Arrangement, evaluation and control device for measuring, evaluating and controlling belt tensions of a lifting device

Abstract

Arrangement for measuring belt tensions of a belt-driven lifting device, wherein the arrangement comprises the following elements: - several threaded rods (1), each having a belt-side belt attachment (12) and a fastening-side threaded section (13); - a coupling plate (4) with several through-openings (40) in which a threaded rod (1) with its threaded section (13) is held axially displaceable for adjusting the respective belt tension; - for each threaded rod (1) a screw fastening (3) screwed onto the threaded rod (1) on the fastening side to receive the respective belt load against the coupling plate (4), wherein the screw fastening has at least one nut (3); - for each threaded rod (1) a pressure measuring device (5, 5') arranged between the coupling plate (4) and the respective screw fastening (3) for recording and measuring the respective belt load.

Description

[0001] The invention is based on an arrangement according to the preamble of independent main claim 1.

[0002] Furthermore, the invention relates to an evaluation device for the arrangement according to claim 1.

[0003] Furthermore, the invention relates to a control device comprising the arrangement according to claim 1 and the evaluation device according to claim 7.

[0004] Furthermore, the invention relates to a lifting device, in particular a scissor lift table, comprising the arrangement according to claim 1.

[0005] Furthermore, a method for measuring and evaluating belt tensions has been disclosed.

[0006] A method for controlling belt tensions with the control device is also disclosed.

[0007] Furthermore, a method for marrying a vehicle's chassis to the vehicle's body by means of a lifting device is disclosed.

[0008] Such lifting devices, especially scissor lift tables, e.g., belt-driven scissor lift tables, are needed, for example, in automotive manufacturing to join the chassis and body at the so-called "marriage stations." Depending on the number of belts and their deflections (pulley principle), such lifting devices can generate particularly high forces, e.g., a lifting force of more than 50,000 N (Newtons), especially more than 100,000 N, and thus, for example, forces of 200,000 N. This allows weights of, for example, 10 t (tons) to be lifted. State of the art

[0009] Lifting devices, e.g. scissor lift tables, are known in the prior art.

[0010] The publication DE 10202310947 4B4 discloses a scissor lift table which can be equipped with a belt drive comprising several belts in a pulley system. A winding shaft drives the several belts, which are guided via a deflection pulley through an inlet arranged in a coupling plate ("roller plate") of a pulley system into the pulley system.

[0011] In the prior art, it is common practice to synchronize the belt forces of the individual belts in such lifting devices so that all belts are subjected to the same load during operation. For this purpose, the belt tensions between the winding shaft and the entry point into the pulley system are measured using an optical frequency measurement method. This involves briefly striking the belts manually, causing them to vibrate. The measured vibration frequency is a unit of measurement for determining the belt tension.

[0012] This requires regular maintenance, for example quarterly, during operational breaks, and can only be carried out under strict safety regulations. However, excessively high deviations in belt tension have frequently been observed in the past. Ultimately, higher loads lead to increased wear and irreversible elongation, which in turn results in even greater stress on the belt, potentially leading to belt breakage and total failure. Task

[0013] The object of the invention is to avoid failures of the lifting device.

[0014] This task is solved by the respective subject matter of the independent claims.

[0015] An arrangement for measuring belt tensions of a belt-driven lifting device, in particular a scissor lift table, comprises the following elements: - several threaded rods, each having a belt-side belt attachment and a fastening-side threaded section; - a coupling plate with several through-holes, in which a threaded rod with its threaded section is held axially displaceable for adjusting the respective belt tension; - for each threaded rod a screw fastening screwed onto the fastening side of the threaded rod to absorb the respective belt load against the coupling plate, the screw fastening having a nut; - for each threaded rod, a pressure measuring device is arranged between the coupling plate and the respective screw fastening to record and measure the respective belt load.

[0016] In an advantageous embodiment, the nut of the screw fastening can be a self-locking nut, or the screw fastening can have a lock nut in addition to the nut. This has the advantage that the nut cannot loosen on its own, e.g., due to vibration or similar causes.

[0017] A lifting device according to one embodiment of the invention, in particular a scissor lift table, has the aforementioned arrangement, as well as: - a lower, stationary base frame and an upper, vertically movable lifting frame, which are connected to each other on both sides via a scissor frame; - wherein the scissor frame has an inner frame part and an outer frame part which are rotatably connected to each other about a horizontal axis via a central bearing, as well as - a feedback plate, wherein both the coupling plate and the feedback plate are opposite each other and are each pivotally attached to intersecting thrust struts of one frame part; - one strap attached to each threaded rod; - wherein at least one deflection pulley is rotatably mounted on the inside of both the coupling plate and the counter-coupling plate for each belt; - where each belt, together with its corresponding pulleys, forms a pulley system, as well as - a winding shaft and a drive for winding the belts together.

[0018] As already mentioned, the lifting device can be designed in particular as a scissor lift table.

[0019] An evaluation device for the above arrangement has at least one microprocessor and one digital memory, as well as an individual calibration for each pressure measuring device, wherein the calibrations are stored as data in the memory.

[0020] A control device has the aforementioned arrangement and the evaluation device, as well as for each threaded rod an actuator controlled by the evaluation device for equalizing the belt tensions of all belts to each other, wherein the respective actuator interacts with the said nut of the screw fastening.

[0021] Advantageous embodiments of the invention are specified in the dependent claims.

[0022] A method for measuring and evaluating belt tensions using the aforementioned arrangement comprises the following steps: a. simultaneous reading of electrical measured quantities from the pressure measuring devices at predetermined time intervals; b. Conversion of the measured quantities into measurement data that provide information about the respective tensile forces of the individual belts; c. Comparison of the measurement data.

[0023] In particular, the following procedure step may follow process step c: d. If necessary, issue a warning message depending on a result of process step c.

[0024] The process steps a. to d. can be repeated regularly. This has the advantage that the belt tensions are equalized at all times. Although the individual belt tensions can vary over time depending on the load due to the weight of the object being lifted, the position of the lifting device, etc., the belts should be subjected to as equal a load as possible at all times.

[0025] A method for controlling belt tensions with the aforementioned control device comprises the following steps: A. Simultaneous reading of electrical measurements from the pressure measuring devices at predetermined time intervals; B. Conversion of the measured quantities into measurement data, which provide information about the respective tensile forces of the individual belts; C. Determination of a maximum and a minimum value of the simultaneously determined tensile forces; D. Adjustment of the respective belt tension of a belt which has the maximum value or the minimum value, if the quotient between the maximum value and the minimum value exceeds a predetermined threshold.

[0026] The process steps A to D can be repeated in a loop.

[0027] A method for joining a vehicle's chassis to its body using the aforementioned lifting device involves the lifting device pressing the chassis against the body from below. This joining method may include the aforementioned measuring method and, in particular, the aforementioned regulating method.

[0028] A particularly great advantage of the invention lies in the possibility of permanent condition monitoring, which can take place during ongoing operation.

[0029] A particular advantage is that the belt tensions under the constantly changing loads can be measured simultaneously and thus compared with each other.

[0030] Another advantage of the invention is that the belts are always subjected to the same load. This significantly reduces wear and increases the service life of the belts.

[0031] A key advantage is that there are no costly failures of the lifting device.

[0032] Each pressure measuring device has a through-hole through which the threaded section of the threaded rod is guided.

[0033] In an advantageous embodiment, each pressure measuring device can have at least one strain gauge. This enables particularly sensitive and easily detectable electrical measurement.

[0034] In particular, the pressure measuring device can be a so-called "pressure sensor," a bending rod, or a shear rod. The pressure sensor typically has a central opening through which the threaded rod can be guided. The pressure sensor can absorb forces at the edge of this opening. The pressure measuring device can determine an electrical measurement corresponding to the mechanical pressure using strain gauges, which are, for example, arranged in a bridge circuit, and output this measurement at an electrical output, such as a connector, for evaluation. The electrical measurement can be, for example, an analog voltage or resistance.

[0035] In an advantageous further development, the individual pressure measuring devices can be identical to each other, with the exception of individual component-related manufacturing tolerances.

[0036] In another preferred embodiment, each pressure measuring device can have an individual identifier. This can, for example, consist of a MAC address, which is located, for example, in a digital electrical component, e.g., in the form of a ROM memory component, e.g., in the connector of the pressure measuring device.

[0037] This allows for individual calibration of each pressure measuring device. This is particularly advantageous because it even compensates for the aforementioned component-related manufacturing tolerances.

[0038] In a preferred embodiment, the actuator for adjusting the belt tension has a self-locking element, e.g., a worm gear. This ensures that, on the one hand, adjustability is guaranteed, and on the other hand, that the nut cannot loosen itself.

[0039] In a preferred embodiment, the lifting device can have an emergency shutdown device on the mounting side of each threaded rod in the event of a belt breakage or belt elongation ("slack belt"). This is advantageous because it ensures automatic shutdown in an emergency.

[0040] In a particularly preferred embodiment, the lifting device has a spring, in particular a helical spring, which surrounds the threaded rod and is arranged between the coupling plate, against which it is directly or indirectly supported, and an actuating disc, the actuating disc being fixed on the threaded rod. The maximum compression of the helical spring can be limited by an enclosing sleeve. In the operating state, the helical spring is compressed and can, for example, be supported by a support disc inside the sleeve. Furthermore, in the operating state, the helical spring exerts a constant force, typically greater than 100 N, against the actuating disc. If the belt breaks, for example, the spring relaxes and presses the actuating disc against an emergency stop switch, such as a roller lever switch.This serves primarily to protect life and limb, but also to protect the lifting device itself and the goods being transported by it.

[0041] In another preferred embodiment, the scissor lift table can have an actuator for each belt to equalize the belt tensions. This actuator can interact with the aforementioned nut of the screw fastening. This allows a control system to ensure that all belts have as similar a belt tension as possible at all times. To this end, they can be equalized manually or automatically in a control process during regular maintenance intervals – for example, within a maintenance window. Naturally, the load on the belts, and thus the belt tensions, change dynamically depending on the lifting height, load, and, if applicable, the acceleration. Even under these dynamic changes, the belt tensions can be continuously measured, evaluated, and readjusted outside of operation or possibly even during operation.The belt tensions can therefore be coordinated at any given time and ideally be identical – at least within a specified tolerance range. Ideally, the belt tensions should be as constant as possible at all times, although these belt tensions can typically vary over time – depending on the operating state of the lifting table – for example, between 0.5 kN (kilonewtons) and 8 kN.

[0042] As already mentioned, a method for measuring and evaluating belt tensions has the following steps: a. simultaneous reading of electrical measured quantities from the pressure measuring devices at predetermined time intervals; b. Conversion of the measured quantities into measurement data, which provide information about the respective tensile forces of the individual belts; c. Comparison of the measurement data.

[0043] In this procedure, process step c. can have the following sub-steps: c1. Determination of a maximum value of the simultaneously determined tensile forces; c2. Determination of a minimum value of the simultaneously determined tensile forces; c3. Forming a quotient between the maximum value and the minimum value.

[0044] The following procedure step can follow process step c.: d. Issuance of a warning message depending on a result of process step c.

[0045] For example, this warning message can be issued as soon as the aforementioned quotient from process step c3 exceeds a threshold – e.g., a percentage.

[0046] The process steps a. to d. can be repeated multiple times during a single lifting and / or lowering cycle. Thus, during a typical lifting and / or lowering process – for example, lasting ten to twenty seconds – ten to one hundred – or possibly even more – measurements can be performed. Technically, even more measurements are possible, e.g., a thousand measurements, but this is generally not necessary.

[0047] The simultaneously acquired measurement data can be saved as a data set with an associated timestamp for possible later analysis. This has the advantage that it is available for subsequent investigations.

[0048] Calibration of the pressure measuring devices can take place before process step a. This allows a correction factor determined during calibration to be taken into account for each pressure measuring device in process step b.

[0049] The previously mentioned procedure for regulating belt tensions has the following steps: A. Simultaneous reading of electrical measurements from the pressure measuring devices at predetermined time intervals; B. Conversion of the measured quantities into measurement data, which provide information about the respective tensile forces of the individual belts; C. Determination of a maximum and a minimum value of the simultaneously determined tensile forces; D. Adjustment of the respective belt tension of a belt which has the maximum value or the minimum value, if the quotient between the maximum value and the minimum value exceeds a predetermined threshold.

[0050] Process steps A to D can be repeated regularly in a loop. This has the advantage that the belt tensions are constantly monitored. This allows defects and wear to be detected, rectified, and / or even prevented at an early stage.

[0051] This arrangement is particularly advantageous because it prevents individual belts from being overloaded in a timely manner. During operation, it can happen that the so-called "steel cables" contained within individual belts are damaged, for example, by breaking or stretching. This results in undesirably higher forces and associated premature wear on the other belts. The aforementioned continuous condition monitoring allows this to be avoided at an early stage.

[0052] Advantageously, the arrangement according to the invention can be integrated into existing scissor lift tables on the market using separate additional components (“Add On”), such as the pressure sensor and / or the evaluation unit, in order to retrofit them for measuring belt tension.

[0053] In an advantageous embodiment, the control device is integrated into a separate control module. This can also be integrated as a separate add-on component into existing scissor lift tables on the market to retrofit them for measuring and adjusting belt tension. Example of implementation

[0054] An embodiment of the invention is shown in the drawings and is explained in more detail below. The drawings show: Fig. 1a a lifting mechanism comprising a scissor frame, two coupling plates, several thrust struts and a guide unit; Fig. 1b a scissor lift table comprising the lifting mechanism of Fig. 1a as well as a drive unit and a base and a lifting frame; Fig. 1c an enlargement of an arrangement comprising the coupling plate from the preceding illustration; Fig. 1d a sectional view showing a section through the coupling plate with a belt fastening designed as a clamping device; Fig. 2a a sectional view showing a section through the coupling plate with a pressure measuring device integrated into the arrangement; Fig. 2b the aforementioned arrangement comprising the pressure measuring device, a spherical bearing and additionally an emergency stop arrangement; Fig. 3a a pressure measuring device designed as a pressure sensor; Fig. 3b a pressure measuring device designed as a shear rod; Fig. 3c an evaluation unit.

[0055] The figures contain simplified, schematic representations. In some cases, identical reference symbols are used for elements that are the same but may not be identical. Different views of the same elements may be scaled differently.

[0056] The Fig. 1a to 1c explain a lifting device known from the prior art, namely a scissor lift table.

[0057] The Fig. Figure 1a shows a lifting mechanism of a lifting device, comprising a scissor frame 6, two coupling plates 4, 4', several thrust struts 61a, 61b, some of which are hidden by the scissor frame 6 and therefore not visible in the drawing, and a guide unit 7. The scissor frame 6 has an outer frame part 6a and an inner frame part 6b.

[0058] The two coupling plates 4, 4', aligned parallel to each other by the guide unit 7, are each connected to the outer 6a and inner 6b frame part by means of intersecting thrust struts 61a, 61b.

[0059] The guide unit 7 has a guide cylinder 70 and a guide rod 71 passing through the guide cylinder 70. The guide cylinder 70 has a mounting section 74. By means of this mounting section 74, the guide cylinder is attached to one of the two coupling plates 4' and the guide rod 71 is guided axially displaceably through a sliding bearing of the other coupling plate 4.

[0060] It is easily recognizable that the hoisting mechanism rises by reducing the distance between the two coupling plates 4, 4' and lowers by increasing this distance.

[0061] Fig. Figure 1b shows the lifting device designed as a scissor lift table, comprising the aforementioned lifting mechanism, as well as a drive unit 8 and a base frame 60a shown below in the drawing and a lifting frame 60b shown above, aligned parallel to the base frame 60a.

[0062] The drive unit 8 has a motor 80 and a winding shaft 81 driven by the motor 80. Several belts 2 are wound or unwound simultaneously by the winding shaft 81. The belts 2 pass through a coupling plate 4. A pulley system arranged between the coupling plates 4, 4' (not described in detail here) allows the distance between the two coupling plates to be varied with a suitable force transmission by deflecting the belts 2 multiple times. This raises or lowers the lifting frame 60b. High forces, e.g., 100 kN (kilonewtons), can easily be applied, enabling the lifting of weights of, e.g., 10 t (tons) or more.

[0063] Fig. Figure 1c shows in an enlarged view detailed belt insertions through the coupling plate 4 of Fig. 1b and strap attachments on the coupling plate 4.

[0064] Fig. Figure 1d shows a sectional view of a section of the lifting device, corresponding to the prior art, with a section through the coupling plate 4 with a belt fastening 12 attached to the threaded rod 1, which is designed as a clamping device 12 welded to the threaded rod. The clamping device 12 has two clamping plates 124, 124', which can be screwed together to clamp the belt 2 between them with high holding force. The threaded rod 1 is guided through a through-opening 40 in the coupling plate 4. On the side of the coupling plate 4 facing away from the belt 2, it passes through a spring assembly 37 and an actuating disc 350, which will also be explained below.

[0065] Behind this, the threaded rod 1 is screwed in place with a screw fastening, namely a screw nut 3, and secured with a lock nut 3'.

[0066] Furthermore, an actuator 351 for an emergency stop switch 355 is shown, which will be described below.

[0067] In this illustration, a section of the pulley system, i.e., a part of the pulley system, is shown on the left. It is easily understood by a person skilled in the art that the coupling plate 4 and the counter-coupling plate 4' (see Fig. 1a) in this example, due to the fourfold constriction of the belt 2 shown on the left, they are connected to each other by the pulley in a fourfold translation.

[0068] Fig. 2a and Fig. Figure 2b shows arrangements in which a pressure measuring device 5 is integrated.

[0069] Fig. Figure 2a shows the coupling plate 4 in a sectional view, featuring the through-hole 40, which is designed as a two-stage through-bore. The threaded rod 1 is guided through this through-hole 40. The threaded rod 1 has a threaded section 13, which can also extend over the entire threaded rod 1. The end-side belt fastening 12, arranged between the coupling plates 4 and 4', is also shown schematically. The belt 2 (not shown here) is fixed to this belt fastening 12, so that the belt tension F R The belt clamping mechanism 12 acts on the threaded rod 1. The belt clamping mechanism 12, together with the belt 2 clamped in it, has already been explicitly shown in the preceding illustration.

[0070] Here, only one through-hole 40, one threaded rod 1, and one belt 2 are shown, representing multiple through-holes 40, threaded rods 1, and belts 2. In reality, however, the lifting device in the version described here has—as already shown—four belts 2 and therefore also four through-holes 40 and four threaded rods 1 passing through them, belt fastenings 12, etc.

[0071] A pressure measuring device 5 with its feedthrough 50 is arranged at each through-opening 40 and fixed to the coupling plate 4. The threaded rod 1 is thus also guided through the feedthrough 50 of the pressure measuring device 5. A washer 35 is attached to the threaded rod 1 by means of a screw fastening 3, abutting the pressure measuring device 5. The screw fastening is formed by at least one nut 3, here supplemented by a lock nut 3'.

[0072] The belt tension force F RThe belt 2 thus acts via the washer 35 on the pressure measuring device 5.

[0073] Fig. Figure 2b shows a further arrangement for measuring belt tensions according to one embodiment of the invention. This arrangement is supplemented by the following compared to the aforementioned arrangement: - a spherical bearing 36 for tilting movable support of the threaded rod 1, comprising a pan disk 36a and a spherical disk 36b; - a spring arrangement 37, comprising a spring sleeve 370 and a helical spring 371 arranged therein, both of which encompass the threaded rod 1; - a support disc 35' arranged between the spring assembly 37 and the spherical bearing 36; - an actuating disc 350 arranged between the spring device 37 and the screw fastening 3; - an emergency stop switch 355 designed as a roller lever switch, comprising an actuator designed as an actuating lever 351, where it is clear to the person skilled in the art that the pre-tensioned spring device 37 actuates the emergency stop switch 355 by means of the actuating disc 350 as soon as the belt tension force F R is less than the spring force, e.g. in the case of a belt breakage.

[0074] The belt tension force F R continues to act on the pressure measuring device 5 via the washer 35.

[0075] The Fig. Figure 3a shows a pressure measuring device designed as a pressure sensor 5. The pressure sensor 5 has a circular outer ring 51 with several axially arranged mounting holes 510 and a radially projecting electrical connector 59. Alternatively, the measuring cable could also lead out of the pressure sensor 5.

[0076] Furthermore, the pressure sensor 5 has a pressure transducer designed as an inner ring 52. The inner ring 52 is designed to absorb the belt tension force F. Rrelative to the outer ring 51, axially slightly, i.e. by less than 1 mm, it is held displaceably and floatingly mounted.

[0077] The pressure measuring device 5 has at least one electromechanical transducer that measures the belt tension force F R converts it into an electrical quantity, e.g., a resistance or a voltage, e.g., a strain gauge or a piezoelectric transducer, etc.

[0078] The Fig. Figure 3b shows an alternative pressure measuring device 5', designed as a shear bar. This has two mounting holes 510', a feedthrough 50' and a connector 59. An axial offset is measured, also via an electromechanical transducer.

[0079] The Fig.Figure 3c shows an evaluation unit 9. The evaluation unit 9 has one electrical connection 95 for each pressure measuring device 5, 5', thus in this example four electrical connections 95. Finally, as can already be seen from the above, a pressure measuring device 5, 5' and thus also one connection 95 is provided for each belt 2.

[0080] The 5.5' pressure measuring devices can each have individual digital identifiers, e.g., in the form of a MAC address. This allows the evaluation unit 9 to assign the 5.5' pressure measuring devices and use their individual calibrations.

[0081] Even though the figures show various aspects or features of the invention in combination, it is apparent to the person skilled in the art – unless otherwise stated – that the combinations shown and discussed are not the only possible ones. In particular, corresponding units or sets of features from different embodiments can be interchanged. Reference symbol list 1 threaded rod 12 Belt fastening, clamping device 124,124' clamping plates 13 Thread section 2 belts 3.3' Screw fastening; nut, lock nut 35 Washer 35' support disc 350 Actuating disc 351 Actuator, actuating lever 355 Emergency stop switch 36 Spherical Storage 36a Pan disc 36b Spherical disc 37 Spring arrangement 370 Spring sleeve 371 Coil spring 4 coupling plate 40 Passage opening 5.5' Pressure measuring device; pressure sensor, shear rod 50, 50' Execution 51 Outer ring 510 mounting holes 52 pressure sensors, inner ring 59 connector plugs 6 scissor frames 60a Basic frame 60b lifting frame 6a outer frame part 6b inner frame part 61a, 61b Thrust struts 7 Command Unit 70 guide cylinders 71 Guide rod 74 Mounting section of the guide cylinder 8 Drive unit 80 engine 81 winding shaft 9 evaluation unit 95 electrical connection F R Belt tension; tensile force of the belt QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10202310947 4B

[0010]

Claims

[1] Arrangement for measuring belt tensions of a belt-operated lifting device, the arrangement comprising the following elements: - several threaded rods (1), each having a belt-side belt attachment (12) and a fastening-side threaded section (13); - a coupling plate (4) with several through-openings (40) in which a threaded rod (1) with its threaded section (13) is held axially displaceable for adjusting the respective belt tension; - for each threaded rod (1) a screw fastening (3) screwed onto the threaded rod (1) on the fastening side to receive the respective belt load against the coupling plate (4), wherein the screw fastening has at least one nut (3); - for each threaded rod (1) a pressure measuring device (5, 5') arranged between the coupling plate (4) and the respective screw fastening (3) for recording and measuring the respective belt load. [2] Arrangement according to claim 1, wherein each pressure measuring device (5, 5') has a through-passage (50, 50') through which the threaded rod (1) is guided. [3] Arrangement according to one of the preceding claims, wherein each pressure measuring device (5, 5') has at least one strain gauge (“SMS”). [4] Arrangement according to one of the preceding claims, wherein the pressure measuring device is a pressure sensor (5), a bending rod or a shear rod (5'). [5] Arrangement according to one of the preceding claims, wherein the individual pressure measuring devices (5, 5') are identical to each other except for individual component-related manufacturing tolerances. [6] Arrangement according to one of the preceding claims; wherein each pressure measuring device (5, 5') has an individual identifier. [7] Evaluation device (9) for an arrangement according to one of the preceding claims, wherein the evaluation device (9) has at least one microprocessor and one digital memory, as well as an individual calibration for each pressure measuring device (5, 5'), wherein the calibrations are stored as data in the memory. [8] Control device comprising an arrangement according to one of claims 1 to 6 and the evaluation device (9) according to claim 7, and for each threaded rod (1) an actuator controlled by means of the evaluation device (9) for equalizing the belt tensions of all belts (2) to each other, wherein the respective actuator interacts with the screw fastening (3) [9] Control device according to claim 8, wherein the actuator has a self-locking element, e.g. a worm gear. [10] Lifting device, in particular scissor lift table, comprising an arrangement according to any one of claims 1 to 6, and further comprising: - a lower, stationary base frame (60a) and an upper, vertically movable lifting frame (60b) which are connected to each other on both sides via a scissor frame (6); - wherein the scissor frame (6) has an outer frame part (6a) and an inner frame part (6b) which are rotatably connected to each other about a horizontal axis via a central bearing, and - a feedback plate (4'), wherein both the coupling plate (4) and the feedback plate (4') are opposite each other and are each pivotally attached to intersecting thrust struts (61a, 61b) of a frame part (6a, 6b); - to each threaded rod (1) a strap (2) attached to it; - wherein at least one deflection pulley (42, 42') is rotatably held on the inside of both the coupling plate (4) and the counter-coupling plate (4') for each belt (2); - wherein each belt (2) with the associated pulleys (42, 42') forms a pulley system, - a winding shaft (81) and a drive (80) for winding the belts (2) together. [11] Lifting device according to claim 10, wherein the lifting device has on the fastening side of each threaded rod (1) a device for emergency shutdown in the event of a belt breakage or elongation of the belt (“slack belt”). [12] Lifting device according to one of claims 10 to 11, wherein the scissor lift table has an actuating element for each belt (2) for equalizing the belt tensions of the belts (2), which interacts with said nut (3) of the screw fastening.

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