Scraper conveyer

Abstract

The invention provides a scraper conveyer. The scraper conveyer comprises a body and a scraper blade, the supporting seat is provided with a bottom plate, a supporting assembly and an adjusting assembly, the supporting assembly and the adjusting assembly are oppositely arranged on the two side edges of the bottom plate in the width direction of the bottom plate, the side edges, oppositely arranged in the width direction, of the body are hinged to the supporting assembly, and the other side edge, oppositely arranged in the width direction, of the body is hinged to the adjusting assembly; the adjusting assembly can adjust the height of the body; the posture detection assembly is arranged between the supporting seat and the body, the posture detection assembly comprises a detection part and a controller, the controller is electrically connected with the adjusting assembly and the posture detection assembly, the detection part is used for judging whether the body inclines in the horizontal direction or not, and the controller can control the adjusting assembly according to a detection result of the detection part. The height of the body is adjusted in the height direction. According to the technical scheme, the problem that in the prior art, the effect of adjusting the inclination angle of the scraper conveyor is poor can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of scraper conveyors, and in particular to a scraper conveyor. Background Art

[0002] In the process of coal seam mining, it is necessary to arrange a scraper conveyor at the coal mining face to transport the coal mined at the coal mining face to the machine tunnel, and then the belt conveyor in the machine tunnel will transport the coal out of the well. Due to geological reasons, the inclination angle of the coal mining face in the steeply inclined coal seam is very large, and the coal seam has a certain inclination angle, so the scraper conveyor is also arranged at an inclination. When the scraper conveyor is arranged at an inclination, especially when the scraper conveyor is arranged at an inclination along the width direction, the gangue will not only move along the carrying direction of the scraper conveyor during transportation, but also slide along the width direction of the scraper conveyor.

[0003] In the prior art, chains are usually used to lift the scraper conveyor to change the inclination angle of the scraper conveyor, so that the scraper conveyor remains horizontal, and then hydraulic struts are used to support the scraper conveyor. This method is cumbersome to operate, requires a high installation space for the lifting equipment, and the method of changing the inclination angle of the scraper conveyor by lifting with chains requires manual adjustment of the lifting height of the scraper conveyor, and the adjustment effect is not precise and the adjustment effect is poor. Summary of the invention

[0004] The invention provides a scraper conveyor to solve the problem of poor effect of adjusting the inclination angle of the scraper conveyor in the prior art.

[0005] The present invention provides a scraper conveyor, which comprises: a body; a support seat, which has a bottom plate, a support assembly and an adjustment assembly, wherein the support assembly and the adjustment assembly are relatively arranged on two side edges of the bottom plate along the width direction of the bottom plate, one side edge of the body relatively arranged along the width direction is hinged to the support assembly, and the other side edge of the body relatively arranged along the width direction is hinged to the adjustment assembly, and the adjustment assembly can adjust the height of the body; a posture detection assembly, which is arranged between the support seat and the body, the posture detection assembly comprises a detection member and a controller, the controller is electrically connected to the adjustment member and the posture detection member respectively, the detection member is used to determine whether the body is tilted in the horizontal direction, and the controller can control the adjustment member according to the detection result of the detection member to adjust the height of the body in the height direction.

[0006] Furthermore, two support assemblies and two adjustment assemblies are provided, the two support assemblies are respectively provided at the two ends of the support seat along the length direction, the two adjustment assemblies are respectively provided at the two ends of the support seat along the length direction, a first side edge and a second side edge are relatively provided in the width direction of the support seat, support assemblies and adjustment assemblies are provided on the first side edge and the second side edge, and the adjustment assemblies on the first side edge and the second side edge are relatively provided along the diagonal of the support seat.

[0007] Furthermore, the detection component includes: a trigger rod, which is vertically arranged on the bottom surface of the main body, the trigger rod is hinged to the main body through a universal joint, and the trigger rod can swing in the width direction of the support seat; a detection box, the detection box is arranged on the bottom plate, the detection box has an opening on the side facing the trigger rod, and the end of the trigger rod away from the support seat extends into the opening, and collision sensors are arranged on two inner walls of the detection box that are relatively arranged in the width direction of the support seat, when the trigger rod is in a vertical state, there is a gap between the trigger rod and the collision sensor; when the trigger rod is in an inclined state, the trigger rod can abut against the collision sensor.

[0008] Furthermore, the trigger rod comprises a rod body and a length adjusting member which are connected in sequence, the length adjusting member is arranged between the main body and the rod body, and the length adjustment is used to adjust the length of the rod body extending into the detection box.

[0009] Furthermore, the length adjusting member includes a shell and two bolts, screw holes are provided at both ends of the shell, the two bolts are respectively threadedly matched with the two screw holes, one of the two bolts is used to connect with the main body, and the other of the two bolts is fixedly connected to the rod body.

[0010] Furthermore, a mounting rod is provided on the body, the mounting rod extends along the width direction of the body and is arranged parallel to the body, and the trigger rod is rotatably arranged on the mounting rod and can rotate around the axis of the mounting rod.

[0011] Furthermore, a buffer seat is provided between the detection box and the bottom plate to reduce vibration of the detection box.

[0012] Furthermore, the buffer seat has a receiving groove, the detection box is arranged in the receiving groove, and a plurality of elastic members are arranged between the ground of the detection box and the bottom of the receiving groove.

[0013] Furthermore, the adjustment assembly includes a hydraulic rod, one end of the hydraulic rod is hinged to the bottom plate, and the other end of the hydraulic rod is hinged to the body.

[0014] Furthermore, the support assembly includes a support rod and an adjustment rod. The support rod is arranged on the base plate and extends in the height direction. The adjustment rod is hinged to the main body. A plurality of first adjustment holes are arranged at intervals along the extension direction on the support rod. A plurality of second adjustment holes are arranged at intervals along the extension direction on the adjustment rod. Fasteners are used to fit between the first adjustment holes and the second adjustment holes.

[0015] By applying the technical solution of the present application, the main body of the scraper conveyor can drive the gangue for transportation. In order to ensure the stability of transportation, the main body is fixed on the bottom plate through the support assembly and the adjustment assembly, and the bottom plate is placed on the bottom plate of the working surface to provide a stable foundation for the scraper conveyor. During transportation, if the main body tilts along the width direction, the gangue may slide, thereby affecting the transportation efficiency and safety. When the main body tilts along the width direction, the height of one side of the main body can be adjusted by the adjustment assembly, so that the main body rotates in the height direction relative to the support assembly to adjust the main body to a horizontal state to prevent the gangue from sliding. Specifically, the present application sets a posture detection assembly, which can adjust the height of the adjustment assembly through the controller according to the current tilt state of the main body, that is, whether it is kept in a horizontal position. The operation is convenient and the adjustment is relatively accurate, ensuring the safety of the gangue transportation process, reducing the loss of gangue caused by tilting, thereby improving the overall transportation efficiency and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A side view of a scraper conveyor provided by the present invention is shown;

[0018] Figure 2 Shows Figure 1 A partial enlarged view of point A in the middle.

[0019] The above drawings include the following reference numerals:

[0020] 10. Main body; 11. Mounting rod; 12. Limiting ring;

[0021] 20. Bottom plate;

[0022] 30. Support assembly; 31. Support rod; 32. Adjustment rod;

[0023] 40. Adjustment components;

[0024] 50. trigger rod; 51. rod body; 52. housing; 53. bolt; 54. collar; 55. universal joint;

[0025] 60. Detection box; 61. Collision sensor;

[0026] 70. Buffer seat. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a scraper conveyor, which includes a body 10, a support seat and a posture detection assembly. The support seat has a base plate 20, a support assembly 30 and an adjustment assembly 40, the support assembly 30 and the adjustment assembly 40 are relatively arranged on two side edges of the base plate 20 along the width direction of the base plate 20, one side edge of the body 10 relatively arranged along the width direction is hinged to the support assembly 30, and the other side edge of the body 10 relatively arranged along the width direction is hinged to the adjustment assembly 40, and the adjustment assembly 40 can adjust the height of the body 10. The posture detection assembly is arranged between the support seat and the body 10, and the posture detection assembly includes a detection member and a controller, and the controller is electrically connected to the adjustment assembly 40 and the posture detection assembly respectively, and the detection member is used to determine whether the body 10 is tilted in the horizontal direction, and the controller can control the adjustment assembly 40 according to the detection result of the detection member to adjust the height of the body 10 in the height direction.

[0029] By applying the technical solution of the present application, the body 10 of the scraper conveyor can drive the gangue for transportation. In order to ensure the stability of transportation, the body 10 is fixed on the bottom plate 20 through the support assembly 30 and the adjustment assembly 40, and the bottom plate 20 is placed on the bottom plate of the working surface to provide a stable foundation for the conveyor. During transportation, if the body 10 tilts in the width direction, the gangue may slide, thereby affecting the transportation efficiency and safety. When the body 10 tilts in the width direction, the height of one side of the body 10 can be adjusted by the adjustment assembly 40, so that the body 10 rotates in the height direction relative to the support assembly 30 to adjust the body 10 to a horizontal state to prevent the gangue from sliding. Specifically, the present application can adjust the height of the adjustment assembly 40 through the controller according to the current tilt state of the body 10, that is, whether it is kept in a horizontal position, by setting a posture detection assembly, which is convenient to operate and relatively accurate to adjust, ensuring the safety of the gangue transportation process, reducing the loss of gangue caused by tilting, thereby improving the overall transportation efficiency and economic benefits.

[0030] Specifically, in a specific embodiment of the present application, two support components 30 and two adjustment components 40 are provided, and the two support components 30 are respectively provided at the two ends of the support base along the length direction, and the two adjustment components 40 are respectively provided at the two ends of the support base along the length direction. In the width direction of the support base, a first side and a second side are relatively provided, and the two support components 30 are both provided on the first side, and the two adjustment components 40 are both provided on the second side. Through the above arrangement, the support components 30 and the adjustment components 40 can provide better support performance and adjustment performance for the body 10. When the body 10 is tilted in the width direction, that is, when it rotates with the first side or the second side as the rotation axis, the two adjustment components 40 can adjust the angle of the body 10 at the same time, thereby improving the adjustment performance.

[0031] Specifically, in another specific embodiment of the present application, two support assemblies 30 and two adjustment assemblies 40 are provided, and the two support assemblies 30 are respectively provided at the two ends of the support seat along the length direction, and the two adjustment assemblies 40 are respectively provided at the two ends of the support seat along the length direction, and the first side and the second side are relatively provided in the width direction of the support seat, and the support assemblies 30 and the adjustment assemblies 40 are provided on the first side and the second side, and the adjustment assemblies 40 on the first side and the second side are relatively provided along the diagonal of the support seat. Through the above-mentioned arrangement, the two diagonally arranged adjustment assemblies 40 can drive the body 10 to rotate along the diagonal formed between the two adjustment assemblies 40, and when the ground inclination of the working surface is more complicated, the two adjustment assemblies 40 can independently adjust the height of the two ends of the body 10 to keep the body 10 in a horizontal state, thereby improving the overall adjustment effect of the adjustment assemblies 40.

[0032] Specifically in the present application, the detection member includes a trigger rod 50 and a detection box 60. The trigger rod 50 is vertically arranged on the bottom surface of the body 10, and the trigger rod 50 is hinged to the body 10 through a universal joint 55, and the trigger rod 50 can swing in the width direction of the support seat. The detection box 60 is arranged on the bottom plate 20, and the detection box 60 has an opening on the side facing the trigger rod 50, and the end of the trigger rod 50 away from the support seat extends into the opening. The detection box 60 is provided with collision sensors 61 on the two inner walls of the detection box 60 that are arranged opposite to each other in the width direction of the support seat. When the trigger rod 50 is in a vertical state, there is a gap between the trigger rod 50 and the collision sensor 61; when the trigger rod 50 is in an inclined state, the trigger rod 50 can abut against the collision sensor 61. Through the above arrangement, when the main body 10 is kept in a horizontal state, the trigger rod 50 will not touch the collision sensor 61, and the adjustment component 40 will not work and only play a supporting role; when the main body 10 is tilted, the trigger rod 50 can swing between the two inner walls of the detection box 60 that are relatively arranged in the width direction of the support seat through the universal joint 55, and touch the collision sensor 61. When the collision sensor 61 detects the collision signal, the controller can be used to control the adjustment component 40 to adjust the height of the main body 10.

[0033] Furthermore, the trigger rod 50 includes a rod body 51 and a length adjustment member connected in sequence, the length adjustment member is arranged between the main body 10 and the rod body 51, and the length adjustment is used to adjust the length of the rod body 51 extending into the detection box 60. Through the above arrangement, the length of the rod body 51 extending into the detection box 60 can be adjusted according to the height of different main bodies 10 to ensure that the trigger rod 50 can be stably matched with the collision sensor 61.

[0034] In a specific embodiment of the present application, Figure 2 As shown, the length adjustment member includes a housing 52 and two bolts 53. Screw holes are provided at both ends of the housing 52. The two bolts 53 are respectively threadedly matched with the two screw holes. One of the two bolts 53 is used to be fixedly connected with the universal joint 55 to be connected with the body 10, and the other of the two bolts 53 is fixedly connected with the rod body 51. Through the above arrangement, the positions of the housing 52 and the rod body 51 relative to the body 10 can be adjusted respectively to adjust the length of the rod body 51 extending into the detection box 60.

[0035] In other embodiments of the present application, the length adjustment component may also be a structure such as a telescopic rod to adjust the length of the rod body 51 extending into the detection box 60.

[0036] Specifically in the present application, the main body 10 is provided with a mounting rod 11, which extends along the width direction of the main body 10 and is arranged parallel to the main body 10, and the trigger rod 50 is rotatably arranged on the mounting rod 11 and can rotate around the axis of the mounting rod 11. When the main body 10 has an inclination along the length direction, the trigger rod 50 can be rotated relative to the mounting rod 11 by setting it, and by cooperating with the universal joint 55, the rod body 51 of the trigger rod 50 can be kept in a vertical state, so as to improve the cooperation effect between the trigger rod 50 and the detection box 60, prevent the trigger rod 50 from being stuck and unable to rotate, and improve the accuracy of the posture detection component.

[0037] In some feasible embodiments of the present application, refer to Figure 2 As shown, a collar 54 is provided at one end of the trigger rod 50 away from the rod body 51, a limiting ring 12 is fixedly provided on the mounting rod 11, a limiting groove is provided in an annular manner on the surface of the limiting ring 12, and the collar 54 is rotatably provided in the limiting groove. Through the above arrangement, the rotation of the trigger rod 50 relative to the mounting rod 11 can be realized, and the displacement of the trigger rod 50 along the extension direction of the mounting rod 11 can be limited by the two side walls of the limiting groove, thereby ensuring the stability of the installation of the trigger rod 50.

[0038] Specifically, a buffer seat 70 is provided between the detection box 60 and the bottom plate 20 to reduce the vibration of the detection box 60. When the coal mining machine is in operation, it may generate certain vibrations to the working face tunnel, and at this time, the support seat may also drive the detection box 60 to vibrate. In this application, by providing the buffer seat 70, the risk of the vibration of the detection box 60 driving the collision sensor 61 to hit the trigger rod 50 can be reduced, so as to ensure the stability of the posture detection component detection.

[0039] In one embodiment of the present application, the buffer seat 70 has a receiving groove, the detection box 60 is arranged in the receiving groove, and a plurality of elastic members are arranged between the ground of the detection box 60 and the bottom of the receiving groove. Through the above arrangement, the plurality of elastic members can absorb the kinetic energy of the vibration of the detection box 60 to reduce the vibration of the detection box 60 and ensure the stability of the detection box 60 placed on the bottom plate 20.

[0040] In the present application, the adjustment component 40 includes a hydraulic rod, one end of which is hinged to the bottom plate 20, and the other end of which is hinged to the body 10. The hydraulic rod is an electro-hydraulic push rod. Through the above arrangement, the controller can control the operating state of the electro-hydraulic push rod through the detection result of the posture detection component to achieve the adjustment effect of the adjustment component 40.

[0041] Specifically, the hydraulic rod may be a multi-section hydraulic rod to improve the supporting performance of the adjustment assembly 40 for the main body 10 , thereby ensuring the stability of the main body 10 while achieving the adjustment function.

[0042] In the present application, the support assembly 30 includes a support rod 31 and an adjustment rod 32. The support rod 31 is arranged on the bottom plate 20 and extends in the height direction. The adjustment rod 32 is hinged to the body 10. A plurality of first adjustment holes are arranged at intervals along the extension direction on the support rod 31. A plurality of second adjustment holes are arranged at intervals along the extension direction on the adjustment rod 32. Fasteners are provided between the first adjustment holes and the second adjustment holes. Through the above arrangement, the overall height of the support assembly 30 can be adjusted by selecting different first adjustment holes and second adjustment holes for connection, so that the scraper conveyor can adapt to the needs of transporting waste rock on working surfaces of different heights.

[0043] Specifically, the fastener may be a bolt.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0046] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0047] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0048] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A scraper conveyor, characterized in that: The scraper conveyor comprises: Ontology(10); A support seat, comprising a base plate (20), a support assembly (30) and an adjustment assembly (40), wherein the support assembly (30) and the adjustment assembly (40) are arranged on two side edges of the base plate (20) in a width direction thereof, one side edge of the body (10) arranged in a width direction thereof is hinged to the support assembly (30), and the other side edge of the body (10) arranged in a width direction thereof is hinged to the adjustment assembly (40), and the adjustment assembly (40) is capable of adjusting the height of the body (10); A posture detection component is arranged between the support seat and the body (10), the posture detection component comprises a detection member and a controller, the controller is electrically connected to the adjustment member (40) and the posture detection component respectively, the detection member is used to determine whether the body (10) is tilted in the horizontal direction, and the controller can control the adjustment member (40) according to the detection result of the detection member to adjust the height of the body (10) in the height direction.

2. The scraper conveyor according to claim 1, characterized in that: The supporting assembly (30) and the adjusting assembly (40) are both provided with two, and the two supporting assemblies (30) are respectively provided at the two ends of the supporting seat along the length direction, and the two adjusting assemblies (40) are respectively provided at the two ends of the supporting seat along the length direction, and a first side edge and a second side edge are relatively provided in the width direction of the supporting seat, and the supporting assembly (30) and the adjusting assembly (40) are both provided on the first side edge and the second side edge, and the adjusting assemblies (40) on the first side edge and the second side edge are relatively provided along the diagonal line of the supporting seat.

3. The scraper conveyor according to claim 1, characterized in that: The detection member comprises: a trigger rod (50), the trigger rod (50) being vertically arranged on the bottom surface of the body (10), the trigger rod (50) being hinged to the body (10) via a universal joint (55), and the trigger rod (50) being capable of swinging in the width direction of the support seat; A detection box (60) is arranged on the bottom plate (20), the detection box (60) has an opening on a side facing the trigger rod (50), one end of the trigger rod (50) away from the support seat extends into the opening, and collision sensors (61) are arranged on two inner walls of the detection box (60) that are arranged opposite to each other in the width direction of the support seat, when the trigger rod (50) is in a vertical state, there is a gap between the trigger rod (50) and the collision sensor (61); when the trigger rod (50) is in an inclined state, the trigger rod (50) can abut against the collision sensor (61).

4. The scraper conveyor according to claim 3, characterized in that: The trigger rod (50) comprises a rod body (51) and a length adjustment member connected in sequence, wherein the length adjustment member is arranged between the body (10) and the rod body (51), and the length adjustment member is used to adjust the length of the rod body (51) extending into the detection box (60).

5. The scraper conveyor according to claim 4, characterized in that: The length adjusting member comprises a housing (52) and two bolts (53); screw holes are provided at both ends of the housing (52); the two bolts (53) are respectively threadedly matched with the two screw holes; one of the two bolts (53) is used to be connected to the body (10); and the other of the two bolts (53) is fixedly connected to the rod body (51).

6. The scraper conveyor according to claim 3, characterized in that: The body (10) is provided with a mounting rod (11), the mounting rod (11) extends along the width direction of the body (10) and is arranged parallel to the body (10), and the trigger rod (50) is rotatably arranged on the mounting rod (11) and can rotate around the axis of the mounting rod (11).

7. The scraper conveyor according to claim 3, characterized in that: A buffer seat (70) is provided between the detection box (60) and the bottom plate (20) to reduce vibration of the detection box (60).

8. The scraper conveyor according to claim 7, characterized in that: The buffer seat (70) has a receiving groove, the detection box (60) is arranged in the receiving groove, and a plurality of elastic members are arranged between the ground of the detection box (60) and the bottom of the receiving groove.

9. The scraper conveyor according to claim 1, characterized in that: The adjustment assembly (40) comprises a hydraulic rod, one end of which is hinged to the base plate (20), and the other end of which is hinged to the body (10).

10. The scraper conveyor according to claim 1, characterized in that: The support assembly (30) comprises a support rod (31) and an adjustment rod (32); the support rod (31) is arranged on the base plate (20) and extends in the height direction; the adjustment rod (32) is hinged to the body (10); a plurality of first adjustment holes are arranged at intervals along the extension direction on the support rod (31); a plurality of second adjustment holes are arranged at intervals along the extension direction on the adjustment rod (32); and fasteners are used to fit between the first adjustment holes and the second adjustment holes.

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