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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of German Utility Model No. DE 20 2006 003 836.1, filed on Mar. 10, 2006, the disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a slab formwork system having a plurality of formwork elements which have first hook members at their lower side for the establishing of a hook connection with second hook members provided at upper end sections of vertical supports, with the first and second hook members being designed such that the hook connection can be established, on the one hand, when the formwork elements and the vertical supports extend parallel or obliquely to one another and such that a pivoting of a formwork element is made possible, on the other hand, while maintaining the hook connection, into such a position in which the formwork element and the vertical supports include an angle of approximately 90°. The invention furthermore relates to a method for the preparation of a slab formwork system of this type. 
     BACKGROUND OF THE INVENTION 
     Slab formwork systems of the named type are used in practice in a number of embodiments in the erection of buildings to provide a reception region for liquid concrete which forms the respectively desired slab structure after its hardening. 
     It is often necessary during the preparation of slab formwork systems, and in particular also in work subsequent thereto, that an erector moves on the surface of already erected formwork elements so that a risk of falling is generally present in this process. To reduce this risk, it is known to couple the formwork elements with railing members after their erection. However, a risk of falling and of accident is also present in this case at least before and during the attachment of railing members of this type. 
     SUMMARY OF THE INVENTION 
     An object of the invention consists of providing a slab formwork system and a method for the preparation of a slab formwork system of this type in which the risk of accident is reduced to a minimum both during the erection and in work subsequent thereto, with the erection in particular being able to be carried out economically in a simple manner. 
     This object is satisfied in accordance with the invention by a slab formwork system in accordance with the features of the embodiments disclosed herein and in particular in that the formwork element can be coupled prior to the pivoting with a railing member extending substantially perpendicular to the formwork element. 
     A method in accordance with the invention for the preparation of a slab formwork system is accordingly characterized by the features of the embodiments disclosed herein. 
     The invention is thus based on the surprisingly simple, but nevertheless very effective, idea of already coupling the formwork elements to the respectively required railing member or members before their final erection so that the railing members are already located in their final destination position when the erection of the respective formwork element is completed. In this process, the invention utilizes the recognition that, after the hooking together of the first and second hook members, a large portion of the weight of the formwork elements is already absorbed by vertical supports so that it is not disturbing with respect to the weight to be handled by the erector if a formwork element additionally also bears at least one railing member. The coupling is preferably established between the formwork element and the railing member after the first and second hook members have been hooked together with one another. Alternatively, the connection between the formwork element and the railing member can, however, also already be provided before the establishing of the named hook connection. 
     After the establishing of the hook connection between the first and second hook members and the coupling of the formwork element with the railing member, the formwork element can be pivoted upwardly into its final position together with the coupled railing member such that the formwork element and the vertical supports then include an angle of approximately 90°. In this process, the pivoting takes place around an axis which extends through the first and second hook members coupled to one another, with a formwork element preferably being hung at two vertical supports such that two first hook members are in engagement with two second hook members on the named pivot procedure. 
     The formwork elements used in accordance with the invention preferably consist of a plurality of longitudinal members extending parallel to one another and at least one cross member extending transversely thereto, with the first hook members being provided at the cross member or being formed by the cross member. In the erected position of the formwork elements, the cross members accordingly extend beneath the longitudinal members, with the cross members and the longitudinal members preferably being rigidly connected to one another to form a grid member. 
     It is particularly advantageous for third hook members, which are coupled or can be coupled to a tensioning member, in particular to a chain, to be able to be hung into the cross members. In this manner, the cross members can be anchored downwardly after the first and second hook members have been hooked together with one another, whereby a lifting of a formwork element from the upper end sections of the vertical supports can be effectively prevented during the pivoting of the formwork elements. This is in particular achieved when the hook connection between the third hook members and the cross members is formed such that it is maintained or is effective when the formwork element and the vertical supports extend parallel or obliquely to one another, when the formwork element and the vertical supports include an angle of approximately 90° and also when the formwork element is pivoted between the aforesaid positions. 
     The third hook members preferably have a force transmitting region whose cross-section is at least substantially circular or partly circular. It can be ensured by the interaction of a force transmission region of this type with a cross beam that the formwork element or the cross member can be pivoted around an axis which substantially extends through the center of the circular or partly circular cross-section of the force transmission region without the position of the third hook member substantially changing. In this manner, it can be achieved that the tensioning member coupled to the third hook member is located in a sufficiently tensioned state during the total pivot procedure. In this process, the center of the cross-section of the force transmission region preferably has a spacing from the pivot axis of the formwork element of less than 2 cm. A sufficiently tensioned state of the tensioning member during the pivot procedure is in particular achieved when the spacing of the center of the cross-section of the force transmission region of the third hook member from the base-side fastening point of the tensioning member coupled to the third hook member only varies by a maximum of 10 mm during the pivoting of the formwork element. 
     It is of advantage for the cross member of the formwork elements to have an at least regionally C-shaped cross-section with two limbs extending away from a base section. One of the limbs in this case forms a support surface for placing on an upper end section of a vertical support, with this upper end section having fixing elements which each engage into a respective recess of the support surface. The limb forming the support surface then simultaneously forms a section of the first hook members in accordance with the invention. A forming of such a cross member with a C-shaped cross-section in this manner advantageously has the result that the third hook members can be hooked to the cross member along its longitudinal direction in almost any desired position thereof so that different erection conditions can be taken into account here. 
     It is particularly preferred for the cross member or for the formwork element to be able to be coupled to the vertical support or supports in two directions offset by 90° with respect to one another. An embodiment of this type is described in the German patent application DE 10 2005 031 152.0 of the applicant. All the features disclosed in this application can also be realized within the framework of the present invention. 
     When coupling the third hook members to the cross members C-shaped in cross-section, the limb of the cross members forming the support surface can be engaged behind by the third hook members. 
     The railing member used in accordance with the invention preferably consists of at least one cross-spar and two supports extending perpendicular thereto which have a respective fastening section at each of their ends remote from the cross-spar for the coupling to a respective longitudinal member of a formwork element. As a rule, a coupling of the supports to the two outermost longitudinal members of a formwork element takes place in this process. 
     A particularly good force transmission between the supports of a railing member and the longitudinal members can be realized in that the fastening sections of the support each engage around a longitudinal member at all sides, with the connection present between the fastening sections and the longitudinal members preferably being made in a releasable manner. 
     The two fastening sections of a railing member can be connected to one another by a latching bar which, in its latched position coupled to a formwork element, supports those longitudinal members which are arranged between the longitudinal members coupled to the fastening sections. In this manner, the latching bar additionally satisfies the function of a cross member arranged beneath the longitudinal members, which is in particular of advantage when a formwork element is only fitted with one cross member, since in this case the latching bar can provide additional stability. 
     It is finally also advantageous for standard formwork elements to have two cross members provided in the end regions of the longitudinal members remote from one another, whereas transverse compensation formwork elements have one or two cross members arranged inwardly offset in comparison with the standard formwork elements. In this case, formwork elements are therefore made available in at least two embodiments differing from one another. If it is then, for example, necessary to provide individual dimensions outside the grid dimensions of the standard formwork elements in a direction extending perpendicular to the longitudinal members, transverse compensation formwork elements are also additionally used. These transverse compensation formwork elements differ from the standard formwork elements in that their cross beams are arranged offset further inwardly. It thereby becomes possible to mesh a standard formwork element and a transverse compensation formwork element with one another such that an outer longitudinal member or also a plurality of outer longitudinal members of a transverse compensation formwork element each come to rest between two adjacent longitudinal members of a standard formwork element. In this manner, individual dimensions can be realized in a transverse direction extending perpendicular to the longitudinal members in that the respectively desired number of longitudinal members of a transverse compensation formwork element is positioned in each case between two adjacent longitudinal members of a standard formwork element. 
     An arrangement of this type is described in the German patent application DE 10 2005 031 153.9 of the applicant. All the features named in this application can also be realized within the framework of the present invention. 
     Further preferred embodiments of the slab formwork system in accordance with the invention and of the method in accordance with the invention for the preparation of a slab formwork system of this type are described herein. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a three-dimensional view of an end section of a cross beam being used within the framework of the invention and being able to be coupled to the upper end section of a vertical support; 
         FIG. 2  is a three-dimensional view of an upper end section of a vertical support, which can be coupled to a cross member in accordance with  FIG. 1 , obliquely from above; 
         FIG. 3  is a three-dimensional view of a cross member in accordance with  FIG. 1 , which is coupled to an upper end section of a vertical support in accordance with  FIG. 2 , obliquely from above; 
         FIGS. 4   a - c  are, in each case, a side view of different method steps on the coupling of a cross member in accordance with  FIG. 1  with an upper end section in accordance with  FIG. 2 ; 
         FIG. 5  is a side view of a region of a slab formwork system in accordance with the invention in two different erection phases; 
         FIG. 6  is a section through a cross beam being used in a slab formwork system in accordance with  FIG. 5  with a third hook member coupled thereto; and 
         FIG. 7  is a three-dimensional view of a formwork element with a railing member coupled thereto. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     The cross member  2  shown in  FIG. 1  is made as an open elongate section element which has a C-shaped section with two limbs extending away from a base section  4 , with the lower limb being designed as a support surface  6  for placing on a head of a vertical support forming the upper end section of a vertical support. The upper limb forms a contact surface  8  for the lower sides of longitudinal members which, for example, extend perpendicular to the cross member  2  so that the named longitudinal members form a formwork or grid element together with the cross member  2 , and optionally further cross members, to which a formwork skin can be applied. Alternatively, the contact surface  8  can also serve directly as a contact surface for a formwork skin. 
     The lower side of the support surface  6  does not extend parallel to the contact surface  8 , but rather obliquely upwardly in the direction of the contact surface  8 . It results in this manner that the thickness of the support surface  6  becomes smaller as the spacing from the base section  4  increases, since the upper side of the support surface  6  facing the contact surface  8  extends, unlike its lower side, parallel to the contact surface  8 . The advantages of this design will be explained in the following in connection with  FIGS. 4   a - c.    
     An upwardly angled lug  10  is shaped on the end of the support surface  6  remote from the base section  4  and extends parallel to the base section  4  in the direction of the contact surface  8 . Alternatively to the named angling, a round transition could also be formed between the support surface  6  and the lug  10  so that e.g. substantially the shape of a quarter-circle is adopted in the cross-section between the support surface  6  and the lug  10 . The lug  10  in the embodiment shown is provided with four V-shaped cut-outs  12 ,  14 ,  16 ,  18  which are spaced apart from one another in the longitudinal direction of the cross member  2 , with the width of these cut-outs  12  to  18  each reducing as the spacing from the contact surface increases. The cut-outs  12  to  18  extend over the total height of the lug  10  and merge in their lower end region into recesses  20 ,  22 ,  24 ,  26  of the support surface  6 . The width of the recesses  20  to  26  in this process corresponds approximately to the width of the V-shaped cut-outs  12  to  18  in their end region facing the recesses  20  to  26 . The recesses  20  to  26  extend into the support surface  6  by less than half the length of the support surface  6 . 
     The cut-outs  12  to  18  can form a “threading aid” for the introduction of fixing elements into the recesses  20  to  26  by the named arrangement of the cut-outs  12  to  18  and of the recesses  20  to  26 , with this threading aid in particular being effective when the cross member  2  is pivoted upwardly by 90° into its position shown in  FIG. 1  after the guiding up to a fixing element. This pivot movement is promoted by the explained oblique orientation of the lower side of the support surface  6 . 
     Only an end region of the cross member  2  is shown in  FIG. 1 . The other end region (not shown) of the cross member  2  is made analogously to the end region shown so that the cross member  2  has four respective cut-outs  12  to  18  and four recesses  20  to  26  in each of its two end regions. The cut-outs  12  and  14  in this process are provided in the outermost end region of the cross member  2  only slightly spaced apart from one another, whereas the spacing between the cut-outs  14  and  16  and the spacing between the cut-outs  16  and  18  is dimensioned larger and in each case corresponds to the spacing from adjacent fixing elements of a head of a vertical support. 
       FIG. 2  shows, in a three-dimensional view, a head  28  which can be coupled to a vertical support (not shown) and then accordingly forms the upper end section of a vertical support. The head  28  in this process is produced from an originally substantially rectangular steel plate which is curved such that a U-shaped curved section  30  is formed in its central region which extends upwardly over the total width of the head  28 . The U-shaped section  30  in this process divides the base surface of the head  28  formed as a support plane  32  into two halves of equal size between one another. With cross members  2  erected at the head  28 , the named support plane  32  absorbs the vertical forces to be transmitted from the cross members  2  onto a vertical support since the support surface  6  of a cross member  2  is ultimately supported on the support plane  32  of the head  28  which will be explained in the following. 
     Spaced apart perpendicularly from the U-shaped section  30 , the support plane  32  has a respective coupling lug  34  which is curved downwardly in U-shape at each of its two end regions remote from one another so that a receiving plane for a head plate (not shown) of a vertical support is defined between the coupling lugs  34  facing one another which extends parallel to the support plane  32 . A head plate of this type can be pushed in the longitudinal direction of the U-shaped section  30  into the coupling lugs  34  until it abuts two abutment members  36  which are made integrally with the U-shaped section and extend downwardly, starting from this, into the named receiving plane for the head plate of the vertical support. 
     A spring member is fastened in the hollow space surrounded by the U-shaped section  30 . The end sections  40  of the spring member are curved in the region of an opening  42  of the U-shaped section  30  and in the region of an end-face end of the U-shaped section  30  such that the spring member is captively held at the head  28 . The spring member  38  is shaped in this process such that a middle section of the same extends downwardly at least up to and into the receiving plane provided for the head plate of a vertical support and formed between the coupling lugs  34  such that the named section of the spring member  38  can snap into an end-face hollow space of a vertical support or of a head plate of a vertical support, whereby the head  28  can be fixed in a defined position with respect to a vertical support. 
     The four corner regions of the support plane  32  are each curved upwardly perpendicular to the support plane  32  so that they form a total of four fixing lugs  44 ,  46 ,  48 ,  50  which each extend at an angle of 45° to the longitudinal direction of the U-shaped section  30 . The width of the fixing lugs  44  to  50  amounts to somewhat more than twice their height, with the two corner regions of the fixing lugs  44  to  50  remote from the support plane  32  in each case being chamfered. Each of the two perpendicular edges  52 ,  54 ;  56 ,  58 ;  60 ,  62 ;  64 ,  66  of the fixing lugs  44  to  50  in this process forms a respective fixing element which is suitable in the sense of the invention for an engagement into a recess  20  to  26  of a cross member  2 . On a coupling of a cross member  2  via one of the fixing lugs  44  to  50 , in each case always only one of the two fixing elements  52  to  66  of a fixing lug  44  to  50  becomes effective. The provision of two fixing elements  52  to  66  per fixing lug  44  to  50  makes it possible selectively to couple a cross member  2  to a fixing lug  44  to  50  in two directions offset to one another by 90° and extending parallel to the support plane  32 . 
     An abutment lug  68 ,  70  curves upwardly out of each of the two halves of the support plane  32 , with each of the two end-face edges extending perpendicular to the support plane  32  of the abutment lugs  68 ,  70  each forming an abutment surface  72 ,  74 ,  76 ,  78  for the rear side of the base section  4  of a cross member  2 . 
     Four further abutment surfaces  80 ,  82 ,  84 ,  86  are formed by regions of the U-shaped section  30  extending perpendicular to the support plane  32 . These abutment surfaces  80  to  86  are also each suitable to cooperate with the rear side of the base section  4  of a cross beam  2 . 
     Specifically, a cross member  2  can be fixed between the following pairs of respective mutually oppositely disposed fixing elements  52  to  66  and abutment surfaces  72  to  86 :  52 ,  80 ;  54 ,  72 ;  56 ,  74 ;  58 ,  82 ;  60 ,  84 ;  62 ,  76 ;  64 ,  78 ;  66 ,  86 . 
       FIG. 3  shows a head plate  88  of a vertical support  90  which is inserted into coupling lugs  34  of a head  28 . A cross member  2  in accordance with  FIG. 1  is coupled to the head  28  and longitudinal members  92  are fastened to its contact surface  8  and extend perpendicular to the cross member  2 . 
     The cross member  2  is coupled to the head  28  such that the fixing element  52  extends into the cut-out  14  and the recess  22  ( FIG. 1 ). At the same time, the fixing element  58  extends into the cut-out  16  and the recess  24  ( FIG. 1 ). The base section  4  of the cross member  2  in this process is supported at its rear side at the abutment surfaces  80  and  82  ( FIG. 2 ) so that ultimately these abutment surfaces  80 ,  82  effectively prevent—together with the fixing elements  52 ,  58 —the cross member  2  from being able to move perpendicular to its base section  4 . The engagement between the fixing elements  52 ,  58  and the recesses  22 ,  24  simultaneously ensures that no movement can take place relative to the head  28  in the longitudinal direction of the cross member  2 . 
     Alternatively, the cross member  2  could also be coupled to the head  28  in a position which is offset in the longitudinal direction of the cross member  2  and in which the fixing elements  52 ,  58  would engage into the cut-outs  16 ,  18  or into the recesses  24 ,  26  corresponding therewith. 
     It would furthermore also be possible only to couple the cross member  2  with the head  28  in that the fixing element  58  is introduced into one of the two cut-outs  12 ,  14  and the recesses  20 ,  22  corresponding therewith. In these cases, the cross member  2  would then no longer extend over the whole support plane  32  of the head  28  as in accordance with  FIG. 3 . It would rather only extend over less than half the width of the support plane  32  so that, for example, a further cross member  2  could be coupled to the head  28  via the fixing element  52  so that both cross members  2  would extend aligned with one another in the longitudinal direction. 
     Finally, a cross member  2  could also be coupled to the head  28  via its cut-outs  12 ,  14  or recesses  20 ,  22  such that it extends perpendicular to its alignment shown in  FIG. 3 . In this case, the fixing element  54  would then engage into one of the recesses  20 ,  22 , with the rear side of the base section  4  of the support being supported at the abutment surface  72  of the abutment lug  68 . 
     It is in particular also possible to couple two or three cross members  2  to the head  28 , with each of the cross members  2  then being able to be fixed between one of the pairs of fixing elements  52  to  66  and abutment surfaces  72  to  86  already named above. The individual cross members  2  can extend parallel or also perpendicular to one another. 
       FIGS. 4   a  to  c  show how a coupling can be established between the cross member  2  and the head  28  as is shown in  FIG. 3 . 
     First, a formwork element  98  comprising cross members  2  and longitudinal members  92  is aligned relative to a vertical support  90  such that the longitudinal members  92  extend either substantially parallel to the vertical support  90  or—as shown in  FIG. 4   a —somewhat obliquely to this alignment. In this alignment, a formwork element  98  can be taken up easily by an erector and raised such that the cross member  2  is ultimately located above a head  28  of the vertical support  90 . Starting from this raised position, the formwork element  98  is then aligned and lowered by the erector such that the fixing elements  52 ,  58  are introduced into the V-shaped cut-outs  14 ,  16  of the lug  10 . This introduction is facilitated by the V shape of the cut-outs  14 ,  16 . In this manner, a hook connection is therefore already established between the head  28  and the cross member  2  in which the weight of the formwork element  98  can be led to a greater part via the support plane  32  into the vertical support  90  such that the person carrying out the erection only has to hold a low part of the weight of the formwork element  98 . In the sense of the invention, the support surface  6  together with the lug  10  forms the first hook members in the named hook connection and the fixing elements  52 ,  58  formed at the fixing lugs  44 ,  46  form the second hook members. 
     Starting from the hook connection in accordance with  FIG. 4   a , the formwork element  98  in accordance with  FIG. 4   b  is now pivoted upwardly in the arrow direction around a pivot axis extending parallel to the longitudinal axis of the cross member  2 , with the fixing elements  52 ,  58 —guided by the V-shaped cut-outs  14 ,  16 —automatically being moved into the recesses  22 ,  24  of the support surface  6  of the cross member  2  during this pivot movement. The named pivot movement is continued for so long until the position in accordance with  FIG. 4   c  is reached in which the formwork element  98  and its longitudinal member  92  extend perpendicular to the vertical support  90  in the horizontal direction. It can be seen particularly illustratively from  FIG. 4   c  that the abutment surfaces  80 ,  82  in this completely erected position effectively prevent the cross member  2  from moving in the arrow direction perpendicular to the base section  4  of the cross member  2  such that the fixing elements  52 ,  58  move out of engagement with the recesses  22 ,  24 . 
     If, within the framework of the dismantling of the formwork element  98 , work is carried out in the reverse order, the slope formed at the lower side of the support surface  6  and which includes an angle of approximately 75° with the base section  4  comes advantageously into effect. It namely becomes possible on the basis of this slope to pivot the formwork element  98  away, starting from the position in accordance with  FIG. 4   c , against the arrow direction of  FIG. 4   b , without a clamping effect occurring between the upper side of the formwork element  98 , a formwork skin lying thereon and an already prepared concrete slab. The slope rather ensures that all parts of the formwork element  98  move downwardly on the pivoting away such that a problem-free removal from the formwork becomes possible. 
     In accordance with the invention, a railing member is coupled to the formwork element comprising cross members  2  and longitudinal members  92  before the pivot procedure described in connection with  FIG. 4   b . This is illustrated in  FIG. 5 . 
     An already completely erected formwork element  100  is supported at the base  102  at its one end region via two vertical supports  90  arranged sequentially perpendicular to the plane of the drawing of  FIG. 5 . The upper end section of the vertical support  90  is made as a head  28  in accordance with  FIG. 2 . A further formwork element  104  is now hung into this head  28  in the already described manner such that the first hook elements  6 ,  10  of the formwork element  104  move into engagement with the second hook members  44 ,  46  of the head  28 . On this hooking together of the formwork element  104  and the head  28 , a railing member  106  can already be coupled to the formwork element  4 . In accordance with  FIG. 5 , the railing member  106  is located in the end region of the formwork element  104  remote from the head  28 . The railing member  106  and the formwork element  104  extend perpendicular to one another in this process. At its lower end, the railing member  106  has two fastening sections  107  which engage around the two outer longitudinal members of the formwork element  104  at all sides. 
     Alternatively, it is also possible only to couple the formwork element  104  with the railing member  106  after the hook connection has been established between the formwork element  104  and the head  28 . 
     Upon establishing the named hook connection, the formwork element  104  extends obliquely to the vertical support  90  analogously to  FIG. 4   a . This position of the formwork element  104  is marked by the letter A in  FIG. 5 . 
     Directly after the establishing of the hook connection between the formwork element  104  and the head  28 , that is, even before an upward pivoting of the formwork element  104 , the third hook member  108  shown in  FIG. 6  is hooked to that cross member  2  which is hung into the head  28  in accordance with  FIG. 5 . The third hook member  108  has a force transmission region  110  which is circular in cross-section and which almost completely fills the space present between the lug  10 , the support surface  6  and the base section  4  of the cross member  2 . The force transmission region  110  is then coupled via a U-shaped member  112  with a lug region  114  in which an eyelet  116  is formed into which a tensioning chain  118  ( FIG. 5 ) can be hung. The free end of the tensioning chain  118  is anchored to the base  102  such that it substantially extends perpendicular to the formwork element  104  located at position A. 
       FIG. 6  illustrates that a pivoting of the cross member  2  in the arrow direction around the center of the force transmission region  110  is possible, without the third hook member  108  substantially being moved, due to the design of the force transmission region  110  substantially circular in cross-section. In this respect, a tensioning of the tensioning chain  118  is also always maintained on a pivoting of the cross member  2 . 
     After it has been ensured by the tensioning chain  118  that the formwork element  104  can no longer release from the head  28 , the formwork element  104  is pivoted upwardly by means of a lifting rod  120  ( FIG. 5 ) around the pivot axis extending perpendicular to the plane of the drawing of  FIG. 6  through the center of the force transmission region  110  until it is in position B. In this pivot procedure, the railing member  106  is moved upwardly together with the formwork element  104  until the formwork element  104  extends horizontally and the railing member  106  extends vertically. 
     Subsequently, the formwork element  104  can be supported at the base side at its end remote from the tensioning chain  118  by means of further vertical supports (not shown). 
     It is thus ensured in accordance with the invention that, directly after the end of the erection of one formwork element  104 , a railing member  106  is also already erected which thus contributes to reducing a risk of falling from the earliest possible time. 
       FIG. 7  shows, in a three-dimensional representation, the manner in which, prior to the pivoting of a formwork element  104 , it can be coupled to a railing member  106 . The formwork element  104  in accordance with  FIG. 7  has a cross member  2  in its end-face end region of its longitudinal members  92 . A further cross member  2  supports the longitudinal members  92  in their central region, whereas the other end-face end of the longitudinal members  92  is made free of a cross member. 
     The railing member  106  coupled with the formwork element  104  consists of two vertical sections  122  which extend parallel to one another and which are connected to one another by a total of four horizontal sections  124 , with these horizontal sections  124  being spaced apart approximately equidistantly. As railing spars, the horizontal sections  124  in this process form the security against falling required in accordance with the invention. 
     At the lower end of the vertical sections  122  facing the formwork element  104 , a respective fastening section  107  is formed via which the railing member  106  can be coupled to the two outermost longitudinal members  92  of the formwork element  104 . 
     The fastening sections  107  each engage around a longitudinal member  92  from above in the manner of a clamp and project at their two limbs downwardly beyond the lower side of the respective longitudinal member  92 . In this projecting region of the limbs, the fastening sections  107  each have a circular opening in each of the two downwardly extending limbs, with a tangent to these openings coinciding with the lower side of the longitudinal member  92 . 
     A latching bar  126  is inserted through the named openings of the fastening sections  107  and its length corresponds approximately to the length of a cross member  2  of the formwork element  104 . The latching bar  126  does not have a circular cross-section. The cross-section can, for example, be oval or substantially circular with a flattened side. What is essential is that the cross-section of the latching bar  126  is larger in one direction than in a direction extending perpendicular thereto. 
     A lever  128  is arranged at an end-face end of the latching bar  126  and the latching bar  126  held in the fastening sections  107  can be rotated around its longitudinal axis by means of it. 
     On the coupling of a railing member  106  with a formwork element  104 , the latching bar  126  is oriented such that its lower cross-sectional dimension is oriented parallel to the vertical sections  122 . In this position, the fastening sections  107  can be threaded via the end-face ends of the longitudinal members  92 . After the railing member  106  has been brought to the desired position along the longitudinal member  92 , the latching bar  126  is rotated by 90° via the lever  128  such that then its larger cross-sectional dimension extends parallel to the vertical sections  122 . In this position, the longitudinal members  92  engaged around by the fastening sections  107  are clamped between the lower end-face end of the respective vertical section  122  and the latching bar  126  such that a relative movement is no longer possible between the railing member  106  and the formwork element  104 . In this rigidly coupled position, the formwork element  104  can be pivoted upwardly in the manner described in connection with  FIG. 5  together with the railing member  106 . 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Summary:
A slab formwork system is disclosed having a plurality of formwork elements which have first hook members at their lower side for establishing a hook connection with second hook members provided at upper end sections of vertical supports. The first and second hook members are designed to establish the hook connection, on the one hand, when the formwork elements and the vertical supports extend parallel or obliquely to one another and such that pivoting of a formwork element is possible, on the other hand, while maintaining the hook connection, into such a position in which the formwork element and the vertical supports include an angle of approximately 90°. The formwork element can be coupled, prior to the pivoting, with a railing member extending substantially perpendicular to the formwork element. A method for the preparation of a slab formwork system of this type is also disclosed.