Abstract:
A framework of a vehicle superstructure, in particular for rail or road bound vehicles for passenger transport, having a side-wall structure containing an inner side facing the interior of the vehicle superstructure and an outer side facing outwards and longitudinal sections ( 1 ) and vertical sections ( 101 ) forming cross-like connecting places, whereby at one, several or all cross-like connecting places made between longitudinal sections ( 1 ) and vertical sections ( 101 ), the longitudinal section ( 1 ) is continuous and crosses behind the vertical section ( 101 ) on the inside at least in part and is releasably attached to the vertical section ( 101 ). For the purpose of releasable connection of the longitudinal section ( 1 ) to the vertical section ( 101 ), the longitudinal section ( 1 ) contains at least one undercut longitudinal groove ( 2 ) which runs in the longitudinal direction and crosses behind the vertical section ( 101 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a framework, in particular a structural frame of a superstructure for a vehicle, in particular for rail or road bound vehicles for passenger transport, having a side-wall structure containing an inner side facing the interior of the vehicle superstructure and an outer side facing outwards and longitudinal sections and vertical sections forming cross-like connecting places. 
     As a rule, the side-wall structures of above mentioned vehicle superstructures are made up of sections that run in the longitudinal and vertical directions and are joined together at their—usually cross-like connecting places by means of welding, bolting or riveting. By longitudinally oriented sections, hereinafter referred to as longitudinal sections, are meant in particular longitudinal profiled rods, parapet sections and strut-shaped sections such as floor struts, base struts, roof and middle struts. By vertically oriented sections, hereinafter referred to as vertical sections are meant in particular profile rods, profile posts such a door posts, vertical columns such as side-wall columns and window posts. The window posts are situated in the region of the window glazing and divide the window front into segments or areas. The door posts serve the purpose of delimiting the sides of the entry openings in the side-wall structure. 
     Superstructures for omnibuses and motor buses of the conventional kind mainly exhibit a structural frame which is flush with its outer contour, onto which outer cladding elements such as aprons and blinds and the glazing of the window areas are mounted. In the present description, by “outer side” is meant lying or arranged towards the outside of the superstructure and by “inner side” is meant lying or arranged towards the inner side of the superstructure. 
     The above mentioned longitudinal and vertical sections in the side-wall structure are structural elements of the vehicle superstructure. They contribute significantly to the rigidity and strength of the superstructure. The requirements made of the mechanical properties of the connecting places or joints between the longitudinal and vertical sections are, therefore, also accordingly high. 
     Conventional side-wall structures contain as a rule roof struts running in the region of the roof, floor struts or base struts running in the region of the floor, and vertical side-wall posts. Further, in order to reinforce the superstructure, the side-wall structures also contain longitudinal sections such as middle-strut sections or parapet sections between the floor struts and the roof struts. 
     The longitudinal and vertical sections of the side-wall structure normally lie flush on the outside in a plane, the so called side-wall plane. The connections between the longitudinal and vertical sections are therefore as a rule cross-like in shape i.e. one section is always interrupted at the connection and lies head on with the un-interrupted crossing section. Both sections are screwed or welded together e.g. by means of corner connecting pieces. 
     In a first known version of side-wall structure the longitudinal sections viz., the roof, central and floor struts at the joints made with the vertical sections, namely the wall columns, are in the form of continuous longitudinal sections which are interrupted only at the openings for the doors. Each of the vertical sections is interrupted at the joining places, and lie head-on in contact with a long side of the longitudinal sections and are screwed or welded to these by means of corner connecting pieces. 
     Also known are side-wall structures in which the vertical sections are continuous and, at the cross-like joints, the longitudinal sections are in the form of interrupted sections. In that case the ends of the lengths of longitudinal sections lie head-on against a long side of the vertical sections and are joined by screwing or welding to them with the aid of corner connecting pieces. 
     Further side-wall structures are known in which both the longitudinal and vertical sections are continuous at the cross-like joints, whereby in that version the vertical sections run behind the longitudinal sections on the inside. That side-wall structure, however, does not form a flush plane on the outside and if repairs are necessary, the vertical sections have to be dismantled from their crossed position at the back—a complicated, expensive process. It has also been found that such side-wall structures have excessively thick walls which, for legal reasons regarding maximum overall vehicle width and minimum interior width of vehicle, are difficult to realise. 
     Also known are side-wall structures in which cross-like connections are made between longitudinal and vertical sections, both of which are continuous and feature interruptions in the form of machined-out recesses. These recesses, however, require additional fabrication steps and therefore complicate the production process. 
     The object of the present invention is to provide a vehicle construction having a side-wall structure that is characterised by way of good strength and rigidity, great ease of assembly and repair, and large freedom in design. 
     SUMMARY OF THE INVENTION 
     The foregoing object is achieved by way of the invention in that, at one several or all cross-like connecting places between longitudinal and vertical sections, the longitudinal section is continuous and the longitudinal section crosses behind the vertical section on the inside at least in part and is releasably attached to the vertical section and, for the purpose of releasable connection of the longitudinal section to the vertical section, the longitudinal section contains at least one undercut longitudinal groove. 
     In the present description “cross-like” means that both sections cross at an angle which is preferably but not essentially 90° or about 90° (degrees of angle). The sections may also cross each other at an angle (smaller angle) e.g. of 45°-90°. It is self explanatory that the vertical sections in this context need not be, but are preferably, vertical to the horizontal, and the longitudinal sections need not be, but are preferably, horizontal. The vertical sections may e.g. arranged away from the vertical by an angle of up to 45°, and the longitudinal sections may likewise be arranged away from the horizontal by an angle of up to 45°. 
     In the present description “crossing at the back” means that the section in question runs without interruption i.e. continuously behind the other section it crosses. 
     The longitudinal section or sections preferably contain one, two or more parallel undercut longitudinal grooves or C-shaped undercut grooves situated on the outside and running in the longitudinal direction of the section, whereby the undercut groove or the vertical section or sections cross at the back at the cross-like connecting places and rest against the inner face of the vertical section or sections. The mentioned longitudinal grooves serve the purpose of releasable connection to the vertical section. If two or more of the longitudinal grooves are foreseen in the longitudinal section, then it is possible to achieve higher strength and rigidity in the joint. In the present description “longitudinal” grooves means grooves running in the longitudinal direction of the section and advantageously running parallel to its sides. 
     At the said cross-like connecting place the longitudinal section and the vertical section are joined together, preferably by means of one or more screw-type connections, whereby the screw-type connection comprises a screw which passes through the vertical section or a connecting element and engages the threaded hole in an insert introduced into the undercut longitudinal groove of a longitudinal section. When the screw has been tightened, the insert engages in a clamping manner behind the undercut groove thereby fixing the vertical section to the longitudinal section. 
     In this version—and in all of the following versions and further developments thereof according to the invention which employ the above mentioned insert—the insert is advantageously in the form of a parallelogram-shaped plate or clamping piece that can be rotated in the undercut longitudinal groove of the longitudinal section. Further, the insert may exhibit one or more threaded holes to accommodate one or more screws. The insert may also be in the form of a strip, in particular a prism-shaped strip, which can be introduced sideways into the undercut groove. The insert strip exhibits one, preferably two or more holes, preferably threaded holes, to accommodate one, preferably two or more screw-type connections. The insert strip may e.g. be dimensioned and arranged such that it crosses the vertical sections at the rear and accommodates the screw-type connections at both sides of the vertical section. 
     In a particular design of the invention the vertical section crosses the longitudinal section without interruption, whereby in that case the longitudinal section crosses the back of the vertical section completely. The vertical section, however, may be interrupted at the cross-like connection and its end face may abut the longitudinal section in a cross-like manner. Whereby the vertical section crosses the longitudinal section at least partly i.e. the longitudinal section crosses behind the vertical section at least partly and with at least one undercut longitudinal groove. 
     In a preferred version the longitudinal section contains at least two outer side faces that run parallel to the side wall plane and are displaced with respect to each other vertical to the side-wall plane by a step running in the longitudinal direction of the section, whereby the side-face or side-faces displaced towards the interior of the vehicle body contains or contain at least one undercut longitudinal groove and crosses or cross behind the vertical section and, the side-face displaced towards the outer side of the vehicle lies flush with the outer side-face of the vertical section. The side-wall plane is thereby defined by the common aligned side-faces of the vertical sections. 
     In a particular further development of the invention one, and preferably both transverse side-faces of the vertical section running transverse, in particular perpendicular, to the side-wall plane may contain one. Two or more undercut longitudinal grooves. In this further development of the invention, the vertical sections may be connected to the crossing longitudinal section via known corner connecting elements. The attachment is made using screw type connections, whereby screws pass through the corner connecting element and engage in the threaded hole in the inserts which are introduced into the undercut longitudinal grooves in both the longitudinal section and in the vertical section. When the screw type connection is screwed tight, the inserts engage in the undercut longitudinal groove in a clamping manner thus fixing the vertical section via the corner connecting element to the longitudinal section. In this version the corner connecting element is oriented transverse, in particular perpendicular to the side-wall plane. 
     The corner connecting element may be in the form of a corner piece or angle piece. The corner piece may be a casting, welded part, forging or machined part. The corner connecting element may also be in the form of a sliding part which can be introduced sideways into the undercut groove, whereby the corner connecting element engages the undercut groove such that the corner element is fixed or anchored in the axis lying transverse to direction in which it was introduced and running through the longitudinal opening. 
     Examples of the above mentioned corner connections—which with respect to their mode of function can be used in the present invention—are described in the patent publications EP 0 136 264 A2, EP 0 671 566 B1 and EP 0 806 338 B1 to which reference is expressly made here. 
     The longitudinal and vertical sections are e.g. sections manufactured by an extrusion or pulltrusion process. The longitudinal and vertical sections are preferably made of metal such as iron or steel and in particular of a light weight metal such as aluminium and its alloys. Particularly suitable are extruded sections of a light weight metal, in particular aluminium or an aluminium alloy. Further, the sections may be made of shaped sheets. 
     The above mentioned sections may also be made of plastic, in particular fibre-reinforced plastic. Further, the sections may also be hybrid sections made up of longitudinal assembled, in particular adhesively bonded section parts, whereby a first section part is of metal, in particular aluminium and its alloys, and a second section part of fibre-reinforced, in particular fibre-glass or carbon fibre reinforced plastic. 
     The longitudinal and vertical sections may be open sections such as angle-shaped sections or channel-shaped sections, half open sections or closed sections such a single or multi-chamber sections. 
     The above mentioned vertical sections are in particular side-wall or window post sections and door posts. The longitudinal sections are sections that run longitudinally and form an upper and lower closure for the side-wall structure, such as roof struts or floor struts or base struts. Further, the longitudinal sections may also be longitudinal sections in the side-wall structure, such as central struts or parapet struts. 
     The strut sections, in particular the roof and floor strut sections, are preferably continuous i.e. uninterrupted over the whole length of the superstructure or vehicle length. The above mentioned strut sections, in particular the middle strut sections, may, however, in some cases be interrupted by one or more openings in the side wall structure for doors. In these cases the strut sections are at least continuous between the door openings. 
     The strut sections may contain places for connection purposes, in particular in the form of undercut longitudinal grooves for attaching interior elements such as lighting fittings, cables, pipes, air channels, covers, or for attaching seat frames or vehicle components. Further, the roof, floor or base struts may contain line-shaped connecting places for securing roof or floor structures. 
     Along their length, the strut sections preferably exhibit a uniform cross-section, especially over their places of connection. When installed, the strut sections preferably feature no machined areas or the like at the places where they cross and are joined to the vertical sections. 
     In a further development of the invention the roof and/or floor or base sections may be in the form of longitudinal sections which are angle-like in cross-section or as longitudinal sections with two flanges that are at an angle to each other, in particular a right angle. In that case one flange is preferably vertical and a second flange horizontal, whereby on the outside both section flanges preferably form a recess—preferably right angled recess—to accommodate the end part of one or more vertical sections. In a highly preferred further development of the invention the above mentioned angle shaped longitudinal section forms an outer side face which lies flush with the outer side face of the vertical section or sections. The above mentioned side face lies usefully on the horizontal section flange. 
     The cross-like connection places according to the invention lie to advantage between the parapet struts and the side-wall or window columns, between the roof struts and the window columns or door posts and between the floor struts and the side-wall columns or door posts. 
     In a preferred version of the invention the side-wall structure contains section struts in the form of a floor or base strut, a middle or parapet strut and a roof strut. Side-wall columns and window columns, and door posts, are provided transverse to these strut sections. The cross-like connection between the middle and parapet strut and the side-wall columns or window columns is characterised by way of the fact that the middle or parapet struts exhibits at least one, two or more undercut longitudinal grooves and is in the form of a continuous longitudinal section which is interrupted only by openings for doors. The middle or parapet strut crosses behind the side-wall or window columns, at least in part or completely, whereby at least one, two or more undercut longitudinal grooves cross behind the side-wall or window columns. The middle or parapet strut is to advantage in the form of a flat section i.e. the breadth of the section is at least twice the thickness of the section. Further, the middle or parapet section may be a T-shaped hollow section with a central elevated part and flanges featuring longitudinal grooves on both sides. 
     The side-wall and window columns may be in the form of vertical sections that are continuous or uninterrupted in the are of the above mentioned connecting places, whereby in the first case the middle or parapet strut crosses completely behind the side-wall or window column and in the second case partially cross behind the said columns. 
     If both the vertical sections and the longitudinal sections crossing behind the vertical sections at the cross-like joints are continuous, then the longitudinal sections are arranged such that their outer longitudinal side is displaced to the inside, as a result of which their is no common, flush outer face. For that reason profile-like attachment elements are to advantage mounted on the outer side face of the longitudinal section or sections. The main purpose of these is to provide a common, flush area on the side-wall structure. These attachment elements are dimensioned in height such that their outer face lies flush with that of the vertical sections. The said attachment elements are e.g. always arranged lying between two vertical struts. The attachment elements are employed in particular at the middle or parapet struts and if necessary at roof or floor or base struts. The attachment elements may also contribute to stiffening the longitudinal sections. 
     The attachment element is usefully attached to the longitudinal section by means of screws, whereby the screws engage in the threaded holes in inserts which are introduced into one or more parallel, undercut longitudinal grooves in the longitudinal section. The attachment element may, however, also be attached to the longitudinal section using other attachment methods such as welding, riveting, push-fit or adhesive bonding. In another version of the invention the attachment element may at the same time be a corner element joining the longitudinal section to the vertical section. 
     In a particular version of the invention the profile-like attachment element contains places for connection, in particular groove-shaped connecting places, to accommodate outer cladding elements, in particular for attaching panel-shaped elements or rubber seals for holding the panel-shaped elements and/or covering elements. The mentioned connecting places may be in the form of grooves, in particular undercut grooves, which are suitable to accommodate the said attachment elements by insertion or push-fit. Further, the attachment element may exhibit connecting places for mechanical shape-dependent connections such as clip-type or push-fit connections. 
     The profile-like attachment element is to advantage made of metal such as iron or steel and in particular of a light metal such as aluminium and its alloys. Especially suitable are extruded sections of a light metal, in particular of aluminium or an aluminium alloy. The profile-like built-on element may, however, be made of plastic, in particular a fibre-reinforced plastic such as a glass-fibre or carbon-fibre reinforced plastic. 
     The attachment element may be made from a solid section, open section, semi-hollow or closed section such as a single or multi-chamber hollow section. 
     Vehicle superstructures according to the invention find application in particular in buses such as omnibuses and e.g. low-floor buses. The vehicle superstructure is suitable both for long distance buses such as tour buses and for town buses e.g. for public transportation in towns. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following the invention is explained in greater detail by way of examples and by reference to the accompanying drawings viz., 
     FIG. 1 a : Cross-section through a connection between a vertical post and a roof strut along the line B—B of a side-wall structure shown in figure 1 b;    
     FIG. 1 b : Side view of a connection between a vertical post and a roof strut; 
     FIG. 2 a : Cross-section, through a connection between a vertical post and a middle strut, along line C—C of a side-wall structure according to the invention as shown in FIG. 2 b;    
     FIG. 2 b : Side view of a connection between a vertical post and a middle strut; 
     FIG. 3 a : Cross-section through a connection between a vertical post and a floor strut or base strut, along line D—D of a side-wall structure according to the invention as shown in FIG. 3 b;    
     FIG. 3 b : Side view of a connection between a vertical post and a floor strut or base strut; 
     FIG.  4 : By way of example a cross-section through a vertical section along line A—A as shown in FIGS. 1,  2  and  3 ; 
     FIG. 5 a : Cross-section through a connection between a vertical post and a roof strut along line F—F of a further side-wall structure according to the invention as shown in FIG. 5 b;    
     FIG. 5 b : Side view of a connection between a vertical post and a roof strut; 
     FIG. 6 a : Cross-section through a connection between a vertical post and a middle strut along line G—G of a further side-wall structure according to the invention as shown in FIG. 6 b;    
     FIG. 6 b : Side view of a connection between a vertical post and a middle strut; 
     FIG. 7 a : Cross-section through a connection between a vertical post and a floor strut or base strut along line H—H of a further structure according to the invention as shown in FIG. 6 b;    
     FIG. 7 b : Side view of a connection between a vertical post and a floor strut or base strut; 
     FIG.  8 : By way of example, a cross-section of a vertical post along line E—E as shown in FIGS. 5,  6  and  7 ; 
     FIG. 9 a : View of an insert; 
     FIG. 9 b : Side view of an insert; 
     FIG.  10 : Cross-section through a example of a screw-type joint made using an insert; 
     FIG.  11 : Perspective view of a connection between a vertical section and a longitudinal section using corner joining elements. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 a ,  2   a ,  3   a ,  5   a ,  6   a  and  7   a  show, in cross-section, parts of the side-wall structure according to the invention, whereby the cross-sectional plane is perpendicular to the side-wall plane. In each case numeral I indicates the outer side of the vehicle superstructure while numeral II indicates the inner side of the vehicle superstructure. FIGS. 1 b ,  2   b ,  3   b ,  5   b ,  6   b  and  7   b  respectively show the related parts of the side-wall structure according to the invention in side view, whereby the side view in each case is from outside the side-wall towards the interior. 
     In order to provide an overview, the screw type connections shown in FIGS. 1,  2 ,  3 ,  5 ,  6 , and  7  and described in the following are only shown schematically. 
     FIGS. 1 a  and  1   b  show the joint made between a vertical post  101  and a roof strut  1  in a first version according to the invention. The roof strut  1  contains two undercut longitudinal grooves  2  on the outside that run parallel to each other, with which the roof strut  1  crosses behind the vertical post  101 . The longitudinal grooves  2  lie against the inner side face of the vertical post  101 . The vertical post  101  is in the form of a section with two flanges  102  at the sides (see FIG.  4  and the related description thereof), whereby the vertical post  101  is attached to the roof strut  1  by means of screw type connections  3   a,c . The vertical section  101  is attached to the roof strut  1  at the longitudinal groove  2  at the lower end via attachment elements  14 . Each of the attachment elements  14  runs between two vertical posts  101  and is attached to the roof strut  1  by means of screw connections  3   b . The outer side face of the attachment element  14  and the vertical post  101  are flush, forming a common plane. 
     The above mentioned screw connections  3   a,b,c  contain the attachment elements  14  and/or the screws that penetrate the section flanges  102  and are screwed into the threaded holes in the inserts  121  introduced into the longitudinal grooves  2  (compare FIGS. 9 and 10 along with the related description). 
     The side-wall region according to FIG. 1 a  contains on the outside towards the roof cladding elements  125  and panel elements  123  which are attached to the outer wall via attachment elements  14 . 
     FIGS. 2 a  and  2   b  show the connections made between the vertical post  101  and a middle strut  11  according to a first exemplified embodiment of the invention. The middle strut  11  contains two outer, peripheral, undercut longitudinal grooves  12  and crosses behind the vertical post  101  completely. The longitudinal grooves  12  lie against the inner side face of the vertical post  101 . The vertical post  101  is in the form of section featuring two side flanges  102  (see FIG.  4  and the related description). The vertical post is secured to the middle strut  11  via attachment elements  14  by means of screw connections  13   a.    
     Each of the attachment elements  14  runs between two vertical posts  101  and are attached to the middle strut  11  by means of screw connections  3   b . The outer side faces of the attachment elements  14  and the vertical post  101  lie flush on a common plane. 
     The screw connections  13   a,b  contain the attachment elements  14  or the screws penetrate the attachment elements  14  and section flanges  102  and are screwed into the threaded holes in the inserts  121  introduced into the longitudinal grooves  12  (see FIGS. 9,  10  and the related description). 
     The side-wall element shown in FIG. 2 contains on the outside panel elements  123  which extend over the upper side-wall area and terminate in the region of the middle strut  11  and are detached from the subsequent cladding elements  124 . The panels  123  and cladding elements  124  are attached to the outer wall via attachment elements  14 . 
     FIGS. 3 a  and  3   b  show the connections made between a vertical post  101  and a floor strut  21  according to a first exemplified embodiment of the invention. The floor strut  21  contains two outer, peripheral undercut longitudinal grooves  22  and crosses behind the vertical post  101 . The longitudinal grooves  22  lie against the inner face of the vertical post  101 . The vertical post  101  is in the form of a section exhibiting two side flanges  102  (see FIG.  4  and the related description). The vertical post  101  is attached to the floor strut  21  via screw connections  23  penetrating the section flanges  102 . 
     The vertical post  101  may also be attached to the floor strut via attachment elements, in a manner analogous to that shown in FIGS. 1 and 2. Reciprocally, the vertical sections shown in FIGS. 1 and 2 may be attached directly to the longitudinal section via their flanges  102  analogous to that shown in FIG.  3 . 
     The screw connections  23  contain the screws that penetrate the section flanges  102  and are screwed into the threaded holes in the inserts  121  introduced into the longitudinal grooves  22  (see FIGS. 9 and 10 and the related description). 
     The side-wall region as shown in FIG. 3 a  contains cladding elements  124  on the outside. The cladding elements may be attached to the outer wall via attachment elements. 
     The vertical post  101  may, as shown in FIG. 4, be in the form of a hollow section or an open section such as a hat-shaped or omega-shaped section. The vertical section contains, preferably two, side flanges or longitudinal strips  102  that lie in the same plane. The flanges  102  are e.g. in the form of an extension of the inner side face of the section and lie parallel to the side-wall plane. The vertical post  101  is e.g. made from an aluminium extrusion or from bent sheet material. 
     Another version of the vertical post  111  is shown in FIG. 8 as a hollow section, whereby each of its transverse faces, lying transverse to the side-wall plane, contains an undercut groove  112 . 
     FIGS. 5 a  and  5   b  show the connection made between a vertical post  111  and a roof strut  31  according to a second exemplified embodiment of the invention. The roof strut  31  contains a first, preferably extended flange  37   a , which has its outer side face  39   a  arranged vertical or parallel to the vertical post  111 . A second, preferably shortened, flange  37   b  is arranged on the outside, its side face  39   b  facing the vertical post  111  arranged horizontal or perpendicular to the vertical post  111 , i.e. parallel to the end face of the vertical post  111 , whereby the angular recess is formed by the two flanges  37   a ,  37   b  to accommodate the vertical post or posts  111 . The roof strut  31  contains two peripheral longitudinal undercut grooves  32  in the outer face  39   a . The roof strut  31  also contains an undercut longitudinal groove  34  in the face  39   b  of the second flange  37   b  facing the vertical post  111 . 
     The first flange  37   a  crosses behind the vertical post  111  completely. The face  39   a  with its longitudinal grooves  32  lies against the inner face of the vertical post  111  and face  39   b  with its longitudinal groove  34  lies against the end face of the vertical post  111 . 
     The vertical post  111  is in the form of a hollow section (see FIG.  8  and the related description) and contains an undercut groove  112  on each of its transverse faces running transverse to the side-wall plane. 
     The vertical post  111  is attached to the roof strut  31  by means of screw connections  33   a ,  33   b  containing corner joining elements  36   a ,  36   b . In the region of the connection towards the floor screw connections  33   a  are provided on both sides of the vertical post section  111 . The related corner joining elements  36   a  are fixed in the longitudinal groove  32  of the first flange  37   a  and in the longitudinal groove  112  of the vertical post  111 . The attachment is made by means of screws which penetrate the corner joining element  36   a  and are screwed into the threaded hole in inserts  121  introduced into the longitudinal grooves  32 ,  112 . (see FIG.  11  and the related description). 
     In the region of the connection towards the roof screw connections  33   b  are provided on both sides of the vertical post section  111 . The related corner joining elements  36   b  are fixed both in the longitudinal grooves  32 ,  112  of the first flange  37   a  and the vertical post  111  and in the longitudinal groove  34  of second flange  37   b . The attachment is made by means of screws which penetrate the corner joining element  36   b  and are screwed into the threaded hole in inserts  121  introduced into the longitudinal grooves  32 ,  112 ,  34 . 
     The two corner joining elements  36   b  towards the roof may, however, also simply be anchored in the longitudinal grooves  32 ,  112  of the first flange  37   a  and the vertical post  111 . 
     The roof struts  31  may also contain further undercut longitudinal grooves  35  on the inside for securing other structures. 
     The side-wall region as shown in FIG. 5 a  contains on the outside towards the roof panel-like elements  123  which are attached to the outer wall. 
     FIGS. 6 a  and  6   b  show the connection made between a vertical post  111  and a middle strut  41  according to an exemplified embodiment of the invention. The middle strut  41  is T-shaped and contains a central, raised box-shaped part  44  and two flanges  45   a  and  45   b  at the sides with outer side face displaced towards the interior of the carriage structure. The middle strut  41  forms a uniformly flush inner side face. 
     The outer side face of the raised part  44  and the vertical post  111  are flush with each other. An undercut longitudinal groove  42  is provided on the outer faces of each of the flanges  45   a ,  45   b.    
     The vertical post  111  is divided into two profile parts  111   a ,  111   b , whereby the central raised part  44  of the middle strut  41  passes between the two parts  111   a ,  111   b  and the end faces of both parts  111   a ,  111   b  abut sideways on the central raised part  44 . The middle strut  41 , with both flanges  45   a ,  45   b  and the related longitudinal grooves  42 , passes behind the inner side face of both parts  111   a ,  111   b , as a result of which the longitudinal grooves  42  come to rest against the inner side face of the parts  111   a ,  111   b.    
     The vertical post  111  or the profile parts  111   a ,  111   b  are in the form of hollow sections (see FIG.  8  and the related description) and contain an undercut longitudinal groove  112  on each of the two faces running transverse to the side-wall plane. 
     The profile parts  111   a ,  111   b  are attached to the middle strut  41  by means of screw connections  43  containing corner joining elements  46 . The corner joining elements  46  on both sides of the parts  111   a ,  111   b  are in each case fixed, both in a longitudinal groove  42 ,  112  of a flange  45   a ,  45   b  and the part  111   a ,  111   b  and in the longitudinal groove  47  in the central raised part  44 . The attachment is made via screws that penetrate the corner joining element  46  and are screwed into the threaded holes in the inserts  121  introduced into the longitudinal grooves  42 ,  112 ,  47 . 
     FIGS. 7 a  and  7   b  show connection made between a vertical post  111  and a floor strut  51  according to a second embodiment of the invention. The floor strut  51  contains a first, preferably extended flange  57   a  which has its outer side face  59   a  arranged vertical or parallel to the vertical post  111 . A second, preferably shorter flange  57   b  on the outside with its side face  59   b  facing the vertical post ill is arranged horizontal or perpendicular to the vertical post  111 , whereby the recesses formed by the two flanges  57   a ,  57   b  is provided to accommodate the vertical post or posts  111 . The floor strut  51  contains a longitudinal groove  52  in the outer face  59   a  of the first flange  57   a  in the region of the connection towards the roof and, with the outer side face  59   a  crosses behind the vertical post  111  completely. The floor strut  51  also contains an undercut longitudinal groove  54  provided in the side face  59   b  of the second flange  57   b.    
     The side face  59   a , has a longitudinal groove  52  on the inner side face of the vertical post  111  and the floor strut has a longitudinal groove  54  on the end face of the vertical post  111 . The vertical post  111  is in the form of a hollow section (see FIG.  8  and the related description) and contains an undercut longitudinal groove  112  on each of its two transverse faces running transverse to the side-wall plane. 
     The vertical post  111  is attached to the floor strut  51  by means of screw connections  53   a ,  53   b  containing corner joining elements  56   a ,  56   b . Screw connections  53   a ,  53   b  are provided on both sides of the vertical post  111  in the region of the connection towards the roof. The related corner joining elements  56   a  are fixed in the longitudinal groove  52  of the first flange  57   a  and in the longitudinal groove  112  of the vertical post  111 . The attachment is made by the screws which penetrate the corner joining element  56   a  and are screwed into the threaded holes in the inserts  121  introduced into longitudinal grooves  52 ,  112  (see FIG.  11  and the related description). 
     Screw connections  53   b  are provided in the region of the connection towards the floor. The related corner joining elements  56   b  are fixed in the longitudinal groove  112  of the vertical post  111  and the longitudinal groove  54  of the second flange  57   b . The attachment is in each case made via screws which penetrate the corner joining element  56   b  and are screwed into the threaded holes in the inserts  121  introduced into the longitudinal grooves  112 ,  54 . The corner joining element  56   b  is therefore in this case arranged in a plane parallel to the side-wall plane. 
     If the first flange  57   a  does contain a second undercut longitudinal groove (not shown) in the region of the connection towards the floor and parallel to the longitudinal groove  52 , then the corner joining elements  56   b  may be anchored in the longitudinal grooves  54 ,  112  of the second flange  57   b  and the vertical post  112  as well as in the additional second longitudinal groove. 
     The above mentioned screw connections  53  contain the screws that penetrate the corner connecting element  56  and are screwed into the threaded hole in the inserts  121  introduced into the undercut longitudinal grooves  52 ,  54 ,  112 . 
     In a preferred version the crossing connection of the longitudinal and vertical sections in the roof region, middle region and in the floor region of the side-wall structure is made in accordance with FIGS. 1,  2  and  3  and the related description. In a further preferred version the crossing connection of the longitudinal and vertical sections in the roof region, middle region and in the floor region of the side-wall structure is made in accordance with FIGS. 4,  5  and  6  and the related description. The side-wall structure may, however, also contain only one or more of the individual section crossing arrangements or connections between sections shown in FIGS. 1-6. 
     FIGS. 9 a  and  9   b  show a preferred version of the insert  121  of a screw connection according to the examples shown in FIGS. 1,  2 ,  3 ,  5 ,  6  and  7  in plan view (FIG. 9 a ) and in cross-section (FIG. 9 b ). The insert  121  is in the form of a parallelo-gramm-shaped platelet with a central threaded hole  122 . In order to make the screw connection, the screw  134 , which penetrates the first joining part  131  i.e. the vertical post or a connecting element, is screwed into the threaded hole  122  in the insert  121 . The long side of the insert  121  is introduced into the undercut groove  133  in the second joining part  132 , i.e. the longitudinal or strut section. By screwing further, the short side of the insert  121  that has been put into place rotates into the undercut part of the longitudinal groove  133 . The screw  134  can then be rotated further into the threaded hole  122  in the insert  121  which is now anchored firmly in the longitudinal groove  133 , thus forming a secure connection (FIG.  10 ). 
     FIG. 11 shows by way of example the manner of joining a vertical post and longitudinal section using a corner joining element such e.g. as is illustrated in FIGS. 5 and 7 with screw connections  33   a ,  53   a . The vertical post  140  is crossed completely at the back by a longitudinal section  141  with undercut longitudinal groove  142 . The vertical post  140  contains an undercut longitudinal groove  143  in each of the side faces lying transverse to the side-wall plane. A corner joining element  146  lies with one side face against the outer side face of the longitudinal section  141  and one side face against the transverse face of the vertical post  140 . Screws pass through the corner joining element  146  and the inserts in both longitudinal grooves  142 ,  143  thus joining the vertical post  140  to the longitudinal section  141 .