Machine for rehabilitating a track bed

A machine for rehabilitating a track bed supporting a track comprising two rails, which comprises

• (a) a machine frame supported on the track by on-track undercarriages for movement along the track in an operating direction, the machine frame comprising, in the operating direction,
• (1) a first machine frame part having a free end supported on the track by one of the on-track undercarriages,
• (2) a second machine frame part and
• (3) a third machine frame part having a free end supported on the track by a second one of the on-track undercarriages,
• (b) a first coupling linking the second machine frame part to the first machine frame part at an end opposite the free end,
• (c) a second coupling linking the third machine frame part to the second machine frame part at an end opposite the free end,
• (d) a third one of the on-track undercarriages being arranged adjacent the first coupling,
• (e) two crawler tractors spaced from each ocher in a direction extending transversely to the machine frame and connected to the second machine frame part, and
• (f) drives connecting the crawler tractors to the second machine frame part for vertically adjusting the crawler tractors,
• (g) a track lifting device having means for engaging the track rails, and
• (h) operating tools for rehabilitating the track bed in a work space under a section of the track lifted by the track lifting device.