The invention relates to a lifting platform for a loading device for a lorry and of the kind-, wherein the platform comprises two parts, one of which is connectable with the loading device and the other of which is hinged to the first part about a pivot axis so as to be pivotal approximately 180 to a position wherein the load surface of the other part faces towards the load surface of the first part.

Lifting platforms of this kind are used in connection with load¬ ing devices comprising a slide which is movable with respect to the platform .of the lorry below the platform of the lorry and generally parallel therewith. In the stowed position the other platform part occupies the pivoted position wherein the loading surface of the other platform part faces the loading surface of the first part, and the slide has been drawn forward below the platform of the lorry to such an extent that the axis, about which the two parts of the lifting platform may be pivoted with recpect to each other, is positio¬ ned immediately below the rear edge of the platform of the lorry. Accordingly, a lifting platform folded in this way allows that parts which project rearwardly with respect to the lorry are avoided which is of great importance, because a maximum length for lorries is priscribed. When the loading device is to be used, the slide is moved rearwardly with respect to the lorry until the folded lifting platform is clear of the rear edge of the platform of the lorry. Now the infolded other part of the platform may be pivoted outwardly into extension of the first part of the lifting platform, whereby the lifting platform achieves a length, as seen in the longitudinal direc¬ tion of the lorry, which is necessary for supporting the goods to be unloaded and loaded. According to this known construction the lifting platform is moved by means of lifting arms connected ^' with the slide and with the side of the lifting platform facing forwardly in the longitudinal direction of the lorry. Previously comparatively light lifting platform constructions of the kind referred to manufactured , e. g. from aluminum, have been satisfactory so that the other plat¬ form part referred to may be pivoted manually from the position wherein it is positioned flush with the first platform part and to the position wherein it is pivoted 180° with respect to the first platform part. However, the ever increasing requirements as regards the capacity of loading devices of the kind here in question require ever stronger constructions as regards the lifting platform itself, and it

is the object of the present invention to provide a lifting platform of the kind referred to which may be constructed from a heavy material and with a great size, and which, nevertheless is easy to handle, and this object is achieved for a lifting platform of the kind referred to above, which according to the invention is characterized by a cylinder device, one end of which is hinged to one of the platform parts, and the other end of which is hinged to one end of a first connecting link, the other end of which is hinged to the other platform part at a location positioned at a distance from the pivot axis and from the load surface of the other platform part and by another connecting link, one end of which is hinged to the first connecting link between the ends of the first connecting link, and the other end of which is hinged to said one platform part. By means of such lifting platform the advantage is achieved that the lifting platform may be manufactured big and strong because the cylinder devide with the connecting links proposed according to the invention in a simple and effective way allows the cylinder device to pivot the other platform part.

A preferred embodiment of the lifting platform according to the present invention is characterized by the other connecting link being angular. Thereby it is achieved that the two platform parts may be constructed with floor plates which in the unfolded position of the lifting platform may abut each other at the position at which the pivot device proposed according to the invention is arranged . The invention will be further explained in the following with reference to the drawing, in which

Fig . 1 schematically illustrates an embodiment of the lifting platform according to the present invention shown in unfolded position, Fig . 2 shows the lifting platform according to Fig-. 1 partly folded. Fig . 3 shows the lifting platform according to Fig . 1 folded completely, and Figs. 4, 5 and 6 on an increased scale details of the lifting platform in the positions shown in Figs. 1 , 2 and 3 respectively. On the drawings, 1 is a lifting platform for a loading device for lorries. The platform 1 consists of two parts 2 and 3, of which one of the parts, 2, is connectable with a corresponding loading device.

seeing that this part at its front end 4 is provided with a bracket structure 5 at each side, provided with holes 6 and 7 for mounting the lifting platform with respect to two lifting arms of the loading device in question . The loading device per se is not shown, but comprises a slide to which the lifting arms are connected, and which is movably arranged below the platform of a lorry in such a way that the slide may be moved in the longitudinal direction of the lorry. I n order to achieve a comparatively short length of stroke of the slide in question the two platform parts 2 and 3 are hinged to each other about a pivot axis 8, viz. in such a way that the other platform part 3 from the pisition shown in Fig . 1 may be pivoted approximately 180°, i .e. to the position shown in Fig . 3, wherein the loading surfaces of the two platform- parts face each other. Hereby the length of the platform will be rather short and the slide of the loading device may have a correspondingly short length of stroke, whereby the lifting platform may be moved in below the platform of the corresponding lorry without leaving any outwardly projecting parts. Accordingly, the length of the platform of the lorry may be selected according to the maximum allowable length for such vehicles, and simultaneously the stroke of the slide may be made sufficiently short to allow accomodatϊoπ of the whole of the loading device to¬ gether with the lifting platform below the platform of the lorry between the rear edge of the platform of the lorry and the rear part of the subframe of the lorry. Both the platform parts 2 and 3 are on their lower sides provi¬ ded with side members schematically illustrated on the drawing and provided with the reference numerals 9 and 10, respectively. In the unfolded position of. the platform shown in Fig . 1 , the side members of the two platfoFm parts abut each other vertically below the pivot axis 8 in such a way that a stable construction is achieved .

In order to achieve an easy pivoting of the other part 3 with respect to the first part 2 the lifting platform is provided with a pivot device, comprising a cylinder device 12, e. g . a hydraulic jack, one end of which by means of a hinge 14 is hinged to the platform part 2, and the piston rod 13 of which by means of a hinge 15 is hinged to one end of a first connecting link 16. The other end of the first connecting link 16 is by means of a hinge 17 hinged to a ^' bracket 18 on the other platform part 3. This hinge 17 is located at a distance from the pivot axis 8 and at a distance from the load

surface of the other platform part 3. According to the embodiment shown in the drawing , the hinge 17 is located aligned with the lower side of one of the side members 9 of the platform part 3. The pivot device illustrated also comprises another connecting link 20, which at one of its ends by means of a hinge 21 is hinged to the first connect¬ ing link 16 between the ends thereof which in the drawing are represented by the hinges 15 and 17. The other end of the other connecting link 20 is by means of a hinge 22 connected with the platform part 2. As it appears from Fig. 1 the lengths of the two connecting links 16 and 20, the hinges of the connecting links 16 and 20 and the hinges of the cylinder device 12 have been selected in such a way that the major part of the force of the cylinder 12, at the beginning of the pivoting of the other platform part 3, causes a comparatively great moment, viz. corresponding generally to the force of the cylinder device multiplied by the distance between the pivot axis 8 and the hinge 17. Accordingly, a great moment is avail¬ able at the beginning of the pivoting of the other platform part 3, which is of great importance because exactly in this position the greatest moment is necessary. As the other platform part 3 is pϊvo- ted, the moment decreases, and when the other part 3 stands verti¬ cally as shown in Figs. 2 and 4 it will be seen that the pivot moment applied upon the other part 3 is comparatively small because this moment now generally is applied due to the moment which the first connecting link 16 is subjected from the force of the piston rod 13 and due to the rotation of the connecting link 16 about the hinge 22. When the other platform part 3 has been pivoted to the folded posi¬ tion as shown in Fig . 3 and again is to be pivoted back to the position shown in Fig . 1 , a comparatively great moment is again available seeing that the piston rod 13 will now try to pivot the first connecting link 16 anti -clockwise and, due to the fact that the connecting link 16 extends generally perpendicular to the longitudi¬ nal direction of the cylinder device and the other connecting link 20 extends generally parallel with the piston rod 13, a force wilt be applied to the hinge 17 of the connecting iϊnk 16 to the left in Fig. 3 and this force generally will correspond to half the force of the cylinder device, because the distance between the hinges 15 and 21 is approximately half the distance between the hinges 21 and 17. Accordingly, at the beginning of the return pivoting also a great moment is available which Is due to the fact that the hinge 17 is now

positioned generally vertically above the pivot axis 8.

In Figs. 1 -3 the pivot device is illustrated schematically and it will be seen that the other connecting link 20 in the position shown in Fig. 3 will have a tendency to extend inwardly over the pivot axis 8. Accordingly, if a rectilinear link is used as the other connec¬ ting link 20, small edge recesses may be necessary in floor plates 25 and 26 which form the loading surfaces of the platform parts cf. Fig . 4. By shaping the other connecting link 20 with a small curva¬ ture as shown on Figs. 4,5 and 6 it may be achieved that this second connecting link in the position of the platform shown in Fig . 6 extends about the pivot axis 8, and accordingly also about the edges of the floor plates in such a way that the floor plates at this place may be shaped so as to abut each other in the unfolded posi¬ tion shown on Fig . 1 .