in the vehicle body construction 1 according to fig1 - 22 there are connected together , by bolting and / or welding , sectional bars 2 , roof longitudinals 3 , central longitudinals 4 serving as wall cladding , intermediate pieces 5 , as well as corner connecting pieces 6 , 6a arranged for reinforcement at particularly loaded points . as can be seen with reference to fig3 - 10 and 12 - 21 , the components 2 , 6 and 6a are provided with grooves 7 and / or ribs 8 , respectively , by which these components are guided in the longitudinal direction of the vehicle body 1 . the grooves 7 and ribs 8 are provided on the sides thereof with obliquely inclined surfaces 9 and 10 respectively , which abut together . furthermore , as can be seen in fig7 , 9 , 10 , 12 and 22 , the grooves 7 have undercuts 11 on each side thereof , adapted to receive a component of clamping piece 12 , for providing a bolted connection as shown in fig9 between components 2 and 6 as can be seen particularly from fig1 . each of the clamping pieces 12 are provided with a threaded bore 14 for reception of a bolt 13 which secures the components together . for producing the clamping bolted connection between a corner connecting piece 6 and a sectional bar 2 , a bolt 13 is inserted , for example through a bore 15 in the corner connecting piece 6 provided with a rib 8 , and thereupon a clamping piece 12 is threaded onto each bolt 13 , introduced in its longitudinal direction into the groove 7 in sectional bar 2 , and swung into the undercuts 11 of the groove 7 by rotation of the bolt 13 in a clockwise direction . by further tightening of the bolt 13 , the corner connecting piece 6 is firmly clamped to the sectional bar 2 while the obliquely inclined surfaces 9 and 10 of the groove 7 and of the rib 8 , respectively , engage firmly together . in connection with the assembly of the vehicle , it should particularly be noted that all the parts of the vehicle body 1 provided with ribs 8 have bores 15 for the production of a clamping bolt connection through which a bolt 13 can be inserted . the corner connecting piece 6a shown in fig1 to 16 , is used for a welded connection with another vehicle component and is provided with a pair of tongues 8 &# 39 ; which extend from each rib 8 beyond the ends of the corner connecting pieces 6a . the tongues guide the corner connecting piece 6a in the grooves 7 in an improved manner . the height of the tongues 8 &# 39 ; is greater than the height of the ribs 8 so that when they are inserted in the grooves 7 of the sectional bar 2 ( see fig1 and 19 ), the tongues 8 &# 39 ; lie with an edge in close proximity to the surface of the web 16 running in the longitudinal direction of the sectional bar 2 . with reference to fig1 , 18 , 19 and 21 , the assembly of welded connections between the components 6a having ribs 8 and the components 2 having grooves 7 and webs 16 is accomplished by inserting ribs 8 in the grooves 7 as best seen in fig1 . the ribs 8 extend over the length of the groove 7 and lie at a predetermined spacing 17 ( fig1 ) from a surface 18 on the part having the grooves 7 , the spacing 17 corresponds approximately to the height of the tongues 8 &# 39 ;. in order to weld the components 6a having ribs 8 in an advantageous manner to the components 2 having grooves 7 , bevels 19 , see fig1 , 15 , 16 , are provided on the components 6a . these bevels enable a weld run 20 to be applied to the side surface of these bevels 19 on the component 6 on one hand and to the groove 7 on component 2 on the other hand . the tongues 8 &# 39 ; extending beyond the two ends of the corner connecting pieces 6a are provided with a gap 21 between them extending in the longitudinal direction , for facilitating the formation of a welded connection . as can be seen in fig1 a weld run 22 is arranged , by which the tongues 8 &# 39 ; of the corner connecting piece 6a are connected with the web 16 of the component 2 having the groove 7 . the roof according to fig1 and 20 is characterized essentially by a high longitudinally extending roof longitudinal 3 in the form of a hollow section , which at the same time serves as outer skin . in the neighborhood of the roof arches 23 and the window pillars 24 , the open section of the roof longitudinal 3 is stiffened by struts 25 , in order to ensure a satisfactory load distribution . the roof longitudinals 3 , arranged on each side of the vehicle body , are connected in any known manner to the roof arches 23 . in the side wall region , the roof longitudinal 3 has a connecting portion 26 for connecting the roof 3 to the window pillars 24 . the hollow section advantageously offers the possibility of installing cables and insulation in the roof as well as providing an air passage . by thermal insulating the roof longitudinals 3 of the roof , as well as by employment of insulating roof arches 23 and struts 25 , the formation of condensed water is totally avoided . the roof can be prefabricated as a whole complete with internal finish . the window portion is so formed that the insertion of glazing can take place , whether by means of adhesive or by means of clamping rubber sections . the window pillars 24 consist of rectangular sections with lateral connecting parts . with glazing secured with adhesive , which for example permits the production of a totally smooth external contour , the window column covering and the retention of the internal skin takes place through a unitary clamping section known per se , not shown , which is applied to the connecting parts of the roof longitudinal 3 , of the window pillars 24 , and of the side wall section 4 . with glazing clamped in a further known manner by means of rubber section , the column covering and the retention of the inner skin takes place by this same glazing retaining section . the side wall is constituted essentially of a high , longitudinally extending , central longitudinal or side wall cladding section 4 open to the interior , which at the same time serves as external skin and collision protection for passengers . in the neighborhood of securing columns or window pillars 24 , the side wall section 4 is stiffened by struts 28 , in order to ensure a satisfactory distribution of load . the vertical position of the side wall section 4 is advantageously so chosen that it does not require to be cut away over the wheel arches . furthermore , by the side wall section 4 preferably extending over the entire length of the vehicle , the possibility was further provided of arranging the window sub - division independently of the distribution of cross beams on the chassis . the connection of the chassis to the side wall section 4 takes place by means of mounting columns 27 , which are connected to the side wall section 4 in the previously described manner according to the invention , with the help of the corner connecting piece 6 or 6a . the lower side wall portion consists externally on the one hand of an easily assembled and dismounted longitudinally extending cladding section 28 , and on the other hand of simple covers 29 , which can be used over the entire length of the bus . the cladding section 28 is connected in the usual way at its upper part with the connecting part of the side wall section 4 , or as the case may be snapped into the latter or inserted , and was riveted or bolted at the lower part to the mounting columns 27 and an intermediate section 5 . the lower part of the cladding section 28 is at the same time so shaped that it can receive one part of a rubber hinge 31 . the covers 29 consist of simply folded aluminum sandwich sheets , the upper edges of which are gripped in a reinforcing section 30 , which at the same time receives a part of the rubber hinge 31 . on the inside of the mounting columns 27 as well as the intermediate section 5 , there is fastened a floor longitudinal section 32 with the help of fastening members known per se , which receives the floor and at the same time provides a fastening possibility for the seats , which are not shown further . by the employment of for example cladding sections 28 of three different heights , as well as by a variable assembly of the intermediate section 5 and of the floor longitudinal 32 , the height of the side wall can be made of continuously different height . the side walls are terminated at the front and rear portion , and also in the door region , by vertically extending column section 33 which , in conjunction with the roof arches 23 and the struts 25 serves as a roll - over hoop . the vehicle body construction according to the invention , in comparison with the known vehicle body constructions of the previously identified kind , has several advantages , which relate essentially first to the improvement of all the junction connections in the vehicle body as well as on the other hand to the simple construction of the vehicle body , preferably made of extruded sections , while in addition it should be mentioned that the vehicle body construction is particularly suited for light construction , in which sections of aluminum alloys , preferably extruded , are employed . it is to be understood that the invention is not limited to the illustrations described and shown herein , which are deemed to be merely illustrative of the best modes of carrying out the invention , and which are susceptible of modification of form , size , arrangement of parts and details of operation . the invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims .