Multi-stage dust-blocking and stone-removing groove for movable intelligent cleaning between hydraulic supports

Abstract

The application discloses a movable intelligent cleaning multi-stage dust falling baffle slot between hydraulic supports, each end head of adjacent hydraulic supports is provided with a slide rail to form a slide rail group, a baffle slot main body is slidably arranged below the slide rail group, the baffle slot main body is divided into an upper layer falling slag area, a middle layer vibration filtering area and a lower layer dust accumulation cleaning area along the cross section of the baffle slot main body, the slide rail comprises horizontal slide rails and inclined slide rails, the baffle slot main body horizontal section is provided with a vertical telescopic connecting assembly, the baffle slot main body inclined section is provided with an inclined telescopic connecting assembly, the vibration filtering area comprises a vibration layer and a filtering layer, the vibration layer comprises an adsorbing carbon plate layer, a piezoelectric ceramic sheet layer, a protective steel plate layer and an alternating current power supply box for applying an alternating voltage signal to the piezoelectric ceramic sheet layer, a fan is arranged on the baffle slot main body corresponding to the end of the vibration filtering area, and a dust collecting box is arranged at the end of the dust accumulation cleaning area, and the application has the advantages of wind negative pressure adsorption, improved mine environment, multi-stage dust falling, no interference to hydraulic support shifting and the like.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic support relocation and dust suppression technology, specifically relating to a movable, intelligent, multi-stage dust suppression and gangue blocking trough for use between hydraulic supports. Background Technology

[0002] The hydraulic support relocation area is a major dust-generating area in fully mechanized mining faces, accounting for approximately 10% of total dust generation during processes such as support lowering, pushing, relocation, and raising. Currently, my country's coal demand has driven the development of ultra-high mining height fully mechanized mining methods. With increasing mining height, the support height of the hydraulic supports in fully mechanized mining faces also increases. During support relocation, dust falls from the support beams at a faster rate and over a wider area, with most of the dust falling into the walkway, directly threatening the lives of miners. Besides dust, falling incompletely broken gangue or coal chunks also pose significant safety hazards and harm miners' health. Currently, dust suppression mainly relies on spraying, but this doesn't consider the humid and harsh environment of the mine tunnels. Spraying further increases air humidity, exacerbating the already poor mine tunnel environment and further impacting miners' health. Furthermore, there is a lack of timely classification and treatment of coal chunks, gangue, and dust, and no consideration is given to the impact and pressure of large coal chunks and gangue falling and accumulating over time on the retaining chutes, creating safety hazards. Summary of the Invention

[0003] This invention aims to provide a movable, intelligent, multi-stage dust suppression and gangue blocking trough for use between hydraulic supports, which improves the working environment, provides efficient multi-stage dust suppression, and solves the problems of current methods that mainly use spraying, which leads to more humid air and exacerbates the harsh environment of mine roadways, and the lack of classification and timely drainage of coal chunks, gangue and dust, resulting in large coal chunks and gangue falling and long-term accumulation of impact and heavy pressure on the gangue blocking trough.

[0004] Therefore, the technical solution adopted by this invention is as follows: a movable intelligent cleaning multi-stage dust suppression and gangue blocking trough for hydraulic supports, wherein a slide rail is installed on the inner side of each of two adjacent hydraulic support ends to form a slide rail assembly, and a gangue blocking trough body is slidably installed below the slide rail assembly. The cross-section of the gangue blocking trough body is divided into an upper slag falling area, a middle vibration filtering area, and a lower dust accumulation cleaning area. The gangue blocking trough body is generally obtuse-angled inverted "L" shape. The slide rail includes a horizontal slide rail located above the corresponding horizontal section of the gangue blocking trough body and an inclined slide rail located above the corresponding inclined section of the gangue blocking trough body. The horizontal section of the gangue blocking trough body is provided with a vertically retractable connecting component that can slide along the horizontal slide rail, and the inclined section of the gangue blocking trough body is provided with an inclinedly retractable connecting component that can slide along the inclined slide rail. The retractable distance of the vertically retractable connecting component is related to the hydraulic... The descent distance of the hydraulic support during movement is adapted to the descent distance of the hydraulic support. The arc length and angle of the inclined telescopic connecting component are adapted to the arc length and angle of the tail beam lifting during hydraulic support movement. The vibration filtering zone includes a vibration layer that guides coal and gangue to roll out of the main body of the gangue blocking trough and a filter layer located below the vibration layer. The vibration layer is provided with through holes for dust to pass through. The vibration layer includes an adsorption carbon plate layer, a piezoelectric ceramic plate layer, and a protective steel plate layer laid from bottom to top, as well as an AC power supply box for applying alternating voltage signals to the piezoelectric ceramic plate layer. A fan is installed at the end of the vibration filtering zone. The fan is used to adsorb the falling dust onto the filter layer through negative pressure. The vibration layer can not only shake off coal and gangue but also shake off the dust on the filter layer to the ash cleaning area. A dust collection box is installed at the end of the ash cleaning area.

[0005] As a preferred embodiment of the above solution, the vertically retractable connecting assembly includes a square sleeve vertically installed on the inner wall of the horizontal section of the main body of the gangue retaining chute and a movable connecting block vertically passing through the square sleeve. The movable connecting block has horizontal pulleys symmetrically arranged on the top left and right sides that slide along the horizontal slide rail, and a limiting baffle at the bottom to prevent it from detaching from the square sleeve. An infrared detector is installed on the inner side of the movable connecting block near the bottom. When the infrared detector detects that the coal gangue exceeds the preset dwell range, the AC power box is activated through the control console to cause the vibration layer to vibrate, thereby shaking off the remaining coal gangue. It can not only allow the coal gangue to slide down by its own weight, but also provide an external force to help it slide down if the coal gangue is too heavy or too light to rely on its own weight. The structural design is ingenious.

[0006] More preferably, the inclined retractable connection assembly includes an arc-shaped sleeve installed on the inner wall of the inclined section of the main body of the rock-blocking trough and a movable connecting arc block passing through the arc-shaped sleeve. The movable connecting arc block is provided with inclined pulleys that slide along the inclined slide rail on the left and right sides of the top, and an anti-detachment block is provided at the bottom to prevent it from detaching from the arc-shaped sleeve. The structure is reasonably designed.

[0007] More preferably, the vibration layer located in the horizontal section of the main body of the gangue retaining trough extends downwards with a specific decreasing trend and smoothly transitions to the vibration layer located in the inclined section of the main body of the gangue retaining trough. The entire inclined angle is greater than 10°. The downward inclined angle of the vibration layer located in the inclined section of the main body of the gangue retaining trough is greater than the angle of the downward inclined section of the main body of the gangue retaining trough. This effectively prevents coal gangue from falling directly out of the inclined section and causing it to scatter in all directions when it falls to the ground due to its high descent speed. This minimizes the impact of gangue on the equipment while guiding the coal gangue into the goaf.

[0008] Preferably, the starting end of the horizontal section of the main body of the waste rock blocking trough is provided with a baffle that covers and is higher than the vibration filtering area and the dust collection cleaning area. The dust collection cleaning area is equipped with a cleaning scraper that fits with the arc-shaped inner wall of the horizontal section of the main body of the waste rock blocking trough, two sets of steel wires that pull the cleaning scraper at the front and rear respectively, and a drive motor that provides pulling force for the steel wires on the same side. This allows the cleaning scraper to move along the inner wall of the main body of the waste rock blocking trough and clean the dust accumulated in the horizontal section of the main body of the waste rock blocking trough to the inclined section. The rotating shaft of the drive motor is equipped with a steel wire drum that collects the steel wires on the same side. The drive motors at the front and rear sides rotate at the same speed and in the same direction through the control console.

[0009] The baffle at the beginning of the horizontal section of the main body of the gangue blocking trough forms a semi-enclosed space, which enhances the negative pressure effect of the fan. The motor rotates at the same speed and in the same direction, ensuring smooth back-and-forth movement of the cleaning scraper. The structure is ingeniously designed.

[0010] A further preferred embodiment features a centrally mounted nozzle facing the inclined section of the waste trough. The other side of the cleaning scraper is mounted on a baffle via multiple telescopic tubes. These tubes house a water supply pipe connected to the nozzle. The baffle has a through-hole for the water supply pipe to pass through. The water supply pipe is connected to a solenoid valve controlled by a control console. When the drive motor is activated to move the cleaning scraper and scrape dust, the control console simultaneously activates the solenoid valve, spraying a small amount of water to prevent dust from scattering during cleaning. This also increases the weight of the dust, facilitating the scraper to move the dust to the inclined section where it falls due to its own weight. The structure is ingeniously designed with interconnected components.

[0011] More preferably, the filter layer adopts an array of filter cartridges, which has low cost, good dust filtration effect, and is easy to install; the main body of the waste rock blocking trough is made of rigid material, which is not easy to deform and has a long service life.

[0012] Preferably, the fan is equipped with protective nets at the front and rear, and a downward-facing air guide duct is provided at the air outlet end of the fan. The main body of the slag-blocking trough is equipped with dust concentration monitors at intervals in the slag discharge area. The output power of the fan can be adjusted through the control panel according to the dust concentration. When the dust concentration is high, the fan power is increased to enhance the negative pressure suction effect and ensure that most of the dust is adsorbed into the filter cartridge. When the dust concentration is low, the fan power is reduced to save electricity costs.

[0013] Further preferably, the ends of the horizontal slide rail and the inclined slide rail are provided with limit blocks to prevent the vertical and inclined retractable connecting components from leaving the rails. In the initial state, the vertical retractable connecting component closest to the inclined section of the main body of the retaining trough is held in place by the limit blocks, which is a reasonable structural design.

[0014] The beneficial effects of this invention are:

[0015] (1) Compared with the current dust suppression measures of equipment, which use spraying and do not classify coal blocks, gangue and dust, this scheme uses the synergistic effect of vibration filter zone and fan to separate gangue and dust; at the same time, the generated dust is treated in multiple stages. First, the coal blocks and dust are separated by vibration filter zone. The coal blocks roll down along the vibration zone, and the dust is adsorbed onto the filter layer by the negative pressure of the fan. The vibration layer shakes the coal blocks and gangue off and also shakes the dust on the filter layer to the dust collection and cleaning area. Then the dust is cleaned into the dust collection box. There is no need for excessive spraying to suppress dust. It is adsorbed by the negative pressure of the wind. Therefore, it will not cause the air to become more humid and aggravate the harsh environment of the mine roadway. The structural design is ingenious.

[0016] (2) The vertically retractable connecting component can extend to a distance that is compatible with the descent distance of the hydraulic support during the movement of the hydraulic support. The arc length and angle of the obliquely retractable connecting component can extend to a distance that is compatible with the arc length and angle of the tail beam when the hydraulic support is moved. This avoids conflicts during the movement of the hydraulic support. The gap between the hydraulic supports is compensated by the vertically retractable connecting component and the obliquely retractable connecting component. During the descent, extension, and lifting of the hydraulic support on one side, the main body of the retaining trough moves with the hydraulic support on one side. The horizontal slide rail provides the space for horizontal movement in the front and back. The vertically retractable connecting component and the oblique slide rail provide the space for vertical movement. The obliquely retractable connecting component provides the space for the tail beam of the hydraulic support to be lifted. The structure is interlocked and the design is ingenious.

[0017] In summary, this invention has advantages such as wind-driven negative pressure adsorption, improvement of the mine environment, multi-stage dust reduction, and undisturbed hydraulic support relocation. Attached Figure Description

[0018] Figure 1 This is an installation diagram for a mobile, intelligent, multi-stage dust suppression and waste rock trap.

[0019] Figure 2 This is a schematic diagram of a mobile, intelligent, multi-stage dust suppression and waste rock trap.

[0020] Figure 3 for Figure 2 The cross-sectional view shows the direction of the coal and gangue, indicated by the arrows.

[0021] Figure 4 This is a structural diagram of a vertically retractable connecting component.

[0022] Figure 5 This is a structural diagram of an obliquely retractable connection component.

[0023] Figure 6 This is a structural breakdown diagram of the vibrating layer. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0025] Combination Figure 1 — Figure 6 As shown, a movable intelligent cleaning multi-stage dust suppression and gangue blocking trough for hydraulic supports is provided. Each of the inner sides of the ends of two adjacent hydraulic supports a is equipped with a slide rail 1 to form a slide rail group. A gangue blocking trough body 2 is slidably installed below the slide rail group.

[0026] The slide rail 1 consists of a horizontal slide rail 11 located above the horizontal section of the corresponding rock-blocking trough body 2 and an inclined slide rail 12 located above the inclined section of the corresponding rock-blocking trough body 2.

[0027] Limiting blocks are provided at the ends of both the horizontal slide rail 11 and the inclined slide rail 12 to prevent the vertical telescopic connecting component 21 and the inclined telescopic connecting component 22 from leaving the track. In the initial state, the vertical telescopic connecting component 21 closest to the inclined section of the main body 2 of the rock slag trough is held in place by the limiting blocks.

[0028] The cross-section of the main body 2 of the waste rock trough is divided into an upper slag drop zone, a middle vibration filtration zone 3, and a lower ash cleaning zone 4.

[0029] The main body 2 of the rock-blocking trough is in the shape of an obtuse-angled inverted "L", and the main body 2 of the rock-blocking trough is adapted to the outline of the left and right side frames of the hydraulic support a.

[0030] The main body 2 of the rock-blocking trough is preferably made of rigid material.

[0031] The horizontal section of the main body 2 of the rock-blocking trough is provided with a vertically retractable connecting component 21 that can slide along the horizontal slide rail 11.

[0032] The inclined section of the main body 2 of the rock-blocking trough is provided with an inclined telescopic connecting component 22 that can slide along the inclined slide rail 12.

[0033] The vertically retractable connecting assembly 21 can be extended to a distance that is adapted to the descent distance of the hydraulic support during relocation.

[0034] The slanted telescopic connection component 22 has a telescopic arc length and angle that adapts to the arc length and angle of the tail beam lifting when the hydraulic support is moved.

[0035] The vertically retractable connecting assembly 21 consists of a square sleeve 211 vertically installed on the inner wall of the horizontal section of the main body 2 of the rock-blocking trough and a movable connecting block 212 that passes vertically through the square sleeve 211.

[0036] The movable connecting block 212 has horizontal pulleys 213 that slide along the horizontal slide rail 11 symmetrically on the top left and right, and a limiting baffle 214 at the bottom to prevent it from detaching from the square sleeve 211.

[0037] An infrared detector 215 is installed on the inner side of the active connecting block 212 near the bottom.

[0038] When the infrared detector 215 detects that the coal and gangue exceed the preset dwell range, the AC power box is activated via the control console, causing the vibration layer 31 to vibrate.

[0039] The oblique telescopic connection assembly 22 consists of an arc-shaped sleeve 221 installed on the inner wall of the inclined section of the main body 2 of the rock-blocking trough and a movable connecting arc block 222 passing through the arc-shaped sleeve 221.

[0040] The movable connecting arc block 222 has symmetrical left and right inclined pulleys 223 that slide along the inclined slide rail 12 at the top, and anti-detachment block 224 at the bottom to prevent detachment from the arc sleeve 221.

[0041] The vibration layer 31 located in the horizontal section of the main body 2 of the waste rock retaining channel extends downward with a specific attenuation trend and smoothly transitions to the vibration layer 31 located in the inclined section of the main body 2 of the waste rock retaining channel, and the inclination angle of the entire section is greater than 10°.

[0042] The vibration layer 31 located in the inclined section of the main body 2 of the gangue retaining trough has a downward tilt angle greater than that of the downward tilt section of the main body 2 of the gangue retaining trough.

[0043] The main body 2 of the gangue blocking trough has a baffle 23 at the beginning of the horizontal section that covers and is higher than the vibration filtering zone 3 and the ash cleaning zone 4.

[0044] The vibrating filter zone 3 consists of a vibrating layer 31 that guides coal blocks and gangue to roll out of the main body 2 of the gangue blocking trough and a filter layer 32 located below the vibrating layer 31.

[0045] The vibrating layer 31 has through holes running through its top and bottom to allow dust to pass through.

[0046] The vibration layer 31 consists of an adsorbent carbon plate layer 311, a piezoelectric ceramic plate layer 312, a protective steel plate layer 313 laid from bottom to top, and an AC power supply box that applies an alternating voltage signal to the piezoelectric ceramic plate layer 312.

[0047] A fan 33 is installed at the end of the vibration filter zone 3.

[0048] The fan 33 is used to adsorb the falling dust onto the filter layer 32 through negative pressure.

[0049] The fan 33 is equipped with protective nets 331 at the front and rear, and a guide tube 34 with the outlet facing downward is provided at the air outlet end of the fan 33.

[0050] The filter layer 32 uses filter cartridges arranged in an array.

[0051] The main body 2 of the slag-retaining trough is equipped with a dust concentration monitor in the slag-falling area, which can adjust the output power of the fan 33 through the control console according to the dust concentration.

[0052] The vibrating layer 31 can not only shake off coal and gangue, but also shake off the dust on the filter layer 32 to the ash cleaning area 4.

[0053] A dust collection box is installed at the end of the dust collection area 4.

[0054] The dust cleaning area 4 is equipped with a cleaning scraper 41 that fits the arc-shaped inner wall of the horizontal section of the main body 2 of the ash removal channel, two sets of steel wires 42 that pull the cleaning scraper 41 from the front and back respectively, and a drive motor that provides pulling force for the steel wires 42 on the same side. This allows the cleaning scraper 41 to move along the inner wall of the main body 2 of the ash removal channel, cleaning the dust accumulated in the horizontal section of the main body 2 of the ash removal channel to the inclined section.

[0055] The rotating shaft of the drive motor is equipped with a wire drum 43 that houses the wires 42 on the same side, and the drive motors on the front and rear sides rotate at the same speed and in the same direction through the control console.

[0056] The cleaning scraper 41 is centrally mounted with a nozzle that faces the inclined section of the main body 2 of the waste rock trough. The other side of the cleaning scraper 41 is mounted on the baffle 23 via a multi-section telescopic tube 411. The multi-section telescopic tube 411 is used to house the water supply pipe connected to the nozzle. The baffle 23 has a through hole for the water supply pipe to pass through. The water supply pipe is connected to a solenoid valve controlled by the control console.

[0057] When the drive motor is started to move the cleaning scraper 41 to scrape dust, the control panel simultaneously activates the solenoid valve.

Claims

1. A movable, intelligent, multi-stage dust suppression and waste rock blocking trough for use between hydraulic supports, characterized in that: Each of the inner sides of two adjacent hydraulic supports (a) is equipped with a slide rail (1) to form a slide rail group. A slidable sluice body (2) is installed below the slide rail group. The cross section of the sluice body (2) is divided into an upper slag drop area, a middle vibration filter area (3), and a lower ash cleaning area (4). The sluice body (2) is generally obtuse-angled inverted "L" shape. The slide rail (1) includes a horizontal slide rail (11) located above the horizontal section of the corresponding sluice body (2). The inclined section of the main body (2) of the rock-blocking trough (2) is equipped with a vertically retractable connecting component (21) that can slide along the horizontal sliding rail (11), and an inclined section of the main body (2) of the rock-blocking trough (2) is equipped with an inclined retractable connecting component (22) that can slide along the inclined sliding rail (12). The retractable distance of the vertically retractable connecting component (21) is adapted to the descent distance when the hydraulic support moves. The extendable arc length and angle are adapted to the arc length and angle of the tail beam lifting when the hydraulic support is moved. The vibration filter zone (3) includes a vibration layer (31) that guides coal and gangue to roll out of the main body (2) of the gangue blocking trough and a filter layer (32) located below the vibration layer (31). The vibration layer (31) is provided with through holes for dust to pass through from top to bottom. The vibration layer (31) includes an adsorption carbon plate layer (311), a piezoelectric ceramic plate layer (312), and a protective steel layer laid from bottom to top. The plate layer (313) and the AC power supply box for applying alternating voltage signals to the piezoelectric ceramic plate layer (312) are provided. A fan (33) is installed at the end of the vibration filter zone (3). The fan (33) is used to adsorb the falling dust onto the filter layer (32) by negative pressure. The vibration layer (31) can not only shake off coal and gangue but also shake off the dust on the filter layer (32) to the ash cleaning zone (4). A dust collection box is installed at the end of the ash cleaning zone (4).

2. The movable intelligent cleaning multi-stage dust suppression and gangue blocking trough for hydraulic supports according to claim 1, characterized in that: The vertically retractable connection assembly (21) includes a square sleeve (211) vertically installed on the inner wall of the horizontal section of the main body (2) of the gangue chute and a movable connection block (212) vertically passing through the square sleeve (211). The movable connection block (212) is provided with horizontal pulleys (213) symmetrically arranged on the top left and right sides, which slide along the horizontal slide rail (11), and a limiting baffle (214) is provided at the bottom to prevent it from falling off the square sleeve (211). An infrared detector (215) is installed on the inner side of the movable connection block (212) near the bottom. When the infrared detector (215) detects that the coal block gangue exceeds the preset dwell range, the AC power box is started through the control console, which causes the vibration layer (31) to vibrate.

3. A movable, intelligent, multi-stage dust suppression and waste rock-blocking trough for use between hydraulic supports according to claim 2, characterized in that: The inclined retractable connection assembly (22) includes an arc sleeve (221) installed on the inner wall of the inclined section of the main body (2) of the rock sluice and a movable connecting arc block (222) passing through the arc sleeve (221). The movable connecting arc block (222) has symmetrical inclined pulleys (223) that slide along the inclined slide rail (12) on the top left and right, and anti-detachment blocks (224) at the bottom to prevent detachment from the arc sleeve (221).

4. A movable, intelligent, multi-stage dust suppression and waste rock-blocking trough for use between hydraulic supports according to claim 1, characterized in that: The vibration layer (31) located in the horizontal section of the main body (2) of the gangue retaining trough has a specific attenuation trend and extends downwards and smoothly transitions to the vibration layer (31) located in the inclined section of the main body (2) of the gangue retaining trough. The entire inclined angle is greater than 10°. The downward inclined angle of the vibration layer (31) located in the inclined section of the main body (2) of the gangue retaining trough is greater than the downward inclined angle of the main body (2) of the gangue retaining trough.

5. A movable, intelligent, multi-stage dust suppression and waste rock blocking trough for use between hydraulic supports according to claim 1, characterized in that: The horizontal section of the main body (2) of the gangue blocking trough is provided with a baffle (23) that covers and is higher than the vibration filter area (3) and the dust collection cleaning area (4). The dust collection cleaning area (4) is equipped with a cleaning scraper (41) that fits the arc-shaped inner wall of the horizontal section of the main body (2), two sets of steel wires (42) that pull the cleaning scraper (41) at the front and back respectively, and a drive motor that provides pulling force for the steel wire (42) on the same side. This allows the cleaning scraper (41) to move along the inner wall of the main body (2) of the gangue blocking trough and clean the dust accumulated in the horizontal section of the main body (2) of the gangue blocking trough to the inclined section. The rotating shaft of the drive motor is equipped with a steel wire drum (43) that collects the steel wire (42) on the same side. The drive motors on the front and back sides rotate at the same speed and in the same direction through the control console.

6. A movable, intelligent, multi-stage dust suppression and waste rock-blocking trough for use between hydraulic supports, as described in claim 5, is characterized in that: The cleaning scraper (41) is centrally mounted with a nozzle that faces the inclined section of the main body (2) of the waste trough. The other side of the cleaning scraper (41) is mounted on the baffle (23) via a multi-section telescopic tube (411). The multi-section telescopic tube is used to house the water supply pipe connected to the nozzle. The baffle (23) has a through hole for the water supply pipe to pass through. The water supply pipe is connected to a solenoid valve controlled by the control console. When the drive motor is started to move the cleaning scraper (41) to scrape dust, the control console simultaneously turns on the solenoid valve.

7. A movable, intelligent, multi-stage dust suppression and waste rock blocking trough for use between hydraulic supports according to claim 4, characterized in that: The filter layer (32) is made of an array of filter cylinders, and the main body (2) of the gangue blocking trough is made of rigid material.

8. A movable, intelligent, multi-stage dust suppression and waste rock blocking trough for use between hydraulic supports according to claim 1, characterized in that: The blower (33) is equipped with a protective net (331) at the front and rear, and a guide tube (34) with the outlet facing downward is provided at the air outlet end of the blower (33). The main body (2) of the slag discharge area is equipped with a dust concentration monitor, which can adjust the output power of the blower (33) according to the dust concentration through the control console.

9. A movable, intelligent, multi-stage dust suppression and waste rock blocking trough for use between hydraulic supports according to claim 1, characterized in that: The ends of the horizontal slide rail (11) and the inclined slide rail (12) are provided with limit blocks, and the vertical telescopic connecting component (21) closest to the inclined section of the main body (2) of the rock sluice is held in place by the limit blocks in the initial state.

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