Ladder

Abstract

The invention relates to a ladder (1) for accessing shafts, in particular sewage shafts, with two vertical stiles (2) running parallel to each other and made of a corrosion-resistant, weldable metal, and a plurality of vertically arranged steps (3) formed of a corrosion-resistant, weldable metal, wherein the steps (3) are welded to the stiles (2) via two fastening points (4) and connect the two stiles (2) to each other, wherein the steps (3) each have a horizontal tread area (5) for stepping onto the steps (3), wherein at least the tread area (5) of the steps (3) has a plastic coating (6) over the corrosion-resistant, weldable metal of the steps (3), and a connection system (16) for connecting two such ladders (1).

Description

[0001] The invention relates to a ladder for accessing shafts, in particular sewage shafts, with two vertical, parallel stiles made of a corrosion-resistant, weldable metal and a plurality of tread elements arranged vertically one above the other, which are made of a corrosion-resistant, weldable metal, wherein the tread elements are welded to the stiles via two fastening points each and connect the two stiles to one another, wherein the tread elements each have a horizontal tread area for accessing the tread elements.

[0002] Such a ladder is known, for example, from EP 1 253 281 B1. Accessibility through shafts is a vital requirement for maintenance and repair work. Therefore, in sewer construction, such ladders or brackets are usually attached to the shaft walls and protrude into the shaft cross-section. The advantage of these metal ladders and brackets is their durability, so repairs and replacements are rarely necessary. The disadvantage of these ladders or brackets is that the tread areas of the tread elements or brackets only partially prevent slipping, especially in damp environments such as sewer shafts, because the damp metal provides a very slippery surface.

[0003] From DE 201 06 892 U1 a ladder is known, wherein an anti-slip coating is provided on the treads of the ladder.

[0004] It is therefore an object of the invention to provide an improved ladder which effectively prevents slipping from the tread elements even in damp environments, such as sewage shafts, and which enables a particularly simple manufacture of the ladder.

[0005] This problem is solved by a ladder having the features of claim 1.

[0006] Because at least the tread area of ​​the tread elements has a plastic coating over the corrosion-resistant, weldable metal of the tread elements, slipping from the tread elements can be effectively prevented, even in damp environments such as sewer shafts. With the plastic coating, the tread areas of the tread elements can easily exhibit greater friction than metal surfaces, particularly in damp environments, so that slipping from the tread elements can be effectively prevented. This durable ladder enables comfortable and safe use in sewer shafts. Such a plastic coating can be easily applied to the metal tread elements using injection molding. The corrosion-resistant, weldable metal of the tread elements and stiles is preferably V4A steel (material no. 1.4571). After welding the tread elements to the stiles, pickling and passivation can take place.

[0007] According to the invention, the corrosion-resistant, weldable metal of the tread elements is free of the plastic coating in two joining areas for attaching the tread elements to the stiles. The stiles each have receiving holes for receiving the joining areas at the attachment points. The tread elements can be inserted particularly easily into the receiving holes of the stiles via the joining areas free of the plastic coating. The plastic coating does not form a load-bearing connection, so even if the plastic coating is damaged, the stability of the ladder is not compromised.

[0008] According to the invention, the plastic coating forms contact surfaces for the tread elements on the stiles, with the contact surfaces at the attachment points ensuring the positioning of the joining areas in the receiving holes. With the plastic coatings forming the contact surfaces of the tread elements on the stiles, the tread elements can be positioned particularly easily at the attachment points with the joining areas in the receiving holes. This enables particularly simple production of the ladder.

[0009] According to the invention, the stiles are hollow, with the joining areas of the tread elements in the receiving holes protruding through the stiles from a front side to a back side, with the tread elements being welded to the stiles at the back and resting on the front side with a clearance fit. The welding of the tread elements at the back of the stiles allows the tread elements to easily rest on the front side in the receiving holes of the stiles with a clearance fit. With the support at the front and the welding at the back, the plastic coating extending to the front of the stiles is sufficiently spaced from the weld of the tread elements to the stiles so that the plastic coating is not damaged during welding.The joining areas that are free of the plastic coating and that protrude through the hollow stiles ensure that there is sufficient distance between the weld on the back of the stiles and the plastic coating of the tread elements on the front of the stiles.

[0010] Advantageous embodiments and further developments of the invention emerge from the dependent claims. It should be noted that the features listed individually in the claims can also be combined with one another in any technologically expedient manner, thus revealing further embodiments of the invention.

[0011] According to an advantageous embodiment of the invention, the plastic coating is made of polypropylene. A plastic coating made of polypropylene is easy to manufacture, durable, and prevents slipping from the tread elements, particularly effectively in humid environments such as sewer shafts. Furthermore, polypropylene is particularly easy to apply to the metal tread areas of the tread elements by injection molding.

[0012] Particularly preferred is an embodiment in which the corrosion-resistant, weldable metal of the tread elements is overmolded with the plastic coating. Overmolded metal tread elements make it particularly easy to create an excellently holding plastic coating in the tread area of ​​the tread elements. Overmolded metal tread elements by injection molding ensures a firm and precise fit of the plastic coating.

[0013] A particularly advantageous embodiment of the invention relates to the plastic coating forming knob-like or ridge-like, profile-forming elevations in the tread area. It is particularly easy to form knobs or ridges in the plastic coating as profile-forming elevations, which can particularly effectively prevent slipping from the tread area. The profile of the elevations creates a particularly high level of friction on the plastic coating in the tread area of ​​the tread elements, effectively preventing the feet or hands of the ladder user from slipping, even in damp environments.

[0014] An advantageous embodiment provides that the joining areas of the tread elements do not penetrate the backs of the stiles at the attachment points, and that the tread elements are connected to the stiles at the attachment points via a build-up weld in the receiving holes. With optimal positioning of the joining areas of the tread elements in the receiving holes of the stiles, the tread elements can be easily attached to the attachment points in the stiles via a build-up weld. Since the joining areas do not penetrate the backs of the stiles, the joining areas or the build-up weld protrude little or not at all from the back of the stiles, allowing the ladder to be connected to the stiles very flush with the shaft wall of the sewage shaft.

[0015] According to a preferred embodiment of the invention, a screw hole is provided on the stiles between each attached tread element for screwing the stiles to a shaft wall. With a large number of screw holes, the ladder stiles can be attached to shaft walls particularly flexibly. If a screw hole is provided between each attached tread element for screwing the stiles to a shaft wall, the large selection of screw holes creates particularly high flexibility when attaching the ladder to the shaft wall. A further advantage is that the ladder can be shortened as required and the remaining piece can be reused elsewhere or in the next sewer shaft. This means that the ladder can be pre-produced as a standard element and there is no need to measure each shaft beforehand.

[0016] A particularly advantageous embodiment is one in which the hollow stiles have a plurality of screw holes on the back for screwing the stiles to a shaft wall, with through holes concentric with the screw holes being formed on the front of the stiles and being larger than the screw holes. The hollow design of the stiles makes it possible to achieve a lightweight yet stable structure for the ladder stiles. The back of the stiles can be easily screwed to the shaft wall through the through holes using the larger through holes in the front of the stiles, which are arranged concentrically with the screw holes in the back. For this purpose, a screw and, for example, a tool for turning the screw can be easily passed through the through holes.This allows for particularly simple and secure installation of the ladder stiles on the shaft wall. The screw head, located inside the stiles, is also protected after screwing.

[0017] A particularly advantageous embodiment of the invention provides for the stiles to be formed from square profiles. The square profiles form a front and a back particularly easily, allowing the ladder to be easily positioned against the shaft wall. During ladder manufacturing, the positioning of the square profiles and the tread elements is particularly simple.

[0018] According to an advantageous embodiment of the invention, the ladder has a connection system for connecting two ladders as described in more detail above and below, wherein the connection system has a rectangular plate which has a side length which corresponds to the diagonal inner dimension of the square profile of the stiles, wherein the plate for connecting two ladders can be inserted in the diagonal of a stile of a first ladder and a stile of a second ladder can be plugged onto the inserted plate of the connection system, which partially protrudes from the stile of the first ladder. Using this connection system, two ladders can be positioned one above the other in the sewer shaft particularly easily, such that the assembly of the two ladders to form a connected ladder system is particularly simple.Since a ladder can simply be plugged onto the protruding plate, the ladder system can be extended as required using such connection systems, so that even larger height differences in the sewage shafts can be easily bridged with the ladder system consisting of several ladders.

[0019] According to a preferred embodiment of a ladder with a connecting system described above, the corners of the plate are chamfered with centering bevels. The centering bevels, designed as chamfers, make it particularly easy to insert the plate of the connecting system into the stile of the first ladder, and also facilitate the positioning of the second ladder when plugging it onto the connecting system. Advantageously, the centering bevels are designed the same at all corners of the plate, allowing for multiple mounting directions when using the connecting system.

[0020] Further features, details, and advantages of the invention will become apparent from the following description and the drawings, which show an exemplary embodiment of the invention. Corresponding objects or elements are provided with the same reference numerals in all figures. They show: Figure 1 shows a ladder according to the invention, Figure 2 shows a top view of the ladder, Figure 3 shows a top view of a stile, Figure 4 shows a further top view of a stile, Figure 5 shows a view of a fastening point, Figure 6 shows a rear view of the ladder, Figure 7 shows a detailed view of a screw hole, Figure 8 shows an individual view of the connection system, and Figure 9 shows a detailed view of the connection system in a stile.

[0021] In the Figure 1Denoted by the reference numeral 1, a ladder according to the invention is shown. The ladder 1 is intended to facilitate the access to shafts, in particular sewage shafts. It has two vertical, parallel stiles 2. These are advantageously made of a corrosion-resistant, weldable metal. In addition, the ladder 1 has a plurality of tread elements 3 arranged vertically one above the other. These tread elements 3 are advantageously also made of a corrosion-resistant, weldable metal. The tread elements 3 are each connected to the shaft via two fastening points 4 ( Fig. 6) welded to the stiles 2. In this way, the tread elements 3 connect the two stiles 2 of the ladder 1 to one another. The tread elements 3 each have a horizontal tread area 5 for stepping on the tread elements 3. Walking on the ladder 1, and in particular holding on to the tread elements 3, is much easier for the user if the advantageously U-shaped tread elements 3 have a substantially round cross-section. Furthermore, the preferably U-shaped tread elements 3 should be designed such that the two legs of the U-shape protrude towards the section between the legs from the horizontal plane defined by the section between the two legs and thus offer protection against lateral slipping from the tread area 5 formed between the legs.Such a design of the tread elements 3 is particularly advantageous in view of the generally humid, friction-reducing environment in sewers. According to the invention, at least the tread area 5 of the tread elements 3, and in the illustrated embodiment also the legs, are provided with a plastic coating 6 over the corrosion-resistant, weldable metal of the tread elements 3. This can prevent slipping from the tread elements 3 even more effectively, even in humid environments, such as sewer shafts. The plastic coating 6 is preferably made of polypropylene. For this purpose, the corrosion-resistant, weldable metal of the tread elements 3 is advantageously simply overmolded with the plastic coating 6 using an injection molding process.

[0022] The Figure 2 shows the ladder 1 according to Figure 1in a top view. This illustration shows the knob-like, or rather web-like, profile-forming elevations 7 in the tread areas 5, which are formed from the plastic coating 6 in the tread area 5 of the tread elements 3.

[0023] In the Figure 3 is an example of a top view of the right stile 2 of the ladder 1 according to the Figure 1 and 2shown. This plan view thus shows a view into one of the stiles 2, which are preferably formed from square profiles 15. It can also be seen that the corrosion-resistant, weldable metal of the tread elements 3 is free of the plastic coating 6 in two joining areas 8 for fastening the tread elements 3 to the stiles 2. This can be achieved in the prefabrication of the tread elements 3 when coating the corrosion-resistant, weldable metal in plastic injection molding simply by using a suitable mold that omits the joining areas 8. The stiles 2 of the ladder 1 each have receiving holes 9 for receiving the free joining areas 8 at the fastening points 4 ( Fig. 6 ). As a result, the plastic coating 6 does not form a load-bearing connection, so that even if the plastic coating 6 is damaged, the stability of the ladder 1 is not endangered.

[0024] In Figure 4is a further top view of the exemplary shown spar 2 according to Figure 3 From this perspective, however, it can be seen that the plastic coating 6 forms contact surfaces 10 of the tread elements 3 on the stiles 2.

[0025] The prefabricated tread elements 3, which are already coated with plastic 6, can be easily positioned using these contact surfaces 10 at the fastening points 4. This allows the joining areas 8 of the tread elements 3 to be easily arranged in the receiving holes 9 of the stiles 2.

[0026] The Figure 5 represents the example shown spar 2 according to Figure 3 and 4in a rear view, so that the uppermost fastening point 4 is clearly visible. In this illustration, it can be seen that the joining areas 8 of the tread elements 3 in the receiving holes 9 protrude through the hollow stiles 2 from a front side 11 to a rear side 12. The tread elements 3 are welded to the stiles 2 at the rear side 12 and rest on the front side 11 in a clearance fit in the receiving holes 9. At the rear sides 12 of the stiles 2, the joining areas 8 of the tread elements 3 do not penetrate the stiles 2. The tread elements 3 are connected here at the joining areas 8 via build-up welds in the receiving holes 9 to the stiles 2 at the fastening points 4. The joining areas 9 or the build-up welds at the fastening points 4 do not protrude or, as in Figure 5As can be seen, it barely protrudes from the back 12 of the stiles 2, so that the ladder 1 on the stiles 2 can be connected very flush with the shaft wall of the sewage shafts.

[0027] In Figure 6 is a rear view of the Figure 1shown from the front. In addition to the six fastening points 4 for the three tread elements 3 on the two stiles 2, the screw holes 13 in the stiles 2 can also be seen. Between each fastened tread element 11 there is a screw hole 13 for screwing the stiles 2 to a shaft wall. To fasten the ladder 1 to the shaft wall, the use of at least four screw holes 13 is sufficient. Thanks to the large selection of available screw holes 13, a high degree of flexibility is provided when fastening the ladder 1 to the shaft wall. If the shaft wall of the shaft in which the ladder 1 according to the invention is to be installed has projections and undercuts, it is advisable to arrange spacers between the ladder 1 and the shaft wall to bridge differences in the distance level.Here, too, another advantage of the ladder 1 according to the invention over conventional stirrups comes into play, since steps in the shaft wall with conventional stirrups always resulted in different depth levels of the tread elements 3 relative to the shaft wall. These differences can be conveniently compensated for with the ladder 1 according to the invention by placing spacers or spacer sleeves underneath.

[0028] The detailed view according to Figure 7 shows that in the bars 2 at the back 13 ( Fig. 6) Screw holes 13 for screwing the stiles 2 to a shaft wall are recessed. On the front side 11 of the stiles 2, shown here, there are through holes 14 concentric with the screw holes 13, which are larger than the screw holes 13. Thanks to the larger through holes 14 in the front side 11 of the stiles 2, the back of the stiles 2 can be easily screwed to the shaft wall through the through holes 14. For this purpose, a screw and, for example, a tool for turning the screw can be easily passed through the through holes 14.

[0029] The Figure 8 shows a single view of a connection system 16 for connecting two conductors, as shown in the Figures 1 to 7 The connection system 16 is formed by a rectangular plate 17, which has a side length 18 corresponding to the diagonal inner dimension 19 ( Fig. 9 ) of the square profile 15 ( Fig. 9) of the spars 2 ( Fig. 9 ). To connect two conductors 1, the plate 17 is used as shown in Figure 9 or also in Figure 2 shown in the diagonal of a spar 2 of a first ladder 1 ( Fig. 2 ). The stile 2 of a second ladder 1 can thus simply be placed on the inserted one, made from the stile 2 of the first ladder 1, as shown in Figure 9 As can be seen, the partially protruding plate 17 of the connection system 16 is plugged onto it. The corners of the plate 17 are chamfered with centering bevels 20. The chamfer of the centering bevels 20 makes it particularly easy to insert the plate 17 of the connection system 16 into the stile 2 of the first ladder 1, and the positioning of the second ladder 1 when plugging it onto the connection system 16 is also made easier. The centering bevels 20 at the corners of the plate 17 are designed the same everywhere, so that several mounting directions are possible when using the connection system 16 shown. Bezuas character list

[0030] 1Ladder 2Straights 3Tread elements 4Attachment point 5Tread area 6Plastic coating 7Elevations 8Joining area 9Hole 10Contact surface 11Front 12Rear 13Screw hole 14Through hole 15Square profile 16Connection system 17Plate 18Side length 19Diagonal inside dimension 20Centering bevel

Claims

1. Ladder (1) for accessing manholes, in particular sewage manholes, having two vertical, parallel ladder stringers (2) made of a corrosion-resistant, weldable metal and a plurality of step elements (3) arranged vertically one above the other, which are formed from a corrosion-resistant, weldable metal, wherein the step elements (3) are each welded to the ladder stringers (2) via two fastening points (4) and connect the two ladder stringers (2) to one another, wherein the step elements (3) each have a horizontal step area (5) for stepping on the step elements (3), characterised in that at least the step area (5) of the step elements (3) has a plastic coating (6) over the corrosion-resistant, weldable metal of the step elements (3), wherein the corrosion-resistant, weldable metal of the step elements (3) is free of the plastic coating (6) in two joining areas (8) for fastening the step elements (3) to the ladder stringers (2), wherein the ladder stringers (2) each have receiving holes (9) for receiving the joining areas (8) at the fastening points (4), wherein the plastic coating (6) forms respective contact surfaces (10) of the step elements (3) on the ladder stringers (2), wherein the contact surfaces (10) at the fastening points (4) cause the joining areas (8) to be positioned in the receiving holes (9), wherein the ladder stringers (2) are hollow, wherein the joining areas (8) of the step elements (3) in the receiving holes (9) project through the ladder stringers (2) from a front side (11) to a rear side (12), wherein the step elements (3) are welded to the ladder stringers (2) at the rear (12) and rest on the front (11) in a clearance fit.

2. Ladder (1) according to claim 1, characterised in that the plastic coating (6) is made of polypropylene.

3. Ladder (1) according to claim 1 or 2, characterised in that the corrosion-resistant, weldable metal of the step elements (3) is overmoulded with the plastic coating (6).

4. Ladder (1) according to any one of the preceding claims, characterised in that the plastic coating (6) forms nub-like or web-like, profile-forming elevations (7) in the step area (5).

5. Ladder (1) according to any one of the preceding claims, characterised in that the joining areas (8) of the step elements (3) do not penetrate the rear sides (12) of the ladder stringers (2) at the fastening points (4) and in that the step elements (3) are connected to the ladder stringers (2) at the fastening points (4) via a build-up weld in the receiving holes (9).

6. Ladder (1) according to any one of the preceding claims, characterised in that a screw hole (13) for screwing the ladder stringers (2) to a shaft wall is arranged on the ladder stringers (2) between each fastened step element (11).

7. Ladder (1) according to any one of the preceding claims, characterised in that the ladder stringers (2) are hollow, wherein the ladder stringers (2) have a plurality of screw holes (13) on a rear side (12) for screwing the ladder stringers (2) to a shaft wall, wherein concentric feed-through holes (14) are formed on a front side (11) of the ladder stringers (2) relative to the screw holes (13), which feed-through holes are larger than the screw holes (13).

8. Ladder (1) according to any one of the preceding claims, characterised in that the ladder stringers (2) are formed from square profiles (15).

9. Ladder (1) according to claim 8, characterised in that the ladder (1) has a connection system (16), wherein the connection system (16) has a rectangular plate (17), wherein the plate (17) can be used to connection two ladders (1), wherein the plate (17) has a side length (18) that corresponds to the diagonal internal dimension (19) of the square profile (15) of the ladder stringers (2), wherein the plate (17) can be used to connect two ladders (1) in the diagonal of a ladder stringer (2) of a first ladder (1) and a ladder stringer (2) of a second ladder (1) can be pushed onto the inserted plate (17) of the connection system (16) that partially protrudes from the ladder stringer (2) of the first ladder (1).

10. Ladder (1) according to claim 9, characterised in that the corners of the plate (17) are chamfered with centring bevels (20).

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