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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119(a) to German Patent Application No. 10 2014 011 403.1 filed Aug. 6, 2014, which is incorporated herein by reference in its entirety for all purposes. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a ram-boring device having a pressure fluid-driven striking piston in a device housing and a rotating reversing device of the striking piston from a forward operation to a reverse operation in order to create oblique or horizontal bores in the ground. 
       BACKGROUND OF THE INVENTION 
       [0003]    Ram boring devices of this kind are known and have a striking piston, which is moved pneumatically back and forth in the device housing and in so doing, hits a front-facing or a rear-facing striking surface of the housing, depending on the direction in which the device is moving. The kinetic energy of the striking piston thereby transferred ensures the acceleration of the ram-boring device in the ground, and the creation of a borehole through the radial displacement of the soil. 
         [0004]    Such a ram boring device having a control pipe and a striking piston, which can be displaced thereon is known from the German patent application, 39 09 567 A1. The control pipe is connected at the rear end thereof to a pressurized air source, and is connected to a component that is affixed to the housing such that said control pipe can be moved both along the longitudinal axis, and rotated via a pretensioned, exterior helical spring. The above-mentioned helical spring forces the control pipe into a forward motion position and locks said tube in this position after a quarter turn in a front locking groove. When reversing the device from a forward operation to a reverse operation, the control pipe is first unlocked with a quarter turn against the force of the preloaded spring, so that said control pipe is displaced under the influence of the pressurized air (service air) against the spring force exerted in the direction of the longitudinal axis in the reverse operation position thereof. Thus, the reverse operation movement of the striking piston is lengthened resulting in a rear-striking surface that is affixed to the housing being acted upon by the striking piston. 
         [0005]    As in the forward operation position, the control pipe is locked in the reverse operation position under the influence of the likewise rotationally pretensioned helical spring in a rear-locking groove. A renewed reversal of the ram boring device back into the forward motion position therefore requires that the control pipe be rotated back and that said control pipe be pushed back into the forward motion position. 
       SUMMARY 
       [0006]    Against this background, the invention is based on the problem of creating a ram boring device of the above described type, which makes a simple reversal possible without the necessity of pulling/turning the pressure fluid tube or, the pressurized air line. 
         [0007]    This problem is solved by a ram-boring device, in which the chamber of a rotary piston or rotary slide is connected to an instrument air or control fluid line in order to mechanically reverse the device using control fluid. 
         [0008]    The invention is based on the fundamental idea of providing the ram-boring device with a rotary drive of the control pipe and/or of the locking sleeve for the control pipe, said rotary drive being located inside or outside, but preferably inside the device housing. To this end, the control pipe is mounted in an axially displaceable manner, and thus can be mechanically displaced from the control position for the forward operation into the control position for the reverse operation. The longitudinal displacement of the control pipe for the forward operation thus is achieved by means of a helical spring and, for the reverse operation, by means of the service air as well as the rotation of the control pipe and/or locking sleeve with the aid of the rotary slide. 
         [0009]    Therefore in the case of the ram-boring device according to the invention, there is no rotation of the control pipe by an operator. In reversing, the invention dispenses with any arbitrary manual rotation of the line for the service air and thus of the control pipe as well; instead, the invention uses an application of a pressurizing medium to a rotary piston, which application can be controlled completely autonomously and independently of the service air, said rotary piston preferably being disposed inside the device housing, but which may also be disposed outside of the housing. 
         [0010]    Thus the invention is associated with the particular advantage that the requirements for the leak tightness of the reversal mechanism are low, because pressurized air is only applied to the rotary piston drive for the reversal. In so doing, the use of a pressurized fluid or, respectively, of pressurized air is therefore only necessary for one of the two control movements of the control pipe, because the reverse movement and the locking is brought about solely by the helical spring. The consumption of instrument air for this process is so low that a very small diameter of the instrument air line is sufficient, and as a result, a service air hose in the instrument air line is also feasible. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention is described in greater detail below on the basis of an exemplary embodiment, which is depicted in the drawings. 
           [0012]      FIG. 1  shows a longitudinal section of the rear end of a ram boring device in its forward operation position; 
           [0013]      FIG. 2  shows the longitudinal section from  FIG. 1 , however in the reverse operation position; 
           [0014]      FIG. 3  shows a perspective view of the control pipe of the ram-boring device according to  FIGS. 1 ,  2  in the forward operation position; 
           [0015]      FIG. 4  shows the control pipe according to  FIG. 3 , in its reverse operation position, however, 
           [0016]      FIG. 5  shows a cross-sectional view along the line V-V of  FIG. 1 ; 
           [0017]      FIG. 6  shows a cross-sectional view along the line VI-VI of  FIG. 1  and 
           [0018]      FIG. 7  shows a cross-sectional view along the line VII-VII of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The ram-boring device  1  has a cylindrical housing  2 , of which, however, only the rear part with its screw tail end  3  is depicted. A striking piston  4  that can be moved back and forth is mounted in the housing  2 , the reverse movement of which striking piston is delimited by an annular impact surface  5 . The striking piston  4  is oscillated by a pressurized fluid supplied via a line  6  and thereby provides the kinetic energy of said piston to a head of the ram boring device located in the front part of the housing  2 , or to the device housing via the annular impact surface  5 , the head of the ram boring device of which is disposed such that it can be moved axially within the housing  2 . 
         [0020]    The pressure fluid line  6  is connected to a pivoted control pipe  9  via a two-piece coupling piece  7 ,  8 , which control pipe is pivoted with respect to a locking sleeve  19 . This control pipe is mounted on one side at the front end in a control sleeve  10  in the cylinder chamber  11  of the striking piston  4 , and on the other side at the rear end in a ventilation block  12 , which is disposed in the tail end  3  of the housing  2 . The control sleeve  10  is connected to the control pipe  9  via an elastic bushing  13 . This sleeve is mounted in an annular groove  14  of the control pipe  9 , which is connected to an annular shoulder  15  of the control pipe  9 . 
         [0021]    The shoulder  15  has a recess, which is not apparent, and which is open towards the tail end of the device ( FIGS. 1 and 2 ), in which recess the front end of a cylindrical helical spring  16  engages. The helical spring encloses the control pipe  9  and is fixed at the rear end  17  thereof in the recess  18  of a pivotable locking sleeve  19  located opposite the control pipe  9 . These parts are a part of the rotating reversing device according to the invention, as is evident from the sectional drawings in  FIGS. 5 through 7 . 
         [0022]    This reversing device essentially comprises a rotary piston drive in the shape of a finned tube component  20  having longitudinal fins  21 ,  22 . The finned tube component  20  forms in conjunction with the locking sleeve  19  a rotary piston  23  connected to the locking sleeve  19  as well as the piston chamber  24  of the rotary piston drive with the cylindrical outer sleeve  32 , to which separate instrument air is applied via an instrument air line  25  having a instrument air valve  26 . 
         [0023]    As an alternative locking method, the control pipe  9  has a crosswise slot  27 ,  28  in the rear part thereof, which slots are spaced apart from one another, and into which a locking crosspiece  29  alternatively engages. The crosswise slot  27  determines the forward operation position ( FIG. 1 ) and the crosswise slot  28  determines the reverse operation position ( FIG. 2 ) of the control pipe  9 . The two crosswise slots  27 ,  28  thereby define the two operating positions of the control pipe  9 . 
         [0024]    The sectional view in  FIG. 6  depicts two fixed stop bars  30 ,  31  located opposite one another, which delimit the movement of the rotary piston during the reversal using the instrument air valve  26 . 
         [0025]    The reversal is achieved in such a way that the piston chamber  24  of the rotary piston  23  is pressurized by opening the instrument air valve  26 . After the rotary piston has then reached its end position, the helical spring  16  slides the control sleeve  10  with the control pipe  9  forward as a result of a decrease of the pressure in the pressurized air line  6 . To this end, the pressure is reduced to such a degree that the helical spring  16  moves the control sleeve  10  out of the position for the reverse operation depicted in  FIG. 2 , into the position for the forward operation ( FIG. 1 ) in opposition to the residual pressure of the pressurized medium (service air) still exerted in the cylinder chamber  11  of the striking piston  4 . The rotary piston  23  can be vented during the movement of the control pipe  9  from the position for the reverse operation depicted in  FIG. 2 , to the position for the forward operation ( FIG. 1 ). In other words: Instrument air is only applied to the rotary piston to unlock the control pipe  9 , i.e. for a very brief period of time. 
         [0026]    This is possible because the helical spring  16  places the control pipe  9  in the front position thereof for the forward operation ( FIG. 1 ) after the rotary piston  23  has been vented, in which position a locking crosspiece  29  engages in a rear crosswise slot  28  of the control pipe  9  ( FIG. 1 ) and thereby prevents an axial movement of the control pipe. As soon as this is the case, the pressure of the service air can again be increased and the forward operation can begin. 
         [0027]    In order to initiate the reverse operation, the device must first be unlocked with the help of the rotary piston  23  pressurized with instrument air, while maintaining the full pressure level of the service air, in such a way that the control pipe  9  can move, under the influence of the service air, from its position in  FIG. 1  into the position according to  FIG. 2 . In this position, the front crosswise slot  27  and the locking crosspiece  29  once again engage ( FIG. 2 ) under the influence of the helical spring  16  when the rotary piston  23  is no longer pressurized, and the reverse operation begins at full pressure level.

Summary:
A ram boring device has a pressurized-fluid driven striking piston in a device housing and a rotating reversing device configured to urge the striking piston from a forward operation to a reverse operation in order to create oblique or horizontal bores in the ground, in which the piston chamber of a rotary piston drive is connected to a control fluid line.