Work platform for a cavity structure

Abstract

The invention relates to a work platform for use in shaft structures. To enable the work platform to be deployed at different positions within the shaft structure with minimal effort and without a separate winch, a self-propelled work platform is proposed. This platform comprises a drive platform and at least one work platform, which can be moved relative to each other within the shaft structure by means of a linear drive. Simultaneously, the work platform and the drive platform can be clamped against the side walls of the shaft structure by means of clamping devices. To change the position of the work platform within the shaft structure, the clamping devices on the work platform and the drive platform are alternately released, and the respective released platform is moved in the desired direction within the shaft structure by means of the linear drive.

Description

[0001] The invention relates to a work platform for use in an elongated cavity structure with a longitudinal axis and side walls that define the cavity structure and surround the longitudinal axis.

[0002] A work platform is generally understood to be an elevated platform or lifting device used to transport and support people and / or equipment to work areas at height.

[0003] Aerial work platforms come in various designs, including scissor lifts, articulated boom lifts, and telescopic boom lifts; they are often equipped with safety features such as guardrails, safety belts, and stabilizers to ensure user safety. Aerial work platforms are commonly used in workshops, warehouses, production facilities, and other industrial environments where a stable and safe working platform is required.

[0004] A scissor lift consists of a platform that is raised vertically by a scissor mechanism. This mechanism comprises several crossed metal arms that open and close like scissors to raise or lower the platform. This design allows for stable and smooth platform movement. Scissor lifts are particularly space-saving and well-suited for working in confined spaces.

[0005] An articulated platform consists of a platform that is lifted and moved by one or more articulated arms. These arms allow the platform to move flexibly in various directions, including vertical and horizontal movements. The design of the articulated platform makes it possible to overcome obstacles and reach difficult-to-access areas.

[0006] A telescopic platform consists of a platform that is raised by a vertical mast. The mast is telescopic, meaning it is made up of several segments that slide into one another. This design allows for stable and smooth vertical movement of the platform.

[0007] All of the aforementioned platforms can be designed as stationary platforms or as mobile work platforms, e.g. as trailer work platforms, truck work platforms or tracked work platforms.

[0008] The invention relates to the use of a work platform in a cavity structure, such as those found particularly in shaft structures. A shaft structure is a vertical or inclined, elongated cavity structure that extends into the ground or rises from it and serves as access to underground areas or difficult-to-access vertical areas. It includes various types of shafts, such as mining shafts, utility shafts, ventilation shafts, elevator shafts, and chimney shafts. These structures enable the transport of people, materials, or media and often serve as transport routes, supply lines, or ventilation structures.

[0009] To construct a work platform in an elevator shaft, it is already known to attach so-called joist hangers to the inside of the shaft wall. After the joist hangers are installed, wooden beams or formwork beams can be inserted into them, and boards can be laid on top of the beams to create a work platform (see https: / / safetyrespect.de / arbeitsbuehnen-und-plattformen-inaufzugsschaechten / accessed on March 3, 2025). One disadvantage of this known work platform is that its position within the elevator shaft can only be changed with considerable effort.

[0010] The "Mining Regulations Collection of the Arnsberg District Government, A2 Technical Guidelines and Basic Orders, A2.10 Shaft Hoisting, Man-riding, Lifting Systems / Working Scaffolds in Shafts" defines the requirements and procedures for the use of working scaffolds in shafts. Conventional working scaffolds are sometimes used as work platforms in shafts. However, no equipment or machinery (e.g., drilling rigs) may be permanently mounted on such working scaffolds. Furthermore, the position of such working scaffolds in the shaft can only be changed with considerable manual effort.

[0011] From the "Arnsberg District Government, Mining and Energy Department NRW, Technical Requirements for Shaft and Inclined Conveyor Systems (TAS), Status: December 2005, 9. Platforms and Grab Systems," mobile work platforms in shafts are known. A distinction is made between single-level and multi-level platforms, as well as platforms with single-point or multi-point suspension, whereby the work platforms cover the shaft cross-section completely or partially, depending on the operational purpose. The mobile platforms are moved within the shaft using platform winches to raise and lower loads. The TAS specifies extensive regulations for the design of such platform winches. In addition to the complex construction of the platform winches, these take up additional space in the already confined shaft structures and can obstruct work processes within the shaft.

[0012] RU 2 592 580 C1 discloses a device with two interacting platforms: a lower drilling frame for rock destruction and an assembly frame positioned above it for constructing the shaft lining. The drilling frame has downward-facing, supporting hydraulic cylinders on its outer circumference, ensuring direct support on the shaft bottom. Horizontal spreaders are arranged on its side faces to radially align and center the drilling frame relative to the shaft axis, pressing against the shaft wall. The assembly frame is positioned above the drilling frame and is also equipped with peripherally arranged horizontal spreaders for centering and stable fixation to the wall. Vertical movement of the assembly frame is achieved via hydraulic cylinders attached to its outer circumference, which bear directly against the top of the drilling frame below.By coordinating the movement of these cylinders, the assembly frame can be lowered gradually relative to the fixed drilling frame to install new segments of the shaft lining. Although the system can theoretically be held in a suspended position against the shaft wall by means of the spreaders, regular operation relies on ground support provided by the vertical cylinders.

[0013] DE 826 971 B discloses a work platform for the construction of factory chimneys, comprising a rigid central section with box-shaped girders into which profile irons are inserted from both sides. These profile irons provide passive support, with their free ends projecting into prepared recesses in the masonry. Locking pawls are used to secure the manually movable profile irons. These pawls engage behind flat irons attached to the profile irons, thus preventing them from being pushed back into the box girders. A protective platform located beneath the work platform is constructed in the same manner. Both platforms are connected by a lifting device. The lifting device can consist of four winches, the racks of which are attached directly to the box girders of the work platform and the housings of which are attached to the box girders of the protective platform.To prevent the work platform from swinging during the lifting process when it is freely supported by the lifting device, the lifting device, consisting of four racks and housings, is braced by cross braces.

[0014] EP 3 816 086 A1 discloses a self-climbing elevator machine room for transporting personnel and equipment during the construction phase of a building. The self-climbing elevator machine room comprises two vertically stacked decks. Lifting devices, designed as hydraulic telescopic cylinders and located on opposite sides of the elevator machine room, are provided for vertical relative movement between the decks. The decks are guided by guide elements along guide rails pre-installed in the shaft. Locking devices, which may be designed with pivoting claws, serve to fix the decks in place by interacting with the guide rails. These claws are designed to engage positively with the upper support surfaces of lugs that connect the individual elements of the guide rails when locked.This fixing prevents downward movement of the decks and directs the load directly into the rail system.

[0015] Based on this state of the art, the invention aims to create a working platform that can be used at different positions of cavity structures, in particular shaft structures, with little effort and without a separate winch, and that allows the movement of heavy loads on the working platform while maintaining high positioning accuracy of the working platform.

[0016] The solution to this problem is based on the idea of ​​providing a self-propelled work platform that can be deployed at different positions within the cavity structure, i.e., at varying distances from the bottom of the shaft structure. For the sake of simplicity, the cavity structure, including the shaft structure, will henceforth be referred to simply as the shaft structure.

[0017] A drive platform and at least one work platform of the work platform are movable relative to each other within the shaft structure by means of a linear drive. Simultaneously, the work platform and the drive platform can be clamped against the side walls of the shaft structure by means of clamping devices. To change the position of the work platform within the shaft structure, the clamping devices on the work platform and the drive platform are alternately released, and the released platform is moved in the desired direction within the shaft structure by means of the linear drive.

[0018] Once the desired position within the shaft structure has been reached, the work platform is secured again by clamping both the clamping devices on the work platform and the drive platform against the side walls of the shaft structure. To enable the described walking movement of the work platform, it is necessary that the clamping devices on the work platform can be operated independently of the clamping devices on the drive platform.

[0019] For moving heavy loads on the work platform while maintaining high positioning accuracy, the drive unit for the square tube longitudinal profile comprises two rack and pinion drives. Each drive unit consists of a rack and a meshing gear driven by a geared motor. Each rack is mounted on the square tube longitudinal profile, and each geared motor is located on the drive platform. The rack and pinion drive is ideal for moving heavy loads on the work platform in mine shafts. Furthermore, it allows for very precise positioning of the work platform. Rack and pinion drives are also robust, durable, and require little maintenance, making them ideal for the harsh environments of mining shafts.In order to optimally introduce the driving forces of the linear drive into the longitudinal profile designed as a square tube, the two rack and pinion drives are provided as a drive unit, with the two racks being attached to opposite side walls of the square tube.

[0020] Specifically, this problem is solved by a work platform with the features of claim 1. Advantageous embodiments of the invention result from the features of the dependent claims.

[0021] If the work platform comprises only one work platform in addition to the drive platform, this platform can be connected to the longitudinal profile either above or below the drive platform. The connection to the longitudinal profile is preferably made at the upper or lower end face of the longitudinal profile. Equipment or machinery, such as drilling rigs, excavators, lifting devices, or grabs, can be permanently mounted to the upper and / or lower surface of the work platform. For this purpose, each work platform is preferably designed for the detachable attachment of work equipment to its upper and / or lower surface.

[0022] If work is to be carried out simultaneously on several levels, with respect to the longitudinal axis of the shaft structure, an advantageous embodiment of the invention provides that a working platform is attached to each of the two ends of the longitudinal profile of the working platform.

[0023] In one embodiment of the invention, the drive platform has a frame, which is in particular a rectangular frame with two parallel longitudinal beams and two parallel transverse beams. The necessary attachments, such as in particular the clamping devices, the at least one drive unit for the longitudinal profile, and the linear guide for the longitudinal profile, can be easily mounted to the beams of the rectangular frame using brackets, flanges, or by direct attachment to the beams.

[0024] A linear guide for a longitudinal profile designed as a square tube can be advantageously implemented on a work platform designed as a rectangular frame by comprising guide rails running parallel to the longitudinal axis of the cavity structure, each with a sliding surface, wherein at least one sliding surface bears against each side wall of the square tube. Preferably, two guide rails extend from the surface of each of the two transverse beams and the two longitudinal beams of the rectangular frame in the longitudinal direction of the shaft structure, i.e., perpendicular to the plane spanned by the work platform, so that two sliding surfaces of two guide rails bear against each side wall of the square tube.The sliding surfaces, which rest against the side walls of the square tube, ensure low-friction and precise movement. These sliding surfaces can be recessed into or mounted on the surface of the guide rails and are made of materials such as hardened steel, cast iron, or plastic. Additionally, the surfaces of the sliding surfaces can be machined to ensure the smoothest and most uniform finish possible.

[0025] To increase the stability of the linear guide for absorbing high loads, to dampen vibrations in the linear guide, and to prevent overloading of the drive platform, all guide rails, in an advantageous embodiment of the invention, extend between the work platform, which is designed as a frame, and an auxiliary frame. Preferably, the auxiliary frame is also designed as a rectangular frame.

[0026] To secure each work platform and the drive platform to the side walls of the shaft structure, each clamping device is preferably designed as a telescopic tube with a telescopic segment. Depending on the distance of the respective platform to the side wall of the shaft structure, the telescopic segment of the tube is extended until its end face rests against the side wall. For the walking function of the work platform, it is necessary that the first clamping devices for the drive platform and the second clamping devices for the work platform can be clamped and released independently of each other.

[0027] If the telescopic segment is driven by a hydraulic cylinder, this can be housed inside the telescopic tube in a space-saving and protected manner.

[0028] In order to improve the interlocking between the clamping devices and the side walls of the shaft structure, an advantageous embodiment of the invention provides that the end face of the telescopic segment of each telescopic tube is profiled.

[0029] The multiple clamping devices extend from an outer boundary of the work platform and / or the drive platform, each in the plane of the platform, towards the side walls of the cavity structure. This ensures optimal force transmission from the clamping devices into the frame of the drive platform or the frame surrounding the work platform at its outer edge.

[0030] Depending on the size and geometry of the work platform and drive platform, the multiple clamping devices extend radially from an outer boundary of the work platform and / or the drive platform, relative to the longitudinal axis of the longitudinal profile, at uniform angular intervals towards the side walls of the cavity structure. If the drive platform is designed as a rectangular frame, preferably four clamping devices extend at angular intervals of 90° relative to the longitudinal axis of the slidingly guided square profile towards the side walls of the shaft structure.

[0031] To support the movement of the work platform and / or to secure its position in the shaft structure, an advantageous embodiment of the invention provides that a system has a cable winch arranged above the work platform in the direction of the longitudinal axis of the shaft structure and that at least one cable of the cable winch is connected to the work platform.

[0032] The winch runs alongside the work platform during its walking motion, thereby reducing the forces required for upward movement. This allows the drive components of the work platform's linear drive to be less stressed or designed to be smaller. During downward movement of the work platform, the winch can apply additional braking forces, thus ensuring a safe walking motion.

[0033] Once the desired position of the work platform has been reached, the winch serves to additionally secure its position.

[0034] The winch can have a single cable connected to the work platform. However, if greater safety, improved load distribution, and the ability to move heavier loads are required, multi-cable winches with parallel cable runs can be used.

[0035] To effectively secure the work platform after reaching the desired position in the shaft structure, the winch is equipped with a locking device. This locking device can be a braking mechanism that holds the cable drum securely in position, even when the winch drive is not active. The locking device may also include a backstop that prevents the cable drum from rotating backward.

[0036] The at least one rope is preferably attached to the load-bearing longitudinal profile of the work platform. Additionally or alternatively, the at least one rope can be attached to the upper work platform of the work platform.

[0037] At least one control unit, or optionally separate controls for the winch and the work platform, which communicate with each other via a data link, are installed to coordinate the operation of the winch with the walking movement of the drive platform. In particular, data on the direction, speed, and duration of the walking movement are transmitted to control the winch drive, so that the cable force continuously and evenly supports the movement of the work platform.

[0038] The invention will be explained in more detail below with reference to the figures. They show Fig. 1 a perspective overall view of a work platform according to the invention in a first position of the work platform, Fig. 2 a perspective overall view of the work platform after Fig. 1 in a second position on the work platform, Fig. 3 an enlarged view of a drive platform and linear guide of the work platform according to Fig. 1 and Fig. 2, Fig. 4. A representation of different designs of the work platforms with A) a work platform above the drive platform, B) a work platform below the drive platform, C) a work platform above and below the drive platform, Fig. 5 a representation of alternative embodiments of drive units of a linear drive of the work platform not belonging to the invention with A) Hydraulic cylinders, B) a rope and a pulley / double drum, C) a chain and a chain drive, Fig. 6 A representation illustrating the walking process of the work platform according to the invention in a vertical shaft structure with steps A) - H)

[0039] Fig. Figure 1 shows a perspective overall view of a work platform 1 according to the invention, which is designed for use in a cavity structure 2. The cavity structure 2 is, for example, a shaft structure 2.1, which is located in the Fig. 4 - 6 is a circular cross-section seeshaft. The seeshaft extends along a longitudinal axis 2.2 and is bounded by side walls 2.3 that surround the longitudinal axis 2.2.

[0040] The main components of the work platform 1 are a work platform 3, a drive platform 4, a linear drive 5, and first clamping devices 6 and second clamping devices 7. The clamping devices 6 and 7 are designed to clamp the drive platform 4 and the work platform 3, respectively, against the side walls 2.3 of the structure. Fig. 1 and Fig. to fix the shaft structure 2.1, which is not shown.

[0041] The linear drive 5 is shown in the enlarged view according to Fig. 3 shown and comprises a longitudinal profile 5.2 guided in a linear guide 5.1 parallel to the longitudinal axis 2.2 of the shaft structure 2.1 and a drive unit 5.3 to move the longitudinal profile 5.2 in the direction of the longitudinal axis 2.2.

[0042] As especially from Fig. As can be seen in Figure 3, the drive platform 4 is designed as a rectangular frame comprising two parallel longitudinal beams 4.1 and two parallel transverse beams 4.2. The linear guide 5.1 attached to the drive platform 4 is formed by a total of eight slide rails 5.1.1, with two slide rails 5.1.1 extending vertically from each longitudinal beam 4.1 and from each transverse beam 4.2 parallel to the longitudinal axis 2.2 of the shaft structure 2.1. Each slide rail 5.1.1 is provided with a sliding surface 5.1.2. All slide rails 5.1.1 are connected to each other at the top by a rectangular auxiliary frame 5.4 for stabilization.

[0043] In the illustrated embodiment according to the invention, the longitudinal profile 5.2 guided by the linear guide 5.1 is a square tube 5.2.1, wherein the sliding surfaces 5.1.2 of the slide rails 5.1.1 bear against each side wall of the square tube 5.2.1.

[0044] The drive unit 5.3 for the longitudinal profile 5.2 has two rack and pinion drives 5.3.1. A rack 5.3.2 of each rack and pinion drive 5.3.1 meshes with a gear of a geared motor 5.3.3. The two geared motors 5.3.3 are attached to opposing crossbeams 4.2 of the rectangular frame by means of mounting brackets. Each geared motor 5.3.3 has an electric motor combined with a reduction gear to reduce the speed of the electric motor and increase the output torque. Since a braking device is arranged on the input side of the reduction gear, relatively small braking forces are required to fix the longitudinal profile 5.2, which supports the work platform 3, in a pre-tensioned position before clamping. The racks 5.3.2 of the two rack drives 5.3.1 are mounted centrally on a bracket 5.2 on opposite sides of the longitudinal profile 5.2, which is designed as a square tube 5.2.1.2 is attached, which protrudes into a gap between adjacent slide rails 5.1.1, so that the gear of the geared motor 5.3.3 can easily engage with the respective rack 5.3.2.

[0045] Furthermore, it is from Fig. 3. It is evident that the outwardly facing surfaces of the longitudinal beams 4.1 and transverse beams 4.2 are flanges 4.3 to which the first clamping devices 6 are screwed. The first clamping devices 6 are all telescopic tubes 8 with a telescopic segment 8.1, on the end face of which there is a profile 8.2 which is Fig. 1 and Fig. 2 is recognizable. In each telescopic tube 8 there is a hydraulic cylinder (not shown in the figures) for extending and retracting the telescopic segment 8.1. The first clamping devices 6 all lie in the plane of the drive platform 4 and are arranged at a uniform angular interval of 90° with respect to the longitudinal axis of the longitudinal profile 5.2.

[0046] From the Fig. As can be seen from Figures 1 and 2, the second clamping devices 7 extend from an outer boundary of the work platform 3, designed as a frame 3.1, in the plane of the work platform 3 towards the side walls 2.3 of the shaft structure 2.1. The second clamping devices 7 are also bolted together via flanges 3.2. Like the first clamping devices 6, the second clamping devices 7 are designed as telescopic tubes 8 with a telescopic segment 8.1 and a hydraulic cylinder arranged in the telescopic tube 8.

[0047] Fig. 4 A) shows a side view of a work platform 1 according to the Fig. 1-3, which is braced in the shaft structure 2.1.

[0048] The Fig. Figure 4 B) shows an alternative embodiment of the work platform 1 according to the Fig. 1-3, where the deviation is from Fig. 1 the work platform 3 is not attached to the top of the longitudinal profile 5.2, but to its underside.

[0049] The Fig. Figure 4C) shows a further, alternative embodiment of the work platform 1 according to the Fig. 1-3, where the deviation is from Fig. 1 a work platform 3 is attached not only to the top but also to the underside of the longitudinal profile 5.2.

[0050] Fig. Figure 5 A) shows an embodiment of the work platform 1 not belonging to the invention according to the Fig. 1-3, in which the drive unit 5.3 has two hydraulic cylinders 5.3.4 instead of the rack and pinion drives 5.3.1, each hydraulic cylinder 5.3.4 being attached on one side to the drive platform 4 and on the other side to the working platform 3.

[0051] Fig. Figure 5 B) shows a further embodiment of the work platform 1, not belonging to the invention, according to the Fig. 1-3, in which the drive unit 5.3, instead of the rack and pinion drives 5.3.1, has a pulley 5.3.5 attached to the drive platform 4 for a circulating rope 5.3.6 with two ends, wherein the rope 5.3.6 is guided on one side over a deflection 5.3.7 arranged directly below the top of the longitudinal profile 5.3 and on the other side over a deflection 5.3.8 arranged directly above the bottom of the longitudinal profile 5.2, and the two free ends of the rope 5.3.6 are attached to the drive platform 4. A double drum can also be arranged on the work platform 4 instead of the pulley 5.3.5.

[0052] Fig. Figure 5 C) shows a further embodiment of the work platform 1 not belonging to the invention according to the Fig. 1-3, in which the drive unit 5.3 has, instead of the rack and pinion drives 5.3.1, a chain drive 5.3.9 attached to the drive platform 4 for a circulating chain 5.3.10 with two ends, wherein the chain 5.3.10 is guided on one side over a deflection 5.3.7 arranged directly below the top of the longitudinal profile 5.3 and on the other side over a deflection 5.3.8 arranged directly above the bottom of the longitudinal profile 5.2 and the two free ends of the chain 5.3.10 are attached to the drive platform 4.

[0053] The following describes an upward vertical stepping movement of a work platform 1 according to the invention. Fig. 1-3 in a shaft structure 2.1 based on the sequence of Fig. 6 A)-6 H) explains: Fig. Figure 6 A) shows the work platform 1 in its initial position within the shaft structure 2.1. In this initial position, both the work platform 3 and the drive platform 4 below it are braced against the side walls 2.3 of the shaft structure 2.1. Both the first tensioning devices 6 on the drive platform 4 and the second tensioning devices 7 on the work platform 3 are extended. Fig. Figure 6 B) shows the relaxation of the work platform 3. To relax, the second clamping devices 7 on the work platform 3 are retracted, while the first clamping devices 6 on the drive platform 4 remain extended and hold the work platform 1 in its starting position. Fig. Figure 6 C) shows the movement of the work platform 4 vertically upwards using the linear drive 5. During the movement, the second clamping devices 7 on the work platform 3 remain retracted, while the clamping devices 6 on the drive platform 4 remain extended and continue to hold the work platform 1 in its initial position. Fig. Figure 6D) shows the clamping of the work platform 3 according to the procedure in the vertical direction. During clamping, the second clamping devices 7 on the work platform 3 are extended again until their end faces are in contact with the side walls 2.3 of the shaft structure 2.1. The clamping devices 6 on the drive platform 4 remain extended and have not changed their position compared to the initial position. Fig. Figure 6E) shows the release of the drive platform 4 after the tensioning of the work platform 3. During release, the first tensioning devices 6 on the drive platform 4 are retracted. The second tensioning devices 7 on the work platform 3 remain extended and do not change their elevated position in the shaft structure 2.1. Fig. Figure 6 F) shows the movement of the drive platform 4 vertically from its starting position upwards using the linear drive 5. During this movement, the first clamping devices 6 on the drive platform 4 remain retracted, while the second clamping devices 7 on the work platform 3 remain extended and continue to hold the work platform 3 in the raised position. Fig. Figure 6G shows the clamping of the drive platform 4 according to the procedure in the vertical direction. During clamping, the first clamping devices 6 on the drive platform 4 are extended again until their end faces rest against the side walls 2.3 of the shaft structure 2.1. The second clamping devices 7 on the work platform 3 remain extended in the raised position. The work platform 1 is now in a position different from its initial position. Fig. 6A) increased starting position within the shaft structure 2.1 and the cycle begins anew with the relaxation of the working platform 3, as in Fig. 6H) shown. Reference symbol list 1 work platform 2 Cavity structure 2.1 Shaft structure 2.2 Longitudinal axis 2.3 Side walls 3 work platform 3.1 Frame 3.2 Flange 4 Drive platform 4.1 Longitudinal beams 4.2 Crossbeams 4.3 Flange 5 Linear drive 5.1 Linear guide 5.1.1 Sliding rails 5.1.2 Sliding surface 5.2 Longitudinal profile 5.2.1 Square tube 5.2.2 Console 5.3 Drive unit 5.3.1 Rack and pinion drive 5.3.2 Rack 5.3.3 Geared motor 5.3.4 Hydraulic cylinders 5.3.5 Pulley 5.3.6 Rope 5.3.7 Deflection 5.3.8 Deflection 5.3.9 Chain drive 5.3.10 Chain 5.4 Subframe 6 First clamping devices (drive platform) 7 Second clamping devices (work platform) 8 telescopic tube 8.1 Telescopic Segment 8.2 Profiling

Claims

A work platform (1) designed for use in an elongated cavity structure (2) with a longitudinal axis (2.2) and side walls (2.3) bounding the cavity structure (2) and surrounding the longitudinal axis (2.2), comprising: - a work platform (3), - a drive platform (4), - a linear drive (5) with a longitudinal profile (5.2) guided in a linear guide (5.1) parallel to the longitudinal axis (2.2) of the cavity structure (2), and a drive unit (5.3) for the longitudinal profile (5.2), wherein: - the longitudinal profile is designed as a square tube (5.2.1), - the drive unit (5.3) for the longitudinal profile (5.2) designed as a square tube (5.2.1) comprises two rack and pinion drives (5.3.1), each with a rack (5.3.2) and a drive driven by a geared motor (5.3.3) meshing with the rack (5.3.2). has a gear, wherein the two racks (5.3.2) are attached to opposite side walls of the square tube and each geared motor (5.3.3) is arranged on the drive platform (4),- wherein the linear guide (5.1) is attached to the drive platform (4) and the work platform (3) is connected to the longitudinal profile (5.2) designed as a square tube (5.2.1),- first clamping devices (6) arranged to fix the drive platform (4) relative to the side walls (2.3) of the cavity structure (2),- second clamping devices (7) arranged to fix the work platform (3) relative to the side walls (2.3) of the cavity structure (2),- wherein the first and the second clamping devices (6, 7) can be actuated independently of each other such that optionally only the work platform (3) or only the drive platform (4) is fixed or both the work platform (3) and the drive platform (4) are fixed. Working platform according to claim 1, characterized in that the working platform (3) is connected above or below the drive platform (4) to the longitudinal profile (5.2) designed as a square tube (5.2.1). Work platform according to claim 1, characterized in that a work platform (3) is attached to each of the two ends of the longitudinal profile (5.2) designed as a square tube (5.2.1). Work platform according to one of claims 1 to 3, characterized in that each work platform (3) is equipped for the detachable attachment of work equipment to its upper and / or lower surface. Work platform according to one of claims 1 to 4, characterized in that the drive platform (4) has a frame. Working platform according to claim 5, characterized in that - the longitudinal profile (5.2) designed as a square tube (5.2.1) has a top and bottom surface, - the linear guide (5.1) comprises sliding rails (5.1.1) running parallel to the longitudinal axis (2.2) of the cavity structure (2) each with a sliding surface (5.1.2), wherein at least one sliding surface (5.1.2) is in contact with each side wall of the square tube. Work platform according to claim 6, characterized in that all sliding rails (5.1.1) extend between the frame and an auxiliary frame (5.4). Working platform according to one of claims 1 to 7, characterized in that each clamping device (6, 7) is designed as a telescopic tube (8) with a telescopic segment (8.1). Working platform according to claim 8, characterized in that the telescopic segment (8.1) is driven by a hydraulic cylinder. Working platform according to claim 8 or 9, characterized in that an end face of the telescopic segment (8.1) is profiled. Working platform according to one of claims 1 to 10, characterized in that the multiple clamping devices (6, 7) extend from an outer boundary of the working platform (3) and / or the drive platform (4) in the plane of the platform (3, 4) in the direction of the side walls (2, 3) of the cavity structure (2). Working platform according to one of claims 1 to 11, characterized in that the several clamping devices (6, 7) extend radially from an outer boundary of the working platform (3) and / or the drive platform (4) with respect to the longitudinal axis of the longitudinal profile (5.2) designed as a square tube (5.2.1) at uniform angular intervals in the direction of the side walls (2.3) of the cavity structure (2). System comprising a work platform according to one of claims 1 to 12, characterized in that the system has a cable winch arranged in the direction of the longitudinal axis (2.2) of the cavity structure (2) above the work platform and at least one cable of the cable winch is connected to the work platform (1). System according to claim 13, characterized in that the winch is a single-rope or a multi-rope winch with a locking device. System according to claim 13 or 14, characterized in that the at least one rope is attached to the longitudinal profile (5.2) designed as a square tube (5.2.1) and / or to the work platform (3) of the work platform (1) attached to the upper end of the longitudinal profile (5.2) designed as a square tube (5.2.1). System according to one of claims 13 - 15 , characterized by at least one control system, configured to coordinate the operation of the winch to a walking movement of the work platform (1).

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