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TECHNICAL FIELD OF THE INVENTION 
       [0001]    The invention relates to a method for the continuous renewal of a ballast bed of a track from which the rails and sleepers have been removed, by carrying away old ballast and depositing cleaned ballast or new ballast on the substrate from which the old ballast has been removed, in which method a removal device which can travel in the working direction continuously picks up the old ballast of the ballast bed, the excavated material is conveyed away from the excavation region and possibly passed on for ballast cleaning and at the same time cleaned ballast or new ballast is continuously deposited in the working direction on the substrate from which the old ballast has been removed, to form a new ballast bed. The scope of the invention also includes an arrangement of appliances for carrying out the method and a transport carriage. 
       PRIOR ART 
       [0002]    A method for the cleaning of ballast of a track is known from EP-A-1 191 147. A ballast cleaning machine which is used for this purpose is moved over the section of track to be cleaned for the purposes of cleaning the ballast. Using an endless, rotating clearing chain, which is fed through transversely to the longitudinal direction of the machine below the locally raised track, the ballast located below the track is continuously carried away and passed on to a screening installation. The cleaned ballast issuing from the screening installation is subsequently discarded back onto the track. 
         [0003]    If a track renewal or relaying of the existing tracks is carried out at the same time as the ballast cleaning, the ballast bed is renewed in a portion in which the track has in each case been removed beforehand. As the ballast cleaning advances, in each case on the one hand a new or the previously dismantled piece of track is laid out on the renewed ballast bed and on the other hand a piece of track is removed on a ballast bed which has not yet been renewed. 
         [0004]    In the case of a known method of the type mentioned at the outset, the old ballast of the ballast bed to be renewed is continuously carried away by a bucket conveyor which is arranged upstream of a ballast cleaning machine through the machine moving forward in the working direction, cleaned in a screening installation on the machine and subsequently, immediately after the bucket conveyor, brought out again as cleaned ballast on the substrate from which the old ballast has been removed. The excavated earth is conveyed, for the purposes of disposal, counter to the working direction into a transport carriage positioned after the machine. 
         [0005]    The method described hereinbefore has the drawback that the relaying of a track which was previously removed from the old ballast bed on the renewed ballast bed cannot be carried out directly at the same location and the track portions must for this reason in each case be placed in a relatively short time and at great expense after the machine, wherein the relaying of the tracks can be carried out only when the excavation has been completed and the ballast cleaning machine has left the excavation region. A further drawback is the high weight of the known excavation and cleaning machine. 
       ACCOUNT OF THE INVENTION 
       [0006]    The invention is based on the object of providing a method of the type mentioned at the outset and also an arrangement which is suitable for carrying out the method, allowing the drawbacks from which the methods and devices according to the prior art suffer to be avoided. A further aim of the invention is the provision of a method and an arrangement which are suitable both for normal ballast cleaning and for substrate redevelopment with total excavation. 
         [0007]    With regard to the method, the object is achieved, in accordance with the invention, in that the removal device, as part of an excavating machine traveling in the working direction on the old ballast bed, is arranged downstream of the running gear of the excavating machine. 
         [0008]    In the case of a preferred implementation of the method according to the invention, the old ballast, which is carried away by the removal device from the ballast bed, is conveyed as excavated material in the working direction into a first transport carriage, which is provided before the excavating machine and can travel on the old ballast bed, and the cleaned ballast or the new ballast is conveyed from the first transport carriage counter to the working direction after the removal device and deposited onto the substrate from which the old ballast has been removed. 
         [0009]    For ballast cleaning without total excavation, the first transport carriage expediently comprises a ballast cleaning unit and the old ballast, which is conveyed from the removal device, is cleaned in the ballast cleaning unit and the cleaned ballast is conveyed back after the removal device and deposited on the substrate from which the old ballast has been removed. 
         [0010]    For substrate redevelopment with total excavation, the first transport carriage preferably contains new ballast and sand separately from each other and new ballast and sand are conveyed from the first transport carriage separately after the removal device and deposited as separate layers on the substrate from which the old ballast has been removed and which is covered by an underlay made of geotextile or geogrid. 
         [0011]    In the case of a first preferred manner of carrying out the method according to the invention, the first transport carriage oscillates, for loading and/or unloading, between the excavating machine and a second transport carriage which is positioned on a track ending at the ballast bed to be removed and provided for the supply and removal of materials. In the case of this procedure, the excavating machine is stationary during the oscillating travel of the first transport carriage, i.e. its excavating performance is zero during this time. 
         [0012]    In the case of a second preferred manner of carrying out the method according to the invention, the first transport carriage remains stationary in the excavating machine and a third transport carriage oscillates, for loading and/or unloading, between the first transport carriage and a second transport carriage which is positioned on a track ending at the ballast bed to be removed and provided for the supply and removal of materials. In the case of this shuttle mode of a third transport carriage, the excavating machine can be used for continuous conveyance at maximum power. 
         [0013]    An arrangement which is suitable for carrying out the method according to the invention comprises an excavating machine which can travel on the old ballast bed in the working direction and has a removal device which is arranged following the running gear of the excavating machine, at least one transport carriage for loading and/or unloading with/of materials which are produced/required during renewal of a ballast bed, optionally a ballast and sand distributing machine, and also conveying means for transporting the materials which are produced/required during renewal of a ballast bed. 
         [0014]    The removal device of the excavating machine and a ballast silo provided for the depositing of ballast are preferably arranged on a swivel arm which can swivel about a vertical axis of rotation and a horizontal pitch axis. 
         [0015]    The removal device is preferably a feed screw. A feed screw is less noisy than other excavation systems, has a compact design, is effective and displays good efficiency. A further preferred removal device is an impeller wheel. 
         [0016]    For ballast cleaning without total excavation, one of the transport carriages preferably comprises a ballast cleaning unit. 
         [0017]    For substrate redevelopment with total excavation, the transport carriages preferably have a first loading plane for the interim storage of excavated material and a second loading plane arranged above the first loading plane for the interim storage of ballast and/or sand and the second loading plane for the supply of ballast and/or sand can be lowered for the purposes of lowering the center of gravity of the transport carriage and can be raised above the first loading plane for increasing the size of the loading volume which is provided for the interim storage of excavated material. 
         [0018]    The loading surfaces of the transport carriages are preferably embodied as conveyor belts. 
         [0019]    The ballast and sand distributing machine preferably comprises a swivel arm which can swivel about a vertical axis of rotation and a horizontal pitch axis and two silos, which are provided for the depositing of sand and ballast, are arranged on the swivel arm. At their lower end, the silos are preferably equipped with a compressor. 
         [0020]    The machines and vehicles which are provided for traveling on the ballast bed and on tracks, in particular the excavating machine, the ballast and sand distributing machine and the transport carriages, are expediently equipped with an alternately usable tracked running gear and a rail running gear. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Further advantages, features and details of the invention will emerge from the subsequent description of preferred exemplary embodiments and also with reference to the drawings, in which: 
           [0022]      FIG. 1  is a schematic side view of an excavating machine; 
           [0023]      FIG. 2  shows schematically a measurement and control scheme for the excavating machine of  FIG. 1 ; 
           [0024]      FIG. 3  is a schematic side view of a ballast cleaning arrangement with the excavating machine of  FIG. 1  and a transport carriage; 
           [0025]      FIG. 4-6  show schematically a shuttle mode of the arrangement of  FIG. 3 ; 
           [0026]      FIG. 7  is a schematic side view of the excavating machine of  FIG. 1  in combination with a ballast and sand distributing machine; 
           [0027]      FIG. 8  is a schematic side view onto the arrangement of  FIG. 7  in combination with a transport carriage; 
           [0028]      FIG. 9  is a schematic section through the transport carriage of  FIG. 8  along the line I/I thereof in transport mode; 
           [0029]      FIG. 10  shows schematically the section of  FIG. 9  through the transport carriage in working mode; and 
           [0030]      FIG. 11  shows schematically a shuttle mode with the arrangement of  FIG. 8 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0031]    An excavating machine  10  illustrated in  FIG. 1  has a movable base  12  with a tracked running gear  14  for advancing on a ballast bed and a rail running gear  16  for advancing on tracks. A swivel tower  18  having a vertical swivel axis z protrudes from the movable base  12  perpendicularly to a notional bearing plane of the running gears  14 ,  16 . A swivel arm  20  is mounted on the swivel tower  18  so as to be able to rotate about the swivel axis z. 
         [0032]    A feed screw  22 , which is inclined in the working direction x and encloses an acute angle with the notional bearing plane of the running gears  14 ,  16 , is secured to the swivel arm  20 . On its back, the feed screw  22  is surrounded by a dozer blade  23  with a compressor  25 . The lower edge of the dozer blade  23  rests on the excavated track formation. A ballast silo  26 , with a compressor  28  arranged at the bottom-side end thereof, is located at the free end of the swivel arm  20 . 
         [0033]    The excavating machine  10  is equipped with conveyor belts  30 ,  32 ,  36 , the function of which will be examined in greater detail hereinafter. A drive and energy unit  40  serves inter alia to advance the excavating machine, to carry out swiveling movements of the swivel arm  20  about the swivel axes z, y and to drive  24  the feed screw  22 . 
         [0034]    The tracked running gear  14  of the excavating machine  10  rests on a ballast bed  41  made of old ballast  42 . During the traveling of the excavating machine  10  in the working direction x, the old ballast  42  is continuously conveyed by the feed screw  22  onto the conveyor belt  30 , which is secured to the swivel arm  20 , and therefrom further onto the conveyor belt  32 , which is fixedly mounted on the movable base. To the same degree as the carrying-away of old ballast  42  via the feed screw  22  and the two conveyor belts  30 ,  32 , cleaned ballast or new ballast  44  is passed on via the conveyor belt  34  into a silo  38  arranged on the conveyor belt  36 . From the conveyor belt  36 , the cleaned ballast or new ballast  44  falls into the ballast silo  26  and is continuously deposited on the excavated track formation  47  of the earth foundation  46  and compressed via the compressor  28  onto the desired ballast track formation  45  of the ballast bed  43 . 
         [0035]    The measurement and control scheme shown in  FIG. 2  for the excavating machine  10  illustrated in  FIG. 1  reveals the swiveling movements which are carried out by the swivel arm  20  and thus by the feed screw  22  and by the ballast silo  26 . A swiveling movement of the swivel arm  20  about the vertical swivel axis z leads to a horizontal swiveling movement of the feed screw  22  and of the ballast silo  26  over the entire width of the ballast bed  41 ,  43  to be carried away or to be newly constructed. The height of the lower edge of the feed screw  22  and the height of the lower edge of the ballast silo  26  with respect to a reference value are set by a corresponding swiveling movement of the swivel arm  20  about a horizontal pitch axis y, which is arranged at right angles to the swivel axis z, by means of a lifting cylinder  39 . 
         [0036]    The excavation depth and excavation width are each measured using an angle gauge  118  for the angle of rotation of the vertical swivel axis z and an angle gauge  120  for the angle of rotation of the horizontal pitch axis y and passed on to a computer unit  122 . Based on the inputs via a keyboard  124 , the computer unit  122  defines the vertical and transverse positions for the excavated track formation  47  and the ballast track formation  45 . Construction site data, such as for example the construction site geometry, the excavated depth, the excavated transverse position, the ballast track formation height and the ballast track formation transverse position, can be collected off-line, i.e. before work commences, and stored on a floppy disk  126 . 
         [0037]    The measurement and control scheme is designed for at least three different levels of automation, so that in the event of problems with the electronics it is possible to switch back to the respectively simpler level. In the event of a computer failure, work can nevertheless be continued using a manual or emergency controller by direct activation of the hydraulic valves. The following control commands can be sent to the excavating machine via a remote controller: advancement, excavation width, material flow, various interventions into the automatic controller such as for example stop, start, etc. 
         [0038]    As shown in  FIG. 3 , the excavated earth of the old ballast  42  is removed by the excavating machine  10  via the conveyor belt  32  to a first transport carriage  48  from which cleaned ballast  44  is passed on to the silo  38  via the conveyor belt  34  and to the ballast silo  26  via the conveyor belt  36 . 
         [0039]    The first transport carriage  48  is equipped both with a tracked running gear  50  and with a rail running gear  52 . The excavated earth of the old ballast  42  is passed on via a cleaning unit  54  which is arranged in the carriage interior, in the region of one of the carriage ends, and from which the cleaned ballast  44  is returned via the conveyor belt  34 . The residual material, consisting of undersize particles and oversize particles, remains as excavated earth  49  in the first transport carriage  48 , which serves as an interim storage means, and is conveyed away from the cleaning unit  54  toward the more remote carriage end via a conveyor belt  56  spanning the bottom of the carriage. 
         [0040]    As soon as the first transport carriage  48  is filled with excavated earth  49  ( FIG. 4 ), the excavation is interrupted and the first transport carriage  48  returns, on the ballast bed  41  made of old ballast  42 , up to a second transport carriage  58  which is deposited at a free track end  57 . The excavated earth  49  is transferred from the first transport carriage  48  into the second transport carriage  58 , which is ready for use, via the conveyor belt  56 , which spans the bottom of the carriage, and a further conveyor belt  60  which is adjoined to said conveyor belt  56  ( FIG. 5 ). The emptied first transport carriage  48  subsequently returns back to the excavating machine  10 . 
         [0041]    In the case of the variant shown in  FIG. 6  of the removal of excavated earth  49  from first transport carriages  48 , a third transport carriage  62 , which corresponds to a first transport carriage  48  without a cleaning unit  54  but with a conveyor belt bottom  56 , is used as a shuttle between the first transport carriage  48 , which remains in the excavating machine  10 , and the second transport carriage  58 . In this shuffle mode, the excavating machine  10  can continuously convey at maximum power. 
         [0042]    The arrangement shown in  FIG. 7  is used when the ballast bed  41  made of old ballast  42  has to be removed within a total excavation and a new ballast bed having an underlay  64  made of geotextile or a geogrid, a first layer  66  made of sand  67  and a second layer  68  made of new ballast  44  has to be constructed. 
         [0043]    An excavating machine  10 ′ used for this purpose is substantially identical in its basic construction to the excavating machine  10  shown in  FIG. 1 , but does not have a ballast silo  26 . Furthermore, a second conveyor belt  35 , with a silo  37  which is arranged upstream for the transportation of sand  67 , is arranged parallel to the conveyor belt  36 , with a silo  38  which is arranged upstream for the transportation of new ballast  44 . 
         [0044]    A stand and ballast distributing machine  70 , which is substantially identical in its basic construction to the excavating machine  10 ′, is arranged downstream of the excavating machine  10 ′ in the working direction x. 
         [0045]    The sand and ballast distributing machine  70  has a movable base  72  with a tracked running gear  74  and a rail running gear  76 . A swivel tower  78  having a vertical swivel axis z protrudes from the movable base  72  perpendicularly to a notional bearing plane of the running gears  74 ,  76 . A swivel arm  80  is mounted on the swivel tower  78  so as to be able to rotate about the vertical swivel axis z. 
         [0046]    A ballast silo  82  and a sand silo  84  are arranged one after the other and offset from each other on the swivel arm  80 , the sand silo  84  being further removed from the swivel tower  78  than is the ballast silo  82 . Two silos  86 ,  88 , each having conveyor belts  90 ,  92  leading from the silos  86 ,  88  via the sand silo  84  or the ballast silo  82 , are also secured to the swivel tower  78 . In the region of their bottom-side ends, the sand silo  84  and the ballast silo  82  are equipped with compressors  85  and  83  respectively. 
         [0047]    The sand and ballast distributing machine  70  rests with its tracked running gear  74  on a newly constructed ballast bed consisting of an underlay made of geotextile or geogrid  64 , a first layer  66  made of sand  67  and a second layer  68  made of new ballast  44 . 
         [0048]    As may be seen from  FIG. 8 , a first transport carriage  94  for passing on sand and ballast is mounted upstream of the excavating machine  10 ′ in the working direction x. The first transport carriage  94  for passing on sand and ballast is equipped both with a tracked running gear  96  and with a rail running gear  98 . The first transport carriage  94  has a carriage bottom  100  with a first conveyor belt  101  spanning said carriage bottom for the interim storage of excavated material made of old ballast  42  and an intermediate bottom  102  which is arranged above the carriage bottom  100  and is in the form of two conveyor belts  104 ,  106 , which are guided in the carriage longitudinal direction parallel next to each other, for the interim storage of sand  67  and new ballast  44 . The height of the intermediate bottom  102  can be adjusted via hydraulic cylinders  108 . During the transfer on the rail from a ballast and sand loading site to a work site, the intermediate bottom  102  is lowered in order to keep the center of gravity S as low as possible ( FIG. 9 ). In working mode, the intermediate bottom  102  is raised to provide an interim storage space which is as large as possible for the excavated material ( FIG. 10 ). The excavated earth of the old ballast  42  is passed on by the excavating machine  10 ′ via the conveyor belt  32  onto the carriage bottom  100  or onto the conveyor belt  101  resting on the carriage bottom  100 . Sand  67  and new ballast are passed on from the intermediate bottom  102  of the first transport carriage  94  to the sand and ballast distributing machine  70  via further conveyor belts  110 ,  112  into the silos  37 ,  38  which are mounted upstream of the conveyor belts  35 ,  36 . 
         [0049]    The sand and ballast distributing machine  70 , the excavating machine  10 ′ and the first transport carriage  94  for passing on sand and ballast are moved during the working operation in synchronization and at the same speed in the working direction x. 
         [0050]    As soon as the first transport carriage  94  has been emptied of sand  67  and new ballast  44  and at the same time loaded with old ballast  42 , the excavation is interrupted and the carriage  94  returns, on the ballast bed  41  made of old ballast  42 , up to a second transport carriage  114 , which is deposited at a free track end  57 , for passing on sand and ballast. The excavated earth made of old ballast  42  is transferred from the first transport carriage  94  into the second transport carriage  114 , which is ready for use, via the conveyor belt  101  forming the carriage bottom  100  and a further conveyor belt  103  which is adjoined to said conveyor belt  101 . At the same time, sand  67  and new ballast  44  are transferred from the second transport carriage  114  into the first transport carriage  94 . The first transport carriage  94  subsequently returns, freshly loaded with sand  67  and new ballast  44 , back to the excavating machine  10 ′. 
         [0051]    In the case of the variant shown in  FIG. 11  of the removal of excavated earth into, and the passing-on of sand and new ballast from, the first transport carriage  94  for the passing-on of sand and ballast, a third transport carriage  116  is used as a shuttle between the first transport carriage  94 , which now remains in the excavating machine  10 ′, and the second transport carriage  114 . In this shuttle mode, the excavating machine  10 ′ can convey continuously at maximum power. 
       LIST OF REFERENCE NUMERALS 
       [0052]      10  Excavating machine 
         [0053]      12  Movable base 
         [0054]      14  Tracked running gear 
         [0055]      16  Rail running gear 
         [0056]      18  Swivel tower 
         [0057]      20  Swivel arm 
         [0058]      22  Feed screw 
         [0059]      23  Dozer blade 
         [0060]      24  Drive of  22   
         [0061]      25  Compressor 
         [0062]      26  Ballast silo 
         [0063]      28  Compressor 
         [0064]      30  Conveyor belt 
         [0065]      32  Conveyor belt 
         [0066]      34  Conveyor belt 
         [0067]      36  Conveyor belt 
         [0068]      37  Silo on  35   
         [0069]      38  Silo on  36   
         [0070]      39  Lifting cylinder on  20   
         [0071]      40  Drive and energy unit 
         [0072]      41  Ballast bed made of old ballast 
         [0073]      42  Old ballast 
         [0074]      43  Ballast bed made of cleaned ballast or new ballast 
         [0075]      44  Cleaned ballast or new ballast 
         [0076]      45  Ballast track formation 
         [0077]      46  Earth foundation 
         [0078]      47  Excavated track formation 
         [0079]      48  First transport carriage 
         [0080]      49  Excavated earth 
         [0081]      50  Tracked running gear 
         [0082]      52  Rail running gear 
         [0083]      54  Cleaning unit 
         [0084]      56  Conveyor belt as bottom of  48   
         [0085]      57  Free track end 
         [0086]      58  Second transport carriage 
         [0087]      60  Conveyor belt on  48   
         [0088]      62  Third transport carriage 
         [0089]      64  Underlay made of geotextile or geogrid 
         [0090]      66  Layer made of sand 
         [0091]      67  Sand 
         [0092]      68  Layer made of new ballast  44   
         [0093]      70  Ballast and sand distributing machine 
         [0094]      72  Movable base 
         [0095]      74  Tracked running gear 
         [0096]      76  Rail running gear 
         [0097]      78  Swivel tower 
         [0098]      80  Swivel arm 
         [0099]      82  Ballast silo 
         [0100]      84  Sand silo 
         [0101]      86  Silo 
         [0102]      88  Silo 
         [0103]      90  Conveyor belt 
         [0104]      92  Conveyor belt 
         [0105]      94  First transport carriage 
         [0106]      96  Tracked running gear 
         [0107]      98  Rail running gear 
         [0108]      100  Carriage bottom 
         [0109]      101  Conveyor belt 
         [0110]      102  Intermediate bottom 
         [0111]      103  Conveyor belt 
         [0112]      104  Conveyor belt 
         [0113]      106  Conveyor belt 
         [0114]      108  Hydraulic cylinder 
         [0115]      110  Conveyor belt 
         [0116]      112  Conveyor belt 
         [0117]      114  Second transport carriage 
         [0118]      116  Third transport carriage 
         [0119]      118  Angle gauge for the angle of rotation of z 
         [0120]      120  Angle gauge for the angle of rotation of y 
         [0121]      122  Computer unit 
         [0122]      124  Keyboard 
         [0123]      126  Floppy disk 
         [0124]    x Working direction 
         [0125]    S Center of gravity 
         [0126]    y Pitch axis 
         [0127]    z Vertical axis

Summary:
In a method for the continuous renewal of a ballast bed ( 41 ) of a track from which the rails and sleepers have been removed, by carrying away old ballast ( 42 ) and depositing cleaned ballast or new ballast ( 44 ) on the underlying surface ( 46 ) from which the old ballast ( 42 ) has been removed, a removal device ( 22 ) which can travel in the working direction (x) continuously picks up the old ballast ( 42 ) of the ballast bed ( 41 ). The excavated material is conveyed away from the excavation area and possibly passed on for ballast cleaning. At the same time, cleaned ballast or new ballast ( 44 ) is continuously deposited in the working direction (x) on the underlying surface ( 46 ) from which the old ballast ( 42 ) has been removed, to form a new ballast bed ( 43 ). The removal device ( 22 ), as part of an excavating machine ( 10 ) travelling in the working direction (x) on the old ballast bed ( 41 ), is arranged downstream of the running gear ( 14, 16 ) of the excavating machine ( 10 ).