BACKGROUND OF THE INVENTION 0001 The invention relates, in general terms, to the technical field of tower cranes, such as those used on building construction sites. More particularly, this invention is concerned with tower cranes having what are known as suspended driver's cabs, and, even more specifically, its subject is a foldable cab/pivot unit for a tower crane of this type.

DESCRIPTION OF THE PRIOR ART 0002 In a tower crane, the suspended driver's cab can be associated with the pivot located at the top of the mast and serving for orienting the jib of the crane, in order to form an assembly designated as a cab/pivot unit. One example of a cab/pivot unit can be found in the document FR 256 5950 A; here, the cab occupies a fixed position in relation to the jib of the crane, the cab/pivot unit not being intended to be foldable. 0003 In view of the dimensions of such a cab/pivot unit and because of the constraints attached to the transport of the crane, for example, from one site to another, however, it is advantageous to implement the cab/pivot unit in such a way that it is at least partially foldable. 0004 In a known embodiment, already used by the company POTAIN TECHNIK and described particularly in the brochure of its crane MDT 132, page 3.17, the folding of the cab/pivot unit is provided by a tilting of the cab about a horizontal axis. This folding principle and the overall design of the cab/pivot unit which results from this still have various disadvantages: 0005 The use of an auxiliary handling appliance is necessary for the operations of unfolding and folding the cab/pivot unit. 0006 The prone position of the cab, in the folded transport position, makes it necessary to immobilize its internal components. 0007 The folding system is not suitable in the case of a spacious driver's cab, since the bulk of the cab/pivot unit, even in the folded transport position, is then greater than the dimensions of a container. 0008 Arrangements must be made to ensure the protection of the exposed surfaces of the cab in this folded transport position. 0009 During the unfolding of the cab/pivot unit in order to bring the cab into the operating position, it is still appropriate to assemble the elements for access to the cab, thus complicating and lengthening the operations of putting into the operating position. 0010 Moreover, access to the cab, on the one hand, and access for maintenance and adjustment operations, on the other hand, are separate, this being an uneconomical solution. 0011 Finally, in the operating position, the driver's cab is level with the jib of the crane, and this does not afford the crane operator optimum visibility for driving the crane.

SUMMARY OF THE INVENTION 0012 The present invention is aimed at avoiding all these disadvantages by providing an improved cab/pivot unit which, while preserving a simple and economical structure, makes it possible, in particular, to carry out quickly and easily the bringing of the cab into the operating position, while at the same time allowing a folding of the cab into a minimum bulk and without the addition of protective elements. 0013 To this effect, the subject of the invention is a foldable cab/pivot unit for a tower crane, which comprises essentially, in combination: 0014 an upper mast element associated with a pivot, 0015 a cab access platform extending at one side of the mast element, and 0016 a crane driver's cab mounted pivotably about a vertical axis located at the side of the mast element and linked to this mast element, the cab thus being orientable about said vertical axis and through approximately 90, in particular by manual action, between: 0017 an operating position, in which this cab is located in the extension of the access platform, in front of the mast element, and 0018 a transport position, in which this cab is folded above the access platform, against the mast element. 0019 According to one embodiment of this foldable cab/pivot unit, the driver's cab is articulated on the mast element by means of a vertical double hinge comprising, toward the mast element, an upper support and a lower support which are fastened respectively to the top and to the base of the mast element, and, toward the cab, an upper support and a lower support which are fastened respectively to the top and to the base of the carrying structure of the cab, the upper supports and the lower supports being connected by means of respectively upper and lower vertical axles. 0020 Advantageously, the cab/pivot unit also comprises means for locking the driver's cab in its operating position and in its folded transport position. These locking means may consist as follows: 0021 for locking the driver's cab in the operating position: these means consist of plates integral respectively with the base of the cab and with the access platform to this cab and intended to be bolted to one another, so as to stiffen the access platform initially in a cantilevered manner; 0022 for locking the driver's cab in the folded transport position: these means consist of a turnbuckle tensioner mounted between the top of the mast element and the top of the carrying structure of the cab, in combination with an elastic stop fastened to the access platform, thus making it possible to damp the shocks during transport. 0023 According to another advantageous arrangement, the access platform comprises a removable and/or inclinable lateral railing which: 0024 in the operating position of the driver's cab, is fastened in a vertical position and is located in the extension of a lateral face of this cab, and 0025 in the folded transport position of the driver's cab, is fastened in a vertical position or in an oblique position projecting toward the outside of the access platform, so as to protect the front face of the cab, in particular the lower glazed part of this front face. 0026 The means for fastening the lateral railing to the access platform to the cab may comprise, on one outer edge of said platform, double chocks receiving the feet of the uprights of the railing, at the same time, depending on the chock used, fixing the vertical or oblique orientation of these uprights and therefore of the railing. 0027 The access platform to the cab also advantageously supports, perpendicularly to its lateral railing, an electrical cabinet which is thus accessible from this platform, the driver's cab, in the folded transport position, also taking its place against said electrical cabinet, in such a way that the lateral glazed part of the cab is also protected. 0028 Overall, the foldable cab/pivot unit which is the subject of the invention possesses the following advantages: 0029 by virtue of its principle of folding the cab by orientation about a vertical axis, the cab can be unfolded or folded manually, quickly and without the need for an auxiliary handling appliance, thus allowing rapid and easy implementation on sites. 0030 The cab, even when folded, always remains in the upright position, so that there is no longer any risk of a fall of the internal components of the cab or any obligation to immobilize these components before the cab is folded. 0031 Even where a spacious cab is concerned, the method of folding the latter makes it possible to bring the cab/pivot unit into a reduced bulk, thus making it possible to transport it in a container. 0032 The access platform to the cab remains connected to the mast element, and, after the unfolding of the cab, it immediately occupies a position giving access to this cab, thus dispensing with any operations to bring up and assemble access elements. 0033 Moreover, this platform gives spacious common access to the driver's cab and to the electrical cabinet, thus forming a compact and economical arrangement making the operations of maintaining and adjusting the crane easier. 0034 The lateral railing of the access platform and the electrical cabinet supported by this platform are elements for protecting the cab in the folded transport position, thus making it unnecessary to have any additional protective elements for the painted surfaces and the windows of the cab. In particular, the lateral railing ensures the protection of the front window of the cab, the inclined position of the railing allowing adaptation to the usually rounded or projecting shape of the front face of the cab. As regards the electrical cabinet, this ensures the protection of the side window of the cab. Thus, the cab is suitably protected from the shocks which may occur during the transport and the handling of the cab/pivot unit. Furthermore, the placing of the cab against the electrical cabinet in the folded transport position ensures that access both to the cab and to the cabinet is prohibited, thus preventing thefts or malicious acts. 0035 Finally, in the operating position, the driver's cab takes its place below the jib of the crane, thus ensuring that the crane operator has optimum visibility for driving the crane. 0036 The subject of the invention, as such, is also a tower crane comprising a foldable cab/pivot unit, as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS 0037 The invention will be understood more clearly from the following description, with reference to the accompanying diagrammatic drawing which illustrates, by way of example, an embodiment of this foldable cab/pivot unit for a tower crane and in which: 0038 FIG. 1 is an overall perspective view of a cab/pivot unit according to the invention, the cab being in the operating position; 0039 FIG. 2 is another more bird's eye perspective view of the cab/pivot unit, still in the operating position; 0040 FIG. 3 is another perspective view of this cab/pivot unit, the cab being in the folded transport position; 0041 FIG. 4 is a first perspective view of a detail, showing the means for fastening the lateral railing of the access platform; 0042 FIG. 5 is another perspective view of a detail, showing the means for locking the cab in the operating position; 0043 FIG. 6 is another view of a detail, in plan from above, showing the means for locking the cab in the folded transport position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 0044 FIGS. 1 to 3 show, as a whole, a cab/pivot unit for a tower crane, which comprises, as main components: 0045 a pivot 1 surmounted by an upper mast element 2 orientable about a vertical axis 3; 0046 a horizontal platform 4 which extends horizontally at the side of the mast element 2 and which is integral with this mast element 2; 0047 a crane driver's cab 5 mounted pivotably about another vertical axis 6 located at the side of the mast element 2 and linked in terms of rotation to this mast element 2 and therefore also to the platform 4. 0048 The pivot 1 is intended to be fastened to the top of the mast (not illustrated) of a tower crane. The upper mast element 2 orientable on the pivot 1 is intended to support the jib (not illustrated) of the crane. 0049 The pivotable mounting of the cab 5 about the vertical axis 6 in relation to the upper mast element 2 is carried out by means of a double hinge. This hinge comprises, toward the mast element 2, a triangulated upper support 7, welded to an upper frame 8 of the mast element 2, and a triangulated lower support 9, welded to the base of the mast element 2. The hinge also comprises, toward the cab 5, an upper support 10, welded to a vertical beam 11 of the carrying structure 12 of the cab 5, toward the top of this carrying structure 12, and a lower support 13, welded to the vertical beam 11 of the carrying structure 12 of the cab 5, toward the base of this carrying structure 12. Finally, the hinge comprises two vertical axles, to be precise an upper axle 14 connecting the two upper supports 8 and 10 in an articulated manner and a lower axle 15 connecting the two lower supports 9 and 13 in an articulated manner. 0050 The platform 4, which allows access to the driver's cab 5, comprises a lateral railing 16 which extends along one of its outer edges 17. This platform 4 also supports an electrical cabinet 18 which extends along the outer edge 19, perpendicular to the edge 17, of said platform. 0051 In detail, as also shown in FIG. 4, the platform 4 comprises, on its outer edge 17, two double chocks 20, 21 provided for receiving removably the two feet of the uprights 22 of the railing 16 which has two fastening positions. The chocks 20 make it possible to fasten the railing 16 in a vertical orientation. The other chocks 21 make it possible to fasten the same railing 16 in an oblique orientation, projecting outward in relation to the edge 17 of the platform 4. Dowels ensure that the fastening of the railing 16 is secured, to prevent any accidental release from the chocks 20 or 21. 0052 By virtue of its pivotable mounting about the vertical axis 6, the driver's cab 5 can be brought into an operating position (FIGS. 1 and 2) or into a folded transport position (FIG. 3), the passage from one position to the other taking place manually as a result of a rotation through 90 about the vertical axis 6 in one direction or in the othersee the arrows F1 and F2 of FIG. 1. 0053 In the operating position (FIGS. 1, 2 and 5), the driver's cab 5 is located in the extension of the access platform 4, in front of the upper mast element 2. The lateral railing 16, then fastened vertically to the outer edge 17 of the platform 4, is located in the extension of a lateral face 23 of the cab 5. The platform 4 thus gives access to the cab 5, the rear face 24 of this cab 5 being provided with a door 25 which opens toward the platform 4. 0054 As shown particularly in FIG. 5, the driver's cab 5 is locked in its operating position by means of a device which comprises: 0055 on the base of the cab 5, at the rear of the latter (toward the lateral face 23): a bent plate 26 fastened by bolting of the cab 5, with a projecting part pierced with a slot 27; 0056 on the platform 4: a plate 28 having a chamfer 29 and fastened by welding; 0057 between the two plates 26 and 28: a connection by bolt 30, put in place when the cab 5 is brought into the operating position. 0058 In the transport position (FIG. 3), the driver's cab has an orientation at 90 with respect to its operating position, and it is thus folded: 0059 on the one hand, against the upper mast element 2, the rear face 24 of the cab 5 being turned toward this mast element 2; 0060 on the other hand, against the electrical cabinet 18, the lateral face 23 of the cab 5 taking its place in front of this cabinet 18. 0061 The cab 5 is thus brought above the platform 4 (and no longer in front of this platform 4), thus considerably reducing the bulk of the cab/pivot unit. 0062 Referring also to FIG. 6, the driver's cab 5 is locked in its folded transport position by means of a turnbuckle tensioner 31 mounted between the top of the mast element 2, on the one hand, and the top of the carrying structure 12 of the cab 5, on the other hand. The action of the tensioner 31 presses the base of the cab 5 against a rubber stop 35 (FIG. 6) fastened to the structure of the platform 4. When the cab 5 is in the operating position, the turnbuckle tensioner 31 is placed in a storage position, indicated (by a single axis) in broken lines. 0063 Still considering the folded transport position of the cab 5 (see FIG. 3), the lateral railing 16 is then fastened in its oblique orientation to the outer edge 17 of the platform 4, so as to take its place in front of the front face 32 of the cab 5, taking into account the rounded shape of this front face 32. The railing 16 thus ensures the protection of the front face 32 of the cab 5, in particular of its lower glazed part 33, while the electrical cabinet 18 protects the lateral face 23 of the cab 5, in particular its lateral glazed part 34. 0064 To pass from the folded transport position (FIGS. 3 and 6) to the operating position (FIGS. 1, 2 and 5), it is appropriate to release the turnbuckle tensioner 31 and to place it in the storage position, after which the cab 5 is oriented manually through 900 (arrow F1 of FIG. 1). When it has thus reached the operating position, the cab 5 is locked by the plates 26 and 28 being bolted to one another. Finally, the lateral railing 16 is fastened in its vertical position. 0065 The entire cab/pivot unit is prewired electrically, so that there is no electrical connection operation to be performed at the time when it is put into operation, thus contributing to the simplicity and rapididity of implementation. 0066 Of course, to pass from the operating position to the transport position, the operations described above are carried out in reverse order: separation of the bolted plates 26 and 28, then manual orientation of the cab through 90 in the opposite direction (arrow F2 of FIG. 1), finally putting in place and tightening of the tensioner 31, and fastening of the railing 16 in its oblique position. 0067 The cab/pivot unit described above can be used for tower cranes with a suspended driver's cab, of any configuration. 0068 There will be no departure from the scope of the invention, as defined in the accompanying claims: 0069 by modifying the structural details, such as those of the articulated connection between the cab and the mast element; 0070 by using other means for locking the cab in its operating position and in its folded transport position; 0071 by adapting the invention to cranes with driver's cabs of any configuration and of any dimension.