A circuit breaker with a combined protection structure

Abstract

The application provides a circuit breaker with a combined protection structure, and belongs to the technical field of circuit breakers, which comprises a circuit breaker body, wire ends arranged at both ends of the circuit breaker body, a control switch connected to the circuit breaker body, a fastening assembly for locking and connecting a conductor, an unlocking assembly for unlocking the fastening assembly, and a limiting assembly for limiting the position of the control switch. The application has the beneficial effects that when the circuit breaker body is used, the clamping and fixing of the conductor can be completed through the cooperation of the pressing roller and the supporting roller, and when the device is tripped due to overload or short circuit, the pressing roller is lifted by the push block through the arc-shaped groove and the limiting clamping rod, so that the conductor is released from the pressing roller and the supporting roller, thereby facilitating the separation of the conductor from the circuit breaker body, reducing the operation steps of maintenance and inspection, and limiting the control switch to further increase the protection effect.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more specifically, to a circuit breaker with a combined protection structure. Background Technology

[0002] A circuit breaker is a switching device capable of closing, carrying, and interrupting current under normal circuit conditions and closing, carrying, and interrupting current under abnormal circuit conditions within a specified time. Circuit breakers are used to distribute electrical energy, protect power lines, and automatically disconnect the circuit when serious overload, short circuit, or undervoltage faults occur. Circuit breakers are classified into high-voltage and low-voltage circuit breakers according to their application range. The boundary between high and low voltage is somewhat blurred; generally, those above 3kV are considered high-voltage electrical appliances. Circuit breakers can be used to distribute electrical energy, infrequently start asynchronous motors, and protect power lines and motors. When serious overload, short circuit, or undervoltage faults occur, they automatically disconnect the circuit. Their function is equivalent to a combination of a fuse switch and an over / under-temperature relay, and generally, no parts need to be replaced after interrupting the fault current. Currently, they are widely used.

[0003] Circuit breakers typically involve stripping the insulation from the wire terminals to expose the conductor, which is then inserted into the circuit breaker's mounting holes and secured with screws. However, in existing technology, to prevent the conductor from coming loose due to vibration after bolting, a limiting mechanism is usually installed on one side of the circuit breaker to further secure the conductor and increase the stability of the connection. However, the installation of these conductor clamping and limiting mechanisms in some circuit breakers often requires multiple tools and involves complex procedures, increasing both the difficulty and time of installation. Furthermore, in some electrical equipment, the circuit breaker's installation location may be quite compact, limiting the operator's space for clamping and limiting the conductor, hindering quick maintenance and disassembly, and making it difficult to complete the operation smoothly. Therefore, inventing a circuit breaker with a combined protection structure to solve these problems has become a pressing issue for those skilled in the art. Summary of the Invention

[0004] To overcome the above shortcomings, the present invention provides a circuit breaker with a combined protection structure, which aims to solve the problems of complicated operation steps, increased difficulty in wire installation, and limited operating space when the circuit breaker is installed in a compact location, making it difficult to complete the operation smoothly.

[0005] This invention is implemented as follows:

[0006] This invention provides a circuit breaker with a combined protection structure, including a circuit breaker body, with terminals at both ends of the circuit breaker body, and a control switch connected to the circuit breaker body, and further comprising:

[0007] A fastening assembly located inside the terminal block, the fastening assembly being used to lock the connecting wire;

[0008] An unlocking component, which is connected to a terminal block, is used to unlock the fastening component;

[0009] A limiting component is fixedly connected to a control switch and is used to limit the position of the control switch.

[0010] Preferably, the circuit breaker body is fixedly connected to the terminal block, a limit frame is fixedly connected to the side wall of the circuit breaker body, a fixed cavity is provided inside the terminal block, a movable slot is provided at one end of the fixed cavity, a groove is provided on one side inner wall of the fixed cavity, a wiring hole is provided on the inner wall of the fixed cavity away from the groove, and a fixing bolt is threaded to the side wall of the terminal block.

[0011] Preferably, a voltage-conducting sheet and a connecting seat are fixedly connected to the inner wall of the fixed cavity, the voltage-conducting sheet and the connecting seat are slidably connected, and the voltage-conducting sheet is located below the fixing bolt.

[0012] Preferably, the fastening assembly includes a fixed plate, a pressure roller, and a support roller. The fixed plate is fixedly connected to the inner wall of the fixed cavity. A fixed rod is fixedly connected to one side of the fixed plate, and a movable plate is rotatably connected to the end of the fixed rod away from the fixed plate.

[0013] Preferably, a torsion spring is sleeved on the outer wall of the fixed rod, and the two ends of the torsion spring are respectively fixedly connected to the side wall of the corresponding movable plate. The end of the movable plate away from the fixed rod is rotatably connected to the pressure roller, and a number of protective strips distributed in a circumferential array are fixedly connected to the outer wall of the pressure roller.

[0014] Preferably, the support roller is located below the pressure roller, and both ends of the support roller are rotatably connected to the inner wall of the fixed cavity. Several sets of circumferentially distributed convex balls are fixedly connected to the outer wall of the support roller. Both the support roller and the pressure roller are located on one side of the connecting seat, and the convex balls are elastic.

[0015] Preferably, the unlocking component includes a limiting rod and a push rod, wherein the side wall of the limiting rod is slidably connected to the inner wall of the movable slot, and the limiting rod is slidably connected to the limiting frame.

[0016] Preferably, one end of the limiting lever located inside the fixed cavity is fixedly connected to the push rod, and a return spring is fixedly connected to the side wall of one end of the limiting lever. The end of the return spring away from the limiting lever is fixedly connected to the inner wall of the groove.

[0017] Preferably, a push block is fixedly connected to the end of the push rod away from the limiting lever. The push block is arranged in a trapezoidal shape, and one side wall of the push block can be slidably connected to the pressing roller. The push rod and the push block are located on one side of the connecting seat.

[0018] Preferably, the limiting component includes a rotating disk, one end of which is fixedly connected to a control switch. The side wall of the rotating disk has an arc-shaped groove, and the outer wall of the rotating disk has a limiting groove adapted to the limiting rod. The limiting groove is located on one side of the arc-shaped groove, and the center line of the limiting groove and the center line of the end of the limiting rod away from the fixed cavity are on the same horizontal plane. The inner wall of the arc-shaped groove is slidably connected to one end of the limiting rod.

[0019] The beneficial effects of this invention are:

[0020] 1. When using the circuit breaker body, the limit lever can be pushed to further stretch the return spring. After one end of the limit lever separates from the limit groove, the control switch can be rotated to push it to the open state. During this process, due to the rotation of the control switch and the elastic recovery of the return spring, the limit lever can be driven back to its original position, allowing it to insert into the deepest part of the arc-shaped groove. At this time, the push block no longer applies external force to the clamping roller. Through the elastic recovery of the torsion spring and the rotational connection between the movable plate and the fixed rod, the clamping roller can be moved downward, simultaneously working with the support roller to clamp and fix the conductor. Furthermore, when the circuit breaker... When the circuit breaker trips due to overload or short circuit, during the reset process of the control switch, the arc-shaped groove gradually squeezes the limit lever, causing the limit lever to stretch the reset spring. This stretches the limit lever and drives the push block to move towards the wiring hole side via the push rod. Simultaneously, the push block slides against the pressure roller, causing the pressure roller to rise. The rotation of the movable plate causes the torsion spring to deform, thereby releasing the pressure roller and support roller from restricting the conductor. This facilitates the quick separation of the conductor from the circuit breaker body after loosening the fixing bolts, reducing maintenance and inspection steps, improving efficiency, and ensuring smooth operation.

[0021] 2. During the control switch reset process, after one end of the limit lever separates from the arc-shaped groove, the control switch is not yet fully reset. As the control switch rotates during the reset process, one end of the limit lever will first slide against the outer wall of the rotating disk. After the control switch finishes rotating, the limit groove is located on one side of the limit lever. At this moment, the limit lever is no longer subjected to external pressure, and the elastic recovery of the reset spring causes the limit lever to move towards the limit groove. Finally, one end of the limit lever is inserted into the interior of the limit groove, thereby limiting the control switch and preventing operators from accidentally turning on the control switch during maintenance and inspection, which would cause the circuit to reconnect, further increasing the protection effect. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the limiting component structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0025] Figure 3 This invention provides a circuit breaker with a combined protection structure. Figure 2 Enlarged schematic diagram of the structure at point A in the middle;

[0026] Figure 4 This is a schematic diagram of the connection end structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the internal structure of the fixed cavity of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the unlocking component structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of a half-section of the connection end of a circuit breaker with a combined protection structure provided by an embodiment of the present invention.

[0030] Figure 8This is a schematic diagram of the fastening assembly structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the control switch reset structure of a circuit breaker with a combined protection structure provided by an embodiment of the present invention.

[0032] In the diagram: 1. Terminal; 101. Movable slot; 102. Wiring hole; 103. Fixed cavity; 1031. Groove; 2. Fixing bolt; 3. Unlocking assembly; 31. Limiting lever; 32. Return spring; 33. Push rod; 34. Push block; 4. Limiting frame; 5. Control switch; 6. Limiting assembly; 61. Rotating disk; 62. Limiting groove; 63. Arc groove; 7. Circuit breaker body; 8. Conductive plate; 9. Fastening assembly; 91. Fixing plate; 911. Torsion spring; 912. Fixing rod; 913. Movable plate; 92. Pressure roller; 921. Protective strip; 93. Support roller; 931. Convex ball; 10. Connecting seat. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0034] Example 1, refer to Figures 1-9 A circuit breaker with a combined protection structure includes a circuit breaker body 7, with terminals 1 at both ends of the circuit breaker body 7, and a control switch 5 connected to the circuit breaker body 7. It also includes:

[0035] Fastening component 9, located inside terminal 1, is used to lock the connecting wires;

[0036] Unlocking component 3 is connected to terminal 1 and is used to unlock fastening component 9;

[0037] Limiting component 6 is fixedly connected to control switch 5 and is used to limit the position of control switch 5.

[0038] Furthermore; the circuit breaker body 7 is fixedly connected to the terminal 1, and a limit frame 4 is fixedly connected to the side wall of the circuit breaker body 7. A fixed cavity 103 is opened inside the terminal 1. A movable slot 101 is opened at one end of the fixed cavity 103. A groove 1031 is opened on one side inner wall of the fixed cavity 103. A wiring hole 102 is opened on the inner wall of the fixed cavity 103 away from the groove 1031. A fixing bolt 2 is threadedly connected to the side wall of the terminal 1. A voltage conductive piece 8 and a connecting seat 10 are fixedly connected to the inner wall of the fixed cavity 103. The voltage conductive piece 8 and the connecting seat 10 are slidably connected. The voltage conductive piece 8 is located below the fixing bolt 2. The fastening assembly 9 includes a fixing plate 91, a pressure roller 92, and a support roller 93. The fixing plate 91 is fixedly connected to the inner wall of the fixed cavity 103. A fixed rod 912 is fixedly connected to one side of the fixed plate 91, and a movable plate 913 is rotatably connected to the end of the fixed rod 912 away from the fixed plate 91. A torsion spring 911 is sleeved on the outer wall of the fixed rod 912, and the two ends of the torsion spring 911 are fixedly connected to the side wall of the corresponding movable plate 913. The end of the movable plate 913 away from the fixed rod 912 is rotatably connected to the pressure roller 92. Several protective strips 921 distributed in a circumferential array are fixedly connected to the outer wall of the pressure roller 92. A support roller 93 is located below the pressure roller 92. The two ends of the support roller 93 are rotatably connected to the inner wall of the fixed cavity 103. Several sets of convex balls 931 distributed in a circumferential array are fixedly connected to the outer wall of the support roller 93. The support roller 93 and the pressure roller 92 are both located on one side of the connecting seat 10. The convex balls 931 are elastic.

[0039] Positioning of the wire by fastening assembly 9: In the initial state, the limiting groove 62 on the rotating disk 61 is engaged with one end of the limiting rod 31. At this time, the return spring 32 is in a stretched state, and the limiting rod 31 is no longer close to one end of the movable slot 101, and there is a certain distance between it and the other end of the movable slot 101. At this time, the push rod 33 drives the push block 34 to lift the pressure roller 92. When connecting the wire, one end of the wire can first be inserted into the inside of the fixed cavity 103 through the wiring hole 102, and then pass through the gap between the pressure roller 92 and the support roller 93. Then the wire is inserted between the voltage conductive piece 8 and the connecting seat 10. Then the fixing bolt 2 is rotated to squeeze the voltage conductive piece 8 at one end of the fixing bolt 2, so that the voltage conductive piece 8 is pressed down and contacts the wire, thereby completing the initial fixing of the wire and completing the connection between the wire and the circuit breaker body 7. The voltage conductive piece 8 has a certain elasticity and is the existing technology inside the circuit breaker body 7.

[0040] When using the circuit breaker body 7, the limit lever 31 can be pushed to continuously move one end of the limit lever 31 inside the movable slot 101. At the same time, the return spring 32 is stretched. When one end of the limit lever 31 separates from the limit slot 62, the control switch 5 can be rotated to push it to the open state. During this process, due to the rotation of the control switch 5 and the elastic recovery of the return spring 32, the limit lever 31 can be driven back to its original position, and the limit lever 31 is inserted into the deepest part of the arc-shaped slot 63. At this time, the push block 34 no longer applies external force to the clamping roller 92. Through the elastic recovery of the torsion spring 911 and the rotational connection between the movable plate 913 and the fixed rod 912, the clamping roller 92 can be moved down, and at the same time, it cooperates with the support roller 93 to complete the clamping and fixing of the conductor. Furthermore, there is a certain angle between the clamping roller 92 and the inner wall of the fixed cavity 103. When the clamping roller 92 is not squeezed by the push block 34, the distance between the clamping roller 92 and the support roller 93 is smaller than the outer diameter of the wire. Therefore, when the wire moves outward, the mutual clamping between the clamping roller 92 and the support roller 93 can effectively prevent the wire from separating from the terminal 1. The protective strip 921 on the surface of the clamping roller 92 can be made of rubber, which can not only protect the surface of the wire and prevent damage to the wire during clamping, but also increase the friction between it and the wire, thereby increasing the tightness of the wire. Through the above operation, it can effectively prevent the conductor plate 8 from no longer clamping the wire after the fixing bolt 2 loosens, thus preventing the wire from separating from the circuit breaker body 7.

[0041] The convex ball 931 ensures a stable connection between the conductor and the voltage-conducting plate 8. Furthermore, both the clamping roller 92 and the support roller 93 are made of insulating material, while the convex ball 931 on the surface of the support roller 93 can be made of rubber or plastic (but is not limited to these materials) to ensure that the convex ball 931 has a certain elasticity and insulating effect. The uppermost outer wall of the support roller 93 is higher than one end of the connecting seat 10. Therefore, during the clamping process of the conductor by the clamping roller 92 and the support roller 93, the tightening of the fixing bolt 2 causes the voltage-conducting plate 8 to move the conductor downwards, and the conductor to squeeze the convex ball 931, compressing the convex ball 931 to a certain extent. However, when the fixing bolt 2 loosens during use, the pressure applied by the voltage-conducting plate 8 to the conductor will weaken. At this time, the elastic recovery of the convex ball 931 can move the conductor upwards a certain distance. Moreover, the convex ball 931 can increase the friction between itself and the conductor, thereby effectively increasing the firmness of the conductor connection and ensuring that the end of the conductor can continuously contact the voltage-conducting plate 8, thus ensuring the stability of the connection between the conductor and the circuit breaker body 7.

[0042] Reference Figures 5-7Furthermore, the unlocking component 3 includes a limiting rod 31 and a push rod 33. The side wall of the limiting rod 31 is slidably connected to the inner wall of the movable slot 101, and the limiting rod 31 is slidably connected to the limiting frame 4. One end of the limiting rod 31 located inside the fixed cavity 103 is fixedly connected to the push rod 33. A reset spring 32 is fixedly connected to the side wall of one end of the limiting rod 31. The end of the reset spring 32 away from the limiting rod 31 is fixedly connected to the inner wall of the groove 1031. A push block 34 is fixedly connected to the end of the push rod 33 away from the limiting rod 31. The push block 34 is set in a trapezoidal shape. One end of the push block 34 can be slidably connected to the pressing roller 92. The push rod 33 and the push block 34 are located on one side of the connecting seat 10.

[0043] Unlock component 3 to prevent loosening of the wires: such as Figure 1 As shown, when the circuit breaker body 7 is in use, the control switch 5 is in the open position. However, when the circuit breaker body 7 trips due to overload or short circuit, this is existing technology and the specific reason will not be described further. At this time, during the reset process of the control switch 5, the arc groove 63 gradually squeezes the limit lever 31, causing the limit lever 31 to stretch the reset spring 32, and through the push rod 33, it drives the push block 34 to move towards the wiring hole 102 side. At the same time, through the mutual sliding between the inclined surface of the push block 34 and the pressure roller 92, the pressure roller 92 is raised. The rotation of the movable plate 913 causes the torsion spring 911 to deform, so as to... This removes the restriction of the clamping roller 92 and the support roller 93 on the conductor, making it easier to quickly separate the conductor from the circuit breaker body 7 after loosening the fixing bolt 2. This reduces the number of maintenance and inspection steps and improves efficiency. Therefore, when it is necessary to repair or replace the circuit breaker body 7 or the conductor, the disassembly process of the conductor clamping and limiting mechanism is no longer cumbersome, and it is not necessary to remove multiple parts to take out the conductor. This reduces the difficulty and time cost of maintenance. In addition, in order to prevent the limiting rod 31 from shaking during the movement, the limiting frame 4 can increase its stability and also prevent the limiting rod 31 from deviating.

[0044] Example 2, refer to Figures 1-3 Furthermore, the limiting component 6 includes a rotating disk 61, one end of which is fixedly connected to the control switch 5. The side wall of the rotating disk 61 is provided with an arc-shaped groove 63, and the outer wall of the rotating disk 61 is provided with a limiting groove 62 that is adapted to the limiting rod 31. The limiting groove 62 is located on one side of the arc-shaped groove 63. The center line of the limiting groove 62 and the center line of the end of the limiting rod 31 away from the fixed cavity 103 are on the same horizontal plane. The inner wall of the arc-shaped groove 63 is slidably connected to one end of the limiting rod 31.

[0045] The positioning of the control switch 5 by the limit component 6: During the reset process of the control switch 5, after one end of the limit lever 31 separates from the arc groove 63, the control switch 5 is not yet fully reset. As the control switch 5 rotates during the reset process, one end of the limit lever 31 will first slide against the outer wall of the rotating disk 61. After the control switch 5 finishes rotating, the limit groove 62 is located on one side of the limit lever 31. At this moment, the limit lever 31 is no longer squeezed by external force, and the elastic recovery of the reset spring 32 causes the limit lever 31 to move towards the limit groove 62. Finally, one end of the limit lever 31 is inserted into the interior of the limit groove 62, thereby completing the limit of the control switch 5. This prevents the operator from accidentally opening the control switch 5 during maintenance and inspection, causing the circuit to reconnect, and further increases the protection effect. This linkage method not only solves the problems of inconvenient disassembly and difficult maintenance, but also increases the safety of equipment use, thereby effectively enhancing the combined protection effect of the circuit breaker body 7.

[0046] It should be noted that the specific model and specifications need to be selected and determined based on the actual specifications of the device. The specific selection and calculation method adopts the existing technology in this field, so it will not be described in detail here.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A circuit breaker with combined protection structure, comprising a circuit breaker body (7), both ends of the circuit breaker body (7) are provided with terminal ends (1), the circuit breaker body (7) is connected with a control switch (5), characterized in that, Also includes: Fastening assembly (9), which is located inside the terminal (1), is used to lock the connecting wire; Unlocking component (3), which is connected to terminal (1), is used to unlock fastening component (9). Limiting component (6), the limiting component (6) is fixedly connected to the control switch (5), the limiting component (6) is used to limit the position of the control switch (5); The fastening assembly (9) includes a fixed plate (91), a pressure roller (92) and a support roller (93). The fixed plate (91) is fixedly connected to the inner wall of the fixed cavity (103). A fixed rod (912) is fixedly connected to one side of the fixed plate (91), and a movable plate (913) is rotatably connected to the end of the fixed rod (912) away from the fixed plate (91). A torsion spring (911) is sleeved on the outer wall of the fixed rod (912). The two ends of the torsion spring (911) are fixedly connected to the side wall of the corresponding movable plate (913). The end of the movable plate (913) away from the fixed rod (912) is rotatably connected to the pressure roller (92). A number of protective strips (921) arranged in a circular array are fixedly connected to the outer wall of the pressure roller (92). The support roller (93) is located below the pressure roller (92). Both ends of the support roller (93) are rotatably connected to the inner wall of the fixed cavity (103). Several sets of circumferentially distributed convex balls (931) are fixedly connected to the outer wall of the support roller (93). The support roller (93) and the pressure roller (92) are both located on one side of the connecting seat (10). The convex balls (931) are elastic. The unlocking component (3) includes a limiting rod (31) and a push rod (33). The side wall of the limiting rod (31) is slidably connected to the inner wall of the movable slot (101), and the limiting rod (31) is slidably connected to the limiting frame (4). The end of the limiting rod (31) located inside the fixed cavity (103) is fixedly connected to the push rod (33), and a return spring (32) is fixedly connected to the side wall of one end of the limiting rod (31). The end of the return spring (32) away from the limiting rod (31) is fixedly connected to the inner wall of the groove (1031). The push rod (33) is fixedly connected to a push block (34) at the end away from the limit lever (31). The push block (34) is arranged in a trapezoidal shape. One side wall of the push block (34) can be slidably connected to the pressure roller (92). The push rod (33) and the push block (34) are located on one side of the connecting seat (10). The limiting component (6) includes a rotating disk (61), one end of which is fixedly connected to a control switch (5). The side wall of the rotating disk (61) is provided with an arc-shaped groove (63), and the outer wall of the rotating disk (61) is provided with a limiting groove (62) that is adapted to the limiting rod (31). The limiting groove (62) is located on one side of the arc-shaped groove (63). The center line of the limiting groove (62) and the center line of the limiting rod (31) away from the fixed cavity (103) are on the same horizontal plane. The inner wall of the arc-shaped groove (63) is slidably connected to one end of the limiting rod (31).

2. The circuit breaker having a combined shield structure according to claim 1, wherein, The circuit breaker body (7) is fixedly connected to the terminal (1). A limit frame (4) is fixedly connected to the side wall of the circuit breaker body (7). A fixed cavity (103) is provided inside the terminal (1). A movable slot (101) is provided at one end of the fixed cavity (103). A groove (1031) is provided on one side inner wall of the fixed cavity (103). A wiring hole (102) is provided on the inner wall of the fixed cavity (103) away from the groove (1031). A fixing bolt (2) is threadedly connected to the side wall of the terminal (1).

3. The circuit breaker having a combined shield structure according to claim 2, wherein, The inner wall of the fixed cavity (103) is fixedly connected with a voltage conductive sheet (8) and a connecting seat (10). The voltage conductive sheet (8) and the connecting seat (10) are slidably connected. The voltage conductive sheet (8) is located below the fixing bolt (2).

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