Mobile apparatus for the continuous replacement of ties

A mobile apparatus for the continuous replacement of ties of an old track section resting on a ballast bed by ties of a new track section, which comprises a train of a plurality of track-bound freight cars including a last freight car movable in a working direction over the old track section, old and new ties being stored on selected ones of the freight cars, a traveling gantry crane including means for gripping the ties, the gantry crane being movable on the train to and from respective ones of the freight cars, a work car having a front frame end, a pivot supporting the front frame end of the work car for pivoting about a vertical axis on the last freight car, devices mounted on the work car for removing the ties of the old track section and for laying the ties of the new track section, elongated conveyor means mounted on the work car for conveying the ties of the old track section from the tie removing device and the ties of the new track section to the tie laying device, and a tie transfer vehicle having front and rear gantry undercarriages, the undercarriages defining an axle distance therebetween, the front gantry undercarriage of the tie transfer vehicle being movable only on the last freight car and the rear gantry undercarriage of the tie transfer vehicle being movable only on the work car, the tie transfer vehicle including two tie gripping devices arranged successively in the working direction for simultaneously receiving the ties of the old track section and delivering the ties of the new track section while the ties are positioned transversely to the old track section.