Automatic cable reeling device for mining electric shovel truck and method thereof

Abstract

This invention discloses an automatic cable winding and unwinding device and method for mining electric shovels, belonging to the technical field of auxiliary devices for underground mining equipment in coal mines. It includes a device frame fixed to the electric shovel, a drum rotatably mounted on the frame via bearing seats, and a drive mechanism for driving the drum to roll, all mounted on the side of the frame. A slide rail is mounted on the frame, and a pulley-type cable winding and unwinding trigger mechanism is slidably mounted on the slide rail. A control device is installed next to the drive mechanism. The device automatically triggers the winding or unwinding of the drum based on the cable's tension state during winding and unwinding, achieving real-time sensing and precise control of the cable's status. This further automates the cable winding and unwinding process, improving the continuous operation efficiency of the electric shovel, completely replacing manual cable handling, eliminating the need for construction personnel to enter the shovel's operating danger zone, and further preventing cable dragging and scraping by loose debris, thus preventing explosion-proof accidents caused by damage to the cable sheath.

Description

Technical Field

[0001] This invention relates to the field of auxiliary devices for underground coal mining equipment, specifically to an automatic cable retraction and deployment device and method for a mining electric shovel. Background Technology

[0002] Electric shovels (also known as electric excavators) are one of the core pieces of equipment in underground ore mining. They use an electric motor to drive the bucket for excavation and require a continuous and stable power supply. Due to the narrow space and frequent movement of equipment in underground tunnels, electric shovels typically use cable power supply, meaning that power is transmitted from the substation to the shovel via cable. To meet the needs of the shovel's forward and backward movement within the tunnel, the cable must be of sufficient length and is retracted and wound up using a reel installed at the rear of the shovel: when the shovel moves forward, the reel releases the cable; when it moves backward, the reel winds up the cable, ensuring that the cable is always under appropriate tension and does not drag on the ground.

[0003] However, in existing technologies, cable winding and unwinding mainly rely on manual operation: during operation, a dedicated person must follow the electric forklift to observe the cable status in real time and manually adjust the drum speed or directly drag the cable. This method generally has the following problems: High personnel safety risks: Operators need to move within the operating range of the electric loader (especially when reversing, the blind spot is large), and are very likely to be crushed by the loader body, bucket or other equipment, resulting in limb crushing injuries or even death. Cables are prone to damage and loss of explosion: If manual handling is not timely, cables may drag on the ground and rub against the loose debris and sharp rocks accumulated on the tunnel floor, causing damage to the outer sheath of the cable; if the damage reaches the inner insulation layer, it may cause leakage or short circuit, resulting in the cable "loss of explosion". Low operating efficiency: Manual adjustment relies on experience and cannot accurately match the moving speed of the electric loader with the rhythm of cable winding and unwinding, often resulting in the cable being too loose or too tight, affecting the continuous operation of the equipment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an automatic cable winding and unwinding device for mining electric shovels. By automatically triggering the winding or unwinding of the control drum based on the tension state of the cable during winding and unwinding, the device achieves real-time perception and precise control of the cable status, eliminates the safety hazards of manual handling, protects the cable from damage caused by dragging on the ground, ensures the safety of underground power supply, and solves the problems of safety risks, cable damage and low work efficiency of existing manual cable handling.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is implemented as follows: An automatic cable winding and unwinding device for a mining electric shovel includes a frame fixed to the electric shovel, a drum rotatably mounted on the frame via bearing seats, and a drive mechanism for driving the drum to roll on the side of the frame. The core improvement is that a slide rail located directly behind the drum and arranged laterally is mounted on the frame, a pulley-type cable winding and unwinding trigger mechanism for guiding and triggering the drum to wind up and unwind the cable is slidably mounted on the slide rail, and a control device electrically connected to the pulley-type cable winding and unwinding trigger mechanism is mounted next to the drive mechanism.

[0006] By adopting the above solution, the winding or unwinding of the reel is automatically triggered by the tension state of the cable during winding and unwinding, realizing real-time perception and precise control of the cable status. This further realizes the automated control of the cable winding and unwinding, which reduces downtime for adjustment, improves the continuous operation efficiency of the electric loader, completely replaces manual cable handling, and eliminates the need for construction personnel to enter the dangerous area where the loader is operating. This further avoids cable dragging on the ground and scratching by loose debris, preventing explosion accidents caused by damage to the outer sheath.

[0007] As a preferred embodiment of an automatic cable retraction and deployment device for mining electric shovel loader, the pulley-type cable retraction and deployment triggering mechanism includes a slide block slidably mounted on a slide rail, a vertically arranged guide frame fixed on the slide block, three sets of rotatable fixed pulleys mounted on the upper part of the guide frame, and two sets of vertical grooves vertically opened inside the guide frame between the three sets of fixed pulleys. A rotatable movable pulley is slidably mounted in each vertical groove, and a counterweight is coaxially mounted at both ends of the movable pulley. A trigger switch for use with the movable pulley is fixed at the upper and lower ends of each vertical groove. The entire cable is guided sequentially along all the fixed and movable pulleys, and the two sets of movable pulleys can slide up and down along the grooves under the tension of the cable. The position change of the movable pulleys reflects the tension / slack of the cable in real time, providing a precise status signal for the control device.

[0008] In a preferred embodiment of an automatic cable retraction and deployment device for a mining electric shovel loader, all fixed pulleys are labeled as fixed pulley A, fixed pulley B, and fixed pulley C from front to back; all movable pulleys are labeled as movable pulley D and movable pulley E from front to back; and all trigger switches are labeled as trigger switch a, trigger switch b, trigger switch c, and trigger switch d from front to back. The control device is a PLC, which has four control modes; Control Mode 1: When trigger switches b and c are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism stops working; here, PLC control mode 1 is defined as the initial mode of the pulley-type cable winding and unwinding trigger mechanism. Control Mode 2: When trigger switches a and c are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism drives the drum to continuously release the cable; Control Mode 3: When trigger switch b and trigger switch d are simultaneously pressed into contact by two sets of moving pulleys, the PLC controls the drive mechanism to drive the drum to continuously wind up the cable; Control Mode 4: When trigger switches a and d are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism stops working. By combining multiple states, the system can accurately distinguish between the three working conditions of the cable: "needs to be released", "needs to be retracted", and "holding", thus avoiding excessive movement of the reel that could cause the cable to pile up or drag on the ground.

[0009] As a preferred embodiment of an automatic cable retraction device for mining electric shovels, the length of the slide rail is greater than or equal to the length of the drum, and the length of the slide rail is adapted to the working range of the drum. A guide key is fixed on the side of the slide rail and arranged parallel to it. A keyway that cooperates with the guide key is opened in the slide block. The entire slide block can only slide along the axial direction of the slide rail. The combination of the guide key and the keyway can ensure the sliding accuracy of the triggering mechanism and avoid cable guidance failure due to offset.

[0010] As a preferred embodiment of an automatic cable winding and unwinding device for mining electric shovels, the drive mechanism includes a drive motor eccentrically positioned with the drum. The eccentric positioning of the drive motor reduces spatial interference. A drive gear is coaxially connected to the motor shaft, and a driven gear plate that meshes with the drive gear is coaxially connected to the side of the drum. The drive gear is located inside the driven gear plate, and the diameter of the drive gear is smaller than the diameter of the driven gear plate. The combination of the small-diameter drive gear and the large-diameter driven gear plate can achieve speed reduction and torque increase, improving the stability and torque output of the drum winding and unwinding.

[0011] An automatic cable retraction method for mining electric shovel loader involves marking the front and rear ends of the cable as end M and end N, respectively. End M is connected to a roller, and end N is connected to a substation. The automatic cable retraction device for the mining electric shovel loader automatically controls the cable retraction and extension as the shovel loader moves. The retraction and extension control steps are as follows: S1. Before the electric shovel starts working, adjust the pulley-type cable winding and unwinding trigger mechanism to the initial mode. At this time, it corresponds to the PLC control mode one, that is, the trigger switch b and the trigger switch c are pressed and contacted by the two sets of moving pulleys at the same time, and the drive mechanism stops working. S2. When the electric shovel is in forward gear, the entire cable is gradually tensioned. Under the tension of the cable, the movable pulley D gradually moves upward along the slide groove. When the cable on the movable pulleys D and E is fully tensioned, and the trigger switches a and c are simultaneously pressed into contact by the two sets of movable pulleys, the PLC controls the drive mechanism to drive the drum to release the cable. S3. When the cable is continuously released, the cable located on the movable pulley D is in a relaxed state first. Trigger switches b and c are simultaneously pressed into contact by the two sets of movable pulleys, and the drive mechanism stops working to stop the cable release. S4. When the electric shovel is in reverse gear, the entire cable is gradually loosened. Under the loosening effect of the cable, the movable pulley E gradually moves downward along the slide groove. When the cable on the movable pulley D and the movable pulley E is completely loosened, and the trigger switch b and the trigger switch d are pressed and contacted by the two sets of movable pulleys at the same time, the PLC controls the drive mechanism to drive the drum to wind up the cable. S5. When the cable is continuously being wound up, the cable located on the movable pulley D is in a tensioned state first. When the trigger switches a and d are pressed into contact by the two sets of movable pulleys at the same time, the PLC control drive mechanism stops working to stop the cable winding.

[0012] After adopting the above technical solution, the beneficial effects of the present invention are: 1. Enhanced safety: By automatically triggering the winding or unwinding of the reel based on the tension status of the cable during winding and unwinding, the real-time perception and precise control of the cable status are achieved, further realizing the automated control of cable winding and unwinding, completely replacing manual cable handling, and eliminating the need for construction personnel to enter the dangerous area where the forklift is operating; 2. Cable protection: Further prevents cables from dragging on the ground and being scratched by loose debris, preventing explosion-proof accidents caused by damage to the outer sheath; 3. Enhanced reliability: Through multi-state trigger switches and PLC intelligent control, the actual tension / slack requirements of the cable are accurately matched to prevent overload or under-reeling of the reel; 4. Efficiency Optimization: Automatic retraction and extension can effectively reduce downtime for adjustment, improving the continuous operation efficiency of electric loader; 5. Wide adaptability: The length of the slide rail and the guide structure can be adapted to drums of different specifications, and the control modes cover common working conditions (forward / reverse). Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A three-dimensional structural diagram of the automatic cable retraction device for a mining electric shovel loader from the first angle; Figure 2 A three-dimensional structural diagram of the automatic cable retraction device for a mining electric shovel loader at a second angle; Figure 3 for Figure 1 Three-dimensional structural diagram of the intermediate drum and frame; Figure 4 for Figure 3 Three-dimensional structural diagram of the intermediate winding drum; Figure 5 for Figure 1 3D structural diagram of the pulley-type cable retraction trigger mechanism; Figure 6 To showcase Figure 5 A three-dimensional structural diagram of the internal structure; Figure 7 This is a schematic diagram of the pulley-type cable winding and unwinding trigger mechanism when triggering the PLC operation control mode 1. Figure 8 This is a schematic diagram of the pulley-type cable winding and unwinding trigger mechanism when triggering the PLC operation control mode two. Figure 9 This is a schematic diagram of the pulley-type cable winding and unwinding trigger mechanism when triggering the PLC operation control mode three. Figure 10 This is a schematic diagram of the pulley-type cable winding and unwinding trigger mechanism when triggering the PLC operation control mode four.

[0015] The markings in the diagram are: 1-device frame; 2-bearing seat; 3-drum; 4-drive mechanism; 41-drive motor; 42-drive gear; 43-driven gear disc; 5-slide rail; 6-pulley type cable winding and unwinding trigger mechanism; 61-slide block; 62-guide frame; 63-fixed pulley; 64-slide groove; 65-moving pulley; 66-counterweight; 67-trigger switch; 7-PLC; 8-cable. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1 to 2As shown, an automatic cable winding and unwinding device for a mining electric shovel is provided, including a device frame 1 fixed on the electric shovel, a drum 3 rotatably mounted on the device frame 1 via a bearing seat 2, a drive mechanism 4 for driving the drum 3 to roll is mounted on the side of the device frame 1, a slide rail 5 located directly behind the drum 3 and arranged laterally is mounted on the device frame 1, a pulley-type cable winding and unwinding trigger mechanism 6 for guiding and triggering the drum 3 to wind up and unwind the cable 8 is slidably mounted on the slide rail 5, and a control device electrically connected to the pulley-type cable winding and unwinding trigger mechanism 6 is mounted next to the drive mechanism 4. By automatically triggering the winding or unwinding of the drum 3 based on the tension status of the cable 8 during winding and unwinding, real-time perception and precise control of the cable 8's status are achieved. This further automates the winding and unwinding of the cable 8 by the drum 3. Automatic winding and unwinding reduces downtime for adjustment, improves the continuous operation efficiency of the electric shovel, and completely replaces manual handling of the cable 8. Construction personnel do not need to enter the dangerous area where the shovel is operating, further avoiding the cable 8 dragging on the ground and being scratched by loose debris, thus preventing explosion accidents caused by damage to the outer sheath.

[0018] like Figures 3 to 4 As shown, the length of the slide rail 5 is greater than or equal to the length of the drum 3. The length of the slide rail 5 is adapted to the working range of the drum 3. A guide key is fixed on the side of the slide rail 5 and is arranged parallel to it. A keyway that works with the guide key is opened in the slide block 61. The entire slide block 61 can only slide along the axial direction of the slide rail 5. The combination of the guide key and the keyway can ensure the sliding accuracy of the trigger mechanism and avoid the failure of the cable 8 due to offset.

[0019] like Figure 4 As shown, the drive mechanism 4 includes a drive motor 41 that is eccentrically arranged with the drum 3. The eccentric arrangement of the drive motor 41 can reduce spatial interference. A drive gear 42 is coaxially connected to the motor shaft. A driven gear 43 that meshes with the drive gear 42 is coaxially connected to the side of the drum 3. The drive gear 42 is located inside the driven gear 43, and the diameter of the drive gear 42 is smaller than the diameter of the driven gear 43. The combination of the small-diameter drive gear 42 and the large-diameter driven gear 43 can achieve speed reduction and torque increase, thereby improving the stability and torque output of the drum 3 during winding and unwinding.

[0020] like Figures 5 to 6As shown, the pulley-type cable winding and unwinding trigger mechanism 6 includes a slide base 61 slidably mounted on a slide rail 5. A vertically arranged guide frame 62 is fixed on the slide base 61. Three sets of fixed pulleys 63, capable of rotation and located on the same horizontal line, are installed above the interior of the guide frame 62. Two sets of vertical grooves 64 are vertically opened inside the guide frame 62, located between the three sets of fixed pulleys 63. A movable pulley 65, capable of rotation, is slidably mounted in each vertical groove 64. A counterweight 66 is coaxially mounted at both ends of the movable pulley 65. A trigger switch 67, which works in conjunction with the movable pulley 65, is fixed at the upper and lower ends of each vertical groove 64. The entire cable 8 is guided sequentially along all the fixed pulleys 63 and the movable pulleys 65. The two sets of movable pulleys 65 can slide up and down along the grooves 64 under the tension of the cable 8. The position change of the movable pulleys 65 reflects the tension / slack of the cable 8 in real time, providing a precise status signal for the control device.

[0021] like Figure 6 As shown, all fixed pulleys 63 are labeled as fixed pulley 63A, fixed pulley 63B and fixed pulley 63C from front to back; all movable pulleys 65 are labeled as movable pulley 65D and movable pulley 65E from front to back; and all trigger switches 67 are labeled as trigger switch 67a, trigger switch 67b, trigger switch 67c and trigger switch 67d from front to back.

[0022] like Figures 7 to 10 As shown, the control device is a PLC7, which has four control modes; Control Mode 1: When trigger switches 67b and 67c are simultaneously pressed into contact by two sets of moving pulleys 65, PLC7 controls the drive mechanism 4 to stop working; wherein, PLC7's control mode 1 is defined as the initial mode of the pulley-type cable winding and unwinding trigger mechanism 6. Control Mode 2: When trigger switches 67a and 67c are simultaneously pressed into contact by two sets of movable pulleys 65, PLC7 controls drive mechanism 4 to drive drum 3 to continuously release cable 8; Control Mode 3: When trigger switches 67b and 67d are simultaneously pressed into contact by two sets of movable pulleys 65, PLC7 controls drive mechanism 4 to drive drum 3 to continuously wind up cable 8; Control Mode 4: When trigger switches 67a and 67d are simultaneously pressed into contact by two sets of movable pulleys 65, PLC7 controls the drive mechanism 4 to stop working. By combining multiple states, the system can accurately distinguish between the three working conditions of cable 8: "needs to be released", "needs to be wound up", and "holding", thus avoiding excessive movement of the drum 3 that could cause cable 8 to accumulate or drag on the ground.

[0023] Continue as Figures 7 to 10As shown, an automatic cable retraction method for a mining electric shovel loader is provided. The front and rear ends of the cable 8 are sequentially marked as end M and end N, respectively. End M is connected to a roller, and end N is connected to a substation. This method employs the aforementioned techniques. The automatic cable retraction device for the mining electric shovel loader automatically controls the retraction and extension of the cable 8 as the shovel loader moves. The retraction and extension control steps are as follows: S1. Before the electric shovel loader starts working, adjust the pulley-type cable retraction trigger mechanism 6 to the initial mode. At this time, it corresponds to control mode one of PLC7, that is, trigger switches 67b and 67c are simultaneously pressed and contacted by two sets of moving pulleys 65. Figure 7 As shown, drive mechanism 4 stops working; S2. When the electric shovel is in forward gear, the entire cable 8 is gradually tensioned. Under the tension of the cable 8, the movable pulley 65D gradually moves upward along the slide groove 64. When the cable 8 on the movable pulleys 65D and 65E is fully tensioned, and the trigger switches 67a and 67c are simultaneously pressed into contact by the two sets of movable pulleys 65, as shown... Figure 8 As shown (red arrows indicate the forward or reverse direction of the electric shovel, blue arrows indicate the cable reeling or releasing direction), PLC7 controls drive mechanism 4 to drive drum 3 to release cable 8; S3. When cable 8 continues to release, cable 8 located on movable pulley 65D is preferentially in a relaxed state, and trigger switches 67b and 67c are simultaneously pressed into contact by the two sets of movable pulleys 65. Figure 7 As shown, the drive mechanism 4 pauses operation to stop the release of cable 8; S4. When the electric shovel is in reverse gear, the entire cable 8 is gradually loosened. Under the loosening effect of the cable 8, the movable pulley 65E gradually moves downwards along the slide groove 64. When the cable 8 on the movable pulleys 65D and 65E is completely loosened until the trigger switches 67b and 67d are simultaneously pressed into contact by the two sets of movable pulleys 65, as... Figure 9 As shown (red arrows indicate the forward or reverse direction of the electric shovel, blue arrows indicate the cable winding or releasing direction), PLC7 controls drive mechanism 4 to drive drum 3 to wind up cable 8; S5. When cable 8 is continuously wound up, cable 8 located on movable pulley 65D is preferentially in a tensioned state. When trigger switches 67a and 67d are simultaneously pressed into contact by the two sets of movable pulleys 65, as... Figure 10 As shown, PLC7 controls the drive mechanism 4 to pause operation to stop the winding of cable 8.

[0024] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic cable reeling and unloading device for a mining electric shovel loader, comprising a frame fixed to the electric shovel loader, a drum rotatably mounted on the frame via bearing seats, and a drive mechanism for driving the drum to roll mounted on the side of the frame; characterized in that: A slide rail is installed on the device frame, located directly behind the drum and arranged laterally. A pulley-type cable winding triggering mechanism for guiding and triggering the winding and unwinding of the cable is slidably installed on the slide rail. A control device electrically connected to the pulley-type cable winding triggering mechanism is installed next to the drive mechanism.

2. The automatic cable retraction device for mining electric shovels according to claim 1, characterized in that: The pulley-type cable winding and unwinding triggering mechanism includes a slide block slidably mounted on a slide rail, a vertically arranged guide frame fixed on the slide block, three sets of rotatable fixed pulleys located on the same horizontal line installed above the inside of the guide frame, and two sets of vertical grooves located between the three sets of fixed pulleys vertically opened inside the guide frame. A rotatable movable pulley is slidably mounted in each vertical groove, and a counterweight is coaxially mounted at both ends of the movable pulley. A trigger switch for use with the movable pulley is fixed at the upper and lower ends of each vertical groove. The entire cable is guided in an orderly manner along all the fixed pulleys and movable pulleys in sequence, and the two sets of movable pulleys can slide up and down along the grooves under the tension of the cable.

3. The automatic cable retraction device for mining electric shovels according to claim 2, characterized in that: All fixed pulleys are labeled as fixed pulley A, fixed pulley B, and fixed pulley C from front to back; all movable pulleys are labeled as movable pulley D and movable pulley E from front to back; all trigger switches are labeled as trigger switch a, trigger switch b, trigger switch c, and trigger switch d from front to back.

4. The automatic cable retraction device for mining electric shovels according to claim 3, characterized in that: The control device is a PLC, which has four control modes; Control Mode 1: When trigger switch b and trigger switch c are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism stops working; Control Mode 2: When trigger switches a and c are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism drives the drum to continuously release the cable; Control Mode 3: When trigger switch b and trigger switch d are simultaneously pressed into contact by two sets of moving pulleys, the PLC controls the drive mechanism to drive the drum to continuously wind up the cable; Control Mode 4: When trigger switches a and d are simultaneously pressed into contact by two sets of moving pulleys, the PLC-controlled drive mechanism will stop working.

5. The automatic cable retraction device for mining electric shovels according to claim 4, characterized in that: The control mode of the PLC is defined as the initial mode of the pulley-type cable winding and unwinding trigger mechanism.

6. The automatic cable retraction device for mining electric shovels according to claim 1, characterized in that: The length of the slide rail is greater than or equal to the length of the drum.

7. The automatic cable retraction device for mining electric shovels according to claim 1, characterized in that: A guide key is fixed on the side of the slide rail and is arranged parallel to it. A keyway that works with the guide key is opened in the slide block. The entire slide block can only slide along the axial direction of the slide rail.

8. The automatic cable retraction device for mining electric shovels according to claim 1, characterized in that: The drive mechanism includes a drive motor eccentrically positioned with respect to the drum, a drive gear coaxially connected to the motor shaft, and a driven gear plate coaxially connected to the side of the drum, which meshes with the drive gear for transmission.

9. The automatic cable retraction device for mining electric shovels according to claim 8, characterized in that: The driving gear is located inside the driven gear disk, and the diameter of the driving gear is smaller than the diameter of the driven gear disk.

10. A method for automatically retracting and extending a towing cable of a mining electric shovel, wherein the front and rear ends of the cable are sequentially marked as end M and end N, wherein end M is connected to a roller and end N is connected to a substation, characterized in that... This method employs the automatic cable retraction and deployment device for mining electric shovel trucks as described in claim 5, which automatically controls the cable retraction and deployment as the electric shovel truck moves. The retraction and deployment control steps are as follows: S1. Before the electric shovel starts working, adjust the pulley-type cable winding and unwinding trigger mechanism to the initial mode. At this time, it corresponds to the PLC control mode one, that is, the trigger switch b and the trigger switch c are pressed and contacted by the two sets of moving pulleys at the same time, and the drive mechanism stops working. S2. When the electric shovel is in forward gear, the entire cable is gradually tensioned. Under the tension of the cable, the movable pulley D gradually moves upward along the slide groove. When the cable on the movable pulleys D and E is fully tensioned, and the trigger switches a and c are simultaneously pressed into contact by the two sets of movable pulleys, the PLC controls the drive mechanism to drive the drum to release the cable. S3. When the cable is continuously released, the cable located on the movable pulley D is in a relaxed state first. Trigger switches b and c are simultaneously pressed into contact by the two sets of movable pulleys, and the drive mechanism stops working to stop the cable release. S4. When the electric shovel is in reverse gear, the entire cable is gradually loosened. Under the loosening effect of the cable, the movable pulley E gradually moves downward along the slide groove. When the cable on the movable pulley D and the movable pulley E is completely loosened, and the trigger switch b and the trigger switch d are pressed and contacted by the two sets of movable pulleys at the same time, the PLC controls the drive mechanism to drive the drum to wind up the cable. S5. When the cable is continuously being wound up, the cable located on the movable pulley D is in a tensioned state first. When the trigger switches a and d are pressed into contact by the two sets of movable pulleys at the same time, the PLC control drive mechanism stops working to stop the cable winding.

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