Water stop device for aqueduct expansion joint

Abstract

The invention discloses an aqueduct expansion joint water stop device which is used for water stop of an expansion joint of an aqueduct, the aqueduct comprises two adjacent groove bodies, the expansion joint is formed between the two groove bodies, the water stop device comprises a water stop belt, the water stop belt stretches across the upper portion of the expansion joint, and the two ends of the water stop belt are fixed to the two groove bodies respectively; and the stretching mechanism is adapted to be capable of driving the water-stop belt to generate concave deformation at the expansion joint, so that extrusion sealing is formed between the water-stop belt and the top edge of the expansion joint. When the water stop belt leaks water, the stretching mechanism can be controlled to drive the water stop belt to sink inwards in the expansion joint, and therefore the water stop belt is squeezed to the top edge of the expansion joint to achieve the temporary water stop effect. Compared with the prior art, active deformation of the water stop belt can be achieved through the stretching mechanism, the temporary water stop effect is achieved, preorder preparation of water stop belt replacement by maintenance personnel is facilitated, and the situation of water leakage is not prone to occurring.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy engineering, and in particular to a water-stopping device for an aqueduct expansion joint. Background Art

[0002] In water conservancy and hydropower projects, aqueducts are overhead water channels that transport channel water across rivers, valleys, depressions and roads. They are commonly used for irrigation and water delivery, as well as for flood and sand drainage. Large aqueducts can also be navigable. Aqueducts are mainly built with materials such as stone masonry, concrete and reinforced concrete. Due to the long span, aqueducts generally adopt a multi-span design scheme, and expansion joints are formed between the trough bodies of adjacent spans. In order to reduce water leakage at the expansion joints, water stopping treatment is required at the expansion joints.

[0003] At present, the commonly used water-stopping method is the pressure plate water-stop structure, which mainly embeds or post-implants bolts on both sides of the expansion joint of the aqueduct, and tightens the nuts to compress the flat steel, so as to fix the rubber waterstop at the joint of the aqueduct expansion joint. The effect of this water-stopping method mainly relies on the nuts to press the flat steel and waterstop tightly onto the trough body. However, with the long-term operation of the aqueduct, the waterstop is prone to aging and the waterstop is not tightly fitted to the trough body, which causes water leakage. When maintenance personnel discover a water leak, they usually need to make preparations before replacing the waterstop, such as taking a new waterstop or carrying the tools needed, which will lead to the leakage being neglected. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a water-stopping device for an aqueduct expansion joint.

[0005] The objective of the present invention is achieved through the following technical solutions: A water-stop device for an aqueduct expansion joint, used for water-stopping the expansion joint of an aqueduct, the aqueduct comprising two adjacent trough bodies, an expansion joint being formed between the two trough bodies, the water-stop device comprising: a water-stop strip, the water-stop strip spanning over the expansion joint and having two ends respectively fixed to the two trough bodies; a stretching mechanism, the stretching mechanism being adapted to drive the water-stop strip to produce an inwardly concave deformation at the expansion joint, thereby forming an extrusion seal between the water-stop strip and the top edge of the expansion joint.

[0006] Preferably, the waterstop is U-shaped, flat-plate-shaped or V-shaped.

[0007] Preferably, the stretching mechanism includes an ejector mounted above the aqueduct, and a top plate for abutting the waterstop is provided on the ejector end of the ejector, the top plate is U-shaped, and the two side arms of the top plate are inclined away from each other, and the distance between the two side arms of the top plate gradually decreases from top to bottom.

[0008] Preferably, the stretching mechanism includes an electromagnet arranged in the expansion joint, and a plurality of the electromagnets are arranged along the waterstop in the lateral direction, and the waterstop is constructed so that at least the portion opposite to the expansion joint can be attracted by magnetic force.

[0009] Preferably, the stretching mechanism includes a pull hook arranged in the expansion joint and movable at least away from one side of the waterstop strip, and the pull hook is arranged in a plurality along the waterstop strip in the transverse direction, and a plurality of hanging rings are arranged on the bottom surface of the waterstop strip opposite to the expansion joint, and the pull hook can be hung on the hanging ring.

[0010] Preferably, a magnetic plate is provided on the bottom surface of the water stop belt opposite to the expansion joint.

[0011] Preferably, the draw hook is adapted to move closer to and away from the water stop by rotating.

[0012] Preferably, the stretching mechanism also includes a transmission shaft rotatably arranged in the expansion joint, and a connecting disk and a driving disk are sequentially arranged on the transmission shaft, and the connecting disk is disconnectably connected to the transmission shaft through a clutch mechanism, a slideway is radially arranged on the connecting disk, a connecting rod is slidably adapted in the slideway, the hook is arranged on the end of the connecting rod, an arc-shaped driving groove is constructed on the end surface of the driving disk, and a driving shaft extending into the driving groove is arranged on the connecting rod, and the water-stopping device has at least two selectable modes through the control of the clutch mechanism: an engagement mode, in which the clutch mechanism is in an engagement state, at which the transmission shaft drives the connecting disk and the driving disk to rotate synchronously, and drives the hook to be hung on the hanging ring; a water-stopping mode, in which the clutch mechanism is in a disconnected state, at which the transmission shaft only drives the driving disk to rotate, and then under the transmission of the arc-shaped driving groove and the driving shaft, the hook radially pulls the water-stop belt to become concave.

[0013] Preferably, the clutch mechanism is an electromagnetic clutch mechanism.

[0014] The beneficial effects of the present invention are: 1. When the water stop is leaking, the stretching mechanism can be controlled to drive the water stop to be concave in the expansion joint, so that the water stop is squeezed at the top edge of the expansion joint to achieve a temporary water stop effect. Compared with the prior art, the present invention can realize the active deformation of the water stop through the stretching mechanism and has a temporary water stop effect, which is convenient for maintenance personnel to make preliminary preparations for replacing the water stop, and is not prone to leakage.

[0015] 2. The stretching mechanism achieves the concave sealing of the waterstop belt by magnetic attraction of the waterstop belt by the electromagnet arranged in the expansion joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The schematic diagram of the structure of the top plate is a stretching mechanism; Figure 2 The schematic diagram of the structure of the stretching mechanism is an electromagnet; Figure 3 For Figure 2 Schematic diagram of the structure where the water stop strip on the foundation is concave; Figure 4 It is a schematic diagram of the structure in which the stretching mechanism is a draw hook; Figure 5 for Figure 4 A magnified view of part A; Figure 6 Schematic diagram of the lateral distribution structure of the stretching mechanism (the distribution position is indicated in the form of a dotted circle).

[0017] Figure numerals: 1. water stop; 2. stretching mechanism; 3. ejector; 4. ejector plate; 5. electromagnet; 6. hook; 7. hanging ring; 8. magnetic plate; 9. transmission shaft; 10. connecting plate; 11. driving plate; 12. clutch mechanism; 13. slideway; 14. connecting rod; 15. arc-shaped driving groove; 16. driving shaft; 18. groove body; 19. expansion joint; 20. first side arm; 21. bottom arm; 22. second side arm; 23. mounting box; 24. blade body; 25. cam surface; 26. inclined surface; 27. carrier plate; 28. gear; 29. ​​belt. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] The existing aqueduct water stop device mainly relies on nuts to press the flat steel and the water stop strip 1 tightly onto the trough body 18. In detail, the water stop strip 1 spans between the two trough bodies 18 and covers the expansion joint 19. Under the locking of the nut, the water stop strip 1 fits the trough body 18 to prevent moisture from passing over the water stop strip 1 and leaking into the expansion joint 19.

[0020] When the aqueduct expands and contracts due to temperature changes or loads, the size of the expansion joint 19 also changes accordingly, and the waterstop 1 can expand and contract accordingly to maintain the water-stopping effect. However, as the aqueduct operates for a long time, the waterstop 1 is prone to aging and may not fit tightly with the trough body 18 at some point, causing water leakage. For example, when the waterstop 1 is in a stretched state for a long time, hollowing may occur between adjacent nuts on the waterstop 1, and moisture will penetrate into the expansion joint 19 through the hollowing. However, tightening the nuts alone cannot effectively eliminate the hollowing, and the waterstop 1 needs to be replaced. However, the existing waterstop device does not have the ability to temporarily stop water, and maintenance personnel can only allow leakage to occur between the time they discover the leakage and the time they complete the preparations for replacing the waterstop 1.

[0021] like Figures 1 to 6 As shown, in response to the above technical problems, the present disclosure proposes a waterstop device for aqueduct expansion joints, including a waterstop strip 1, which uses a means similar to the prior art to fix the two ends respectively on two adjacent trough bodies 18, thereby spanning over the expansion joint 19 to achieve a waterstop effect. For example, the ends of the waterstop strip 1 and the trough body 18 can be fixed by nut pressing or gluing. The waterstop strip 1 can be U-shaped, flat or V-shaped, but it does not limit the waterstop strip 1 to other possible configurations in the prior art.

[0022] In addition, the water stop device disclosed herein further includes a stretching mechanism 2, which is adapted to drive the water stop strip 1 to produce a concave deformation at the expansion joint 19. It can be imagined that when water leakage occurs, the stretching mechanism 2 can actively drive the water stop strip 1 to produce a concave deformation, and then the water stop strip 1 and the top edge of the expansion joint 19 are squeezed, thereby producing a temporary sealing section to achieve a temporary water stop effect.

[0023] Where possible, the above-mentioned temporary waterstop can be used to prevent water leakage before the waterstop 1 is replaced, or, after eliminating other faults that require replacement of the waterstop 1, control the stretching mechanism 2 to release the waterstop 1, thereby restoring the free expansion and contraction of the waterstop 1 at the expansion joint 19 to meet the expansion and contraction requirements of the aqueduct.

[0024] like Figure 1 As shown, in some embodiments, the stretching mechanism 2 includes an ejector 3 mounted above the aqueduct, and a top plate 4 is provided on the ejection end of the ejector 3. The ejector 3 can be a linear ejector 3 such as an electric cylinder or a pneumatic cylinder, and the top plate 4 and the expansion joint 19 are in a relative position aligned up and down.

[0025] The top plate 4 is specifically a U-shape that matches the cross section of the aqueduct, and may include, for example, a first side arm 20, a bottom arm 21, and a second side arm 22 that are connected in sequence. The first side arm 20 and the second side arm 22 are adapted to be arranged in an inclined manner that diverges from each other, and the description of the inclination is particularly relative to the inner wall of the aqueduct. For example, when the cross section of the aqueduct is a trumpet-shaped shape that gradually expands upward, the first side arm 20 and the second side arm 22 have a slope that expands more outward relative to the side of the cross section of the aqueduct.

[0026] When water leakage occurs, the top plate 4 will gradually be embedded into the expansion joint 19 under the push of the ejector 3. During this period, the two side arms squeeze the two sides of the waterstop 1 until the bottom arm 21 squeezes the bottom of the waterstop 1. At this point, the waterstop 1 will be in a concave state in the transverse direction of the aqueduct to achieve a temporary water-stopping effect without omissions.

[0027] like Figure 2 , Figure 3 As shown, in some embodiments, the stretching mechanism 2 includes an electromagnet 5 disposed in the expansion joint 19, and a plurality of electromagnets 5 are evenly spaced apart and arranged along the water stop 1 in the transverse direction, and the water stop 1 is configured to be able to be attracted by magnetic force at least at a position opposite to the expansion joint 19. For example, a magnetic block may be embedded inside the water stop 1, or a magnetic plate 8 may be bonded to the bottom surface of the water stop 1 to satisfy the above-mentioned ability to be attracted by magnetic force.

[0028] When water leakage occurs, all the electromagnets 5 or the electromagnets 5 corresponding to the water leakage points can be controlled to be in an energized state, and then under the attraction of magnetic force, the waterstop 1 will undergo the expected concave deformation to achieve a temporary water-stopping effect.

[0029] For example, in the expansion joint 19, the side walls of the two adjacent troughs 18 are provided with a carrier plate 27, and each carrier plate 27 is provided with an electromagnet 5. The two carrier plates 27 opposite to each other on the two troughs 18 are stacked in the vertical direction, so that after the aqueduct expands and contracts, the electromagnets 5 on the two carrier plates 27 can cooperate to achieve the maximum magnetic attraction of the center of the water stop 1 exposed in the expansion joint 19, thereby making it easier for the water stop 1 to undergo the expected concave deformation.

[0030] Compared with the above-mentioned embodiment of squeezing the waterstop 1 from top to bottom through the top plate 4, the electromagnet 5 can realize the concave stretching of the waterstop 1 in the expansion joint 19, which makes it easier for maintenance personnel to maintain the waterstop device in the aqueduct. Where possible, the electromagnet 5 can be selected with a larger power, for example, the waterstop 1 can be stretched to break in the expansion joint 19. In this case, the maintenance personnel can directly stack the new waterstop 1 on the original waterstop 1, and after the original waterstop 1 is stretched to break, on the one hand, the hollowing caused by the stretching and aging of the waterstop 1 can be eliminated (at this time, the part of the original waterstop 1 trapped at the top of the trough 18 can be used as the elastic cushion layer of the new waterstop 1), and on the other hand, only one waterstop 1 can be connected between adjacent troughs 18 to ensure the easy expansion and contraction performance of the aqueduct. In this way, the waterstop 1 can be replaced without stopping the water flow of the aqueduct, or the waterstop 1 can be replaced quickly by briefly intercepting the flow upstream.

[0031] like Figure 4 , Figure 5 As shown, in other embodiments, the stretching mechanism 2 includes a hook 6 disposed in the expansion joint 19 and adapted to move at least away from one side of the water stop 1. A plurality of hanging rings 7 are disposed on the bottom surface of the water stop 1 opposite to the expansion joint 19, and the plurality of hanging rings 7 are arranged at equal intervals along the transverse direction of the aqueduct. For example, when the water stop 1 is formed by a mold, the hanging rings 7 can be integrally formed, or the hanging rings 7 can be attached to the water stop 1 by bolts or the like. Accordingly, a plurality of hooks 6 are also arranged at equal intervals along the transverse direction, and each hook 6 can be hung on a corresponding hanging ring 7.

[0032] When water leakage occurs, all the hooks 6 or the hooks 6 corresponding to the leakage points can be controlled to move away from the side of the waterstop 1, so that the hooks 6 can pull the waterstop 1 through the hanging ring 7 to cause an inward concave deformation to achieve a temporary water stopping effect.

[0033] In a possible example, the movement of the hook 6 can be achieved by a linear power source such as a cylinder or an oil cylinder (not shown) arranged in the expansion joint 19, but this relies on manually hanging the hook 6 on the hanging ring 7, and the telescopic performance of the aqueduct may be affected under the restrictions of the hook 6 and the hanging ring 7.

[0034] like Figure 3 , Figure 4 , Figure 5As shown, as another solution, the stretching mechanism 2 may also include a transmission shaft 9 rotatably arranged in the expansion joint 19, and a connecting disc 10 and a driving disc 11 are sequentially arranged on the transmission shaft 9. The connecting disc 10 is disconnectably connected to the transmission shaft 9 through a clutch mechanism 12. For example, the connecting disc 10 is slidable in the axial direction, and a keyway, a toothed mechanism or other power engagement structure is adapted between the transmission shaft 9 and the connecting disc 10. The clutch mechanism 12 may be an electromagnetic clutch or a fork, etc. Alternatively, an electromagnet (not shown) may be arranged at the junction of the transmission shaft 9 and the connecting disc 10 to achieve power engagement and disconnection.

[0035] Among them, a slideway 13 is radially arranged on the connecting disk 10, and a connecting rod 14 is slidably adapted in the slideway 13, and the above-mentioned hook 6 is arranged on the end of the connecting rod 14; an arc-shaped driving groove 15 is constructed on the end surface of the driving disk 11, and a driving shaft 16 extending into the driving groove is arranged on the connecting rod 14, so that the driving shaft 16 and the arc-shaped driving groove 15 cooperate to form a cam structure. When the connecting disk 10 and the driving disk 11 rotate relative to each other, the connecting rod 14 will slide under the push of the driving shaft 16 and the arc-shaped driving groove 15. Therefore, the present disclosure has the following optional usage modes: Engagement mode: When water leakage occurs, the clutch mechanism 12 can be controlled to be in an engaged state, and then the transmission shaft 9 rotates to drive the connecting disk 10 and the driving disk 11 to rotate synchronously, so that the hook 6 will approach the water stop belt 1 in a rotating posture and be hung on the hanging ring 7. In this mode, since the connecting disk 10 and the driving disk 11 rotate synchronously, the driving shaft 16 is not easy to move in the arc-shaped driving groove 15, and the radial position of the hook 6 is not easy to change, so it can be hung on the hanging ring 7.

[0036] Waterstop mode: Based on the engagement mode, the clutch mechanism 12 is controlled to be in the disconnected state, and then the transmission shaft 9 only drives the drive disc 11 to rotate. Driven by the arc-shaped drive groove 15 and the drive shaft 16, the connecting rod 14 drives the hook 6 to pull the waterstop 1 radially to cause it to be concave. In this mode, the hook 6 can still pull the waterstop 1 radially on the basis of hanging the hanging ring 7 by rotation. At this time, the waterstop 1 and the top edge of the expansion joint 19 are more likely to form an effective seal.

[0037] Non-interference mode: on the basis of the engagement mode, the transmission shaft 9 is controlled to rotate to drive the hook 6 away from the hanging ring 7, so as not to affect the telescopic performance of the aqueduct.

[0038] Similar to the solution in which the stretching mechanism 2 is an electromagnet 5, this solution can also be used to achieve replacement of the waterstop 1 without stopping the water flow of the aqueduct, or to quickly complete the replacement of the waterstop 1 by briefly intercepting the flow upstream.

[0039] In a preferred example, when the trough body 18 is cast, a step structure can be reserved at the top of the trough body 18. An installation box 23 can be set on the step, and the expansion joint 19 is defined by two installation boxes 23, and the corners of the installation boxes 23 constitute the top edge of the above-mentioned expansion joint 19. At the same time, the water stop strip 1 can also be fastened by nuts and other means to press its two ends on the top surface of the two installation boxes 23. Correspondingly, the stretching mechanism 2 can be set at the side wall of the installation box 23.

[0040] For example, a motor may be provided in the installation box 23 to provide rotational power for the transmission shaft 9. Specifically, each transmission shaft 9 extends into the installation box 23 and is provided with a gear 28 at its end. A belt 29 is connected between the gears 28, and the motor can drive one of the transmission shafts 9 to rotate, so that the transmission shafts 9 can rotate under the transmission of the belt 29 and the gear 28.

[0041] In some embodiments, a blade 24 is also vertically movably provided on the side wall of the installation box 23, and a cam surface 25 or a slope 26 is also configured on the side wall of the connection plate 10. The blade 24 can be movably provided via an elastic member such as a spring.

[0042] For example, in the scheme of the cam surface 25, when the present disclosure is in the engagement mode, the connecting disk 10 will be rotated until the cam surface 25 pushes the blade 24 upward but does not protrude from the corner of the installation box 23; after the new waterstop 1 is installed, the present disclosure can be controlled to switch back from the waterstop mode to the engagement mode, and the drive shaft 16 can be controlled to rotate further. At this time, the cam surface 25 pushes the blade 24 upward to protrude from the corner of the installation box 23, and then the present disclosure is switched to the waterstop mode again. At this time, when the hook 6 pulls the waterstop 1 further into the expansion joint 19, the blade 24 will penetrate into the waterstop 1, thereby facilitating the expected breakage of the waterstop 1.

[0043] In the scheme of the inclined surface 26, when the water stop 1 needs to be broken, the clutch mechanism 12 can be further controlled to drive the connecting plate 10 to move axially, and then the inclined surface 26 will further push the blade 24 to protrude upward from the corner of the installation box 23 to make the water stop 1 easier to break as expected.

[0044] The clutch mechanism 12 may specifically include an electromagnet arranged on the side wall of the installation box 23, and a spring is also arranged between the electromagnet and the connecting disk 10. By selecting the magnitude of the magnetic force of the electromagnet, the connecting disk 10 can undergo different degrees of axial movement on the transmission shaft 9, for example, it can achieve dynamic engagement and disengagement relative to the transmission shaft 9, and it can also achieve different degrees of pushing of the inclined surface 26 on the blade 24.

[0045] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. An aqueduct expansion joint water-stopping device, used for water-stopping the expansion joint of an aqueduct, the aqueduct comprising two adjacently arranged trough bodies, an expansion joint being formed between the two trough bodies, characterized in that: The water stopping device comprises: A water stop strip (1), the water stop strip (1) spanning over the expansion joint and having two ends respectively fixed to the two trough bodies; A stretching mechanism (2), wherein the stretching mechanism (2) is adapted to drive the water stop strip (1) to produce an inwardly concave deformation at the expansion joint, thereby forming an extrusion seal between the water stop strip (1) and the top edge of the expansion joint.

2. The aqueduct expansion joint water-stopping device according to claim 1 is characterized in that: The water stop strip (1) is U-shaped, flat-plate-shaped or V-shaped.

3. The aqueduct expansion joint water-stopping device according to claim 1 is characterized in that: The stretching mechanism (2) comprises an ejector (3) mounted above the aqueduct, and a top plate (4) for abutting against the water stop belt (1) is arranged on the ejector end of the ejector (3); the top plate (4) is U-shaped, and the two side arms of the top plate (4) are inclined away from each other, and the distance between the two side arms of the top plate (4) gradually decreases from top to bottom.

4. The aqueduct expansion joint water-stopping device according to claim 1 is characterized in that: The stretching mechanism (2) includes an electromagnet (5) arranged in the expansion joint, and a plurality of the electromagnets (5) are arranged along the water stop strip (1) in the transverse direction. The water stop strip (1) is constructed so that at least the portion opposite to the expansion joint can be attracted by magnetic force.

5. The aqueduct expansion joint water-stopping device according to claim 1 is characterized in that: The stretching mechanism (2) comprises a pull hook (6) arranged in the expansion joint and movable at least away from one side of the water stop strip (1); a plurality of the pull hooks (6) are arranged along the water stop strip (1) in the transverse direction; a plurality of hanging rings (7) are arranged on the bottom surface of the water stop strip (1) opposite to the expansion joint; and the pull hook (6) can be hung on the hanging ring (7).

6. The aqueduct expansion joint water-stopping device according to claim 4 is characterized in that: A magnetic plate (8) is provided on the bottom surface of the water stop strip (1) opposite to the expansion joint.

7. The aqueduct expansion joint water-stopping device according to claim 5 is characterized in that: The draw hook (6) is adapted to move closer to and farther away from the water stop (1) by rotating.

8. The aqueduct expansion joint water-stopping device according to claim 7 is characterized in that: The stretching mechanism (2) further comprises a transmission shaft (9) rotatably arranged in the expansion joint, the transmission shaft (9) being provided with a connecting disc (10) and a driving disc (11) in sequence, and the connecting disc (10) being disconnectably connected to the transmission shaft (9) via a clutch mechanism (12), a slideway (13) being radially arranged on the connecting disc (10), a connecting rod (14) being slidably adapted in the slideway (13), the hook (6) being arranged on the end of the connecting rod (14), an arc-shaped driving groove (15) being constructed on the end surface of the driving disc (11), a driving shaft (16) being arranged on the connecting rod (14) and extending into the driving groove, and the water-stopping device having at least two selectable modes as follows by controlling the clutch mechanism (12): an engagement mode, in which the clutch mechanism (12) is in an engagement state, at which time the transmission shaft (9) drives the connecting disk (10) and the driving disk (11) to rotate synchronously, and drives the hook (6) to be hung on the hanging ring (7); Water-stop mode. In the water-stop mode, the clutch mechanism (12) is in a disconnected state. At this time, the transmission shaft (9) only drives the driving disk (11) to rotate. Subsequently, under the transmission of the arc-shaped driving groove (15) and the driving shaft (16), the hook (6) radially pulls the water-stop belt (1) inward.

9. The aqueduct expansion joint water-stopping device according to claim 8 is characterized in that: The clutch mechanism (12) is an electromagnetic clutch mechanism.

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