PATENT ABSTRACT
The present disclosure relates to a rotary joint for rotatable connection of the uppercarriage with the undercarriage of a crane, wherein they can each be connected with the uppercarriage on the one hand and the undercarriage on the other hand via a quick-release coupling.

PATENT DESCRIPTION
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Utility Model Application No. 20 2008 016 876.7, filed Dec. 19, 2008, which is hereby incorporated by reference in its entirety for all purposes. 
     TECHNICAL FIELD 
     The present disclosure relates to a rotary joint for rotatable connection of the uppercarriage with the undercarriage of a crane. 
     BACKGROUND AND SUMMARY 
     Large cranes, such as in particular crawler cranes, are dismantled into individual parts for transport. Accordingly, the crane is disassembled for transport. There are obtained various transport units, which possibly can be moved in road traffic by using special transport vehicles. The regulations applicable for transport relate for instance to the weight or also to the dimensions. 
     Depending on weight and dimension, the crane thus is dismantled into a plurality of parts, for instance into the uppercarriage and various parts of the undercarriage, and into the respective equipment parts. If a crane must now be transported, in which for instance both the uppercarriage and the middle part of the frame of the undercarriage reach the maximum weights admissible in road traffic, it becomes necessary to separately transport the rotary joint arranged between the uppercarriage and the middle part of the frame of the undercarriage with the associated drives. 
     The object of the present disclosure now consists in providing a rotary joint of the generic type for a crane, in particular a crawler crane, which quickly, easily and reliably can be connected both with the undercarriage and with the uppercarriage of the crane and can again be released from the same, in order to be able to be transported separately. 
     In accordance with the present disclosure, this object is solved by a rotary joint for rotatable connection of the uppercarriage with the undercarriage of a crane, wherein the rotary joint can be connected with the uppercarriage on the one hand and the undercarriage on the other hand via a quick-release coupling. Accordingly a rotary joint is provided for rotatable connection of the uppercarriage with the undercarriage of a crane, wherein this rotary joint can each be connected with the uppercarriage on the one hand and the undercarriage on the other hand via a quick-release coupling, in accordance with the present disclosure. 
     Due to this separability of the rotary joint both from the uppercarriage and from the undercarriage in accordance with the present disclosure, a good transportability and in particular a reduction of the transport weights of the individual components of the large crane can be achieved. In addition, the individual assemblies of the crane can optimally be configured, in order to achieve very high lifting capacities of the crane. Via the quick-release coupling, safe and fast assembly or disassembly of the rotary joint is possible. 
     Accordingly, the rotary joint preferably constitutes a roller rotary joint. Such roller rotary joints can absorb very high lifting capacities. 
     The drive advantageously is formed of a plurality of hydraulic drive units, which according to a particularly advantageous aspect of the present disclosure are connected with each other such that only the entirety of the drives must be connected with the hydraulic lines of the uppercarriage. This reduces the assembly time, since it is not necessary to connect each individual drive with hydraulic lines of the uppercarriage. 
     Advantageously, the rotary joint constitutes a circular slewing ring. For coupling the undercarriage and/or for coupling the uppercarriage, two circular opposed webs each can be provided here, in which bolts uniformly distributed around the periphery can pluggably be received, in order to provide a bolt connection with a mounting flange of the undercarriage or the uppercarriage, which can be received between the webs. The quick-release coupling is formed thereby. 
     Particularly advantageously, the inserted bolts each can be lockable via a bolt locking device, which contributes to the operational safety of the crane. Further details and advantages of the present disclosure will be explained in detail with reference to an embodiment illustrated in the drawing, which are drawn approximately to scale. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  shows a perspective representation of a rotary joint in accordance with the present disclosure. 
         FIG. 2  shows a perspective representation of the rotary joint of  FIG. 1  from another viewing angle. 
         FIG. 3  shows a sectional representation through part of the rotary joint of  FIGS. 1 and 2 . 
         FIG. 4  shows the rotary joint of the preceding Figures packed into a transport container. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1 and 2 , the rotary joint  10  consists of a circular roller slewing ring. In a manner not shown here, a non-illustrated uppercarriage can be connected with a non-illustrated undercarriage via the rotary joint  10 . Central part of the rotary joint  10  is the roller rotary joint  12 , which is configured in a conventional way and therefore need not be described further. The roller rotary joint includes six drives  14 , which generate the required torques or driving torques. These are hydraulic drives, which in a manner not illustrated here in greater detail are connected with each other via hydraulic lines  110 , so that they can be connected with the likewise non-illustrated hydraulic lines of the uppercarriage as an entire unit, for example, by a single hydraulic connection. 
     On one side, the roller rotary joint  12  is adjoined by two circular opposed webs  16  and  18 , which extend in parallel offset with respect to each other. As can be taken from  FIGS. 1 and 2 , a large number of bolts  20  uniformly distributed around the periphery are inserted in the webs, which each can be retracted via bolt drawing means  112 , which may be a mechanical lever or other such structure to retract or engage one or more of bolts  20 . For assembly with the undercarriage, the rotary joint  10  is placed on the mounting flange of the undercarriage, wherein the mounting flange is positioned between the webs  16  and  18  (in a manner not shown here). Subsequently, the bolts are inserted, wherein the same do not only extend through the walls  16  and  18 , but also through the non-illustrated mounting flange, which includes corresponding bores. This provides for a safe assembly of the rotary joint with the undercarriage or the uppercarriage of the crane not shown here in greater detail. 
     The connection with a mounting flange  22  of a non-illustrated undercarriage can be taken from the sectional representation of  FIG. 3  showing the axis of rotation at  114 . While  FIG. 3  is drawn approximately to scale, line  116  represents a break where the scale is not maintained from line  116  to the central axis  114 . Here, a bolt  20  is inserted through the webs  16  and  18  of the rotary joint  10  and at the same time through a corresponding bore of the flange  22  of the undercarriage. The bolt is locked via a bolt locking device  24 , wherein this bolt locking device  24  is connected with the bolt via a screw  26 . 
     The section shown in  FIG. 3  also reveals the structure of the roller rotary joint  12  known as such, which is conventional, however, and will therefore not again be described in detail at this point. 
     In the embodiment shown in  FIG. 3 , the connection of the non-illustrated uppercarriage with its slewing platform  28  shown here only schematically is effected in that the mounting flange  30  of the uppercarriage forks into two lateral webs  32  and  34  extending circularly and parallel to each other, which as shown in  FIG. 3  enclose a likewise circular mounting web  36  of the rotary joint. Via the correspondingly inserted bolts  20 , which in turn are locked via the locking device  24 ,  26 , the webs  32  and  34  are fixed with respect to the ring  36 . 
     In  FIG. 4 , the rotary joint is shown in the transport condition. The rotary joint can be loaded as an entire unit, i.e. with the mounted drives  14 . In one embodiment, this unit altogether has a weight of about 32 t and therefore is not suitable for road transport. The external dimensions also are designed for road transport. Thus, the entire unit  10  is accommodated on a special bracket not shown here in greater detail, so that it can be transported on the transport means, for instance the low-bed truck, erected by a defined angle α. This position allows a maximum utilization of the admissible limitations, such as the height h and the width b, which are specified in road traffic.