used in Gansu. The main problem reflected is the poor adaptability of the equipment. The support manufacturers have also adjusted the adaptability of the supports for high-angle working faces, but there is relatively little research on the cutting design and equipment matching of high-angle working faces, support structure, and especially the end head to prevent the support from sliding down. Summary of the invention

[0003] The purpose of the present invention is to provide a method for arranging a fully-mechanized caving working face in a thick coal seam with a large inclination angle, thereby providing a guarantee for the efficient mining of the fully-mechanized caving working face with a large inclination angle.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions.

[0005] A matching method for arranging a fully mechanized caving working face in a thick coal seam with a large inclination angle.

[0006] ① Select a four-quadrant high-angle coal mining machine and a scraper conveyor with anti-skid measures. The scraper conveyor adopts a simple tail and is driven by a single motor at the head, that is, the tail is not driven by a motor and a reducer, the drive part is on the lower side of the working surface, and there is no drive part on the upper side.

[0007] ② Method of opening cutting holes in the fully mechanized caving working face with large inclination angle.

[0008] When excavating rock tunnels, reserve coal skin at the lower section of the working face so that the angle between the lower working face floor and the tunnel floor is less than 25 degrees, and the length of coal left on the lower working face floor is 10-15m; this provides favorable conditions for the subsequent arrangement of hydraulic supports for mining.

[0009] ③Arrange end supports in the tunnel, arrange three transition frames on the lower working surface, and arrange middle supports on the upper working surface to facilitate the addition of middle supports.

[0010] The end bracket adopts a main end bracket and a sub-end bracket. The two brackets are lowered alternately to ensure that the end bracket as a whole does not leave the position, thereby ensuring that the working surface bracket does not slide down; the scraper conveyor head bottom bracket slides on the sub-frame base, reducing friction resistance and utilizing the movement of the front and rear scraper conveyor heads; at the same time, it is also beneficial to the relative distance between the scraper conveyor sprocket center and the transfer machine center to stabilize the coal, so that the coal can be ejected to the center of the transfer machine, reducing the workload of manual coal removal.

[0011] In the large-angle working surface, due to the large inclination angle, the width of the top beam of the middle support is designed to be 1.36 meters. It is a double-sided movable structure that can extend and retract on both sides at the same time. The side push stroke is increased to 200mm, and the width range of the middle support is 1.36-1.76m. The adjustable width of the support is 140mm. When the support slides down, the adjustment speed of the top beam of the support is accelerated, and two teams can adjust the support.

[0012] The main reinforcement of the top beam is fixed, and the other end is fixed to the corresponding side guard plate to achieve the extension and retraction of the side guard plate. Side push jack. The bottom adjustment mechanism of the middle bracket includes a bottom adjustment beam, a front bottom adjustment jack and a rear bottom adjustment jack. The front and rear bottom adjustment jacks adopt an internal liquid inlet structure. The cylinder diameter of the front bottom adjustment jack is 100mm. The bottom of the outer cylinder of the front bottom adjustment jack is hinged to the bottom adjustment beam through a front pin shaft. The fixed end of the piston rod of the front bottom adjustment jack is provided with a clamping head. The clamping head includes a neck section and a limiting section. The radial dimension of the neck section is smaller than the dimension of the piston rod body. The limiting section is rectangular in shape. The reinforcing ribs of the base are provided with a circular hole for the rod of the piston rod to pass through. A vertical long strip hole for the clamping head to pass through is provided on the inner main rib plate. The neck section is located in the vertical long strip hole. The limiting section passes through the vertical long strip and rotates 90 degrees for positioning; the bottom of the outer cylinder of the rear bottom adjustment jack is connected to the bottom adjustment The beam is hinged by a rear pin shaft, and two opposite slots are arranged on the fixed head of the fixed end of the piston rod of the rear bottom adjusting jack. A baffle is welded on the inner side of the main rib plate, and a transverse through hole is arranged on the baffle plate. Vertical holes are arranged in front and behind the transverse through hole respectively, and the vertical hole part passes through the transverse through hole. The fixed head is passed through the transverse through hole, and its slot corresponds to the vertical hole. Pin shafts are inserted in the vertical hole and the slot to realize the outer end positioning of the piston rod of the rear bottom adjusting jack; the fixing method and internal liquid inlet structure of the outer end of the piston rod of the front and rear bottom adjusting jacks increase the stroke of the front bottom adjusting jack to 190mm and the stroke of the rear bottom adjusting jack to 210mm. The front and rear bottom adjusting jacks are controlled separately, and the adjustable stroke of the inter-frame base is increased by 130mm, which increases the pushing force of the rear bottom adjusting jack of the bracket.

[0013] The bottom adjustment mechanism and the push jack are linked by the electro-hydraulic control of the hydraulic system, that is, the upper chamber of the push jack is connected with the lower chamber of the bottom adjustment jack, and the upper chamber of the push jack is filled with liquid to push the hydraulic support. At this time, the bottom adjustment mechanism is in the extended state, pushing the adjacent support below. The adjacent support supports the top plate in the initial support state and does not move, so that the base of this frame has a tendency to move upward to the working surface; the movable side guard mechanism on the lower side of the support is linked with the upper chamber of the column, that is, the upper chamber of the support is filled with liquid, and the support is separated from the top plate and lowered in height. At this time, the lower chamber of the push jack on the lower side of the support is linked with liquid, and the side guard plate is pushed out. The lower adjacent support does not move, so that the top beam of this frame has a tendency to move upward to the working surface. The above two linkage mechanisms realize the tendency of the support to move upward to the working surface as a whole, thereby ensuring that the support does not slide down.

[0014] The beneficial effects of the present invention are as follows: the present invention reduces the inclination angle of the lower working face to below 25 degrees by reserving bottom coal. After the angle of the lower working face is reduced, the downward sliding condition of the lower working face support and the head of the scraper conveyor is improved; at the same time, by improving the width of the support top beam, the double-sided retractable side guard plates, the bottom adjustment structure and the electro-hydraulic automatic control method, the coordinated effect of these parts improves the adaptability of the support to the large-angle working face, thereby realizing the smooth mining of the large-angle fully-mechanized caving working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiment of the present invention, the embodiment will be described below with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of cutting eyes in a thick coal seam with a large dip angle.

[0017] Figure 2 This is a schematic diagram of the structure of a simple tail machine and a middle support without a drive motor in a thick coal seam with a large inclination angle.

[0018] Figure 3 This is a schematic diagram of the structure supporting the machine head tunnel end frame.

[0019] Figure 4 It is a schematic diagram showing the three-dimensional structure of the double-sided movable side guard plates of the middle bracket.

[0020] Figure 5 It is a schematic diagram of the planar structure of the right side movable side thrust mechanism of the double-sided movable side guard plate.

[0021] Figure 6 It is a schematic diagram of the planar structure of the left movable side thrust mechanism of the double-sided movable side guard plate.

[0022] Figure 7 A schematic diagram showing the inter-rack base.

[0023] Figure 8 A top view schematic diagram showing the bottom adjustment mechanism on the base of the middle bracket.

[0024] Fig. 8A for Figure 8 Sectional view along AA direction.

[0025] Figure 8B for Figure 8 Cross-sectional view along the BB axis.

[0026] Fig. 9 for Figure 8 Schematic diagram of the side structure.

[0027] Fig.10 for Figure 8 Schematic diagram of the three-dimensional structure of the midsole adjustment mechanism.

[0028] Fig. 10A yes Fig.10 An enlarged structural schematic diagram of the clamp head is shown in FIG.

[0029] Fig.11 A schematic diagram of the side structure of the baffle.

[0030] Fig.12 A schematic diagram of the structure of the baffle from a top view.

[0031] Fig.13 This is the schematic diagram of the electro-hydraulic control of the hydraulic system. Implementation

[0032] The following examples are merely used to illustrate possible implementations of the present invention, but are not intended to limit the scope of the present invention, so it is necessary to explain them first.

[0033] The following specifically introduces a method for arranging a supporting method for a fully mechanized caving working face in a thick coal seam with a large inclination angle of the present invention.

[0034] ① Select a four-quadrant high-angle coal mining machine and a scraper conveyor with anti-skid measures. The scraper conveyor 1 adopts a simple tail, a single motor drive at the head, and no drive part at the tail, that is, the drive part is on the lower side of the working surface, and there is no drive part on the upper side.

[0035] ② Method of opening cutting holes in the fully mechanized caving working face with large inclination angle.

[0036] Excavation of rock tunnel 2, such as Figure 1As shown, in particular, in order to ensure the comprehensive requirements of pedestrians, transfer machine height, monorail crane transportation and ventilation, the height of the roadway of the thick coal seam with a large dip angle is generally not less than 3.5m, and a trapezoidal roadway is used for excavation, with an upper width of 4.4m and a lower width of 5.4m. Taking an 8.0m thick coal seam as an example, the coal seam dip angle is 45°, the cut eye is excavated along the bottom plate, and the height is 3.0m; the top of the upper drift is a full coal roadway, and the bottom is excavated with a rock length of about 4.16m (4157mm); the upper working face dip angle is 45°, the lower working face is the lower section of the working face, and the coal skin 3 is reserved, so that the angle between the bottom plate of the lower working face and the bottom plate of the roadway is less than 25 degrees, and the coal length of the bottom plate of the lower working face is 10-15m, which provides favorable conditions for the subsequent mining and arrangement of hydraulic supports; the top of the lower drift is excavated with a triangular rock top of about 1.37m (1368mm), and the rest is a full coal roadway. The key to this step is to reserve coal skin so that the angle between the lower working face floor and the tunnel floor is less than 25 degrees, which is also not available in the prior art.

[0037] ③ Arrange the end support in the machine head tunnel, arrange three transition frames on the lower working surface, and arrange the middle support on the upper working surface; when the inclination angle of the working surface changes, the length of the working surface also changes, so it is convenient to add or reduce the middle support.

[0038] Specifically, Figure 3 As shown, the end bracket adopts a main end bracket 4a and a sub-end bracket 4b. The two brackets are lowered alternately to ensure that the end bracket as a whole does not leave the position, thereby ensuring that the working surface bracket does not slide down; the bottom bracket of the scraper conveyor head slides on the sub-frame base, reducing friction resistance and utilizing the movement of the front and rear scraper conveyor heads; at the same time, it is also beneficial to the relative distance between the center of the scraper conveyor sprocket and the center of the transfer machine to stabilize the coal, so that the coal can be ejected to the center of the transfer machine, reducing the workload of manual coal removal.

[0039] like Figure 2 As shown, the middle bracket 5 is arranged on the upper working surface to facilitate the addition and subtraction of the middle bracket. In the past, three transition brackets were used at the tail end of the upper working surface. The transition bracket was an inverted four-link hydraulic bracket, which was connected to the scraper conveyor. Space for the drive motor was required at the front and rear ends of the bracket. In the present invention, the scraper conveyor adopts a simple tail, which has no drive motor, and the upper working surface adopts the middle bracket, which can better adapt to the change of the oblique length of the working surface caused by the continuous change of the angle of the large-angle working surface and facilitate the addition and subtraction of the middle bracket, which has a very good effect in actual use.

[0040] The width series of the middle support is generally designed according to the national standard, that is, 1.25 meters, 1.5 meters, 1.75 meters, 2.05 meters and 2.4 meters. A comparison is made for the 1.5-meter center distance comprehensive caving support: in the conventional design of the 1.5-meter comprehensive caving support, the minimum width of the top beam is generally 1.43 meters, the single-side push jack stroke is 170mm, the maximum width is 1.6 meters, the side push compression stroke is 100mm, and the adjustable width of the support is 70mm. However, in the application of large-angle working faces, due to the large inclination angle, the working face support has a downward trend in each push cycle, the adjustable width of the support top beam is small, the inclination adjustment is difficult, and the speed is slow. In response to the above problems, the width of the support top beam is designed to be a minimum of 1.36 meters, and the structure is a double-sided movable side guard plate that can be extended and retracted on both sides at the same time. The side push stroke is increased to 200mm, that is, the width range of the middle support is 1.36-1.76 meters. The adjustable width of the bracket is 140mm, which is increased from the original 70mm to 140mm. When the bracket slides down, the adjustment speed of the bracket top beam can be accelerated. Generally, two teams can adjust the bracket.

[0041] like Figures 4 to 6 As shown, the double-sided movable side thrust structure of the top beam of the middle bracket includes a right (upper) side thrust mechanism 51 and a left (lower) side thrust mechanism 52. The right side thrust mechanism includes two internal liquid-inlet side thrust jacks A511, and the two liquid inlets of the internal liquid-inlet side thrust jacks are both opened on the piston rod. The piston rod end of each internal liquid-inlet side thrust jack A is fixed to the left outer main rib plate of the top beam, and the bottom end of its outer cylinder is connected to the guide rod A512, and the guide rod A512 is connected to the right side guard plate 513; the left side thrust mechanism 52 includes two internal liquid-inlet side thrust jacks B521, and the piston rod end of each internal liquid-inlet side thrust jack B521 is fixed to the right outer main rib plate of the top beam, and the bottom end of its outer cylinder is connected to the guide rod B522, and the guide rod B522 is connected to the left side guard plate 523. The shielding beam of the middle bracket includes a double-sided movable side thrust mechanism.

[0042] The bottom adjustment mechanism of the high-angle fully mechanized caving support plays a vital role in preventing the support from sliding down. Usually, the design uses jacks of the same specifications at the front and back. Due to the limitation of the base width, the jack stroke is generally not more than 160mm. After removing the 83mm gap between the bases, the effective adjustment distance is 77mm. In the application, the rear of the support slides down seriously, the jack thrust is insufficient, and the stroke is insufficient.

[0043] like Figures 7 to 12As shown, the bottom adjustment mechanism of the base of the middle bracket 5 includes a bottom adjustment beam 531 and a bottom adjustment jack, and the bottom adjustment jack includes a front bottom adjustment jack 532 and a rear bottom adjustment jack 533. The front and rear bottom adjustment jacks adopt an internal liquid inlet structure. The cylinder diameter of the front bottom adjustment jack is 100 mm. The bottom of the outer cylinder of the front bottom adjustment jack 532 is connected to the bottom adjustment beam 531 through a front pin shaft. The fixed end of the piston rod of the front bottom adjustment jack 532 is provided with a clamping head 5321, and the clamping head 5321 includes a neck section 532a and a limiting section 532b. The radial dimension of the neck section 532a is smaller than the dimension of the piston rod body, and the limiting section 532b is in a rectangular shape. A round hole is provided on the reinforcing rib 54 for the piston rod to pass through, and a vertical long hole 550 is provided on the inner main rib plate 55 for the clamp to pass through. The neck section is located in the vertical long hole and is clearance-matched. The limiting section 532b passes through the vertical long strip and is rotated 90 degrees to achieve positioning; the cylinder diameter of the rear bottom adjustment jack 533 is 125mm, and the bottom of the outer cylinder of the rear bottom adjustment jack 533 is connected to the bottom adjustment beam 531 through a rear pin shaft. The outer wall of the fixed head 533a at the fixed end of the piston rod of the rear bottom adjustment jack 533 is provided with two opposite slots 433b, and two liquid inlets and outlets are provided on the fixed head at the outer end of the slot, one of which is connected to the upper cavity, and the other is connected to the lower cavity.

[0044] Weld the baffle 551 inside the main rib plate, such as Fig.11 and Fig.12 As shown, a transverse through hole 551a is provided on the baffle 551, and a notch 551b is connected above the transverse through hole. Vertical holes 551c are respectively provided in front and behind the transverse through hole, and the vertical hole partially passes through the transverse through hole. The fixed head is penetrated by the transverse through hole, and the slot corresponds to the vertical hole. The two liquid inlet and outlet ports on the fixed head are aligned with the notch, and a pin shaft 551d is inserted in the vertical hole 551c and the slot 433b to realize the outer end positioning of the piston rod of the rear bottom adjustment jack; the fixing method of the outer end of the piston rod of the front and rear bottom adjustment jacks and the internal liquid inlet structure of the front and rear bottom adjustment jacks increase the stroke of the front bottom adjustment jack to 190mm, and the stroke of the rear bottom adjustment jack to 210mm. The front and rear bottom adjustment jacks are controlled separately, and the adjustable stroke of the inter-frame base is increased by 130mm, which increases the pushing force of the rear bottom adjustment jack of the bracket.

[0045] like Fig.13As shown, it is the electro-hydraulic control principle diagram of the hydraulic system of the middle support. The control method: realizes the linkage between the bottom adjustment mechanism and the push jack 61 and the movable side push mechanism on the lower side of the middle support and the upper cavity of the column; the bottom adjustment mechanism and the push jack are linked: that is, the upper cavity of the push jack 61 is connected with the lower cavity of the front and rear bottom adjustment jacks, and the upper cavity of the push jack is filled with liquid, and the hydraulic support is pulled and moved. At this time, the bottom adjustment mechanism is in an extended state, pushing the adjacent support below, and the adjacent support is in an initial support state to support the top plate without moving, so that the bottom adjustment mechanism is in an extended state. The frame base has a tendency to move upward; the movable side thrust mechanism on the lower side of the middle support is linked with the upper cavity of the column: the column includes the front left column 71, the front right column 72, the rear left column 73 and the rear right column 74, that is, the upper cavity of the column is filled with liquid, and the support is separated from the coal seam roof and lowered. At this time, the side thrust jacks on the lower side of the middle support (side thrust jacks 52 of the top beam and side thrust jacks 82 of the shield beam) are linked with the lower cavity to enter the liquid, the side guard plate is pushed out, and the lower adjacent support does not move, so that the top beam of the frame has a tendency to move upward. The above two linkage mechanisms realize the upward movement trend of the support as a whole, thereby ensuring that the support does not slide down.

Claims

1. A method for arranging a fully mechanized caving working face in a thick coal seam with a large inclination angle, which is characterized by: ① Select a four-quadrant high-angle coal mining machine and a scraper conveyor with anti-skid measures. The scraper conveyor adopts a simple tail, a single motor drive at the head, and no drive part at the tail, that is, the drive part is on the lower side of the working surface, and there is no drive part on the upper side; ② Method of cutting holes in large-angle fully-mechanized caving working face: The lower trench is excavated into a semi-coal-rock tunnel, and coal skin is reserved at the lower section of the working face, so that the angle between the lower working face floor and the tunnel floor is less than 25 degrees, and the length of coal left on the lower working face floor is 10-15m, which provides favorable conditions for the subsequent arrangement of hydraulic supports for mining; ③ Arrange the end support in the lower chute, arrange three transition supports next to the end support on the lower working surface, arrange the middle supports in the rest, and no transition supports are arranged on the upper working surface. When the inclination angle of the working surface changes, the length of the working surface also changes, so it is convenient to add or remove the middle supports; The end bracket adopts the main end bracket and the auxiliary end bracket. The two brackets are lowered alternately to ensure that the end bracket does not fall out of position as a whole, thereby ensuring that the working face bracket does not slide down; the bottom bracket of the scraper conveyor head slides on the auxiliary frame base, reducing the friction resistance and utilizing the movement of the front and rear scraper conveyor heads; at the same time, it is also conducive to the relative distance between the center of the scraper conveyor sprocket and the center of the transfer machine being stable, so that the coal can be ejected to the center of the transfer machine, reducing the workload of manual coal removal; The bottom adjustment mechanism of the middle bracket includes a bottom adjustment beam, a front bottom adjustment jack and a rear bottom adjustment jack. The front and rear bottom adjustment jacks adopt an internal liquid inlet structure. The cylinder diameter of the front bottom adjustment jack is 100mm. The bottom of the outer cylinder of the front bottom adjustment jack is connected to the bottom adjustment beam through a front pin shaft. The fixed end of the piston rod of the front bottom adjustment jack is provided with a clamping head, and the clamping head includes a neck section and a limiting section. The radial dimension of the neck section is smaller than the dimension of the piston rod body. The limiting section is rectangular in shape. The reinforcing ribs of the base are provided with a circular hole for the piston rod to pass through. A vertical long strip hole for the clamping head to pass through is provided on the inner main rib plate. The neck section is gap-matched with the vertical long strip hole. After the limiting section passes through the vertical long strip hole, it is rotated 90 degrees for positioning; The bottom of the outer cylinder of the rear bottom adjustment jack is connected to the bottom adjustment beam through a rear pin shaft. Two opposite slots are arranged on the fixed head of the fixed end of the piston rod of the rear bottom adjustment jack. A baffle is welded on the inner side of the main rib plate. A transverse through hole is arranged on the baffle plate. Vertical holes are arranged in front and behind the transverse through hole respectively. The vertical hole partly penetrates the transverse through hole. Pin shafts are inserted in the vertical hole and the slot to realize the outer end positioning of the piston rod of the rear bottom adjustment jack. Through the above structure and fixing method, the front and rear bottom adjustment jacks increase the stroke of the front bottom adjustment jack to 190mm and the stroke of the rear bottom adjustment jack to 210mm. The front and rear bottom adjustment jacks are controlled separately, and the adjustable stroke of the inter-frame base is increased by 130mm, which increases the pushing force of the rear bottom adjustment jack of the bracket. Through the electro-hydraulic control of the hydraulic system, the linkage between the bottom adjustment mechanism and the push jack is realized, that is, the upper cavity of the push jack is connected with the lower cavity of the front and rear bottom adjustment jacks, and the upper cavity of the push jack is filled with liquid to push the hydraulic support. At this time, the bottom adjustment mechanism is in an extended state, giving thrust to the lower adjacent support, while the lower adjacent support is in an initial support state, supporting the top plate without moving, so that the base of this frame has a tendency to move upward to the working surface; the movable side guard mechanism on the lower side of the support is linked with the upper cavity of the column, that is, the upper cavity of the support is filled with liquid, and the support is separated from the top plate and lowered in height. At this time, the lower cavity of the push jack on the lower side of the support is linked with liquid, and the side guard plate is in a pushed-out state, and the lower adjacent support is immobile, so that the top beam of this frame has a tendency to move upward to the working surface, realizing the tendency of the overall support to move upward to the working surface, thereby ensuring that the support does not slide down.

2. The method for arranging a fully mechanized caving working face in a thick coal seam with a large inclination angle according to claim 1 is characterized in that: In the large-angle working surface, due to the large inclination angle, the width of the top beam of the middle support is designed to be 1.36 meters. It is a double-sided movable structure that can extend and retract on both sides at the same time. The side push stroke is increased to 200mm, and the width range of the middle support is 1.36-1.76m. The adjustable width of the support is 140mm. When the support slides down, the adjustment speed of the top beam of the support is accelerated, and two teams can adjust the support.

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