DE202021106830U1 - Working platform with height-adjustable platform - Google Patents

Abstract

Working platform (1) with a height-adjustable platform (3), with two support frames (5) with bars (7) and the platform (3), which is height-adjustable and is mounted on the support frames (5) between them, with a height adjustment device (13). each support frame (5), which acts on the platform (3) and has a tension element, in particular a tension cable (15) or a toothed rack, and with a safety device (29) on each support frame (5), which when the tension element is relieved Height adjustment device (13) blocked, characterized in that the fall arrest device (29) has a catch rail (37) on the support frame (5) and a catch bolt (33) on the platform (3) which interacts with it, and that a pretensioning device, in particular a spring (23) prestresses the catch bolt (33) towards the catch rail (37) and that a locking device is mounted on the support frame (5) which, when the tension element is under tension, prevents the catch bolt (33) from engaging, which in particular is part of a catch hook (31) is locked in the catch rail (37) or tries to lock and releases the tension element when the tension is relieved.

Description

The present invention relates to a work platform according to the preamble of claim 1.

Lifting platforms or work platforms are used in many ways, e.g. in building cleaning, in construction and in event technology, to allow people to work, including overhead work, at the required level above ground level.

Such lifting platforms are often used in the maintenance and assembly of vehicles or in construction, for example in the construction of bridges and other structures at a height of between 3m and 8m.

In known work platforms, the height is often adjusted via four spindle drives that are integrated in four telescopic supports of the work platform. This configuration requires a complex mechanism so that the height can be adjusted evenly without tilting occurring.

Conventional lifting platforms often use safety bolts as a locking device and safety mechanism to prevent the platform from falling. For example, in the case of four-bar designs, these can be provided on both sides or on each bar. However, solutions are also known that have only one spar in the middle on each side, to which the platform is attached, so that only one safety bolt is provided per side. This is a simple solution, especially on lower-level platforms, as these locking pins can be easily inserted by hand. In known height-adjustable maintenance platforms, safety bolts are used on each spar of the support frames on both sides, ie a total of four safety bolts, which must be inserted and removed manually.

At higher altitudes, such safety bolts pose a safety problem. Workers who are pressed for time often forget the safety bolt or deliberately ignore it. If the safety bolts are not inserted, the platform can fall down, for example if the spindle drive fails. Without actively using the safety device, workers are therefore at risk of falling.

the DE 20 2006 010 625 U1 shows an improvement on the other hand, since it uses a pawl safety device as the locking device, which is easier to use than conventional safety bolts. However, such a pawl safety device may be difficult to release and, like a safety bolt, must be actively actuated by hand.

Furthermore, further improvements of such solutions with pawls have been proposed, for example by means of an energy store and an electromagnet. However, such a ratchet lock can also be difficult to release.

Therefore, the object of the present invention is to provide a work platform according to the preamble of claim 1, which has a safety device which is also suitable for high working heights and is more reliable in operation.

This object is achieved by claim 1 according to the invention. Advantageous refinements result from the dependent claims.

According to the invention, the work platform has support frames each with at least two beams and a platform lying between the support frames.

The platform is adjustable in height between the support frames and mounted on them. For this purpose, each support frame has a height adjustment device, which acts on the platform. This height adjustment device preferably consists of a lifting mechanism and a tension element attached to it. This traction element can be a traction cable, for example. However, other height adjustment devices such as a rack or trapezoidal thread spindles are also possible.

When using a traction cable, the traction cable is deflected over a fixed pulley at the top, i.e. at the upper end of the support frame. One end of the traction cable is attached to the lifting mechanism, for example a mechanical cable winch, which is operated with a crank, and the other end is attached to a holding element which is fixed to one side of the height-adjustable platform. A spring is attached to this holding element of the cable, which keeps the traction cable under a certain pretension.

Above a certain degree of relaxation of the traction cable, especially if the traction cable breaks, the work platform must be prevented from falling. It is not only the breakage of the traction cable that can lead to a fall, but also the failure of the lifting mechanism, for example if a bearing breaks.

Therefore, according to the invention, a fall arrest device or a combined catch/fall arrest device is provided on each of the at least two support frames, which prevents the work platform from falling when the tension element is completely relieved. by holding the work platform at the current height position.

According to the invention, this catch and/or fall protection has a catch rail with teeth and a catch hook with a catch hook axis and a catch bolt. In order to ensure fall protection, the arresting rail and the arresting hook interact with each other. The catch rail is fixed on one side, preferably on the support frame, and the catch hook is fixed opposite on the other side, preferably on the platform.

First, the embodiment with the catch rail on the support frame and the catch hook on the platform is described.

The catch rail is fixedly and immovably connected to the frame and has teeth, in particular pointing upwards, which are spaced about 10 cm apart. These teeth are preferably rounded at the bottom.

The catch hook has a catch hook axis on one side, preferably at the top, and a catch bolt on the other side, preferably at the bottom. The catch hook is movably connected to the platform via the catch hook axis, in particular pivotably away from the platform in the direction of the support frame. The catch bolt is attached to the side of the catch hook opposite the catch hook axis, ie in this case to the lower end of the catch hook. Furthermore, a pretensioning device is provided on the catch hook. This biasing device can preferably be a spring which biases the catch hook away from the platform.

In order to exert the catching effect, the pretensioning device pretensions the catch hook towards the catch rail, so that the catch bolt, at the end of the catch hook that protrudes the furthest, can interact with the teeth of the catch rail, i.e. snap into them.

Raising the platform is not impeded by the preferably rounded or beveled design of the underside of the teeth. The catch hook, which is pre-tensioned towards the catch rail, is pushed backwards when it is raised by the rounding of the tooth, i.e. towards the platform, and above this tooth automatically snaps forward again, i.e. towards the catch rail.

However, if the catch hook is not pushed away from the catch rail in the direction of the platform, the pre-tensioned catch hook prevents the platform from lowering, since the catch hook pre-tensioned towards the catch rail causes the catch bolt to be in the next following bearing point when the height adjustment device is lowered, i.e. the next tooth of the catch rail , snaps into place. If the catch bolt has engaged in a tooth of the catch rail, the platform cannot be lowered any further.

In order to enable the height adjustment device to be lowered, a free rail with a release lever is attached to the support frame. When the release lever is actuated, in particular actively manually, the retaining rail acts against the prestressing of the catch hook and thus pushes the catch hook away from the catch rail so that it cannot engage. This is the only way to shift the platform downwards against the effect of the safety mechanism.

When the release lever is released, this retaining rail automatically falls back into its original position, so that the catch bolt automatically blocks the lowering again due to the pretensioning device.

For lowering it is therefore necessary to actuate the free holding rail and at the same time the height adjustment in order to overcome the lock of the catch hook.

The profile of the catch rail is preferably designed in such a way that the stage has to be raised in order to release the relevant catch bolt from the rail, since the teeth of the catch rail point upwards. This represents a further measure to increase operational safety. This design of the safety rail prevents the platform from falling even if the safety rail is unintentionally actuated.

However, this does not yet ensure that the platform will fall if the safety rail is intentionally actuated and the platform is being lowered, if the tension element fails at precisely this moment, since the user must actively actuate the safety rail when lowering. In this case, the platform could fall despite the catch hook if, for example, the pull rope used breaks.

In order to rule out this possibility, according to the invention, a further, second catch hook is provided as a locking device on the platform or the support frame, which interacts with the pulling element. In this configuration, the first catch hook forms a standard safeguard for the platform during normal operation and the second catch hook forms an additional safeguard in the event of a failure of the cable pull precisely during the height adjustment of the platform. This is explained in detail below.

The second catch hook can be attached above or below the first catch hook. In one embodiment, the second catch hook is offset upwards or downwards by one tooth in relation to the first catch hook. In a preferred embodiment, the second catch hook is offset upwards or downwards by about 10 to 20 mm more than one tooth in relation to the first catch hook, and is thus outside the grid of the teeth. This guarantees that by default the first hook is engaged and the second hook is not locked for descent, which would otherwise block descent. If the second catch hook were locked, it could not be released by the free holding rail in order to release the platform from the teeth of the catch rail, and lowering would therefore be impossible.

This second catch hook only comes into operation if the traction cable fails. In normal operation, it is under pretension, which keeps it away from the safety rail. In order to generate this pretension, in one embodiment the holding element of the traction cable has a compression spring which is connected to the pretensioning device of the second catch hook and exerts a higher force than the pretensioning device of the catch hook. Thus, in normal operation, the second catch hook is kept away from the catch rail. In another embodiment, a tension spring is provided in the course of the traction cable.

The use of a compression spring is preferred. A compression spring counteracts the tensile force and is compressed according to its spring constant up to a fixed stop. If the traction cable breaks, the pressure spring relaxes.

A tension spring, on the other hand, is pulled apart by the tensioned tension cable without there being a stop. This can lead to overstretching of the spring, or possibly to material fatigue, so that it can no longer or not fully spring back into the starting position when the load is relieved. Consequently, the use of a mainspring with a high spring constant is possible.

Should the traction element lose its pretension, for example if the traction cable breaks or if the deflection pulley 12 breaks, the spring that pretensions the pretensioning device of the second catch hook is relieved so that the pretension of the second catch hook is released. As a result, the second catch hook automatically jumps in the direction of the catch rail if the pull rope tears and snaps with its catch bolt into the nearest tooth of the catch rail when the fall occurs, so that the fall is intercepted as soon as the next tooth is reached. This second catch hook thus serves as an additional fall or fall protection for the platform.

According to the invention, the bolt of the second catch hook preferably has a recess which is positioned exactly at the point at which the free-retaining rail pushes away the bolt of the first catch hook when the working platform is lowered. When lowering the work platform - as described above - the release lever of the free rail must be actuated at the same time as the lifting mechanism. The recess therefore ensures that the second catch hook cannot be released by the free-retaining rail. This cutout on the catch bolt of the second release lever makes it possible to ensure in a simple manner that a failure of the tension element does not lead to a fall, even while the work platform is being lowered. This mechanism is permanently installed and cannot be bypassed by the user due to the cut-out at the point of the free-retention rail.

Both arresting bolts, in particular the second arresting bolt, as well as the teeth of the arresting rail are preferably designed to be resistant to breakage and deformation, since they form the elements of the fall protection system on which the strongest forces act when triggered.

Such a fall arrest device is particularly important for height-adjustable work platforms, which can be extended to a height of around 3m or more, since in the event that a traction cable of the height adjustment device tears or this device fails in some other way, it must still be ensured that any people acting on the stage are not harmed.

Further advantages, details and features result from the following description of several exemplary embodiments of the invention with reference to the drawings.

• 1 eine schematische Darstellung einer erfindungsgemäßen Arbeitsbühne in perspektivischer Ansicht in einer möglichen Ausführungsform;
• 2 eine schematische Darstellung eines Ausschnittes des Stützrahmens einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform; und
• 3 eine schematische Darstellung der einen Seite der Fallsicherung einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform; und
• 4 eine schematische Darstellung der anderen Seite der Fallsicherung einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform; und
• 4a eine schematische Darstellung der anderen Seite der Fallsicherung einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform in Seitenansicht; und
• 4b eine schematische Darstellung der anderen Seite der Fallsicherung einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform in Rückansicht; und
• 5 eine schematische Darstellung des Zusammenwirkens der beiden Seiten der Fallsicherung einer erfindungsgemäßen Arbeitsbühne in einer möglichen Ausführungsform.

Show it:

• 1 a schematic representation of a working platform according to the invention in a perspective view in a possible embodiment;
• 2 a schematic representation of a section of the support frame of a work platform according to the invention in a possible embodiment; and
• 3 a schematic representation of one side of the fall arrester according to the invention ßen work platform in a possible embodiment; and
• 4 a schematic representation of the other side of the fall arrester of a work platform according to the invention in a possible embodiment; and
• 4a a schematic representation of the other side of the fall arrester of a work platform according to the invention in a possible embodiment in side view; and
• 4b a schematic representation of the other side of the fall arrester of a work platform according to the invention in a possible embodiment in rear view; and
• 5 a schematic representation of the interaction of the two sides of the fall arrester of a work platform according to the invention in a possible embodiment.

1 shows a schematic representation of a working platform 1 according to the invention in a perspective view in a possible embodiment. The work platform 1 is constructed with a platform 3 and at least two support frames 5, each of which has at least two bars 7. Furthermore, each support frame 5 has a base frame 9, which in this exemplary embodiment is equipped with two castors 11, which can in particular be locked. However, the base frame 9 can also be moved on rails, can be moved by other mobile constructions, can be designed with fixed supports or, if necessary, can be fixed to the floor.

The platform 3 is mounted on the support frame 5 in a height-adjustable manner. The height is adjusted via at least one height adjustment device 13, in particular a height adjustment device 13 on each side, which acts on the platform 3, with a pulling element, in this exemplary embodiment a cable pull 15, being attached to the height adjustment device 13. In this case, the rope is deflected via a fixed deflection pulley 17 at the top, ie at the upper end of the support frame 5 .

A railing 19 can be attached to the platform 3, which railing can be designed either in one piece or in several parts. In addition, the railing 19 can also have a door, which can preferably only be opened inwards. This can prevent accidents caused by incorrect operation and thus a fall.

2 shows a schematic representation of a section of the support frame of a work platform according to the invention in a possible embodiment. Here, the height adjustment device 13, which acts on the platform 3, is shown in detail. In this embodiment, too, the traction element is realized as a cable 15 . On a holding element 21 of the cable, which in particular connects the cable 15 to the platform 3 and preferably with a second catch hook 31.2 (shown and described in 3 ) is connected, a spring 23 is attached, which prevents the cable from becoming slack when lowering the working platform.

In this embodiment, the traction cable 15 can be operated with a mechanical cable winch 25, which is actuated with a crank 27, to adjust the height.

3 shows a schematic representation of one side of the fall arrest device 29 of a work platform according to the invention in a possible embodiment. This fall arrest device 29 consists of two parts, on the one hand the arresting rail 37 and the free holding rail 41 and on the other hand the arresting hook 31 interacting with the former and the arresting bolt 33. In this embodiment, only the side of the fall arrester 29 with the arresting hook 31 and the arresting bolt 33 is shown , which are attached to the platform 3 in this example.

When the tension element, here the cable 15, is relieved, this fall arrest device 29 blocks the height adjustment device 13.

In this embodiment, two catch hooks 31.1 and 31.2 are provided. These catch hooks can be designed as conventional hooks which show a "J" or "L" shape in side view. However, as shown here, it is also possible for the hooks to form a “U” shape or a rectangular shape with two side legs, a particularly upper catch hook axis 32.1 and 32.2 and a particular lower catch pin 33.1 and 33.2. The catch bolts 33.1 and 33.2 can each snap into a tooth 39 of the catch rail 37.

Each catch hook 31 is biased toward the catch rail 37 by means of a first biasing device, such as a spring. The second, here the upper, catch hook 31.2 has a further pretensioning device, such as a tension or compression spring, which is attached to the holding element of the traction cable and which exceeds the pretension of the first pretensioning device and thus the second, here upper, catch hook 31.2 of the catch rail 37 keeps away. Thus, the second catch hook 31.2 has a first pretension, which pretensions the catch hook 31.2 towards the catch rail, and a further second pretensioning device, which exceeds the force of the first pretensioning device and thus keeps the second catch hook away from the catch rail 37 during normal operation.

When the height adjustment device 13 is lowered, the first catch pin 33.1, which is pretensioned by the pretensioning device, engages in the next following bearing point, ie the next tooth 39 of the catch rail 37. For lowering, a release lever provided for this purpose or a free holding rail 41, which pushes the catch hook 31.1 together with the catch bolt 33.1 away from the catch rail 37, and the cable pull 15 must be actuated at the same time, otherwise the movement is automatically blocked.

The second catch hook 31.2 serves as a locking device and interacts with the traction element, here the traction cable 15, via a second pretensioning device 24. This second pretensioning device 24 is arranged in the holding element 21 and pretensions the second catch hook 31.2 by means of a spring 23 as long as the traction cable 15 is tensioned. In the event that the traction cable 15 becomes slack or tears, the spring 23, in particular the compression spring, of the second pretensioning device 24 relaxes so that the first pretensioning device now engages and allows the second catch hook 31.3 to automatically protrude in the direction of the catch rail 37, so that the catch pin 33.2 automatically engages in the tooth 39 of the catch rail 37 which is closest to the bottom. This second catch hook 31.2 thus serves as fall or fall protection for the working platform 1.

The travel of this spring 23 is preferably about 40 mm, but can be adapted to the requirements.

According to the invention, the second catch pin 33.2 has a recess 35 which is positioned exactly at the point at which the free-retaining rail 41 would push the pin away when actuated. This ensures that a failure of the cable pull 15 during the lowering, during which the free rail 41 has to be pressed continuously, does not result in a fall and that it is also impossible for the user to circumvent the safety mechanism.

4 shows a schematic representation of the other side of the fall arrest device 29 of a work platform 1 according to the invention in a possible embodiment ( 4a in side view, 4b in rear view). As already mentioned, this fall arrest device 29 consists of two parts, on the one hand the catch rail 37 and the free holding rail 41 and on the other hand the catch hook 31 interacting with the former and the catch bolt 33, which in 3 are shown. In this embodiment, only the side of the fall arrest device 29 is shown with the catch rail 37 and the free-retaining rail 41, which in this example are attached to the support frame 5.

The catch rail 37 has a plurality of teeth 39 with which the catch hook 31 can engage with its catch pin 33 . Furthermore, a release rail 41 is provided, which is pushed next to the catch rail 37 when actuated by a release lever 42 in such a way that it covers all the teeth 39 of the catch rail 37 and pushes away the first catch pin 33.1 of the first catch hook 31.1. This prevents the first catch bolt 33.1 from latching in and lowering the platform 3 is only possible in the first place.

Furthermore, it is crucial that the retaining rail 41 is placed at the point of the recess 35 of the catch bolt 33 of that catch hook 31 which is provided as a so-called locking device, ie catch hook 31.2 here. This is the only way to ensure that the locking device is circumvented by means of the free-retention rail 41 .

The release lever 42 is connected to the free holding rail 41 via two link guides, so that this can be moved in a simple manner, preferably approximately horizontally. As described above, this displacement causes the free-holding rail 41 to be pushed next to the catch rail 37 in such a way that it covers all the teeth 39 of the catch rail 37 and pushes away the first catch pin 33.1 of the first catch hook 31.1.

5 shows a schematic representation of the interaction of the two sides of the fall arrest device 29 of a work platform 1 according to the invention in a possible embodiment.

Reference List

1

work platform

3

platform

5

support frame

7

spars

9

floor stand

11

roll

13

height adjustment device

15

cable pull

17

pulley

19

railing

21

holding element

23

Feather

24

second biasing device

25

mechanical winch

27

crank

29

drop protection

31.1

first/lower hook

31.2

second/upper catch hook

32.1

first/lower hook axis

32.2

second/upper catch hook axis

33.1

first/lower catch pin

33.2

second/upper catch pin

35

recess

37

safety rail

39

teeth

41

free rail

42

Release lever of the free holding rail

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 202006010625 U1 [0007]

Claims (8)

Working platform (1) with a height-adjustable platform (3), with two support frames (5) with bars (7) and the platform (3), which is height-adjustable and is mounted on the support frames (5) between them, with a height adjustment device (13). each support frame (5), which acts on the platform (3) and has a tension element, in particular a tension cable (15) or a toothed rack, and with a safety device (29) on each support frame (5), which when the tension element is relieved Height adjustment device (13) blocked, characterized in that the fall arrest device (29) has a catch rail (37) on the support frame (5) and a catch bolt (33) on the platform (3) which interacts with it, and that a pretensioning device, in particular a spring (23) prestresses the catch bolt (33) towards the catch rail (37) and that a locking device is mounted on the support frame (5) which, when the tension element is under tension, prevents the catch bolt (33) from engaging, which in particular is part of a catch hook s (31) is locked in the safety rail (37) or tries to lock and releases the tension element when the tension is relieved. Working platform (1) after claim 1 , characterized in that on the support frame (5) is attached a free holding rail (41), in particular a release lever (42), which acts against the pretension of the catch bolt (33) when actuated and thus separates the catch bolt (33) from the catch rail (37) pushes away. Working platform (1) according to one of the preceding claims, characterized in that the safety rail (37) has teeth (39) pointing upwards and that the working platform (1) can only be lowered if the free-retaining rail (41) and the height adjustment device (13) are actuated at the same time is. Working platform (1) according to one of the preceding claims, characterized in that the locking device is designed as a second catch pin (33.2). Working platform (1) after claim 3 , characterized in that the second catch bolt (33.2) has a recess at the position of the free-retaining rail. Working platform (1) after claim 4 or 5 , characterized in that the second catch hook (31) interacts with the traction element, and in particular that the holding element (21) of the traction cable (15) has a link guide for the second catch hook (31.2). Working platform (1) according to one of the preceding claims, characterized in that the pulling element is a cable pull (15) which can be adjusted in height by means of a mechanical cable winch (25) via a crank (27). Working platform (1) according to one of the preceding claims, characterized in that the first catch hook (31.1), which is pretensioned by the pretensioning device, when the height adjustment device (13) is lowered, with its catch pin (33.1) in the next following bearing point, i.e. the next tooth (39) of the Catch rail (37) snaps into place.

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