Hydraulic support and method of supporting

Abstract

The application discloses a hydraulic support and a supporting method, the hydraulic support comprising a support body, an electric cylinder assembly and a push rod assembly, the electric cylinder assembly being connected with the support body and arranged at the bottom of the support body, the electric cylinder assembly comprising a motor, a clutch and an electric cylinder, the output shaft of the motor and the input shaft of the electric cylinder being connected through the clutch, and the push rod assembly being connected with the output shaft of the electric cylinder. The hydraulic support of the embodiment of the application adopts the electric cylinder assembly with the clutch to drive the hydraulic support to move, the moving precision is higher, and the moving speed is faster, so that the supporting speed of the hydraulic support can follow the coal mining speed of the existing coal mining machine, and the automatic straightening of the coal mining working face can be more easily realized, and the human intervention is reduced.

Description

Technical Field

[0001] This invention relates to the field of mining equipment technology, and in particular to a hydraulic support and support method. Background Technology

[0002] Hydraulic supports are mainly used to support the roof of mechanized longwall mining faces and are used in conjunction with coal mining machines and scraper conveyors to complete automated coal mining. Existing longwall faces have large emulsion pump stations placed in the roadway, using a centralized liquid supply method, and using them as a power source to enable hydraulic supports to complete all actions such as lowering, pulling, raising and pushing the conveyor.

[0003] As coal mining machines become increasingly powerful, the moving speed of hydraulic supports needs to keep up with the traction speed of the machines. However, existing hydraulic support pushing mechanisms all use hydraulic cylinders. While hydraulic cylinders can provide significant power, their starting speed is slow and the pushing distance is not precise enough, failing to meet the two requirements mentioned above. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide a hydraulic support capable of rapid and precise movement.

[0005] The hydraulic support of this invention includes a support body, an electric cylinder assembly, and a push rod assembly. The electric cylinder assembly is connected to the support body and disposed at the bottom of the support body. The electric cylinder assembly includes a motor, a clutch, and an electric cylinder. The output shaft of the motor and the input shaft of the electric cylinder are connected through the clutch. The push rod assembly is connected to the output shaft of the electric cylinder.

[0006] The hydraulic support in this embodiment of the invention uses an electric cylinder assembly with a clutch to drive the hydraulic support to move, which has higher moving accuracy and faster moving speed. It can not only ensure that the support speed of the hydraulic support can keep up with the coal mining speed of existing coal mining machines, but also make it easier to realize automatic straightening of the working face and reduce human intervention.

[0007] In some embodiments, the support body includes:

[0008] Base;

[0009] A top beam, which is located above the base;

[0010] A linkage assembly, wherein the top beam is connected to the base via the linkage assembly;

[0011] The telescopic column has its lower end connected to the base and its upper end connected to the top beam.

[0012] In some embodiments, the linkage assembly includes:

[0013] A protective beam, the first end of which is hinged to one end of the top beam;

[0014] The rear connecting rod has its first end hinged to the second end of the shield beam, and its second end hinged to one end of the base.

[0015] A front connecting rod, the first end of which is hinged to the base, and the second end of which is hinged to the middle of the shield beam.

[0016] In some embodiments, the support body further includes a balancing cylinder, one end of which is hinged to the lower surface of the top beam, and the other end of which is hinged to the shield beam. There are two balancing cylinders, which are respectively located on both sides of the electric cylinder assembly.

[0017] In some embodiments, the electric cylinder has a trunnion, and the bracket body is provided with an ear seat, the trunnion being rotatably disposed within the ear seat.

[0018] In some embodiments, the electric cylinder assembly further includes an explosion-proof stroke sensor disposed on the outer wall of the electric cylinder along the length direction of the electric cylinder.

[0019] In some embodiments, the push rod assembly includes:

[0020] Base plate;

[0021] A push rod body is disposed on the upper surface of the base plate, and one end of the push rod body is connected to the output shaft of the electric cylinder;

[0022] A connector is connected to the other end of the push rod body, and the connector is used to connect to the scraper conveyor.

[0023] In some embodiments, the hydraulic support further includes:

[0024] A lifting bracket, comprising a U-shaped portion and a connecting portion, wherein the U-shaped portion is mounted above the push rod body and the electric cylinder and abuts against the base plate, and the connecting portion is connected to the side of the U-shaped portion away from the base plate;

[0025] A bottom-lifting cylinder is connected to the support body, and one end of the bottom-lifting cylinder is connected to the connecting part, and the piston rod of the bottom-lifting cylinder is connected to the connecting part.

[0026] In some embodiments, the clutch is a hydraulic clutch.

[0027] The support method of the second aspect of the present invention includes:

[0028] After the coal mining machine begins cutting, the motor is pre-started;

[0029] After the coal cutting is completed, the hydraulic support column is lowered. Once the column is in place, the clutch is closed and the support is pulled up.

[0030] Once the support frame is in position, disengage the clutch, cut off the power source, and the hydraulic support will move at a reduced speed until it comes to a complete stop, thus ending the support frame movement.

[0031] The hydraulic support column is raised. After the column meets the initial support force requirements, the clutch is closed and the pushing begins.

[0032] After the material is pushed into position, the clutch is disengaged, the power source is cut off, the scraper conveyor speed decreases until it stops, the pushing process ends, and the motor is turned off. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a hydraulic support according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the hydraulic support after concealing the top beam and the protective beam in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the electric cylinder of the hydraulic support in the retracted state according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the electric cylinder of the hydraulic support in the extended state according to an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the electric cylinder assembly of the hydraulic support according to an embodiment of the present invention;

[0038] Figure 6 This is a flowchart of the support method according to an embodiment of the present invention.

[0039] Figure label:

[0040] Support body 1, base 11, top beam 12, telescopic column 13, protective beam 14, rear connecting rod 15, front connecting rod 16, balance cylinder 17, lug 18.

[0041] Electric cylinder assembly 2, motor 21, clutch 22, electric cylinder 23, trunnion 231, explosion-proof stroke sensor 24.

[0042] Push rod assembly 3, base plate 31, push rod body 32, connector 33.

[0043] The base support 4, the U-shaped part 41, and the connecting part 42. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0045] like Figures 1-5 As shown, the hydraulic support of this embodiment of the invention includes a support body 1, an electric cylinder assembly 2, and a push rod assembly 3.

[0046] The support body 1 is used to support the roof of the longwall face. The electric cylinder assembly 2 is connected to the support body 1 and is located at the bottom of the support body 1. The electric cylinder assembly 2 includes a motor 21, a clutch 22, and an electric cylinder 23. The output shaft of the motor 21 and the input shaft of the electric cylinder 23 are connected through the clutch 22. One end of the push rod assembly 3 is connected to the output shaft of the electric cylinder 23, and the other end of the push rod assembly 3 is connected to the scraper conveyor. The clutch 22 is a hydraulic clutch.

[0047] Electric cylinder assembly 2 is used to push push rod assembly 3, thereby completing the pulling and sliding actions. Because the time from the start to the end of pulling the frame is very short, generally only a few seconds, while the start-up time of motor 21 is relatively long, if motor 21 only starts when pulling the frame begins, it cannot meet the time requirements. Therefore, clutch 22 connects the output shaft of motor 21 and the input shaft of electric cylinder 23. Motor 21 pre-starts, and after reaching its rated speed, clutch 22 is then engaged. When customizing motor 21, the rotational inertia of the motor rotor can be appropriately increased. The greater the rotor inertia, the longer the pre-start time of motor 21, and the more energy stored in the motor rotor. When clutch 22 is engaged, more energy is transferred to electric cylinder 23, resulting in a greater peak push-pull force and a shorter start-up time for electric cylinder 23. Another function of clutch 22 is to provide overload protection. By adjusting the pressure applied to clutch 22, the maximum transmittable torque of clutch 22 can be slightly higher than the torque corresponding to the peak push-pull force of electric cylinder 23. When the push-pull force on electric cylinder 23 is greater than its peak push-pull force, clutch 22 will slip due to overload, and then clutch 22 will be disengaged to cut off the power source and protect electric cylinder 23 from damage.

[0048] The hydraulic support in this embodiment of the invention uses an electric cylinder assembly 2 with a clutch 22 to drive the hydraulic support to move. Compared with the traditional hydraulic support, the hydraulic support in this embodiment of the invention has higher pushing accuracy and faster pushing speed. It can not only ensure that the support speed of the hydraulic support can keep up with the coal mining speed of the existing coal mining machine, but also make it easier to realize the automatic straightening of the working face and reduce human intervention.

[0049] It should be noted that the pushing and pulling force of the electric cylinder assembly 2 needs to meet the pushing and pulling force of the traditional hydraulic support. Simply increasing the power of the motor 21 can improve the pushing and pulling force and moving speed of the electric cylinder 23. However, the space in the middle of the support is limited, and in order to meet transportation requirements, when the support is lowered to its lowest position, the installation space of the electric cylinder will be further compressed in the height direction. Therefore, it is necessary to control the power of the motor 21 and make some improvements to the configuration of the hydraulic support.

[0050] like Figure 1 As shown, in some embodiments, the support body 1 includes a base 11, a top beam 12, a connecting rod assembly, and a telescopic column 13. The top beam 12 is located above the base 11 and is used to support the top plate. The top beam 12 is connected to the base 11 through the connecting rod assembly. The lower end of the telescopic column 13 is connected to the base 11, and the upper end of the telescopic column 13 is connected to the top beam 12. The telescopic column 13 rises, causing the top beam 12 to rise. This process is the lifting process of the hydraulic support. The telescopic column 13 falls, causing the top beam 12 to fall. This process is the lowering process of the hydraulic support.

[0051] Specifically, the linkage assembly includes a shield beam 14, a rear link 15, and a front link 16. The first end of the shield beam 14 is hinged to one end of the top beam 12. The first end of the rear link 15 is hinged to the second end of the shield beam 14 and the second end of the rear link 15 is hinged to one end of the base 11. The first end of the front link 16 is hinged to the base 11 and the second end of the front link 16 is hinged to the middle of the shield beam 14.

[0052] In some embodiments, the support body 1 further includes a balancing cylinder 17, one end of which is hinged to the lower surface of the top beam 12, and the other end of which is hinged to the shield beam 14. There are two balancing cylinders 17, which are respectively located on both sides of the electric cylinder assembly 2.

[0053] Traditional hydraulic supports place the balance cylinder 17 in the middle of the top beam 12. However, in the hydraulic support of this embodiment of the invention, due to the presence of the motor 21, if the balance cylinder 17 is placed in the middle of the top beam 12, the motor 21 of the electric cylinder assembly 2 will interfere with the balance cylinder 17 bracket when the support body 1 is lowered to its lowest height, which cannot meet the installation requirements of the electric cylinder assembly 2. Therefore, two balance cylinders 17 are set and respectively set on both sides of the electric cylinder assembly 2 to avoid interference.

[0054] like Figure 3 As shown, in some embodiments, the electric cylinder 23 has a trunnion 231, and the bracket body 1 is provided with an ear seat 18. The trunnion 231 is rotatably disposed in the ear seat 18. In other words, the electric cylinder 23 is hinged to the bracket body 1, and the electric cylinder 23 can rotate on the bracket body 1.

[0055] like Figure 5As shown, the electric cylinder assembly 2 further includes an explosion-proof stroke sensor 24, which is disposed on the outer wall of the electric cylinder 23 along the length direction of the electric cylinder 23. The explosion-proof stroke sensor 24 is used to collect the stroke information of the electric cylinder 23. When the pushing or pulling distance meets the requirements, the clutch 22 is opened to cut off the power source.

[0056] In some embodiments, the push rod assembly 3 includes a base plate 31, a push rod body 32, and a connector 33. The push rod body 32 is disposed on the upper surface of the base plate 31. One end of the push rod body 32 is connected to the output shaft of the electric cylinder 23, and the connector 33 is connected to the other end of the push rod body 32. The connector 33 is used to connect to the scraper machine. The push rod assembly 3 completes the pulling or pushing operation under the drive of the electric cylinder 23.

[0057] like Figure 2 As shown, in some embodiments, the hydraulic support also includes a bottoming bracket 4 and a bottoming cylinder (not shown), which are used to lift the front end of the hydraulic support to prevent the hydraulic support from being inserted into the ground and thus unable to be moved.

[0058] Specifically, the lifting support 4 includes a U-shaped part 41 and a connecting part 42. The U-shaped part 41 is inverted and is mounted above the push rod body 32 and the electric cylinder 23. The two legs of the U-shaped part 41 abut against the base plate 31. The connecting part 42 is connected to the side of the U-shaped part 41 away from the base plate 31. The lifting cylinder is connected to the support body 1 through a connecting plate. One end of the lifting cylinder is connected to the connecting part 42. The piston rod of the lifting cylinder is connected to the connecting part 42. When the piston rod of the lifting cylinder extends, it can lift the front end of the hydraulic support.

[0059] It should be noted that, since the electric cylinder assembly 2 is longer than the traditional hydraulic cylinder, in order to prevent the total length of the electric cylinder assembly 2 and the push rod from exceeding the length of the base 11, the length of the push rod body 42 must be appropriately shortened. However, the traditional hydraulic support's bottoming cylinder requires the push rod as a support point, while the push rod body 32 of the hydraulic support in this embodiment of the invention is relatively short. When the push rod is pushed out, the bottoming cylinder cannot be directly supported on the push rod body 32. Therefore, based on the traditional push rod, it has been appropriately modified by adding a base plate 31 and a bottoming support 4. The bottoming cylinder is supported on the base plate 31 by the bottoming support 4, thereby completing the bottoming work.

[0060] like Figure 6 As shown, the support method of the second aspect embodiment of the present invention includes the following steps:

[0061] After the coal mining machine begins cutting, motor 21 is pre-started;

[0062] After the coal cutting is completed, the hydraulic support column is lowered. Once the column is in place, clutch 22 is closed, and the support is pulled up.

[0063] Once the support frame is in position, disengage clutch 22 to cut off the power source. The hydraulic support frame will then move at a reduced speed until it comes to a complete stop, thus ending the support frame movement.

[0064] The hydraulic support column is raised. After the column meets the initial support force requirements, clutch 22 is closed, and the pushing begins.

[0065] After the material is pushed into position, the clutch 22 is engaged to cut off the power source. The scraper conveyor's moving speed decreases until it stops, the pushing process ends, and the motor 21 is turned off.

[0066] The support method of this invention utilizes the hydraulic support described in the above embodiments to achieve support, which has the characteristics of high moving accuracy and fast moving speed, ensuring that the support speed of the hydraulic support can keep up with the speed of existing coal mining machines.

[0067] The required power and pushing accuracy of motor 21 are calculated below.

[0068] The target is that the hydraulic support can move 600mm within 6 seconds, with an error of ±10mm.

[0069] During the pushing and pulling process of the scraper conveyor and the hydraulic support, the pushing and pulling force first needs to overcome the static friction force exerted by the ground on the scraper conveyor or hydraulic support. This requires the electric cylinder 23 to have a high peak pushing and pulling force. When the pushing and pulling process is underway, the pushing and pulling force needs to overcome the sliding friction force exerted by the ground on the scraper conveyor or hydraulic support. The sliding friction force is less than the static friction force, so the rated pushing and pulling force of the electric cylinder 23 only needs to be greater than the sliding friction force it needs to overcome. Here, the motor 21 is set with a power of 40kW and a rated speed of 1500r / min. The electric cylinder 23 is set with a rated pushing and pulling force of 20 tons and a peak pushing and pulling force of 40 tons, which is comparable to the pushing and pulling force of the hydraulic cylinder used in traditional hydraulic supports.

[0070] When the rated thrust is 20 tons, the required motor torque is:

[0071]

[0072] Where F is the pushing and pulling force of electric cylinder 23, which is 400000N, S is the lead of the lead screw of electric cylinder 23, which is 6mm, i is the reduction ratio between motor 21 and electric cylinder 23, which is 1, and η is the transmission efficiency, which is 0.8. The calculated value is T = 239kN, and the rated torque of motor 21 is 286.5kN, which meets the requirements.

[0073] Motor 21 is pre-started and reaches its rated speed before clutch 22 is engaged. When customizing motor 21, the rotational inertia of the motor rotor can be appropriately increased. A larger rotor inertia results in a longer pre-start time and more stored energy in the motor rotor. When clutch 22 is engaged, more energy is transferred to electric cylinder 23, leading to a greater peak push-pull force and a shorter start-up time for electric cylinder 23. Once the pushing or pulling distance meets the requirements, clutch 22 is disengaged to cut off the power source. Because the lead screw of electric cylinder 23 is a slender rod with a small rotational inertia, the friction from the ground to the scraper conveyor or hydraulic support provides excellent braking. The inertia of the scraper conveyor or hydraulic support and the lead screw at this point is insufficient to move the scraper conveyor or hydraulic support forward a considerable distance. Here, it is assumed that the coefficient of dynamic friction μ between the ground and the scraper conveyor or hydraulic support is 0.6, and the moving speed v of the load is 100 mm / s. Because the equivalent moment of inertia of the load is much greater than the moment of inertia of the lead screw, the moment of inertia of the lead screw of the electric cylinder 23 is ignored in the calculation. When the electric cylinder 23 moves to its position and the clutch 22 is disengaged to cut off the power source, according to the kinetic energy theorem:

[0074]

[0075] Where m is the mass of the load, L is the distance the load moves forward due to inertia after the power source is cut off, and g is the acceleration due to gravity. Calculations show L = 0.85 mm. The forward distance after power cut-off is within the accuracy range of the electric cylinder 23. Furthermore, based on the conditions of the working surface base plate 31, a brake can be further installed on the electric cylinder to further improve the control accuracy during movement. This achieves both rapid and precise movement.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0080] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0081] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A hydraulic support, characterized in that, include: Support body; An electric cylinder assembly is connected to the bracket body and located at the bottom of the bracket body. The electric cylinder assembly includes a motor, a clutch, and an electric cylinder. The output shaft of the motor and the input shaft of the electric cylinder are connected through the clutch. The motor is pre-started and reaches its rated speed before the clutch is closed. When customizing the motor, the rotational inertia of the motor rotor is appropriately increased. The larger the rotational inertia of the rotor, the longer the pre-start time of the motor, and the more energy stored in the motor rotor. When the clutch is closed, more energy is transferred to the electric cylinder, resulting in a larger peak push-pull force of the electric cylinder and a shorter start-up time. By adjusting the pressure applied to the clutch, the maximum transmittable torque of the clutch is made slightly higher than the torque corresponding to the peak push-pull force of the electric cylinder. When the push-pull force borne by the electric cylinder is greater than its peak push-pull force, the clutch is overloaded and slips, and then the clutch is disengaged to cut off the power source and protect the electric cylinder from damage. A push rod assembly, which is connected to the output shaft of the electric cylinder.

2. The hydraulic support according to claim 1, characterized in that, The support body includes: Base; A top beam, which is located above the base; A linkage assembly, wherein the top beam is connected to the base via the linkage assembly; The telescopic column has its lower end connected to the base and its upper end connected to the top beam.

3. The hydraulic support according to claim 2, characterized in that, The linkage assembly includes: A protective beam, the first end of which is hinged to one end of the top beam; The rear connecting rod has its first end hinged to the second end of the shield beam, and its second end hinged to one end of the base. A front connecting rod, the first end of which is hinged to the base, and the second end of which is hinged to the middle of the shield beam.

4. The hydraulic support according to claim 3, characterized in that, The support body also includes a balancing cylinder. One end of the balancing cylinder is hinged to the lower surface of the top beam, and the other end of the balancing cylinder is hinged to the shield beam. There are two balancing cylinders, which are respectively located on both sides of the electric cylinder assembly.

5. The hydraulic support according to claim 1, characterized in that, The electric cylinder has a trunnion, and the bracket body is provided with an ear seat, and the trunnion is rotatably disposed in the ear seat.

6. The hydraulic support according to claim 1, characterized in that, The electric cylinder assembly also includes an explosion-proof stroke sensor, which is disposed on the outer wall of the electric cylinder along the length of the electric cylinder.

7. The hydraulic support according to claim 1, characterized in that, The push rod assembly includes: Base plate; A push rod body is disposed on the upper surface of the base plate, and one end of the push rod body is connected to the output shaft of the electric cylinder; A connector is connected to the other end of the push rod body, and the connector is used to connect to the scraper conveyor.

8. The hydraulic support according to claim 7, characterized in that, Also includes: A lifting bracket, comprising a U-shaped portion and a connecting portion, wherein the U-shaped portion is mounted above the push rod body and the electric cylinder and abuts against the base plate, and the connecting portion is connected to the side of the U-shaped portion away from the base plate; A bottom-lifting cylinder is connected to the support body, and one end of the bottom-lifting cylinder is connected to the connecting part. The piston rod of the bottom-lifting cylinder is connected to the connecting part.

9. The hydraulic support according to any one of claims 1-8, characterized in that, The clutch is a hydraulic clutch.

10. A support method using a hydraulic support as described in any one of claims 1-9, characterized in that, include: After the coal mining machine begins cutting, the motor is pre-started; After the coal cutting is completed, the hydraulic support column is lowered. Once the column is in place, the clutch is closed and the support is pulled up. Once the support frame is in position, disengage the clutch, cut off the power source, and the hydraulic support will move at a reduced speed until it comes to a complete stop, thus ending the support frame movement. The hydraulic support column is raised. After the column meets the initial support force requirements, the clutch is closed and the pushing begins. After the material is pushed into position, the clutch is disengaged, the power source is cut off, the scraper conveyor speed decreases until it stops, the pushing process ends, and the motor is turned off.

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