Mobile arrangement and method for improving a track bed

A method of improving a track bed comprising a layer of ballast disposed on a subgrade by disposing a layer of a protective material between the subgrade and the ballast, which comprises the following successive steps:

• (a) detaching an assembled track section from the track while leaving the detached track section in place,
• (b) moving a first self-propelled vehicle in one direction over the detached assembled track section, the vehicle including
• (1) a frame having two ends,
• (2) a hoist mounted on the vehicle frame for lifting the detached assembled track section off the track bed whereby a trackless renewal section is created,
• (3) means mounted on the vehicle frame for conveying, discharging and distributing ballast and protective material,
• (4) the vehicle frame having a length bridging the trackless renewal section and respective track sections adjoining the trackless renewal section at respective ends thereof in the regions of the vehicle frame ends,
• (5) a triple-undercarriage arrangement supporting one end of the vehicle frame on one of the adjoining track sections and consisting of two on-track undercarriages and an off-track undercarriage, and
• (6) another undercarriage supporting the frame, the distance between the triple-undercarriage arrangement and the other undercarriage exceeding the length of the assembled track section,
• (c) operating the hoist to lift the detached assembled track section off the track bed and to create the trackless renewal section, and moving the vehicle further in said one direction over the trackless renewal section to the other adjoining track section by selective operation of the respective on- and off-track undercarriages,
• (d) moving a second self-propelled vehicle in the one direction over the trackless renewal section, the vehicle including
• (1) a frame having two ends, the one end of the frame of the first vehicle and one end of the frame of the second vehicle facing each other,
• (2) means mounted on the frame of the second vehicle for excavating the ballast and for conveying the excavated ballast, and
• (3) a triple-undercarriage arrangement supporting the one end of the frame of the second vehicle and consisting of two on-track undercarriages and an off-track undercarriage,
• (e) moving the second vehicle in the one direction over the trackless renewal section by selective operation of the respective on- and off-track undercarriages,
• (f) operating the excavating means to excavate the ballast and operating the conveying means to convey the excavated ballast away from the second vehicle to remove the ballast from the trackless renewal section while moving the second vehicle in the one direction to the one adjoining track section by selective operation of the respective on- and off-track undercarriages,
• (g) moving the first vehicle in a direction opposite to the one direction back over the trackless renewal section by selective operation of the respective on- and off-track undercarriages while operating the conveying, discharging and distributing means to convey, discharge and distribute protective particulate material over the subgrade in the trackless renewal section, and planing and compacting the distributed protective particulate material to provide the layer of protective material,
• (h) moving the first vehicle in the one direction over the trackless renewal section by selective operation of the respective on- and off-track undercarriages while operating the conveying, discharging and distributing means to convey, discharge and distribute ballast over the layer of protective material, and
• (i) moving the first vehicle again over the trackless renewal section and operating the hoist to lower the lifted detached assembled track section onto the ballast.