Patent Publication Number: US-6668728-B2

Title: Machine for rehabilitating a track bed

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to machine for rehabilitating a track bed supporting a track comprising two rails, which comprises a machine frame supported on the track by undercarriages for movement along the track in an operating direction, the machine frame comprising machine frame parts being coupled together. 
     2. Description of the Prior Art 
     British patent No. 2,261,455 discloses a two-part machine for creating a protective layer on a subgrade. A coupling links a second machine frame part to a first machine frame part, and an undercarriage is arranged adjacent the coupling and is displaceable in a longitudinal direction of the machine frame to lengthen the track bed space from which the track has been lifted for performing the rehabilitation work. This space must be long enough to hold the bending curve of the lifted track rails within acceptable limits. 
     British patent No. 2,262,558 discloses another track bed rehabilitating machine comprising a machine frame whose ends are supported on the track by undercarriages. Two vertically adjustable crawler tractors are arranged at the front end of the machine frame to support the front end on the track bed while it is lifted with the track. 
     To lay a new track, French patent No. 2,538,525 proposes a machine having crawler tractors supporting a front end of the machine frame on the track bed while the rear machine frame end is supported by an undercarriage on the track. 
     SUMMARY OF THE INVENTION 
     It is a primary object of this invention to provide a machine for rehabilitating a track bed whose machine frame is supported on the track at its ends while providing an exceptionally long track bed space from which the track has been lifted for performing track bed rehabilitation work. 
     The above and other objects are accomplished according to the invention with a machine for rehabilitating a track bed supporting a track comprising two rails, which comprises a machine frame supported on the track by undercarriages for movement along the track in an operating direction, the machine frame comprising, in the operating direction, a first machine frame part, a second machine and a third machine frame part. A first coupling links the second machine frame part to the first machine frame part, a second coupling links the third machine frame part to the second machine frame part, and one of the undercarriages being arranged adjacent the first coupling. Two crawler tractors are spaced from each other in a direction extending transversely to the machine frame and connected to the second machine frame part, and drives connect the crawler tractors to the second machine frame part for vertically adjusting the crawler tractors. 
     Such a machine provides the possibility of substantially increasing the length of the track bed rehabilitation space at a minor increase in the construction costs. The two crawler tractors enable the second, central machine frame part to be supported on the subgrade subtending the track section limited by the two undercarriages supporting the machine frame ends on the track while this track section is lifted to a required height. Available machines with two-part machine frames may be readily retrofitted to insert a third machine frame part between the two machine frame parts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, advantages and features of the present invention will become more apparent from the following detailed description of a now preferred embodiment thereof, taken in conjunction with the accompanying drawing wherein 
     FIG. 1 shows a schematic side view of the machine; 
     FIG. 2 is an enlarged partial side view, showing some details of the machine; and 
     FIG. 3 is an enlarged end view showing the two crawler tractors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawing and more particularly to FIGS. 1 and 2, there is shown machine  1  for rehabilitating a track bed supporting track  10  comprising two rails  9 . The machine comprises a machine frame supported on track  10  by undercarriages  8  for movement along the track in an operating direction indicated by arrow  2 . The machine frame comprises, in the operating direction, first machine frame part  3 , second machine frame part  5  and third machine frame part  4 . First coupling  6  links second machine frame part  5  to first machine frame part  3 , and second coupling  7  links third machine frame part  4  to second machine frame part  5 . One undercarriage  8  is arranged adjacent first coupling  6 , and a second undercarriage  8  is arranged adjacent second coupling  7 , the second undercarriage comprising track lifting device  11  having means for engaging the track rails (see FIG.  2 ). 
     Two crawler tractors  12  are spaced from each other in a direction extending transversely to the machine frame and are connected to second machine frame part  5 , drives  13  connecting the crawler tractors to the second machine frame part for vertically adjusting the crawler tractors. The crawler tractors are driven by motor  15 . As shown in FIGS. 1 and 2, crawler tractors  12  are positioned at a rear half  14  of second machine frame part  5 , in the operating direction, preferably immediately in front of second undercarriage  8 , in the operating direction. 
     As best shown in FIG. 3, the two crawler tractors  12  are mounted on a common frame and may be spaced from each other a distance of at least 2.5 m in a direction extending transversely to the machine frame so that they may be positioned on subgrade  16  of the track bed at each side of the track. 
     Machine  1  may be operated in the following manner: 
     Supported on track  10  on all undercarriages  8 , the machine frame is driven to the operating site, with crawler tractors  12  lifted into the inoperative position by drives  13  (see phantom lines in FIG.  2 ). To provide a space  17  subtending track  10  for performing track bed rehabilition work, track rails  9  are clamped to track lifting device  11  and crawler tractors  12  are lowered onto subgrade  16 , which causes second coupling  7 , with undercarriage  8  adjacent thereto as well as the end portions of machine frame parts  5 ,  4 , to be raised, as shown in FIG.  2 . Track  10 , being clamped to undercarriage  8  by track lifting device  11 , is similarly raised to provide space  7  between subgrade  10  and raised track  10 . A further track lifting device  18  is mounted on third machine frame part  4  to assist in raising track  10  and maintain it in the raised position. If desired, working space  17  may be further lengthened if undercarriage  8  adjacent first coupling  6  is longitudinally displaceable and is forwardly displaced in the operating direction. 
     As soon as track  10  is raised to provide work space  17 , operating tools  19  may be introduced into the work space by lowering the operating tools onto subgrade  16 . The illustrated operating tools comprise mixing device  20  for mixing soil with lime and a planing and consolidating device  21 , following in the operating direction. However, any desired type of operating tools may be used, depending on the track bed rehabilitation work involved, such as an endless ballast excavating chain for removing ballast from the track bed. 
     An operator in operator&#39;s cab  22  mounted on second machine frame part  5  can operate crawler tractors  12 , to lower and raise the same, as well as to steer it in track curves so that it remains properly centered relative to the track.