DE102011110918A1 - Wall construction structure for load bearing wall of multi-storey building, has vertical spacers that are mounted on upper surface of crosswise top runner, so that upper surface of top runner is set as support portion of floor board - Google Patents

Abstract

The construction structure has wallboards (1) that are provided with timber layer (4) having vertical timber beam. A veneer laminated wood layer (8) is set with timber layer that is provided with crosswise top runner (6) and crosswise bottom runner (7). A cladding portion of timber layer is provided on both inside and outside of fiber portion. Vertical spacers are provided with pressure resistant material made of steel and are mounted on upper surface of crosswise top runner, so that upper surface of crosswise top runner is set as support portion of floor boards. An independent claim is included for a method for manufacturing a wall construction structure.

Description

I. Field of application

The invention relates to a wall structure for multi-storey buildings whose primary building material is wood, which is selected because of its low weight, good technical insulation properties and the sustainability of its production.

II. Technical background

For buildings that are primarily made of wood, different types are known:
One of the oldest known types are log cabins in which horizontally stacked wooden trunks or wooden beams, which at the corners z. B. the building are positively connected with each other, form the wall structure.

In order to reduce the need for wood and to improve the insulation properties, houses are known in wood frame construction, in which the wall structure of frame-like supporting structures made of wood, wherein the cavities are filled in the frame with insulating material and then an inner and outer dense planking, often also made of wood materials, is applied.

In addition, wall structures are known in which a continuous, static-bearing wood layer of z. B. juxtaposed vertical wooden beams is present, which may have on the top and bottom of a horizontally extending beam-shaped cream or threshold as the upper and lower end and may be additionally provided on the outside with an insulating layer, with possibly additional skins as Weather protection, fire protection and the like.

The two last-mentioned wall structures are also used in the form of prefabricated wall panels, which allow a quick construction progress when assembled on the construction site.

The floor slabs are here as prefabricated floor slabs, preferably in turn made of wood materials, delivered and launched.

• – nicht nur vertikaler Lastabtragung, sondern auch Steifigkeit der Tafeln in ihrer Hauptebene,
• – ausreichendem Brandschutz,
• – Berücksichtigung von Setzungs- und Quellungsverhalten des Baustoffes Holz,

zu lösen.However, if you want to realize multi-storey buildings of four or eight storeys with such a wall construction, there are also a number of problems with regard to

• Not only vertical load transfer, but also rigidity of the panels in their main plane,
• - adequate fire protection,
• - Consideration of settlement and swelling behavior of the building material wood,

to solve.

III. Presentation of the invention

a) Technical task

It is therefore the object of the invention to provide a wall structure and a method for its creation, which solve the aforementioned problems in a simple manner.

b) Solution of the task

This object is solved by the features of claims 1 and 16. Advantageous embodiments will be apparent from the dependent claims.

In a conventional building of one or two storey wood-based panels, the floor slabs are located on the walls, in particular wall panels, of the lowest floor, and on top of this floor slab the supporting wall continues upwards.

If, in such a wall structure, subsidence of the wall of the lower floor or of the thickness of the floor slab occurs between the supporting walls standing on top of each other, the supporting walls resting thereon and the floor slabs lying on top of it are lowered by this amount.

Such settling phenomena occur, inter alia, that after the creation of the shell of wood materials, so after placing the blankets on the walls, the floor slabs are also filled with heavy bulk and / or screed for sound insulation between floors, and this high weight leads to a setting of the walls.

This is counteracted according to the invention by complementary measures: First, the wall panels consist of a static bearing wood layer that does not change in the vertical direction or as little as possible by settling or swelling in your measure, for example, by juxtaposed vertical wooden beams made of solid wood or glued wood layers, the fiber orientation is also directed vertically.

Such wooden layers of juxtaposed vertical wooden beams must have, in the transverse direction of the wooden beams, an upper bottom finish in the form of a crimp and a threshold, inter alia for reasons of connection to the individual wooden beams and distribution of vertically acting forces in the horizontal. According to the invention, the Rähm and threshold of several vertical, glued together layers of wood, in particular veneer layers, produced, in which additionally the fiber profile of the individual vertical layers cross each other. As a result, there is the top of such a Rähms and also the bottom of a corresponding threshold to a significant proportion, for. B. at least 30%, better at least 40%, better 50% of end grain, which is thus highly resilient vertically and the change in the vertical dimension of Rähm or threshold tends to zero, even under high loads.

Here, the upright wooden beams of the wood layer are connected with Rähm and threshold.

This alone due to changes in the moisture content of the supporting wood layer this does not change in size, the wooden beams are dried before creating the wall panels to a defined, low moisture content, for example, 12-15 wt.% The stacked wall panels were not supported via the intermediate floor slabs from each other, but on the introduced between the wall panels made of pressure-resistant and height-stable material, which are therefore not subject to vertical dimensional change, so that vertical dimensional changes of the floor slabs does not affect the vertical position of the overlying wall panel.

Since thus after filling the floor slabs with heavy sound insulation neither the individual wall panels themselves in the vertical direction is subject to dimensional change as well as the distance between superimposed wall panels, creates a building structure, which despite the primary material wood is subject to very little and in particular no vertical dimensional changes, the otherwise in the finished building unwanted joints or cracks, especially in a plastered wall surface, can entail.

In order to ensure the fire resistance of such a wall structure made of wood, the wood layer - including Rähm and threshold - coated both on the inside and on the outside with non-combustible material, in particular planked, the non-combustible material in particular additionally has a high fiber content which causes such planking to give to the wall panels, apart from the refractoriness, also a high rigidity in their main plane, by connecting this planking at a sufficient number of fixing points and sufficiently firmly with the wood layer bearing it, in particular with each one of the vertically arranged wooden beams, and of course also with Rähm and threshold. For this purpose, the planking of a blackboard should consist of as few panels as possible of the planking material.

For this reason, the planking of the non-combustible material is preferably directly on the supporting wood layer and extends over the entire inner and outer side, and preferably along the vertical narrow sides and / or the horizontal narrow sides of this wood layer, thus also from the narrow sides Fire can not penetrate unhindered into this layer of wood.

Insofar as an insulation is applied to the outside of the planked wood layer, which is the case above all with load-bearing outer walls, the insulation also consists of nonflammable or hardly flammable material, for example stoneware, which is then usually at a distance between the planked wood layer and an outer lining , which serves as weather protection, is attached, usually leaving a layer of air between insulation and outer lining.

The planking of flame-retardant material should also have a high density of at least 1,000 kg / m ³ , better 1,100 kg / m ³ , so that it also acts sound-absorbing.

The spacers between the superimposed supporting wall panels have such a cross-sectional area in the horizontal that they can absorb the pressures to be transmitted vertically and also the maximum allowable pressure, ie force input per area is not exceeded in the below and above arranged wall panel.

Also, as the load increases from top to bottom in the building, the cross-sectional area of the spacers in the building, as viewed from above, preferably increases from top to bottom either per spacer or in terms of the proportion of the area of the spacers to the area of the top of the wall panels. With always the same spacers this can be achieved by increasing the number of spacers per wall panel in the building from top to bottom.

These spacers can be introduced as shaped bodies, or be introduced from hardenable material, in particular concrete, in corresponding free spaces in the height range of the floor slabs.

By the above measures, a vertical dimensional change of the wall panels and thus the altitude of the floors be largely excluded, and if the building is made entirely of wood materials, small vertical dimensional changes can be compensated by shadow joints and similar measures.

However, the situation is different when a part of the building is made of stone materials, which are hardly subject to dimensional change in the vertical after construction. Thus, sometimes for fire protection reasons and / or stability reasons, especially in higher buildings, a building vertically traversing, lying in the interior of the building or on an outer wall of the building, building core -. As the staircase - made of stone materials, usually made of concrete, which is surrounded by the rest of the building of wood materials.

The dimensional possibly still occurring vertical subsidence of the timber components, especially by the ceiling filling then make compared to the dimensionally unchanging stone core of stone materials may be a problem:
Because if z. B. the top floor ceiling of the wooden building part slightly lowers, but this ceiling is fixed in height fixed to the building core of stone materials, this would result in an imbalance and strong tensions in this building ceiling.

For this reason - in the presence of a building core of stone materials - adjacent to the building core floor slabs vary in height attached to the building core, for example, by running on a part vertical, undercut guide rails, in which a protruding from the other part, form-fitting in-fitting sliding block is guided, which may for example be the head of a lead screw. This can with their shank directly or indirectly -. B. via a mounting bracket - is bolted to the floor slab, is screwed approximately in the narrow side of a floor slab panel and protrudes from this.

Preferably, then a guide nut is screwed onto the shaft between the guide rail and the floor slab, by means of which the guide screw can be fixed after filling the ceiling and setting the walls relative to the guide rail by tightening the lock nut.

The wall panels that adjoin such a building core of stone materials, however, are not itself screwed to this building core, but only on the floor slabs.

The procedure for producing a wall structure described above also has some special features:
If as a spacer molding, for example, cylinder from z. As steel, these can be used simultaneously when placing the floor slabs on the wall panels before or after in corresponding recesses or recesses in the floor slabs.

Preferably, however, the spacers are poured in the form of a curable, initially liquid or pasty material such as concrete in the corresponding recesses or recesses, which thus can be done only after placing the bullet cover panels on top of a wall.

If on a blackboard two bullet boards with their edges abut against each other, always leaving a slight gap between them. If a wall of film or a transversely compressible nonwoven material, coated with film, inserted into the inner circumference of the recess or recess prior to pouring the curable material. This, after subsequent pouring and curing with concrete, on the one hand creates a play in the horizontal direction if the floor slab should expand in that direction and further prevents during the hardening phase of the concrete that the moisture contained therein is released into the slab slabs and also that still liquid concrete can penetrate into the joint between two floor slabs off the intended recess or recess.

The necessary recesses or recesses can, viewed in the plan view, in principle have any cross-sectional shape, and are usually already produced by means of z. B. a CNC milling machine introduced. However, if they are placed in the floor slabs only after they have been placed on the wall panels, a round cross-sectional shape is recommended.

If two bulletin boards are placed with their edges to the center on the top of a wall panel, recesses, for. B. semicircular recesses, available, so that a spacer inserted therein extends over the joint between the two bulletin board panels away.

Preferably, before placing the next panel on the surface of the curable material, a liquid-tight cover z. B. launched from film, which can then be removed again.

c) embodiments

Embodiments according to the invention are described in more detail below by way of example. Show it:

1 : a blackboard, partially cut open,

2a , b: a wall structure in vertical section,

3 : a view of a wall with floor slabs laid up,

4a : a vertical section through a building,

4b : the horizontal section BB off 4a , and

5 : a plan similar to a blackboard 3 ,

1 shows the side view on a single standing blackboard 1 in the vertical direction 20 has the height of a projectile and from which - stacked floor by floor - the wall structure is created with interposed bullet board 2 , as can be seen in the other figures.

These wall panels 1 contain a layer of wood in their interior as a static load-bearing element 4 which essentially covers the entire area of the blackboard 1 extends as they are in 1 is apparent.

This wood layer 4 consists of juxtaposed, in the vertical direction 20 running, usually vertically equal height wooden beams 4a , b, c, with a top and bottom transverse Rähm 6 or a threshold 7 each are made of wood. This is the Rähm 6 and the threshold 7 with each of the wooden beams 4a , b, c, be it positively by screwing or clamping or non-positively.

For the vertical wooden beams 4a , b, c made of solid wood, the cutting is done so that the grain of fibers substantially in the longitudinal direction of the wooden beams 4a , b, c lies, because in the direction of the grain, solid wood has the smallest dimensional changes in the future and the highest static load capacity.

Rähm 6 and threshold 7 also serve the force distribution in the horizontal direction on the individual wooden beams 4a , b, c. At the same time should Rähm 6 and threshold 7 especially in the vertical direction 20 also possible no fading or a dimensional change after assembly of the blackboard 1 exhibit.

That's why Rähm 6 and threshold 7 from vertically standing layers 8th - how best in the 2a to recognize b - glued, taking the fiber orientation 11 in the individual layers 8th each crosswise in adjacent layers 8th runs, so in every second layer 8th the fiber path 11 also in the vertical direction 20 stands, so that the Stirnholzanteil in the top and bottom is relatively high and thus offers a high resistance to dimensional changes in the vertical direction.

Since the Rähm 6 and the threshold 7 These functions can perform better, the more layers are glued together 8th they exist, they are preferably made of layers of veneer, so as veneer plywood.

This wood layer 4 of the 1 is additionally on its two main exterior surfaces with a planking 5 planked from gypsum fiber boards over the entire surface, and this planking 5 is preferably by means of brackets or screws 13 with the wood layer 4 connected, in particular with each of the wooden beams 4a , b the wood layer connected as well as with Rähm and threshold.

The planking 5 fulfills a dual purpose, on the one hand the fire retardancy, by the planking 5 made of refractory or fire-retardant material, for example primarily of gypsum or other stone-dust material.

In addition, the planking 5 but also the force absorption of the wood layer 4 in addition to improving their main level. For this purpose owns the planking 5 a fiber content, preferably in turn made of a non-combustible or poorly combustible material, for example of stone materials, which are arranged in irregular directions and thus the planking 5 a high resistance to forces in their main plane, ie against shear forces give.

Preferably gypsum fiber boards are used, which are on the outer surfaces of the wood layer 4 placed on and firmly connected to these, preferably via screw connections 13 or Verklammerungen be connected, on the one hand should be taken to ensure that the planking of a blackboard 1 per page from as few panels as possible 5 and on the other hand the planking 5 as firmly as possible with the wood layer 4 is connected, preferably with each one of the upstanding wooden beams 4a , b and of course with Rähm 6 and threshold 7 ,

The wood layer 4 should also be on their vertical narrow sides with such a fire-resistant planking 5 be proven to prevent the penetration of fire from these narrow sides in the wood layer 4 unstoppable.

Because like the vertical section of 2a for an interior wall and the 3 in the supervision shows, lying on the top of a blackboard 1 Basement ceiling panels 2 on, either two adjacent bulletin boards 2 each with its edge 2a to the longitudinal center 10 the top of the blackboard 1 reaching, as in 3 represented, or a single bullet board 2 over the blackboard 1 away, as in the upper part of the 3 shown.

Above it will be the next blackboard 1 posed, as in 2a visible, noticeable.

Due to the special construction of the wall panels 1 are vertical dimensional changes of the wall panels 1 minimized for the future. So that the entire wall structure also not by vertical dimensional changes between the wall panels 1 lying floor slabs 2 and whose dimensional change is affected becomes the force from the top wall panel 1 on the wall plate below 1 not on the floor slab 2 removed in between, but by means of special spacers 3 between two wall panels one above the other 1 but only part of the footprint of a blackboard considered in the plan 1 turn off:
In the illustrated embodiment, the spacers 3 in the supervision of a round cross section whose diameter is smaller than the width of the frame 6 , and in corresponding breakthroughs 9 a continuous floor slab 2 or in opposing semicircular recesses 9 ' two each to the longitudinal center 10 a blackboard 1 reaching floor panel 2 are arranged.

These spacers 3 are made of such a material that they are in the vertical direction 20 dimensionally stable and of course sufficiently pressure resistant. They can consist of a prefabricated molded body, for example made of steel, or after placing the floor slab 2 from a curable, initially pasty material, preferably concrete, in the openings 9 or recesses 9 ' are poured, which are preferably previously sealed by means of a circumferentially inserted film strip to prevent the ingress of moisture into the given timber components. The filling then takes place up to the upper edge of the surrounding floor slabs 2 ,

Nevertheless, the next wall panels can 1 be put on it before the curing process of these spacers 3 is completed.

2 B shows a vertical section through a wall structure of an outer wall, wherein the wall panel 1 additionally on its outside a - in this case two-ply - insulation 14 also made of a non-flammable or hardly combustible material, preferably rock wool, carries on the outside of an outer lining 15 is covered as weather protection.

The outer lining 15 is opposite the fireproof planked wood layer 4 by means of ribs 17 made of wood-based material kept at a distance, usually an air gap 16 between the outer surface of the insulation 14 and the outer lining 15 is left as a standing, insulating air layer, which is common practice.

Especially with the blackboards 1 the lowest floor can be below the wood layer 4 and the insulation 14 a threshold pad 18 be available as a continuous board in addition.

The floor slabs 2 consist of laminated plywood glued laminated timber or are board pile ceilings whose layers are horizontal or upright side by side and connected to each other and in the direction transverse to the main plane of the supporting wall panel 1 run underneath.

Special solutions are still required if a building constructed from wall panels 1 and floor boards 2 , in addition a building core 21 Of stone materials containing or generally of a material that underlies virtually no dimensional change in the vertical direction.

Especially in buildings where such a building core 21 is surrounded by a structure of wood materials, although the dimensional changes of the wooden building part in the vertical direction are minimized by the aforementioned measures, but can not be completely ruled out, for. B. by the ceiling filling. Therefore, a vertical movement possibility of the existing wooden part of the building in relation to the stone core building core 21 necessary, as in 4a , b initially for the floor slabs 2 shown:
In the building core 21 facing lower edge of the floor slab 2 is a mounting bracket 25 screwed. Through a hole in the vertical leg of the mounting bracket 25 extends a lead screw 23 in the horizontal direction so that the screw head 23a doing so in the manner of a sliding block with appropriate rotational position exactly in a vertical in the outside of the building core 21 taken in C-rail 22 fits so that it can not be pulled out of this in a horizontal direction, after he z. B. via one at the upper end of the rail 21 befindlicher threading was introduced there.

From the outside becomes a guide nut 24 on the shaft 23b the lead screw 23 screwed by screwing to the C-rail 22 can serve the fixation at the current altitude or by loose application to the C-rail 22 the free guidance of the screw head 23a in the C-rail 22 can ensure.

Likewise, the wall panels must 1 a vertical movement possibility opposite the building core 21 have, as in 5 presented in a possible solution form:
This is achieved by the wall panels 1 on their vertical narrow sides not directly to the building core 21 be connected, but only indirectly via the above-described attachment of the floor slabs 2 at the building core 21 ,

LIST OF REFERENCE NUMBERS

1

blackboard

2

Basement ceiling board

2a

edge

3

spacer

4

wood layer

4a, b

vertical wooden beams

5

Planking, gypsum fiber boards

6

cream

7

threshold

8th

layer

9

breakthrough

9 '

recess

10

longitudinal center

11

grain

12

galvanizing

13

Clamps, screw connection

14

insulation

15

Siding

16

air gap

17

rib

18

threshold edition

19

horizontal direction

20

vertical direction

21

building core

22

C-rail

23

lead screw

23a

screw head

23b

screw shaft

24

lead nut

25

mounting brackets

Claims (20)

Wall construction for the load-bearing walls in a multi-storey building with a) wall panels ( 1 ) with - a static bearing wood layer ( 4 ), in particular of vertical wooden beams ( 4a , b), - whereby the bearing wood layer ( 4 ) a top transverse Rähm ( 6 ) and a bottom transverse threshold ( 7 consisting of layer by layer with intersecting fiber course of the layers ( 8th ) glued wood, especially veneer plywood, consist of upright layers ( 8th ), - a planking ( 1 ) of the wood layer ( 4 ) both on the inside and the outside with non-combustible material with fiber content, and b) vertical spacers ( 3 ) of a pressure-resistant and height-stable material, in particular of concrete or steel, which is only on a part of the top of the Rähms ( 6 ), so that the rest of the top of the Rähms ( 6 ) as a support surface for floor slabs ( 2 ) is available. Wall structure according to claim 1, characterized in that the planking ( 5 ) of non-combustible material directly on the wood layer ( 4 ) and over its entire inside and outside, including Rähm ( 6 ) and threshold ( 7 ) extends. Wall structure according to one of the preceding claims, characterized in that the planking ( 5 ) consists of panels made of hardly combustible material, which are placed on each side of the blackboard ( 1 ) is composed of as few individual parts. Wall structure according to one of the preceding claims, characterized in that the planking ( 5 ) in the day is, lateral forces in the main plane of the planking ( 5 ) and thus also the wood layer ( 4 ), in particular in the horizontal direction ( 19 ), and for this purpose the planking ( 5 ) in a sufficient number of places and sufficiently strong with the wood layer ( 4 ), in particular with each of the wooden beams ( 4a , b) and / or Rähm ( 6 ) as well as threshold ( 7 ). Wall structure according to one of the preceding claims, characterized in that a planking ( 5 ) with non-combustible material also on one or both of the vertical side edges of the wood layer ( 4 ) is available. Wall structure according to one of the preceding claims, characterized in that, in particular for load-bearing outer walls on the outside of the planked wood layer ( 4 ) an insulation ( 14 ) of non-flammable or hardly combustible material, in particular rock wool, is applied, in particular in the distance between the planked wood layer ( 4 ) and one by means of this distance aware ribs ( 6 ), on which an outer lining ( 15 ) is applied flat. Wall structure according to one of the preceding claims, characterized in that the vertical spacers ( 3 ) have such a sectional area viewed in plan view that they can absorb the pressures to be transmitted vertically and the maximum allowable pressure on the underlying wall panel ( 1 ) is not exceeded. Wall structure according to one of the preceding claims, characterized in that the cross-sectional area of the spacers (FIG. 3 ) in the building per spacer ( 3 ) or the proportion of the area of the spacers ( 3 ) to the surface of the top of the blackboard ( 1 ), in particular the number of spacers ( 3 ) per blackboard ( 1 ), increases from top to bottom. Wall structure according to one of the preceding claims, characterized in that the upright wooden beams ( 4a , b) the wood layer ( 4 ) before creating the blackboards ( 1 ) have a defined low moisture content. Wall structure according to one of the preceding claims, characterized in that the floor slabs ( 2 ) consist of horizontal, cross-glued cross-laminated timber or glued laminated timber with vertically standing layers. Wall structure according to one of the preceding claims, characterized in that the planking ( 5 ) of non-combustible material has a high density of at least 1,000 kg / m ³ , better 1,100 kg / m ³ , and at the same time acts as a stiffener and fire protection. Wall structure according to one of the preceding claims, characterized in that cream ( 6 ) and threshold ( 7 ) with each of the wooden beams ( 4a , b) the wood layer ( 4 ), in particular clamped or screwed, are, in particular indirectly via the planking ( 5 ). Wall structure according to one of the preceding claims, characterized in that in a vertically running through the building building core of stone materials, the floor slabs ( 2 ) variable in height at the building core ( 21 ) are attached. Wall structure according to one of the preceding claims, characterized in that on the outer edge of the floor slab ( 2 ) or on the outside of the building core ( 21 ) vertically extending, undercut guide rails, in particular C rails ( 22 ) are present, in which a projecting from the other element guide element, in particular the screw head ( 23a ) a guide screw ( 23 ), extending through the vertical leg of a mounting bracket 25 extends, is positively guided in the vertical direction. Wall structure according to one of the preceding claims, characterized in that on the screw shank ( 23b ) outside the C-rail ( 22 ) a guide nut ( 24 ) is screwed. Method for producing a wall structure for multi-storey buildings with wall panels ( 1 ), Spacers ( 3 ) between the blackboards ( 1 ), as well as floor slabs ( 2 ), where - the wall panels ( 1 ) of the lowest floor erected on the ground and optionally fixed against each other, - on the top of the wall panels ( 1 ) the floor slabs ( 2 ) and the spacers ( 3 ), and - above the wall panels ( 1 ) of this bullet the wall panels ( 1 ) of the overlying projectile, characterized in that the spacers ( 3 ) as a shaped body or as a hardenable material, in particular after laying the floor slab panels ( 2 ), in breakthroughs ( 9 ) or recesses ( 9 ' ) of the floor slabs ( 2 ) on the top of the Rähms ( 6 ) are applied. Method according to claim 16, characterized in that two floor slabs ( 2 ) with its edge ( 2a ) each on one side of the longitudinal middle ( 10 ) of the blackboard ( 1 ) and in their outer edge recesses ( 9 ' ), in particular semicircular recesses ( 9 ' ), in particular in alignment with the analogous recesses ( 9 ' ) of the adjacent floor slab ( 2 ), so that the spacer ( 3 ) in the recesses ( 9 ' ) across the gap between two floor slabs ( 2 ) extends. Method according to one of the preceding method claims, characterized in that the recesses ( 9 ' ) after placing the floor slabs ( 2 ) are filled with curable material, in particular concrete, up to the top of the floor slabs ( 2 ). Method according to one of the preceding method claims, characterized in that the breakthroughs ( 9 ) and / or recesses ( 9 ' ) in the manufacture of floor slabs ( 2 ), in particular milled. Method according to one of the preceding Verfahrensprüche, characterized in that in a building with a building core extending vertically through the building ( 21 ) of stone materials and vertical guidance of the floor slabs ( 2 ) at the building core ( 21 ) by means of undercut guide rails and a guide screw running therein ( 23 ) the floor slabs ( 2 ) at the building core ( 21 ) in the vertical direction ( 20 ) are tightened and fixed by tightening a guide nut ( 24 ) on the guide screw ( 23 ) in the direction of the undercut guide rail.

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