A shearer drum deflection angle detection device

Abstract

The present application relates to a coal cutter drum detection technical field, specifically, a kind of coal cutter drum deflection angle detection device.It includes measuring assembly, the measuring assembly includes support plate, gear is rotationally arranged on the upper side of the support plate, the gear is meshed with the first tooth block for driving gear to rotate, and the first tooth block is fixed with lever at one end.The present application is extruded to lever and drives lever to push the first tooth block when the angle deviation occurs to drum in the process of rotation, the first tooth block slides and drives gear and pointer to rotate under the pushing of lever, and the deflection angle of drum is directly obtained by the angle of pointer rotation observed by user, the device does not need to open the heat dissipation hole on the surface of shell, prevent the dust and water vapor etc. in coal mine into the inside of shell to cause pollution to shell internal parts, improve the stability of device and prolong the service life of device.

Description

Technical Field

[0001] The present invention relates to the technical field of coal shearer drum detection, in particular to a coal shearer drum deflection angle detection device. Background Art

[0002] The drum shearer is the core equipment for comprehensive mechanized coal mining in underground coal mines. It uses a rotating drum as the main cutting component. The picks on the drum cut the coal seam and complete the coal dropping and crushing operations. The spiral blades on the drum load the fallen coal into the scraper conveyor to complete the coal loading operation. It is widely used in longwall mining of gently inclined and inclined coal seams. It is a key equipment for achieving high production and efficiency in coal mines. In order to achieve precise control of the coal mining process by real-time monitoring of the horizontal posture of the drum and ensure that the coal mining operation can be carried out efficiently, safely and with high quality, when using the drum shearer, the staff needs to use the drum deflection angle detection device of the coal shearer to detect the drum deflection angle of the drum shearer.

[0003] In order to make the angle deflection detection process simple and fast, the existing angle detection device usually uses a sensor system to detect the coal mining machine drum. The surface of such detection device is usually provided with heat dissipation holes to dissipate heat from the internal electrical components of the device to prevent the internal temperature of the device from being too high during long-term use, causing damage to its internal parts. However, the environment underground in coal mines is harsh. When using such detection devices, dust and water vapor in the coal mines can easily enter the interior of the detection device through the heat dissipation holes and pollute its internal parts, resulting in reduced detection accuracy or failure of the device; although the traditional device that uses mechanical parts such as levers to detect the drum angle does not require heat dissipation holes on the surface of the device, it requires manual adjustment of the position of the detection device when installing the detection device. It is difficult to accurately adjust the position of the device manually, resulting in the lever being squeezed to a certain extent by the coal mining machine drum during installation, and the pointer angle of the detection device will also deviate, resulting in inaccurate readings of the device. In view of this, we propose a coal mining machine drum deflection angle detection device. Summary of the Invention

[0004] The purpose of the present invention is to provide a coal mining machine drum deflection angle detection device to solve the problems raised in the above background technology:

[0005] 1. Dust and water vapor from underground coal mines entering the detection device will pollute the detection device, resulting in reduced detection accuracy or malfunction of the device;

[0006] 2. During the installation process of the detection device, the lever is easily squeezed to a certain extent by the coal mining machine drum, causing the pointer angle to deviate.

[0007] To achieve the above-mentioned purpose, a coal mining machine drum deflection angle detection device is provided, including a shell, a measuring component is arranged inside the shell, the measuring component includes a support plate, the support plate is fixedly arranged inside the shell, a gear is rotatably arranged on the upper side of the support plate, an adjustment component is arranged in the middle of the gear, a No. 1 tooth block for driving the gear to rotate is meshed and connected to the gear, a No. 1 limit plate for limiting the No. 1 tooth block is fixedly arranged inside the shell, the No. 1 limit plate and the support plate are parallel to each other, the No. 1 tooth block is slidably arranged inside the No. 1 limit plate, a lever is fixedly arranged at one end of the No. 1 tooth block, one end of the lever is arranged on the outside of the shell, the lever is used to push the No. 1 tooth block, and a connecting component is provided at the end of the lever away from the No. 1 tooth block.

[0008] When the lever moves, it pushes the No. 1 gear block and drives the No. 1 gear block to slide. When the No. 1 gear block slides along the direction set by the No. 1 limit plate and drives the gear to rotate.

[0009] As a further improvement of the present technical solution, the adjustment assembly includes a pad, which is fixedly arranged on the upper side of the gear, a connecting block is fixedly arranged on the upper side of the pad, a rotating block is arranged on the upper side of the connecting block, one end of the rotating block is rotatably arranged on the upper side of the shell, and a slot matching the rotating block is opened on the upper side of the shell.

[0010] When the gear rotates, it drives the pad and the connecting block to rotate, and at the same time, the connecting block drives the rotating block to rotate.

[0011] As a further improvement of the present technical solution, a pointer is fixedly provided on one side of the rotating block, and the pointer is arranged on the upper side of the shell. A plurality of protrusions are fixedly and evenly arranged on the lower side of the rotating block, and a tooth groove matching the protrusion is opened on the upper side of the connecting block.

[0012] When the rotating block and the connecting block are fitted together, the protrusion on the lower side of the rotating block is embedded in the tooth groove on the upper side of the connecting block. Then, the connecting block drives the rotating block to rotate during the rotation process, and the rotating block drives the pointer to rotate during the rotation.

[0013] As a further improvement of the present technical solution, a retaining ring is rotatably provided on the lower side of the rotating block, and a plurality of tension springs are fixedly and evenly arranged on the lower side of the retaining ring. The tension springs are fixedly provided on the upper side of the pad, and the tension springs are used to pull the retaining ring downward.

[0014] When the tension spring pulls the clamping ring downward, the rotating block is driven to move downward until it fits with the connecting block. After the connecting block and the rotating block fit together, the protruding block is embedded in the tooth groove on the upper side of the connecting block.

[0015] As a further improvement of the present technical solution, a push rod is fixedly provided on the lower side of the rotating block, and the push rod is rotatably inserted between the connecting block and the support plate. One end of the push rod is rotatably provided on the lower side of the shell. The push rod is used to drive the rotating block to rotate. A compression spring is fixedly provided on the push rod, and the compression spring is fixedly provided on the outside of the push rod. The compression spring is provided inside the shell, and one end of the compression spring is rotatably provided on the lower side of the support plate.

[0016] After the device is installed, the user pushes the push rod upward to drive the rotating block to move upward and push the protrusion into the tooth groove on the upper side of the connecting block. Then the user rotates the push rod to drive the rotating block to rotate, and at the same time the rotating block drives the pointer to rotate until the pointer is turned to the zero scale pointing to the scale line. Then the user stops pushing and turning the push rod, and the tension spring pulls the retaining ring downward while the compression spring pushes the push rod downward to the initial position.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. In the coal mining machine drum deflection angle detection device, when the drum has an angular deviation during rotation, it squeezes the lever and drives the lever to push the No. 1 tooth block. Under the push of the lever, the No. 1 tooth block slides and drives the gear to rotate. At the same time, the gear drives the rotating block and the pointer to rotate. The user can directly obtain the deflection angle of the drum by observing the angle of rotation of the pointer. There is no need to use electrical components such as sensors to read the deflection angle of the drum, and there is no need to open heat dissipation holes on the surface of the shell, which prevents dust and water vapor in the coal mine from entering the interior of the shell and polluting the internal parts of the shell, thereby improving the stability and service life of the device.

[0019] 2. In the coal mining machine drum deflection angle detection device, after the device is installed, the user pushes the push rod upward and rotates the push rod to drive the rotating block to rotate, and at the same time the rotating block drives the pointer to rotate. After adjusting the pointer to the initial position, the user stops pushing and rotating the push rod, and then the tension spring pulls the rotating block downward to fit with the connecting block, preventing the roller from squeezing the lever during the installation process, causing the angle of the pointer to deviate, thereby improving the detection accuracy of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 Schematic diagram of the housing structure of the present invention;

[0022] Figure 3 Schematic diagram of the internal structure of the housing of the present invention;

[0023] Figure 4 It is a schematic diagram of the structure of the measurement component of the present invention;

[0024] Figure 5 A cross-sectional view of the support plate and gear structure of the present invention;

[0025] Figure 6 This is an exploded schematic diagram of the regulating assembly structure of the present invention;

[0026] Figure 7 A bottom view of the partial structure of the adjustment assembly of the present invention;

[0027] Figure 8 For the present invention Figure 1 A magnified view of the structure at center A;

[0028] Figure 9 Schematic diagram of the connection assembly structure of the present invention.

[0029] The meaning of each number in the figure is:

[0030] 1. Housing; 2. Measuring assembly; 21. Support plate; 22. Gear; 23. Gear block No. 1; 24. Stop plate No. 1; 25. Lever; 26. Gear block No. 2; 27. Stop plate No. 2; 28. Damper;

[0031] 3. Adjustment assembly; 31. Spacer; 32. Connecting block; 33. Rotating block; 34. Pointer; 35. Bump; 36. Snap ring; 37. Tension spring; 38. Push rod; 39. Compression spring;

[0032] 4. Connecting assembly; 41. Connecting plate; 42. Fixing block; 43. Slider; 44. Roller; 45. Screw;

[0033] 5. Roller; 6. Connecting ring; 7. Scale line; 8. Protective cover. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. Example

[0036] See also Figure 2-Figure 4 As shown, the purpose of this embodiment is to provide a coal mining machine drum deflection angle detection device, including a shell 1, a measuring component 2 is arranged inside the shell 1, and the measuring component 2 includes a support plate 21, the support plate 21 is fixedly arranged inside the shell 1, and a gear 22 is rotatably arranged on the upper side of the support plate 21. The gear 22 is meshed with a No. 1 gear block 23 for driving the gear 22 to rotate. The No. 1 gear block 23 drives the gear 22 to rotate when sliding.

[0037] See also Figure 2-Figure 4 As shown, a No. 1 limit plate 24 for limiting the No. 1 tooth block 23 is fixedly provided inside the shell 1, and the No. 1 limit plate 24 and the support plate 21 are parallel to each other. The No. 1 tooth block 23 is slidably provided inside the No. 1 limit plate 24. When sliding, the No. 1 tooth block 23 slides along the direction set by the No. 1 limit plate 24. A lever 25 is fixedly provided at one end of the No. 1 tooth block 23, and one end of the lever 25 is provided on the outside of the shell 1. The lever 25 is used to push the No. 1 tooth block 23. When moving, the lever 25 pushes the No. 1 tooth block 23 and drives the No. 1 tooth block 23 to slide.

[0038] See also Figures 1-9 As shown, a connecting assembly 4 is provided at the end of the lever 25 away from the No. 1 tooth block 23, a roller 5 is provided on the side of the connecting assembly 4 away from the lever 25, and a connecting ring 6 is fixedly provided on the side of the roller 5 close to the connecting assembly 4. When using the device, the user first places the device on the side of the roller 5 close to the connecting ring 6. The connecting assembly 4 includes a connecting plate 41, which is rotatably set at the end of the lever 25 away from the No. 1 tooth block 23, and a fixed block 42 is fixedly provided on the side of the connecting plate 41 away from the lever 25. A slider 43 is provided on one side of the fixed block 42. The slider 43 is slidably set on the side of the connecting plate 41 close to the fixed block 42, and a slide rail for limiting the slider 43 is fixed on the side of the connecting plate 41 close to the slider 43. The direction of the slide rail is perpendicular to the direction in which the fixed block 42 is set. When sliding, the slider 43 slides along to adjust the distance between the fixed block 42 and the slider 43.

[0039] See also Figures 1-9 As shown, the side where the fixed block 42 and the slider 43 are close to each other is rotatably provided with a roller 44, and the inner and outer side walls of the connecting ring 6 are provided with slots matching the two rollers 44. The width of the roller 44 is the same as the width of the slot on the side wall of the connecting ring 6. The user places the roller 44 on one side of the fixed block 42 in the slot on the outer wall of the connecting ring 6 and places the roller 44 on the side of the slider 43 on the inner side of the connecting ring 6. The side where the slider 43 is away from the fixed block 42 is rotatably provided with a screw 45, and the screw 45 rotates and is inserted into the connecting ring 6. At one end of the connecting plate 41, the screw 45 is used to drive the slider 43 to slide. The user drives the slider 43 to slide toward the side close to the fixed block 42 by rotating the screw 45 until the slider 43 drives the roller 44 to slide into the groove on the inner wall of the connecting ring 6. The two rollers 44 respectively enter the grooves on the inner and outer walls of the connecting ring 6 to complete the connection between the device and the drum 5. Mounting holes are opened all around the shell 1. Then the user fixes the shell 1 to the swing arm of the coal mining machine by passing bolts through the mounting holes around the shell 1.

[0040] See also Figure 2-Figure 6 As shown, an adjustment component 3 is provided in the middle of the gear 22, and the adjustment component 3 includes a gasket 31, which is fixedly provided on the upper side of the gear 22, and a connecting block 32 is fixedly provided on the upper side of the gasket 31. When the gear 22 rotates, it drives the gasket 31 and the connecting block 32 to rotate. A rotating block 33 is provided on the upper side of the connecting block 32, and one end of the rotating block 33 is rotatably provided on the upper side of the shell 1. The upper side of the shell 1 is provided with a slot matching the rotating block 33, and a pointer 34 is fixedly provided on one side of the rotating block 33. The pointer 34 is provided on the upper side of the shell 1, and the rotating block 33 drives the pointer 34 to rotate when it rotates.

[0041] See also Figure 2 As shown, in order to facilitate the user to observe the rotation angle of the pointer 34, a number of scale lines 7 are opened on the upper side of the shell 1, and the pointer 34 is set in the middle of the several scale lines 7. In order to prevent dust from adhering to the surface of the pointer 34 and the scale lines 7, a protective cover 8 for protecting the pointer 34 is fixed on the upper side of the shell 1. The protective cover 8 is made of transparent material, and the pointer 34 and the scale lines 7 are both set inside the protective cover 8. The reading when the pointer 34 points to the scale lines 7 when it rotates is the deflection angle of the pointer 34.

[0042] See also Figure 3-Figure 7As shown, a plurality of protrusions 35 are fixedly and evenly arranged on the lower side of the rotating block 33, and a tooth groove matching the protrusion 35 is opened on the upper side of the connecting block 32. When the rotating block 33 is in contact with the connecting block 32, the protrusion 35 on the lower side of the rotating block 33 is embedded in the tooth groove on the upper side of the connecting block 32. Then, the connecting block 32 drives the rotating block 33 to rotate during the rotation process. A push rod 38 is fixedly provided on the lower side of the rotating block 33. The push rod 38 rotates and is inserted between the connecting block 32 and the support plate 21. One end is rotatably arranged on the lower side of the shell 1, and the push rod 38 is used to drive the rotating block 33 to rotate. After the device is installed, the user pushes the push rod 38 upward to drive the rotating block 33 to move upward and pushes the protrusion 35 into the tooth groove on the upper side of the connecting block 32. Then the user rotates the push rod 38 to drive the rotating block 33 to rotate. At the same time, the rotating block 33 drives the pointer 34 to rotate until the pointer 34 is rotated to the zero scale pointing to the scale line 7. Then the user stops pushing and turning the push rod 38.

[0043] See also Figure 3-Figure 7 As shown, a snap ring 36 is rotatably provided on the lower side of the rotating block 33, and a plurality of tension springs 37 are fixedly arranged evenly on the lower side of the snap ring 36. The tension springs 37 are fixedly provided on the upper side of the pad 31, and the tension springs 37 are used to pull the snap ring 36 downward. The tension of the tension springs 37 is sufficient to pull the snap ring 36 downward and drive the rotating block 33 to move downward. After the user stops pushing the push rod 38, the plurality of tension springs 37 pull the snap ring 36 downward and drive the rotating block 33 to move downward until it fits with the connecting block 32, and the connecting block 33 is connected. After the connecting block 32 and the rotating block 33 are fitted together, the protrusion 35 is again embedded in the tooth groove on the upper side of the connecting block 32. A compression spring 39 is fixedly provided on the push rod 38. The compression spring 39 is fixedly provided on the outside of the push rod 38. The compression spring 39 is provided inside the shell 1. One end of the compression spring 39 is rotatably provided on the lower side of the support plate 21. The pressure of the compression spring 39 is sufficient to drive the push rod 38 to slide. The tension spring 37 pulls the retaining ring 36 downward, and the compression spring 39 pushes the push rod 38 downward to the initial position.

[0044] See also Figures 1-9 As shown, after adjusting the position of the pointer 34, the user starts the coal mining machine to drive the drum 5 to rotate. When the rotation angle of the drum 5 deviates, it swings. At the same time, the connecting ring 6 drives the connecting component 4 to swing. While the connecting component 4 swings, the connecting plate 41 pushes and pulls the lever 25. At the same time, the lever 25 drives the No. 1 gear block 23 to slide and drives the gear 22 to rotate. The gear 22 drives the rotating block 33 and the pointer 34 to rotate. At this time, the user obtains the real-time deflection angle of the drum 5 by observing the rotation angle of the pointer 34.

[0045] See also Figure 2-Figure 4As shown, the gear 22 is meshed with a No. 2 tooth block 26, and the No. 2 tooth block 26 and the No. 1 tooth block 23 are symmetrical about the support plate 21. The No. 2 tooth block 26 is used to limit the gear 22 and adjust the angle of the gear 22 to prevent the gear 22 from loosening and causing its sensitivity to decrease. A No. 2 limiting plate 27 for limiting the No. 2 tooth block 26 is fixedly provided inside the housing 1. The No. 2 limiting plate 27 is parallel to the No. 1 limiting plate 24. The No. 2 tooth block 26 is slidably set inside the No. 2 limiting plate 27. When sliding, the No. 2 tooth block 26 slides along the direction set by the No. 2 limiting plate 27 and drives the gear 22 to rotate.

[0046] See also Figure 2-Figure 4 As shown, both ends of the No. 2 tooth block 26 are fixedly provided with dampers 28 for pushing the No. 2 tooth block 26. The end of the damper 28 away from the No. 2 tooth block 26 is fixedly connected to the inner wall of the shell 1. The two dampers 28 push the No. 2 tooth block 26 to the middle position of the No. 2 limit plate 27 in the initial state. When the gear 22 rotates, it drives the No. 2 tooth block 26 to slide. At this time, the two dampers 28 extend and retract as the No. 2 tooth block 26 slides. After the user has completed use of the device and removed it from the coal mining machine, the two dampers 28 push the No. 2 tooth block 26 to the initial position. At the same time, the No. 2 tooth block 26 drives the gear 22 to rotate and drives the pointer 34 to rotate to the initial position.

[0047] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A coal mining machine drum deflection angle detection device, comprising a housing (1), a measuring assembly (2) provided inside the housing (1), the measuring assembly (2) comprising a support plate (21), the support plate (21) being fixedly provided inside the housing (1), a gear (22) being rotatably provided on the upper side of the support plate (21), a first gear block (23) being meshed and connected on the gear (22) for driving the gear (22) to rotate, a first limiting plate (24) for limiting the first gear block (23) being fixedly provided inside the housing (1), the first limiting plate (24) and the support plate (21) being parallel to each other, and the first gear block (23) being slidably provided on the upper side of the support plate (21). Inside the No. 1 limit plate (24), one end of the No. 1 tooth block (23) is fixedly provided with a lever (25), one end of the lever (25) is provided on the outside of the housing (1), the lever (25) is used to push the No. 1 tooth block (23), the end of the lever (25) away from the No. 1 tooth block (23) is provided with a connecting assembly (4), the middle of the gear (22) is provided with an adjusting assembly (3), the adjusting assembly (3) includes a pad (31), the pad (31) is fixedly provided on the upper side of the gear (22), the upper side of the pad (31) is fixedly provided with a connecting block (32), the upper side of the connecting block (32) is provided with a rotating block (33), and the characteristics are: A snap ring (36) is rotatably provided on the lower side of the rotating block (33), and a plurality of tension springs (37) are fixedly and evenly arranged on the lower side of the snap ring (36). The tension spring (37) is fixedly provided on the upper side of the cushion block (31), and the tension spring (37) is used to pull the snap ring (36) downward. A push rod (38) is fixedly provided on the lower side of the rotating block (33), and the push rod (38) is rotatably inserted between the connecting block (32) and the support plate (21). One end of the push rod (38) is rotatably provided on the lower side of the shell (1), and the push rod (38) is used to drive the rotating block (33) to rotate. A compression spring (39) is fixedly provided on the push rod (38), and the compression spring (39) is fixedly provided on the outer side of the push rod (38). The compression spring (39) is provided inside the shell (1), and one end of the compression spring (39) is rotatably provided on the lower side of the support plate (21).

2. The coal mining machine drum deflection angle detection device according to claim 1, characterized in that: A second tooth block (26) is meshedly connected to the gear (22), and the second tooth block (26) and the first tooth block (23) are symmetrical about the support plate (21). A second limiting plate (27) for limiting the second tooth block (26) is fixedly provided inside the housing (1), and the second limiting plate (27) and the first limiting plate (24) are parallel to each other. The second tooth block (26) is slidably provided inside the second limiting plate (27), and a damper (28) for pushing the second tooth block (26) is fixedly provided at both ends of the second tooth block (26), and the end of the damper (28) away from the second tooth block (26) is fixedly connected to the inner wall of the housing (1).

3. The coal mining machine drum deflection angle detection device according to claim 1, characterized in that: One end of the rotating block (33) is rotatably arranged on the upper side of the shell (1), and a notch matching the rotating block (33) is provided on the upper side of the shell (1).

4. The coal mining machine drum deflection angle detection device according to claim 3, characterized in that: A pointer (34) is fixedly provided on one side of the rotating block (33), and the pointer (34) is arranged on the upper side of the housing (1). A plurality of protrusions (35) are fixedly and evenly arranged on the lower side of the rotating block (33), and a tooth groove matching the protrusions (35) is provided on the upper side of the connecting block (32).

5. The coal mining machine drum deflection angle detection device according to claim 1, characterized in that: The connecting assembly (4) includes a connecting plate (41), the connecting plate (41) being rotatably arranged on an end of the lever (25) away from the first tooth block (23), a fixed block (42) being fixedly arranged on a side of the connecting plate (41) away from the lever (25), a slider (43) being arranged on one side of the fixed block (42), and the slider (43) being slidably arranged on a side of the connecting plate (41) close to the fixed block (42).

6. The coal mining machine drum deflection angle detection device according to claim 5, characterized in that: The sides of the fixed block (42) and the slider (43) that are close to each other are both rotatably provided with a roller (44), and the side of the slider (43) that is away from the fixed block (42) is rotatably provided with a screw (45). The screw (45) is rotatably inserted into one end of the connecting plate (41), and the screw (45) is used to drive the slider (43) to slide.

7. The coal mining machine drum deflection angle detection device according to claim 6, characterized in that: A roller (5) is provided on the side of the connecting assembly (4) away from the lever (25), and a connecting ring (6) is fixedly provided on the side of the roller (5) close to the connecting assembly (4). Notches matching the two rollers (44) are provided on both the inner and outer side walls of the connecting ring (6).

8. The coal mining machine drum deflection angle detection device according to claim 4, characterized in that: The upper side of the housing (1) is provided with a plurality of scale lines (7), the pointer (34) is arranged in the middle of the plurality of scale lines (7), and a protective cover (8) for protecting the pointer (34) is fixedly provided on the upper side of the housing (1), the protective cover (8) being made of a transparent material, and the pointer (34) and the scale lines (7) are both arranged inside the protective cover (8).

Images